Environmental Toxic Heavy Metal Pollution and Possible Remediating Techniques

**3**

potential [1].

**Chapter 1**

**Abstract**

*Mustafa Ertan Akün*

factors, and recommendations.

**1. Introduction**

Heavy Metal Contamination and

Remediation of Water and Soil

with Case Studies From Cyprus

Some of the heavy metals, (arsenic, cadmium, chromium and nickel) tend to endanger public health, when found above critical limits in soil and water, becoming carcinogenic. The heavy metals are taken by humans through the food chain. As shown by numerous researchers all over the world, the heavy metal contamination mostly come from sewage waters and pesticides, as well as naturally. The natural resources come from the composition of the rock formations present at the area of study. One or all of the above mentioned sources of heavy metal contamination may be present. The study concentrates on the internationally accepted critical limits for soil and water, explains scientific methods of entering into vegetables and fruit, and also tries to shed light on the transfer factors of heavy metals imposing dangers on public health. Remediation of the contaminated soil and water is also discussed, and phytoremediation methods are brought forward, as compared with chemical methods. Details of different phytoremediation (phyto-accumulation, phyto-stabilization, phyto-degradation, phyto-volatilization, and hydraulic control) are also discussed. Actual case studies from North Cyprus are also provided, with real contamination levels observed. Different areas and soil/water/plant species were assessed in detail, displaying concentrations, critical limits, transfer

**Keywords:** heavy metal, contamination, soil, water, critical limit, public health

Public health necessitates concentrated efforts of researchers and public authorities and will be under risk if necessary and timely precautions are not undertaken. Soil and groundwaters are inputs for vegetables and fruits and thus animals and mankind as a whole. Sometimes, the sources of heavy metal contamination could as well be airborne. In certain cases, biomonitoring of airborne heavy metal contamination has been an important issue and has been carried out worldwide. Accordingly, during the last few decades, heavy metal contamination of biotic component of environment has attracted the attention of researchers. In this respect, biological materials were used as cheap indicators to determine airborne environmental pollution. Various types of plants (such as lichens, mosses, bark, and leaves of higher plants) were used to detect deposition, accumulation, and distribution of metal pollution and their accumulative

#### **Chapter 1**

## Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus

*Mustafa Ertan Akün*

#### **Abstract**

Some of the heavy metals, (arsenic, cadmium, chromium and nickel) tend to endanger public health, when found above critical limits in soil and water, becoming carcinogenic. The heavy metals are taken by humans through the food chain. As shown by numerous researchers all over the world, the heavy metal contamination mostly come from sewage waters and pesticides, as well as naturally. The natural resources come from the composition of the rock formations present at the area of study. One or all of the above mentioned sources of heavy metal contamination may be present. The study concentrates on the internationally accepted critical limits for soil and water, explains scientific methods of entering into vegetables and fruit, and also tries to shed light on the transfer factors of heavy metals imposing dangers on public health. Remediation of the contaminated soil and water is also discussed, and phytoremediation methods are brought forward, as compared with chemical methods. Details of different phytoremediation (phyto-accumulation, phyto-stabilization, phyto-degradation, phyto-volatilization, and hydraulic control) are also discussed. Actual case studies from North Cyprus are also provided, with real contamination levels observed. Different areas and soil/water/plant species were assessed in detail, displaying concentrations, critical limits, transfer factors, and recommendations.

**Keywords:** heavy metal, contamination, soil, water, critical limit, public health

#### **1. Introduction**

Public health necessitates concentrated efforts of researchers and public authorities and will be under risk if necessary and timely precautions are not undertaken. Soil and groundwaters are inputs for vegetables and fruits and thus animals and mankind as a whole. Sometimes, the sources of heavy metal contamination could as well be airborne. In certain cases, biomonitoring of airborne heavy metal contamination has been an important issue and has been carried out worldwide. Accordingly, during the last few decades, heavy metal contamination of biotic component of environment has attracted the attention of researchers. In this respect, biological materials were used as cheap indicators to determine airborne environmental pollution. Various types of plants (such as lichens, mosses, bark, and leaves of higher plants) were used to detect deposition, accumulation, and distribution of metal pollution and their accumulative potential [1].

Not only are the heavy metals carcinogenic, but many other diseases such as lung, liver, kidney, and similar diseases are also potential occurrences. Arsenic, cadmium, chromium, and nickel are accepted as group 1 carcinogens by the International Agency for Research on Cancer, and these heavy metals are at the same time utilized commercially [2]. Some other heavy metals are also carcinogenic in nature, and a relevant study listed cobalt, lead, and mercury in addition [3].

Although some of the heavy metals are known to be enhancing the immune system, the same heavy metals above critical limits and some others are hazardous heavy metals for human beings. The critical limits of heavy metals in soil and water are not only different, but they also differ from country to country. Although natural occurrences in different countries and the methods for contamination are the background reasons for this, it is at the same time dependent on the policy makers. Apart from the countries' legislations, some international organizations like the Environmental Protection Agency (EPA) and Food and Agriculture Organization (FAO) also announce and revise these limits periodically. **Table 1** shows critical limits for soils for different countries.

Critical limits of the EPA for water are given below in **Table 2**. The table explains maximum allowable contaminant levels for a wide range of chemicals, either carcinogen or resulting in different health problems.

Numerous researches arrived at scientific findings about the carcinogenic nature of some of the heavy metals and elements. Although not definite and including probability of being a carcinogen, studies reveal the imposed dangers involved, hinting precautions to be taken. Accordingly, the EPA has prepared specific results and cancer descriptors with relevant definitions. **Table 3** below explains cancer descriptors for certain elements.

The heavy metals and carcinogen elements enter the human body via the food chain. The food chain is the mechanism showing the route of heavy metals from soils and waters finally reaching plants, animals, and humans. **Figure 1** shows the journey of heavy metals via food chain.

Thus, public health necessitates to minimize the intake of hazardous heavy metals and elements and if possible to null the amounts. To render this possible, the methodologies by which these metals and elements enter the food chain must be understood correctly, and relevant precautions must be taken.


**5**

*Source: [5].*

**Table 2.**

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

**Chemicals Maximum contaminant level (mg/L) Cancer descriptor** Ammonia — D Antimony 0.006 D Arsenic 010 A Asbestos 7 MFL A Barium 2 N Beryllium 0.004 — Boron — I Bromate 0.01 B2 Cadmium 0.005 D Chloramine3 4<sup>4</sup> — Chlorine 4<sup>4</sup> D Chlorine dioxide 0.84 D Chlorite 1 D Chromium 0.1 D Copper TT6 D Cyanide 0.2 I Fluoride 4 — Lead TT6 B2 Manganese — D Mercury 0.002 D Molybdenum — D Nickel — — Nitrate 10 — Nitrite 1 — Nitrate + Nitrite 10 — Perchlorate2 — L/N Selenium 0.05 D Silver — D Strontium — D Thallium 0.002 I White phosphorous — D

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

Zinc —

*Standards of heavy metals in water and health advisories.*

B Probable human carcinogen B1 Indicates limited human evidence

C Possible human carcinogen

B2 Indicates sufficient evidence in animals and inadequate or no evidence in humans

**Descriptor Definition** A Human carcinogen

#### **Table 1.**

*Regulatory standard of heavy metals in agricultural soil (mg/kg).*


*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

#### **Table 2.**

*Heavy Metal Toxicity in Public Health*

limits for soils for different countries.

descriptors for certain elements.

journey of heavy metals via food chain.

carcinogen or resulting in different health problems.

addition [3].

Not only are the heavy metals carcinogenic, but many other diseases such as lung, liver, kidney, and similar diseases are also potential occurrences. Arsenic, cadmium, chromium, and nickel are accepted as group 1 carcinogens by the International Agency for Research on Cancer, and these heavy metals are at the same time utilized commercially [2]. Some other heavy metals are also carcinogenic in nature, and a relevant study listed cobalt, lead, and mercury in

Although some of the heavy metals are known to be enhancing the immune system, the same heavy metals above critical limits and some others are hazardous heavy metals for human beings. The critical limits of heavy metals in soil and water are not only different, but they also differ from country to country. Although natural occurrences in different countries and the methods for contamination are the background reasons for this, it is at the same time dependent on the policy makers. Apart from the countries' legislations, some international organizations like the Environmental Protection Agency (EPA) and Food and Agriculture Organization (FAO) also announce and revise these limits periodically. **Table 1** shows critical

Critical limits of the EPA for water are given below in **Table 2**. The table explains

Numerous researches arrived at scientific findings about the carcinogenic nature

The heavy metals and carcinogen elements enter the human body via the food chain. The food chain is the mechanism showing the route of heavy metals from soils and waters finally reaching plants, animals, and humans. **Figure 1** shows the

Thus, public health necessitates to minimize the intake of hazardous heavy metals and elements and if possible to null the amounts. To render this possible, the methodologies by which these metals and elements enter the food chain must be

**Country As Cd Cr Cu Hg Ni Pb Zn** Australia 20 3 50 100 1 60 300 200 Canada 20 3 250 150 0.8 100 200 500 China 20–40 0.3–0.6 150–300 50–200 0.3–1.0 40–60 80 200–300 Germany 50 5 500 200 5 200 1000 600 Tanzania 1 1 100 200 2 100 200 150 Holland 76 13 180 190 36 100 530 720 NZ 17 3 290 >104 200 N/A 160 N/A UK 43 1.8 N/A N/A 26 230 N/A N/A USA 0.11 0.48 11 270 1 72 200 1100

understood correctly, and relevant precautions must be taken.

*Regulatory standard of heavy metals in agricultural soil (mg/kg).*

maximum allowable contaminant levels for a wide range of chemicals, either

of some of the heavy metals and elements. Although not definite and including probability of being a carcinogen, studies reveal the imposed dangers involved, hinting precautions to be taken. Accordingly, the EPA has prepared specific results and cancer descriptors with relevant definitions. **Table 3** below explains cancer

**4**

*Source: [4].*

**Table 1.**

*Standards of heavy metals in water and health advisories.*



#### **Table 3.**

*Cancer descriptors.*

**Figure 1.**

*Journey of heavy metals via food chain.*

#### **2. Soil and water contamination and remediation/precautions**

There are numerous sources of heavy metal contamination of soils and water. These are briefly explained below:


**7**

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

levels of spinach [7] following the application of pesticides (DELVAP 1000 EC) displayed that the concentrations before and after the pesticide application changed significantly. The application of pesticides also contaminates the soil in the surrounding, and the included heavy metals may also reach the

c.*Natural resources*: This is a natural activity. Many elements and heavy metals can be naturally present in the surrounding, and erosion of these rock formations including such elements and heavy metals can be transformed into soil. Downward percolation of rain waters may as well result in the arrival of such to groundwaters. A related research forwards that under different and certain environmental conditions, natural emissions of heavy metals occur that may in turn lead to the release of metals from their endemic spheres to different

The remediation methodologies can be chemical or biological in nature. Since heavy metal contamination itself is a chemical process, chemical remediation should be avoided, and biological processes should be introduced. The phytoremediation of heavy metals from the contaminated sites generally happens through any one or more of the following mechanisms or processes [9]: "phyto-accumulation," "phyto-stabilization," "phyto-degradation," "phyto-volatilization," and "hydraulic

Phyto-accumulation is a mechanism through which heavy metals in soil and

In this mechanism, bio-concentration factor (BCF) and biological absorption coefficient (BAC) are also important parameters to be considered. According to the international guidelines, "bioaccumulation" is the process where chemical concentration in an aquatic organism reaches a level that exceeds that in the water as a result of chemical uptake through all routes of chemical exposure. Bioaccumulation takes place under field conditions and is a combination of chemical bio-concentra-

On the other hand, metal accumulation is expressed by the metal biological absorption coefficient (BAC) or the plant-to-soil/water metal concentration ratio. Bio-concentration factors are used to relate pollutant residues in aquatic organisms to the pollutant concentration in ambient waters. Many chemical compounds, especially those with a hydrophobic component, partition easily into the lipids and

water at a specific region are accumulated in native plants and are disposed thereafter. In a research carried out in Pakistan [10], heavy metal accumulation in crops and soils from wastewater irrigation was realized via the usage of *Cannabis sativa* L., *Chenopodium album* L., *Datura stramonium* L., *Sonchus asper* L., *Amaranthus viridis* L., *Oenothera rosea* (LHer), *Xanthium stramonium* L., Polygonum macalosa L., *Nasturtium officinale* L., and *Conyza canadensis* L. Metal concentrations are in the order iron (Fe) > zinc (Zn) > chromium (Cr) > nickel (Ni) > cadmium (Cd). Most of the species accumulated more heavy metals in roots than shoots. Among species, the concentrations were in the order *C. sativa* > *C. album* > *X. stramonium* > *C. canadensis* > *A. viridis* > *N. offici-*

*nale* > *P. macalosa* > *D. stramonium* > *S. asper* > *O. rosea*.

lipid membranes of organisms and bioaccumulate.

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

environment compartments [8].

groundwaters.

**2.1 Types of remediation**

*2.1.1 Phyto-accumulation*

tion and biomagnification.

control."

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

levels of spinach [7] following the application of pesticides (DELVAP 1000 EC) displayed that the concentrations before and after the pesticide application changed significantly. The application of pesticides also contaminates the soil in the surrounding, and the included heavy metals may also reach the groundwaters.

c.*Natural resources*: This is a natural activity. Many elements and heavy metals can be naturally present in the surrounding, and erosion of these rock formations including such elements and heavy metals can be transformed into soil. Downward percolation of rain waters may as well result in the arrival of such to groundwaters. A related research forwards that under different and certain environmental conditions, natural emissions of heavy metals occur that may in turn lead to the release of metals from their endemic spheres to different environment compartments [8].

#### **2.1 Types of remediation**

*Heavy Metal Toxicity in Public Health*

**Descriptor Definition**

H Carcinogenic to humans

L Likely to be carcinogenic to humans N Not likely to be carcinogenic to humans

D Not classifiable as to human carcinogenicity E Evidence of non-carcinogenicity for humans

S Suggestive evidence of carcinogenic potential

I Inadequate information to assess carcinogenic potential

L/N Likely to be carcinogenic above a specified dose but not likely to be carcinogenic below

that dose because a key event in tumor formation does not occur below that dose

**2. Soil and water contamination and remediation/precautions**

These are briefly explained below:

*Journey of heavy metals via food chain.*

soils and groundwaters.

There are numerous sources of heavy metal contamination of soils and water.

a.*Sewage waters*: This is an anthropogenic activity. The sewage waters are those collected via municipal, agricultural, and industrial origin [6]. The potential heavy metal inclusions from these sources are normally collected at treatment plants. Treatment results are never theoretically 100% efficient, and following the treatment process, disposed water is mostly utilized in irrigation of agricultural areas. The irrigation process then transfers the heavy metal content to

b.*Pesticides*: This is an anthropogenic activity. Many plants (vegetables, fruits, and trees) are under the attack of certain pests and are not only decreasing the quality of the products but also contaminating them with heavy metals, due to the presence of such. The research carried out on the heavy metal

**6**

**Figure 1.**

*Source: [5].*

**Table 3.** *Cancer descriptors.*

> The remediation methodologies can be chemical or biological in nature. Since heavy metal contamination itself is a chemical process, chemical remediation should be avoided, and biological processes should be introduced. The phytoremediation of heavy metals from the contaminated sites generally happens through any one or more of the following mechanisms or processes [9]: "phyto-accumulation," "phyto-stabilization," "phyto-degradation," "phyto-volatilization," and "hydraulic control."

#### *2.1.1 Phyto-accumulation*

Phyto-accumulation is a mechanism through which heavy metals in soil and water at a specific region are accumulated in native plants and are disposed thereafter. In a research carried out in Pakistan [10], heavy metal accumulation in crops and soils from wastewater irrigation was realized via the usage of *Cannabis sativa* L., *Chenopodium album* L., *Datura stramonium* L., *Sonchus asper* L., *Amaranthus viridis* L., *Oenothera rosea* (LHer), *Xanthium stramonium* L., Polygonum macalosa L., *Nasturtium officinale* L., and *Conyza canadensis* L. Metal concentrations are in the order iron (Fe) > zinc (Zn) > chromium (Cr) > nickel (Ni) > cadmium (Cd). Most of the species accumulated more heavy metals in roots than shoots. Among species, the concentrations were in the order *C. sativa* > *C. album* > *X. stramonium* > *C. canadensis* > *A. viridis* > *N. officinale* > *P. macalosa* > *D. stramonium* > *S. asper* > *O. rosea*.

In this mechanism, bio-concentration factor (BCF) and biological absorption coefficient (BAC) are also important parameters to be considered. According to the international guidelines, "bioaccumulation" is the process where chemical concentration in an aquatic organism reaches a level that exceeds that in the water as a result of chemical uptake through all routes of chemical exposure. Bioaccumulation takes place under field conditions and is a combination of chemical bio-concentration and biomagnification.

On the other hand, metal accumulation is expressed by the metal biological absorption coefficient (BAC) or the plant-to-soil/water metal concentration ratio. Bio-concentration factors are used to relate pollutant residues in aquatic organisms to the pollutant concentration in ambient waters. Many chemical compounds, especially those with a hydrophobic component, partition easily into the lipids and lipid membranes of organisms and bioaccumulate.

BCF and BAC are described by the following formulas:

$$\text{BCF} = \text{CB/CVMD} = \text{k1/(k2 + kE + kM + kG)} \tag{1}$$

$$\text{BAC} = \text{CB/CND} = \{\text{k1} + \text{kD (CB/CND)}\} / (\text{k2} + \text{kE} + \text{kM} + \text{kG}) \tag{2}$$

where CB is the chemical concentration in the organism (g/kg<sup>−</sup><sup>1</sup> ), k1 is the chemical uptake rate constant from the water at the respiratory surface (L·kg<sup>−</sup><sup>1</sup> ·d<sup>−</sup><sup>1</sup> ), CWD is the freely dissolved chemical concentration in the water (g·L<sup>−</sup><sup>1</sup> ), kD is the uptake rate constant for chemical in the diet (kg × kg<sup>−</sup><sup>1</sup> × d<sup>−</sup><sup>1</sup> ), and k2, kE, kM, and kG are rate constants (d<sup>−</sup><sup>1</sup> ) representing chemical elimination from the organism via the respiratory surface, fecal egestion, metabolic biotransformation, and growth dilution, respectively.

Phyto-accumulation for arsenic was adopted in India and Bangladesh by utilizing two different plant species, namely, *Pteris vittata* and *Chrysopogon zizanioides.* Laboratory scale studies gave way to observations regarding growth of these plants in different concentrations of 10–50 mg As/kg soil. Arsenic accumulation in leaves, stem, and root were analyzed at different time intervals, observing survival of plants. Results were encouraging, and it was observed that they could accumulate significant amounts of arsenic [11].

#### *2.1.2 Phyto-stabilization*

Phyto-stabilization comprises the establishment of a plant cover on the surface of the contaminated sites for reducing the mobility of contaminants within the vadose zone via accumulation by roots or immobilization within the rhizosphere, reducing off-site contamination [12]. The process includes transpiration and root growth that immobilizes contaminants by reducing leaching, controlling erosion, creating an aerobic environment in the root zone, and adding organic matter to the substrate that binds the contaminant.

Microbial activity related with the plant roots may accelerate the degradation of organic contaminants such as pesticides and hydrocarbons to nontoxic forms. Phyto-stabilization can be enhanced by using soil amendments that immobilize metal(loid)s combined with plant species that are tolerant of high levels of contaminants and low-fertility soils or tailings. Although effective in the containment of metal(loid)s, the site requires regular monitoring to ensure that the stabilizing conditions are maintained. Soil amendments used to enhance immobilization may need to be periodically reapplied to maintain their effectiveness.

#### *2.1.3 Phyto-degradation*

Phyto-degradation, which is also known as phyto-transformation, is the breakdown of contaminants taken up by plants through metabolic processes within the plant or the breakdown of contaminants surrounding the plant through the effect of enzymes produced by the plants. Plants are able to produce enzymes that catalyze and accelerate degradation. Hence, organic pollutants are broken down into simpler molecular forms and are incorporated into plant tissues to aid plant growth.

**Figure 2** shows the degradation process. Enzymes in plant roots break down (degrade) organic contaminants. The fragments are incorporated into new plant material.

A relevant research [13] put forth that the phyto-degradation of organic compounds can take place inside the plant or within the rhizosphere of the plant.

**9**

**Figure 3.**

*Direct and indirect phyto-volatilization.*

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

Many different compounds and compound classes can be removed from the environment by phyto-degradation, including solvents in groundwater, petroleum and aromatic compounds in soils, and volatile compounds in the air. Although currently a relatively new area of research, studies regarding the underlying science necessary for a wide range of applications for plant-based remediation of organic contami-

Phyto-volatilization is a process where plants take up contaminants from soil and release them as volatile form into the atmosphere via transpiration. The process

It is possible for plants to interact with a variety of organic compounds and affect the fate and transport of many environmental contaminants. Volatile organic compounds may be volatilized from stems or leaves (direct phyto-volatilization) or from soil due to plant root activities (indirect phyto-volatilization) [14]. Fluxes of contaminants volatilizing from plants range from local contaminant spills to global fluxes of methane emanating biochemically reducing organic carbon. In this article past studies are reviewed to differentiate between direct and indirect phytovolatilization. Findings of the study revealed that compounds with low octanol-air partitioning coefficients are more likely to be phyto-volatilized. Reports of direct phyto-volatilization compared favorably to model predictions. **Figure 3** represents

occurs as growing plants absorb water and organic contaminants.

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

nants are continuing.

**Figure 2.**

*Degradation process.*

*2.1.4 Phyto-volatilization*

direct and indirect phyto-volatilization.

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

**Figure 2.** *Degradation process.*

*Heavy Metal Toxicity in Public Health*

kG are rate constants (d<sup>−</sup><sup>1</sup>

significant amounts of arsenic [11].

substrate that binds the contaminant.

dilution, respectively.

*2.1.2 Phyto-stabilization*

*2.1.3 Phyto-degradation*

BCF and BAC are described by the following formulas:

BAC = CB/CWD = {k1 + kD (CB/CWD)}/

uptake rate constant for chemical in the diet (kg × kg<sup>−</sup><sup>1</sup>

BCF = CB/CWD = k1/

where CB is the chemical concentration in the organism (g/kg<sup>−</sup><sup>1</sup>

CWD is the freely dissolved chemical concentration in the water (g·L<sup>−</sup><sup>1</sup>

chemical uptake rate constant from the water at the respiratory surface (L·kg<sup>−</sup><sup>1</sup>

via the respiratory surface, fecal egestion, metabolic biotransformation, and growth

Phyto-accumulation for arsenic was adopted in India and Bangladesh by utilizing two different plant species, namely, *Pteris vittata* and *Chrysopogon zizanioides.* Laboratory scale studies gave way to observations regarding growth of these plants in different concentrations of 10–50 mg As/kg soil. Arsenic accumulation in leaves, stem, and root were analyzed at different time intervals, observing survival of plants. Results were encouraging, and it was observed that they could accumulate

Phyto-stabilization comprises the establishment of a plant cover on the surface of the contaminated sites for reducing the mobility of contaminants within the vadose zone via accumulation by roots or immobilization within the rhizosphere, reducing off-site contamination [12]. The process includes transpiration and root growth that immobilizes contaminants by reducing leaching, controlling erosion, creating an aerobic environment in the root zone, and adding organic matter to the

Microbial activity related with the plant roots may accelerate the degradation of organic contaminants such as pesticides and hydrocarbons to nontoxic forms. Phyto-stabilization can be enhanced by using soil amendments that immobilize metal(loid)s combined with plant species that are tolerant of high levels of contaminants and low-fertility soils or tailings. Although effective in the containment of metal(loid)s, the site requires regular monitoring to ensure that the stabilizing conditions are maintained. Soil amendments used to enhance immobilization may

Phyto-degradation, which is also known as phyto-transformation, is the breakdown of contaminants taken up by plants through metabolic processes within the plant or the breakdown of contaminants surrounding the plant through the effect of enzymes produced by the plants. Plants are able to produce enzymes that catalyze and accelerate degradation. Hence, organic pollutants are broken down into simpler

molecular forms and are incorporated into plant tissues to aid plant growth. **Figure 2** shows the degradation process. Enzymes in plant roots break down (degrade) organic contaminants. The fragments are incorporated into new plant

A relevant research [13] put forth that the phyto-degradation of organic compounds can take place inside the plant or within the rhizosphere of the plant.

need to be periodically reapplied to maintain their effectiveness.

(k2 + kE + kM + kG) (1)

× d<sup>−</sup><sup>1</sup>

) representing chemical elimination from the organism

(k2 + kE + kM + kG) (2)

), k1 is the

), and k2, kE, kM, and

·d<sup>−</sup><sup>1</sup> ),

), kD is the

**8**

material.

Many different compounds and compound classes can be removed from the environment by phyto-degradation, including solvents in groundwater, petroleum and aromatic compounds in soils, and volatile compounds in the air. Although currently a relatively new area of research, studies regarding the underlying science necessary for a wide range of applications for plant-based remediation of organic contaminants are continuing.

#### *2.1.4 Phyto-volatilization*

Phyto-volatilization is a process where plants take up contaminants from soil and release them as volatile form into the atmosphere via transpiration. The process occurs as growing plants absorb water and organic contaminants.

It is possible for plants to interact with a variety of organic compounds and affect the fate and transport of many environmental contaminants. Volatile organic compounds may be volatilized from stems or leaves (direct phyto-volatilization) or from soil due to plant root activities (indirect phyto-volatilization) [14]. Fluxes of contaminants volatilizing from plants range from local contaminant spills to global fluxes of methane emanating biochemically reducing organic carbon. In this article past studies are reviewed to differentiate between direct and indirect phytovolatilization. Findings of the study revealed that compounds with low octanol-air partitioning coefficients are more likely to be phyto-volatilized. Reports of direct phyto-volatilization compared favorably to model predictions. **Figure 3** represents direct and indirect phyto-volatilization.

**Figure 3.** *Direct and indirect phyto-volatilization.*

#### *2.1.5 Hydraulic control*

Hydraulic control is the method of phytoremediation, where the contaminated aqueous medium's flow direction is altered and contaminated flow is oriented. The relevant research study [15] designed such a system at the field.

The goal of this hydraulic capture model for remediation purposes was to design a well field so that the groundwater flow direction was altered. In so doing, halting or reversing the migration of a contaminant plume was made possible. Management strategies typically require a well design that will contain or shrink a plume at minimum cost. Objective functions and constraints can be nonlinear, non-convex, non-differentiable, or even discontinuous. Computational efficiency and accuracy is normally desirable and often affects the solution method.

#### **2.2 Precautions against soil and water contamination**

The precautions against contamination also differ according to the sources of contamination.

Accordingly, the precautions according to the sources are provided below:


**11**

*Source: [18]*

**Table 4.**

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

limits [16]. At some instances, it may become must to apply the pesticide, and under such circumstances, the adequate dose must be applied by expert

c.*Natural resources*: Just like the areas polluted by anthropogenic activities, in case of natural occurrence of heavy metals also, bioremediation can be an effective precaution. A relevant research titled "**Heavy Metal Polluted Soils: Effect on Plants and Bioremediation Methods**" in 2014 applied bioremediation and analyzed the results [17]. Microorganisms and plants employ different mechanisms for the bioremediation of polluted soils. Using plants for the treatment of polluted soils is a more common approach in the bioremediation of heavy metal polluted soils. Combining both microorganisms and plants is an approach to bioremediation that ensures a more efficient cleanup of heavy metal polluted soils. However, success of this approach largely depends on the

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

species of organisms involved in the process.

**3. Case studies of soil and water contamination from Cyprus**

Selected locations in Cyprus were investigated by the Cancer Research Fund and Frederick Institute of Technology in search of distribution of heavy metals. The collaborative research investigated for lead, arsenic, and cadmium [18]. The observations of cancer incidents triggered the research all over the island, and the findings displayed contamination at certain areas. To achieve an analytical distribution, 260 composite soil samples (140 from North Cyprus and 120 from South Cyprus) were investigated for the presence of heavy metal contamination. The soil samples were obtained from Güzelyurt Bostancı, Yuvacık, Lefkoşa, Karpaz, Alevkayası, Kırnı, and Mesarya in North Cyprus. The concentration of lead in these areas ranged between 8 and 45 ppm, while that of arsenic ranged between 8 and 15 ppm and that of cadmium ranged between 0 and 0.7 ppm. These findings

In South Cyprus, the soil samples were obtained from Dali, Sotira, Omodos, Acheleia, Polis, and Evrychou. The concentration of lead in these areas ranged between 6 and 53 ppm, while that of arsenic ranged between 6 and 19 ppm and that

**Area Pb (ppm) As (ppm) Cd (ppm)** Alevkayası 32.58 11.25 0.34 Lefkoşa 44.29 11.87 0.69 Kırnı 40.51 14.63 0.47 Yuvacık 32.42 8.98 0.34 Bostancı 8.02 9.47 0.2 Mesarya 12.6 11.09 0.33 Karpaz 17.19 13.56 0.3

of cadmium ranged between 0 and 0.4 ppm, given below in **Table 5**.

*Distribution of lead, arsenic, and cadmium in North Cyprus.*

**3.1 Arsenic, cadmium, and lead distribution of Cyprus soils**

personnel.

are given in **Table 4**.

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

limits [16]. At some instances, it may become must to apply the pesticide, and under such circumstances, the adequate dose must be applied by expert personnel.

c.*Natural resources*: Just like the areas polluted by anthropogenic activities, in case of natural occurrence of heavy metals also, bioremediation can be an effective precaution. A relevant research titled "**Heavy Metal Polluted Soils: Effect on Plants and Bioremediation Methods**" in 2014 applied bioremediation and analyzed the results [17]. Microorganisms and plants employ different mechanisms for the bioremediation of polluted soils. Using plants for the treatment of polluted soils is a more common approach in the bioremediation of heavy metal polluted soils. Combining both microorganisms and plants is an approach to bioremediation that ensures a more efficient cleanup of heavy metal polluted soils. However, success of this approach largely depends on the species of organisms involved in the process.

#### **3. Case studies of soil and water contamination from Cyprus**

#### **3.1 Arsenic, cadmium, and lead distribution of Cyprus soils**

Selected locations in Cyprus were investigated by the Cancer Research Fund and Frederick Institute of Technology in search of distribution of heavy metals. The collaborative research investigated for lead, arsenic, and cadmium [18]. The observations of cancer incidents triggered the research all over the island, and the findings displayed contamination at certain areas. To achieve an analytical distribution, 260 composite soil samples (140 from North Cyprus and 120 from South Cyprus) were investigated for the presence of heavy metal contamination. The soil samples were obtained from Güzelyurt Bostancı, Yuvacık, Lefkoşa, Karpaz, Alevkayası, Kırnı, and Mesarya in North Cyprus. The concentration of lead in these areas ranged between 8 and 45 ppm, while that of arsenic ranged between 8 and 15 ppm and that of cadmium ranged between 0 and 0.7 ppm. These findings are given in **Table 4**.

In South Cyprus, the soil samples were obtained from Dali, Sotira, Omodos, Acheleia, Polis, and Evrychou. The concentration of lead in these areas ranged between 6 and 53 ppm, while that of arsenic ranged between 6 and 19 ppm and that of cadmium ranged between 0 and 0.4 ppm, given below in **Table 5**.


#### **Table 4.**

*Distribution of lead, arsenic, and cadmium in North Cyprus.*

*Heavy Metal Toxicity in Public Health*

Hydraulic control is the method of phytoremediation, where the contaminated aqueous medium's flow direction is altered and contaminated flow is oriented. The

The goal of this hydraulic capture model for remediation purposes was to design a well field so that the groundwater flow direction was altered. In so doing, halting or reversing the migration of a contaminant plume was made possible. Management strategies typically require a well design that will contain or shrink a plume at minimum cost. Objective functions and constraints can be nonlinear, non-convex, non-differentiable, or even discontinuous. Computational efficiency and accuracy

The precautions against contamination also differ according to the sources of

a.*Sewage waters*: The *municipal* sewage waters are those connected from houses at inhabited areas. Hazardous elements and heavy metals may enter the system from any location by any liquid or solid. The inhabitants must be trained about the disposal system at the start point to minimize their entrance into the system. Frequent analysis of input and output at the treatment plant must be carried out; methods of minimizing contamination levels must be employed; and output containing hazardous elements and heavy metals with lower than critical limits must be used for irrigation purposes. The *agricultural* sewage waters are those collected at the farms and greenhouses used for cleaning purposes. These may from time to time include disposed plant parts, some soil, and some fertilizers. Thus, probability of presence of hazardous elements and heavy metals is quite high, and serious precautions are necessary. These are also entering the treatment plants, and like municipal sewage waters, the relevant people must again be trained about the disposal system at the start point to minimize their entrance into the system. Frequent analysis of input and output at the treatment plant must again be carried out; methods of minimizing contamination levels must be employed; and output containing hazardous elements and heavy metals with lower than critical limits must be used for irrigation purposes. The most dangerous of the types of sewage waters is definitely *industrial* sewage waters. This group includes slaughterhouse waste, whey of milk processing factories, paint factory waste, animal breeding waste, and similar factory wastes. These also enter treatment plants, and again frequent input and output sewage analysis is required. The relevant people must again be trained about the disposal system to minimize their entrance

b.*Pesticides*: Though the application of pesticides is connected with the quality of the agricultural products, the included heavy metals are in fact decreasing the quality and reliability. In many countries, many pesticide types are banned in conformance with the technological advancements and information regarding heavy metals. A study carried out in Nigeria showed the presence of heavy metals (Pb, As, Cd, Cr, and Zn) in different parts of the plants and at different concentrations, with some above the WHO/FAO permissible

Accordingly, the precautions according to the sources are provided below:

relevant research study [15] designed such a system at the field.

is normally desirable and often affects the solution method.

**2.2 Precautions against soil and water contamination**

*2.1.5 Hydraulic control*

contamination.

**10**

into the system.


#### **Table 5.**

*Distribution of lead, arsenic, and cadmium in South Cyprus.*

The regulatory standards given in **Table 1** hints that lead can be at safe concentrations but arsenic and cadmium need attention and may be regarded as present at above critical limits.

#### **3.2 Heavy metal contamination of agricultural soils of Yedidalga abandoned copper mine**

At Yedidalga harbor of abandoned copper mine at North Cyprus, agricultural soils were investigated for levels of soil contamination by heavy metals. **Figure 4** shows the study area and the sampling locations.

Copper, lead, chromium, cadmium, and zinc concentrations were investigated on samples collected at nine different locations. The heavy metal contents were

**13**

**Figure 5.**

*Heavy metal contamination levels at Yedidalga harbor [19].*

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

The findings displayed average concentration levels (mg/kg) as follows: Cu, 208.4; Pb, 119.4; Cr, 18.38; Cd, 6.19; and Zn, 144.2. The corresponding critical limits of the same heavy metals are as follows: Cu, 13–24; Pb, 22–44; Cr, 12–83; Cd, 0.37–0.78; and Zn, 45–100. Accordingly, there is significant pollution of Cu, Pb, Cd,

The study also evaluated the level of contamination and assessed the potential ecological risk posed by heavy metals. Several quantitative indices were utilized to assess the soil pollution status. Results revealed that comparatively all heavy metals exceeded the background values. The peak values were observed in the soils from the locations close to the Yedidalga farming lands. Spatial distribution of pollution load index (PLI) and potential ecological risk index (RI) is given in **Figure 6**.

determined using atomic absorption spectrophotometer (AAS). The results

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

and Zn, while there is no pollution with respect to Cr.

obtained are presented in **Figure 5**.

**Figure 4.** *Study area and sampling locations [19].*

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

determined using atomic absorption spectrophotometer (AAS). The results obtained are presented in **Figure 5**.

The findings displayed average concentration levels (mg/kg) as follows: Cu, 208.4; Pb, 119.4; Cr, 18.38; Cd, 6.19; and Zn, 144.2. The corresponding critical limits of the same heavy metals are as follows: Cu, 13–24; Pb, 22–44; Cr, 12–83; Cd, 0.37–0.78; and Zn, 45–100. Accordingly, there is significant pollution of Cu, Pb, Cd, and Zn, while there is no pollution with respect to Cr.

The study also evaluated the level of contamination and assessed the potential ecological risk posed by heavy metals. Several quantitative indices were utilized to assess the soil pollution status. Results revealed that comparatively all heavy metals exceeded the background values. The peak values were observed in the soils from the locations close to the Yedidalga farming lands. Spatial distribution of pollution load index (PLI) and potential ecological risk index (RI) is given in **Figure 6**.

**Figure 5.** *Heavy metal contamination levels at Yedidalga harbor [19].*

*Heavy Metal Toxicity in Public Health*

above critical limits.

*Source: [18]*

**Table 5.**

**copper mine**

shows the study area and the sampling locations.

*Distribution of lead, arsenic, and cadmium in South Cyprus.*

The regulatory standards given in **Table 1** hints that lead can be at safe concentrations but arsenic and cadmium need attention and may be regarded as present at

**Area Pb (ppm) As (ppm) Cd (ppm)** Dali 10.25 7.17 0.39 Sotira 14.02 11.68 0.26 Omodos 6.81 6.37 0.20 Acheleia 20.58 10.06 0.35 Evrychou 52.39 18.30 0.26 Polis 13.59 12.43 0.23

**3.2 Heavy metal contamination of agricultural soils of Yedidalga abandoned** 

At Yedidalga harbor of abandoned copper mine at North Cyprus, agricultural soils were investigated for levels of soil contamination by heavy metals. **Figure 4**

Copper, lead, chromium, cadmium, and zinc concentrations were investigated on samples collected at nine different locations. The heavy metal contents were

**12**

**Figure 4.**

*Study area and sampling locations [19].*

**Figure 6.**

*Spatial distributions of PLI and RI [19].*

**Figure 7.** *Sample collecting locations [20].*

**15**

**Sample no**

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 **Table 6.** *Heavy metal distribution of Güzelyurt agricultural waters.*

**As (μg/L)** 2.95 ± 0.02 0.71 ± 0.03 0.47 ± 0.03 0.41 ± 0.00 0.93 ± 0.04 1.43 ± 0.05 0.05 ± 0.01 0.61 ± 0.02 0.19 ± 0.01 1.12 ± 0.01 0.18 ± 0.01 0.12 ± 0.01 0.92 ± 0.01 0.32 ± 0.03 0.88 ± 0.01 1.49 ± 0.02 0.63 ± 0.01 3.07 ± 0.02

**Cd (μg/L)**

<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.02 ± 0.01 0.03 ± 0.01 0.03 ± 0.01 0.04 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.08 ± 0.01 0.01 ± 0.01 0.03 ± 0.01

<0.01 0.01 ± 0.01

<0.01

**Cr (μg/L)** 6.97 ± 0.19 12.16 ± 0.06

5.79 ± 0.06 5.78 ± 0.18 14.46 ± 0.10

8.10 ± 0.03 0.32 ± 0.01 0.57 ± 0.01 0.85 ± 0.01 7.44 ± 0.08 9.31 ± 0.12 0.13 ± 0.01 9.55 ± 0.30 1.17 ± 0.09 2.25 ± 0.02 12.42 ± 0.07 13.39 ± 0.17 11.86 ± 0.01

**Hg (μg/L)** 0.11 ± 0.006

0.03 ± 0.01 0.03 ± 0.01 0.01 ± 0.01 0.02 ± 0.01 0.03 ± 0.01

<0.01 0.01 ± 0.01

<0.01 0.03 ± 0.01 0.01 ± 0.01

<0.01 <0.01 <0.01 0.01 ± 0.01 0.02 ± 0.01 0.01 ± 0.01 0.03 ± 0.01

**Pb (μg/L)**

<0.01 0.24 ± 0.01 1.09 ± 0.01 1.25 ± 0.03

<0.01 1.40 ± 0.05 0.21 ± 0.01

<0.01 0.01 ± 0.003

<0.01 0.03 ± 0.01 0.26 ± 0.01 0.71 ± 0.02 0.63 ± 0.01 2.79 ± 0.03 0.33 ± 0.03 0.67 ± 0.02 0.68 ± 0.01

**Fe (μg/L)**

1266.9 ± 11.55

305.24 ± 0.88

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

600.90 ± 25.48

686.90 ± 1.53

313.90 ± 2.89

532.90 ± 7.55

2253.57 ± 61.73

302.90 ± 4.16

370.24 ± 3.76

577.90 ± 0.58

386.90 ± 6.08

754.24 ± 3.84

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

310.57 ± 4.26

260.57 ± 9.67

186.57 ± 6.84

392.24 ± 1.76

294.90 ± 14.64

602.24 ± 3.48

**Figure 8.** *Geological nature of study area [20].*


*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

> **Table 6.**

*Heavy metal distribution of Güzelyurt agricultural waters.*

*Heavy Metal Toxicity in Public Health*

*Spatial distributions of PLI and RI [19].*

**14**

**Figure 8.**

*Geological nature of study area [20].*

**Figure 7.**

**Figure 6.**

*Sample collecting locations [20].*

Pollution load index graded the overall studied area as moderately–heavily contaminated level. Potential ecological risk analysis forwarded that the ecological risk level indicated that 55.6% of sampling locations exceeded 300 (RI > 300). These study results definitely suggest that pollution precautions must be implemented. The main cause of accumulation of these metals is found to be related with the presence of mine wastes at Yedidalga mine harbor.

#### **3.3 Quality and heavy metal contamination of Güzelyurt agricultural waters**

The most active agricultural region of Güzelyurt in North Cyprus was investigated with respect to agricultural quality and heavy metal content. At the same time, the aim of the research is to shed light on the irrigation water management in the said region and to assess the groundwater quality. The management methodology was studied, and representative groundwater samples collected from different villages (**Figure 7**) were analyzed for physicochemical parameters and contamination [20].

Within the scope of the study, the geological nature of the study area is also effective and is given in **Figure 8**.

The research put forth that the concentration of heavy metals was all below the FAO guideline threshold limits, following the order Fe > Cr > As>Pb > Hg > Cd. **Table 6** displays the distribution of heavy metals at the study area.

Main cations, on the other hand, indicated Na+ > Mg2+ > Ca2+ > K+, while that of anions displayed Cl- > HCO3- > SO42- > CO32- that comply with irrigation water standards. Seawater intrusion was determined by Revelle index; piper diagram indicated Ca2 + -Mg2 + -Cl − as the major hydro chemical facies; and USSL salinity diagram was also used for salinity and sodium hazard. Irrigation water quality was evaluated by sodium adsorption ratio (SAR), residual sodium carbonate, percent of sodium, magnesium adsorption ratio (MAR), Kelly's index, total hardness, permeability index, residual Mg2+/Ca2+ ratio, and electrical conductivity. Only SAR values displayed perfect groundwater quality, while others showed good quality, except for MAR, which was unsuitable.

In conclusion, the study put forth in general the safe use of the groundwater for the purpose of irrigation. High amounts of Mg2+ in water resulted in unsuitable MAR values. Majority of groundwater samples were in the field of Ca2 + -Mg2 + -Cl − water types. Lack of water management policies brings problems to farmers.

#### **4. Conclusion**

Heavy metal contamination of water and soil is dangerous to human life; but the issue becomes much critical when the region in question is an agricultural region. The reason behind this is the entrance of natural or anthropogenic potential hazardous heavy metals into the human body via food chain. Not only conventional diseases but various cancer diseases are also observed as a result of research studies.

Consequently, agricultural soil and water must be carefully investigated before the initiation of the agricultural activities. Acceptable sampling and laboratory analyses should be executed and evaluated accordingly. In this respect, sources of contamination (natural or anthropogenic) have to be identified and analyzed for the presence of contamination.

In case of presence of contamination of soil and water by heavy metals, and if the concentrations are above the acceptable limits, necessary and timely precautions must be taken. Of the general biological and chemical methods of remediation, the former should be preferred, so as not to introduce new chemicals to the medium.

**17**

**Author details**

Mustafa Ertan Akün

Republic of North Cyprus, Turkey

\*Address all correspondence to: eakun@ciu.edu.tr

provided the original work is properly cited.

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies from Cyprus*

The method of remediation must be selected among *phyto-accumulation*, *phytostabilization*, *phyto-degradation*, *phyto-volatilization*, and *hydraulic control*. There are numerous researches which discuss different types of plant species getting rid of heavy metals through different methods, without introducing new chemical

Such research should not only be left on paper and must be implemented in agricultural regions all over the world, with the objective of enhancing the health and well-being of the humans. Creating necessary awareness in areas of potential contamination through social responsibility projects will enhance such studies.

Faculty of Engineering, Cancer Research Foundation, Biotechnology Research Center, Environmental Research Center, Cyprus International University, Turkish

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

contaminations.

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies from Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

The method of remediation must be selected among *phyto-accumulation*, *phytostabilization*, *phyto-degradation*, *phyto-volatilization*, and *hydraulic control*. There are numerous researches which discuss different types of plant species getting rid of heavy metals through different methods, without introducing new chemical contaminations.

Such research should not only be left on paper and must be implemented in agricultural regions all over the world, with the objective of enhancing the health and well-being of the humans. Creating necessary awareness in areas of potential contamination through social responsibility projects will enhance such studies.

### **Author details**

*Heavy Metal Toxicity in Public Health*

effective and is given in **Figure 8**.

MAR, which was unsuitable.

the presence of contamination.

lems to farmers.

**4. Conclusion**

ence of mine wastes at Yedidalga mine harbor.

Pollution load index graded the overall studied area as moderately–heavily contaminated level. Potential ecological risk analysis forwarded that the ecological risk level indicated that 55.6% of sampling locations exceeded 300 (RI > 300). These study results definitely suggest that pollution precautions must be implemented. The main cause of accumulation of these metals is found to be related with the pres-

**3.3 Quality and heavy metal contamination of Güzelyurt agricultural waters**

The most active agricultural region of Güzelyurt in North Cyprus was investigated with respect to agricultural quality and heavy metal content. At the same time, the aim of the research is to shed light on the irrigation water management in the said region and to assess the groundwater quality. The management methodology was studied, and representative groundwater samples collected from different villages (**Figure 7**) were analyzed for physicochemical parameters and contamination [20]. Within the scope of the study, the geological nature of the study area is also

The research put forth that the concentration of heavy metals was all below the FAO guideline threshold limits, following the order Fe > Cr > As>Pb > Hg > Cd.

Main cations, on the other hand, indicated Na+ > Mg2+ > Ca2+ > K+, while that of anions displayed Cl- > HCO3- > SO42- > CO32- that comply with irrigation water standards. Seawater intrusion was determined by Revelle index; piper diagram indicated Ca2 + -Mg2 + -Cl − as the major hydro chemical facies; and USSL salinity diagram was also used for salinity and sodium hazard. Irrigation water quality was evaluated by sodium adsorption ratio (SAR), residual sodium carbonate, percent of sodium, magnesium adsorption ratio (MAR), Kelly's index, total hardness, permeability index, residual Mg2+/Ca2+ ratio, and electrical conductivity. Only SAR values displayed perfect groundwater quality, while others showed good quality, except for

In conclusion, the study put forth in general the safe use of the groundwater for the purpose of irrigation. High amounts of Mg2+ in water resulted in unsuitable MAR values. Majority of groundwater samples were in the field of Ca2 + -Mg2 + -Cl − water types. Lack of water management policies brings prob-

Heavy metal contamination of water and soil is dangerous to human life; but the issue becomes much critical when the region in question is an agricultural region. The reason behind this is the entrance of natural or anthropogenic potential hazardous heavy metals into the human body via food chain. Not only conventional diseases but various cancer diseases are also observed as a result of research studies. Consequently, agricultural soil and water must be carefully investigated before the initiation of the agricultural activities. Acceptable sampling and laboratory analyses should be executed and evaluated accordingly. In this respect, sources of contamination (natural or anthropogenic) have to be identified and analyzed for

In case of presence of contamination of soil and water by heavy metals, and if the concentrations are above the acceptable limits, necessary and timely precautions must be taken. Of the general biological and chemical methods of remediation, the former should be preferred, so as not to introduce new chemicals to the medium.

**Table 6** displays the distribution of heavy metals at the study area.

**16**

Mustafa Ertan Akün Faculty of Engineering, Cancer Research Foundation, Biotechnology Research Center, Environmental Research Center, Cyprus International University, Turkish Republic of North Cyprus, Turkey

\*Address all correspondence to: eakun@ciu.edu.tr

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Mehran H, Mitra A, Payam N. Biomonitoring of airborne heavy metal contamination. In: Air Pollution: Monitoring, Modelling, Health and Control. IntechOpen, London-UK; Vol. 20. 2012. DOI: 10.5772/32963

[2] Hyun K, Yeo JK, Young RS. An overview of carcinogenic heavy metal: Molecular toxicity mechanism and prevention. Journal of Cancer Prevention. 2015;**20**(4):232. DOI: 10.15430/JCP.2015.20.4.232

[3] Preeyaporn K, Young RS. Advances in carcinogenic metal toxicity and potential molecular markers. International Journal of Molecular Sciences. 2011;**12**:9576- 9595. DOI: 10.3390/ijms12129576

[4] Bakshi S, Banik C, He Z. The impact of heavy metal contamination on soil health. In: Managing Soil Health for Sustainable Agriculture. Burleigh Dodds Series In Agricultural Science, USA Vol. 2. 2018. pp. 63-95. DOI: 10.19103/ AS.2017.0033.20

[5] Environmental Pollution Agency, EPA. Edition of the Drinking Water Standards and Health Advisories Tables; 2018

[6] Behbahaninia A, Mirbagheri SA, Khorasani N, Nouri J, Javid AH. Heavy metal contamination of municipal effluent in soil and plants. Journal of Food, Agriculture and Environment. 2009;**7**(3-4):851-856

[7] Chiroma TM, Abdulkarim BI, Kefas HM. The impact of pesticide application on heavy metal (Cd, Pb and Cu) levels in spinach. Leonardo Electronic Journal of Practices and Technologies. 2007;**11**:117-122. Available from: https://www.researchgate.net/ publication/26492971

[8] Masindi V, Muedi KL. Environmental contamination by heavy metals. In:

Heavy Metals. Rijeka: Intech Open; 2018. pp. 115-133. DOI: 10.5772/ intechopen.76082

[9] Muthusaravanan S, Sivarajasekar N, Vivek JS, Paramasivan T, Naushad M, Prakashmaran J, et al. Phytoremediation of heavy metals: Mechanisms, methods and enhancements. Environmental Chemistry Letters. 2018;**16**(4):1339- 1359. DOI: 10.1007/s10311-018-0762-3

[10] Irshad M, Ruqia B, Hussain Z. Heavy phytoaccumulation of heavy metals in natural vegetation at the municipal wastewater site in Abbottabad, Pakistan. International Journal of Phytoremediation. 2015;**17**(12):1269-1273. DOI: 10.1080/15226514.2014.950409

[11] Sateesh NH. Removal of arsenic by phyto-re mediation- a study of two plant species. International Journal of Scientific Engineering and Technology. 2012;**1**(5):218-224

[12] Bolan NS, Park JH, Robinson B, Naidu R, Huh KY. Phytostabilization: A green approach to contaminant containment. Advances in Agronomy. 2011;**112**:145-204. DOI: 10.1016/ B978-0-12-385538-1.00004-4

[13] Newman LA, Reynolds CM. Phytodegradation of organic compounds. Current Opinion in Biotechnology. 2004;**15**(3):225-230. DOI: 10.1016/j. copbio.2004.04.006

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*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus*

*DOI: http://dx.doi.org/10.5772/intechopen.90060*

[16] Barau BW, Abdulhameed A, Ezra AG, Muhammad M, Kyari EM, Bawa U. Heavy metal contamination of some vegetables from pesticides and the potential health risk in Bauchi, northern Nigeria. Affrev Stech: An International Journal of Science and Technology. 2018;**7**(1):1-11. DOI: 10.4314/stech.v7i1.1

[17] Chibuike GU, Obiora SC. Heavy Metal Polluted Soils: Effect on Plants and Bioremediation Methods. Vol. 2014. UK: Hindawi Publishing Corporation, Applied and Environmental Soil Science; 2014. p. 752708. 1-12. DOI:

[19] Barkett MO, Akün E. Heavy metal contents of contaminated soils and ecological risk assessment in abandoned copper mine harbor in Yedidalga, Northern Cyprus. Environment and Earth Science. 2019;**77**:378. DOI: 10.1007/s12665-018-7556-6

[20] Arslan B, Akün E. Management, contamination and quality evaluation of groundwater in North Cyprus. Agricultural Water Management. 2019;**222**:1-11. DOI: 10.1016/j.

agwat.2019.05.023

10.1155/2014/752708

[18] Akun ME, Yamacı RF, Charalambous C, Lechtvich S, Djamgoz MBA. The distribution of carcinogenic heavy metals in Cyprus soil. In: Conversion of Agricultural Wastes into Value Added Product with high Protein Content by Growing *Pleurotus ostreatus*. Switzerland Springer; 2011. pp. 353-359. DOI: 10.1007/978-3-540-95991-5\_33

*Heavy Metal Contamination and Remediation of Water and Soil with Case Studies From Cyprus DOI: http://dx.doi.org/10.5772/intechopen.90060*

[16] Barau BW, Abdulhameed A, Ezra AG, Muhammad M, Kyari EM, Bawa U. Heavy metal contamination of some vegetables from pesticides and the potential health risk in Bauchi, northern Nigeria. Affrev Stech: An International Journal of Science and Technology. 2018;**7**(1):1-11. DOI: 10.4314/stech.v7i1.1

[17] Chibuike GU, Obiora SC. Heavy Metal Polluted Soils: Effect on Plants and Bioremediation Methods. Vol. 2014. UK: Hindawi Publishing Corporation, Applied and Environmental Soil Science; 2014. p. 752708. 1-12. DOI: 10.1155/2014/752708

[18] Akun ME, Yamacı RF, Charalambous C, Lechtvich S, Djamgoz MBA. The distribution of carcinogenic heavy metals in Cyprus soil. In: Conversion of Agricultural Wastes into Value Added Product with high Protein Content by Growing *Pleurotus ostreatus*. Switzerland Springer; 2011. pp. 353-359. DOI: 10.1007/978-3-540-95991-5\_33

[19] Barkett MO, Akün E. Heavy metal contents of contaminated soils and ecological risk assessment in abandoned copper mine harbor in Yedidalga, Northern Cyprus. Environment and Earth Science. 2019;**77**:378. DOI: 10.1007/s12665-018-7556-6

[20] Arslan B, Akün E. Management, contamination and quality evaluation of groundwater in North Cyprus. Agricultural Water Management. 2019;**222**:1-11. DOI: 10.1016/j. agwat.2019.05.023

**18**

*Heavy Metal Toxicity in Public Health*

**References**

20. 2012. DOI: 10.5772/32963

[2] Hyun K, Yeo JK, Young RS. An overview of carcinogenic heavy metal: Molecular toxicity mechanism and prevention. Journal of Cancer Prevention. 2015;**20**(4):232. DOI: 10.15430/JCP.2015.20.4.232

[3] Preeyaporn K, Young RS. Advances in carcinogenic metal toxicity and potential molecular markers. International Journal of Molecular Sciences. 2011;**12**:9576- 9595. DOI: 10.3390/ijms12129576

[4] Bakshi S, Banik C, He Z. The impact of heavy metal contamination on soil health. In: Managing Soil Health for Sustainable Agriculture. Burleigh Dodds Series In Agricultural Science, USA Vol. 2. 2018. pp. 63-95. DOI: 10.19103/

[5] Environmental Pollution Agency, EPA. Edition of the Drinking Water Standards and Health Advisories Tables;

[6] Behbahaninia A, Mirbagheri SA, Khorasani N, Nouri J, Javid AH. Heavy metal contamination of municipal effluent in soil and plants. Journal of Food, Agriculture and Environment.

[7] Chiroma TM, Abdulkarim BI, Kefas HM. The impact of pesticide application on heavy metal (Cd, Pb and Cu) levels in spinach. Leonardo Electronic Journal of Practices and Technologies. 2007;**11**:117-122. Available from: https://www.researchgate.net/

[8] Masindi V, Muedi KL. Environmental contamination by heavy metals. In:

AS.2017.0033.20

2009;**7**(3-4):851-856

publication/26492971

2018

[1] Mehran H, Mitra A, Payam N. Biomonitoring of airborne heavy metal contamination. In: Air Pollution: Monitoring, Modelling, Health and Control. IntechOpen, London-UK; Vol. Heavy Metals. Rijeka: Intech Open; 2018. pp. 115-133. DOI: 10.5772/

[9] Muthusaravanan S, Sivarajasekar N, Vivek JS, Paramasivan T, Naushad M, Prakashmaran J, et al. Phytoremediation of heavy metals: Mechanisms, methods and enhancements. Environmental Chemistry Letters. 2018;**16**(4):1339- 1359. DOI: 10.1007/s10311-018-0762-3

[10] Irshad M, Ruqia B, Hussain Z. Heavy phytoaccumulation of heavy metals in natural vegetation at the municipal wastewater site in Abbottabad, Pakistan. International Journal of Phytoremediation. 2015;**17**(12):1269-1273. DOI: 10.1080/15226514.2014.950409

[11] Sateesh NH. Removal of arsenic by phyto-re mediation- a study of two plant species. International Journal of Scientific Engineering and Technology.

[12] Bolan NS, Park JH, Robinson B, Naidu R, Huh KY. Phytostabilization: A green approach to contaminant containment. Advances in Agronomy. 2011;**112**:145-204. DOI: 10.1016/ B978-0-12-385538-1.00004-4

[13] Newman LA, Reynolds CM. Phytodegradation of organic compounds. Current Opinion in Biotechnology. 2004;**15**(3):225-230. DOI: 10.1016/j.

Volatilization of Organic Contaminants. USA: American Chemical Society; 2016.

Kees CE, Miller CT. A hydraulic capture application for optimal remediation design. Developments in Water Science.

[14] Limmer M, Burken J. Phyto-

DOI: 10.1021/acs.est.5b04113

2004;**55**(Part 2):1149-1157. DOI: 10.1016/S0167-5648(04)80131-X

[15] Fowler KR, Kelley CT,

2012;**1**(5):218-224

copbio.2004.04.006

intechopen.76082

**21**

**Chapter 2**

Materials

*Nesrine Boujelben*

of phosphorus ions (PO4

**1. Introduction**

**Abstract**

Sorption of Phosphorus, Nickel,

and Lead from Aqueous Solution

Using Manganese Oxide-Coated

Manganese oxide-coated sand (MOCS) and manganese oxide-coated crushed brick (MOCB) were prepared and characterized and employed for the removal

To study the surface properties of the adsorbents, scanning electron microscopy (SEM), X-ray diffraction (XRD) methods, and BET analyses were used. Adsorption was investigated by batch experiments. The estimated optimum pH was 7 for Ni(II) and 5 for all other ions retention by the two considered adsorbents. Both the Freundlich and Langmuir isotherms provided a reasonable fit to the experimental data for the adsorption. The adsorption capacities of the coated adsorbents at a considered pH value and a temperature of 20°C were 1.96 and 2.08 mg/g for PO4

2.4 and 3.33 mg/g for Ni(II), and 6 and 6.25 for Pb(II) onto MOCS and MOCB, respectively. The pseudo-first-order and pseudo-second-order equations as well as the intraparticle diffusion model were determined to test the adsorption kinetics and the rate constants derived from the three kinetic models being calculated. The pseudo-second-order kinetic model was better appropriated. Results obtained from this study confirm that the manganese oxide-coated sorbent is considerably considered like suitable for the removal of anions and cations from aqueous solutions.

**Keywords:** manganese oxide-coated sorbents, nickel copper and lead removal,

Due to the rapid development of such industries as plating, petrochemicals, and fertilizers, there has been excessive discharge of contaminant, like phosphorus and heavy metals, into the environment, resulting in health hazards [1]. Phosphorus is the key nutrient for the growth of algal and other biological organisms, which in excess causes eutrophication of water bodies and heavy metals such as lead and nickel, which are harmful and can cause disease and damage to human health if present above certain concentrations [2, 3]. For this reason, it is important to remove them from wastewater before it is discharged into the environment [2]. There are many methods to eliminate heavy metals from wastewater [2], including chemical precipitation [4], electrochemical reduction [5], ion exchange [6],

phosphorus ions, kinetic study, thermodynamic parameters

<sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solution.

<sup>3</sup><sup>−</sup>,

#### **Chapter 2**

## Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese Oxide-Coated Materials

*Nesrine Boujelben*

### **Abstract**

Manganese oxide-coated sand (MOCS) and manganese oxide-coated crushed brick (MOCB) were prepared and characterized and employed for the removal of phosphorus ions (PO4 <sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solution. To study the surface properties of the adsorbents, scanning electron microscopy (SEM), X-ray diffraction (XRD) methods, and BET analyses were used. Adsorption was investigated by batch experiments. The estimated optimum pH was 7 for Ni(II) and 5 for all other ions retention by the two considered adsorbents. Both the Freundlich and Langmuir isotherms provided a reasonable fit to the experimental data for the adsorption. The adsorption capacities of the coated adsorbents at a considered pH value and a temperature of 20°C were 1.96 and 2.08 mg/g for PO4 <sup>3</sup><sup>−</sup>, 2.4 and 3.33 mg/g for Ni(II), and 6 and 6.25 for Pb(II) onto MOCS and MOCB, respectively. The pseudo-first-order and pseudo-second-order equations as well as the intraparticle diffusion model were determined to test the adsorption kinetics and the rate constants derived from the three kinetic models being calculated. The pseudo-second-order kinetic model was better appropriated. Results obtained from this study confirm that the manganese oxide-coated sorbent is considerably considered like suitable for the removal of anions and cations from aqueous solutions.

**Keywords:** manganese oxide-coated sorbents, nickel copper and lead removal, phosphorus ions, kinetic study, thermodynamic parameters

#### **1. Introduction**

Due to the rapid development of such industries as plating, petrochemicals, and fertilizers, there has been excessive discharge of contaminant, like phosphorus and heavy metals, into the environment, resulting in health hazards [1]. Phosphorus is the key nutrient for the growth of algal and other biological organisms, which in excess causes eutrophication of water bodies and heavy metals such as lead and nickel, which are harmful and can cause disease and damage to human health if present above certain concentrations [2, 3]. For this reason, it is important to remove them from wastewater before it is discharged into the environment [2]. There are many methods to eliminate heavy metals from wastewater [2], including chemical precipitation [4], electrochemical reduction [5], ion exchange [6],

membrane separation, reverse osmosis [7], and adsorption [8–10]. Adsorption is considered the most effective one due to its properties of simple operation, low cost, and high efficiency over a wide concentration range of pollutants [11]. Typical adsorbents which have been extensively employed to remove heavy metals are clay minerals [12], carbon-based materials [13], and metal oxides [14]. Recently, different types of low-cost natural and modified minerals for the removal of heavy metals from aqueous solutions have been used. Due to the high surface charge density, various Mn oxides (e.g., including pyrolusite (β-MnO2) and birnessite (σ-MnO2)) have been extensive as high efficient adsorbents to remove arsenic [15], nickel [16], and lead [17], for example.

Recent studies have shown that some filtration materials such as sand and burned clay coated with oxides (oxyhydroxides) of iron, aluminum, or manganese act as good and inexpensive sorbents [18–21].

In the present study, the characteristics of two prepared coated adsorbents, namely, manganese oxide-coated sand and manganese oxide-coated crushed brick, have been investigated.

Thermodynamic and kinetic studies of phosphorus ions (PO4 <sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solution adsorption onto these materials were also undertaken. The main objectives of this investigation were to examine quantitatively the effect of contact time, pH, and concentration on the removal of phosphorus ions (PO4 <sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solutions as well as to check in detail the kinetics of the phosphorus ions (PO4 <sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solution and ion-removal process.

#### **2. Materials and methods**

#### **2.1 Sample preparation**

In our previous works [20, 21], the average diameter for sand and crushed brick grains was 0.6–0.7 and 0.9–1.2 mm, respectively [20, 21], and the specific gravities were 2.50 and 2.39 g/cm3 for sand and crushed brick, respectively [20, 21].

The manganese oxide-coated adsorbents (MOCS, sand, and MOCB, crushed brick) were prepared by impregnation according to the procedure proposed by Bajpai and Chaudhuri and adopted in our previous research work [20–22].

Before MnO2 impregnation, an acidic purification procedure (acid wash with 1 M HCl) [20, 21, 23] was made to the adsorbents to remove impurities, which could affect the adsorption results. The reaction of KMnO4 with hot MnCl2 solution (48–50°C) under alkaline conditions (pH 9) over a period of 48 h [20] was the favorable conditions to ensure the application of the MnO2 coating on the two adsorbent surfaces.

#### **2.2 Chemicals**

To prepare aqueous solutions containing phosphates and metal ions at various concentrations, sodium phosphate salt (NaH2PO4), lead nitrate salt [Pb(NO3)2], and nickel chloride salt (NiCl2\_6H2O, analytical grade) solutions were used. The initial pH values of the solutions were adjusted by adding either nitric acid or sodium hydroxide solution [20, 21].

All chemicals used for the pre-treatment of the adsorbents, as well as for the adsorption tests, were of analytical grade (HCl, MnCl2, KMnO4, NaOH, HNO3).

A calibrated pH meter (model pH 540 GLP) equipped with a combined glass electrode (SENTIX 41) [20, 21] was used to ensure the measurements of pH.

**23**

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

X-ray diffractometer (Siemens, Germany) with Cu Kα radiation (λ = 0.154 nm) was used to determine the mineralogy of the manganese oxide-coating sorbents. The single-point BET (N2) adsorption procedure was employed to characterize the

The pH of the point of zero charge (pHpzc) was determined by adding 0.1 g of adsorbent to a series of bottles that contained 50 ml of deionizer water. The pH of each solution was adjusted in the range of 1.0–9.0 by the addition of either 0.1 M HNO3 or 0.1 M NaOH solutions. The bottles were then rotated for 1 h in a shaker and the pH values of the contents measured at the end of the test. The pH values of the suspensions were plotted as a function of the initial pH of the solutions, the resulting curve theoretically crossing the bisector of the axes at the point of zero charge [20, 21]. It is to note that the pHpzc values of 4.5 and 4.3 were obtained for

Philips XL 30 scanning electron microscope (SEM) was used to describe the morphology of the adsorbents before and after coating, and elemental spectra were obtained using energy-dispersive X-ray spectroscopy during the SEM observations

The two prepared materials were first used in batch experiments to check the effect of the initial metal ion concentration on the adsorption kinetics and the influence of the initial pH. Five grams of manganese oxide-coated sorbent was added to 250 ml of each ion solution of known initial concentration [20, 21] and was used for the kinetic studies. The initial pH was adjusted to 5 with dilute HNO3 or NaOH solution. Prepared solutions were shaken continuously for 4 h at the desired temperature (10, 20, and 40°C). This experiment was released by using a thermostatically controlled shaking water bath. Samples were taken at various time intervals and were immediately vacuum-filtered through a 0.45-μm membrane filter [20, 21]. Atomic absorption spectrophotometry (Hitachi Z-6100) was used to determine the residual ion concentration in each filtrate. Five percent was estimated to be the analytical errors. To ensure the veracity of the experimental results, all experiments

To understand the influence of pH on the considered ion adsorption, experiments were performed at various initial pH values within the range 2–7 with the initial Pb(II) ion concentration being maintained at 50 mg/l and from 2 to 11 for

ered ion solution, with the suspensions being shaken for 4 h at 20 ± 1°C [20, 21].

Experiments were conducted at 10°C, 20°C, and 40°C, respectively. At each temperature, 5 g of sorbent were contacted for 4 h with 250 ml of ion solution of different initial concentration [20, 21]. The adsorption equilibrium data were analyzed in terms of the Langmuir and Freundlich isotherm models. The linear forms of the Langmuir and Freundlich isotherms [24] may be expressed, respectively, by

<sup>3</sup><sup>−</sup> ions. For each test, 1 g of sorbent was added to 25 ml of all consid-

Ce/qe = 1/q0b + Ce/q0 (1)

/g) of each adsorbent before and after coating [20, 21].

*DOI: http://dx.doi.org/10.5772/intechopen.85318*

**2.3 Sorbent characterization**

specific surface area (m<sup>2</sup>

MOCS and MOCB, respectively.

**2.4 Adsorption experiments**

were duplicated [20, 21].

**2.5 Adsorption isotherms**

*2.5.1 Isotherm determination*

the following equations [20, 21]:

Ni(II) and PO4

[20, 21].

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

#### **2.3 Sorbent characterization**

*Heavy Metal Toxicity in Public Health*

and lead [17], for example.

have been investigated.

(PO4

act as good and inexpensive sorbents [18–21].

detail the kinetics of the phosphorus ions (PO4

aqueous solution and ion-removal process.

**2. Materials and methods**

**2.1 Sample preparation**

were 2.50 and 2.39 g/cm3

adsorbent surfaces.

sodium hydroxide solution [20, 21].

**2.2 Chemicals**

membrane separation, reverse osmosis [7], and adsorption [8–10]. Adsorption is considered the most effective one due to its properties of simple operation, low cost, and high efficiency over a wide concentration range of pollutants [11]. Typical adsorbents which have been extensively employed to remove heavy metals are clay minerals [12], carbon-based materials [13], and metal oxides [14]. Recently, different types of low-cost natural and modified minerals for the removal of heavy metals from aqueous solutions have been used. Due to the high surface charge density, various Mn oxides (e.g., including pyrolusite (β-MnO2) and birnessite (σ-MnO2)) have been extensive as high efficient adsorbents to remove arsenic [15], nickel [16],

Recent studies have shown that some filtration materials such as sand and burned clay coated with oxides (oxyhydroxides) of iron, aluminum, or manganese

In the present study, the characteristics of two prepared coated adsorbents, namely, manganese oxide-coated sand and manganese oxide-coated crushed brick,

Ni(II) ions from aqueous solution adsorption onto these materials were also undertaken. The main objectives of this investigation were to examine quantitatively the effect of contact time, pH, and concentration on the removal of phosphorus ions

<sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from aqueous solutions as well as to check in

In our previous works [20, 21], the average diameter for sand and crushed brick grains was 0.6–0.7 and 0.9–1.2 mm, respectively [20, 21], and the specific gravities

The manganese oxide-coated adsorbents (MOCS, sand, and MOCB, crushed brick) were prepared by impregnation according to the procedure proposed by Bajpai and Chaudhuri and adopted in our previous research work [20–22].

Before MnO2 impregnation, an acidic purification procedure (acid wash with 1 M HCl) [20, 21, 23] was made to the adsorbents to remove impurities, which could affect the adsorption results. The reaction of KMnO4 with hot MnCl2 solution (48–50°C) under alkaline conditions (pH 9) over a period of 48 h [20] was the favorable conditions to ensure the application of the MnO2 coating on the two

To prepare aqueous solutions containing phosphates and metal ions at various concentrations, sodium phosphate salt (NaH2PO4), lead nitrate salt [Pb(NO3)2], and nickel chloride salt (NiCl2\_6H2O, analytical grade) solutions were used. The initial pH values of the solutions were adjusted by adding either nitric acid or

All chemicals used for the pre-treatment of the adsorbents, as well as for the adsorption tests, were of analytical grade (HCl, MnCl2, KMnO4, NaOH, HNO3). A calibrated pH meter (model pH 540 GLP) equipped with a combined glass electrode (SENTIX 41) [20, 21] was used to ensure the measurements of pH.

for sand and crushed brick, respectively [20, 21].

<sup>3</sup><sup>−</sup>) and Pb(II) and

<sup>3</sup><sup>−</sup>) and Pb(II) and Ni(II) ions from

Thermodynamic and kinetic studies of phosphorus ions (PO4

**22**

X-ray diffractometer (Siemens, Germany) with Cu Kα radiation (λ = 0.154 nm) was used to determine the mineralogy of the manganese oxide-coating sorbents. The single-point BET (N2) adsorption procedure was employed to characterize the specific surface area (m<sup>2</sup> /g) of each adsorbent before and after coating [20, 21].

The pH of the point of zero charge (pHpzc) was determined by adding 0.1 g of adsorbent to a series of bottles that contained 50 ml of deionizer water. The pH of each solution was adjusted in the range of 1.0–9.0 by the addition of either 0.1 M HNO3 or 0.1 M NaOH solutions. The bottles were then rotated for 1 h in a shaker and the pH values of the contents measured at the end of the test. The pH values of the suspensions were plotted as a function of the initial pH of the solutions, the resulting curve theoretically crossing the bisector of the axes at the point of zero charge [20, 21]. It is to note that the pHpzc values of 4.5 and 4.3 were obtained for MOCS and MOCB, respectively.

Philips XL 30 scanning electron microscope (SEM) was used to describe the morphology of the adsorbents before and after coating, and elemental spectra were obtained using energy-dispersive X-ray spectroscopy during the SEM observations [20, 21].

#### **2.4 Adsorption experiments**

The two prepared materials were first used in batch experiments to check the effect of the initial metal ion concentration on the adsorption kinetics and the influence of the initial pH. Five grams of manganese oxide-coated sorbent was added to 250 ml of each ion solution of known initial concentration [20, 21] and was used for the kinetic studies. The initial pH was adjusted to 5 with dilute HNO3 or NaOH solution. Prepared solutions were shaken continuously for 4 h at the desired temperature (10, 20, and 40°C). This experiment was released by using a thermostatically controlled shaking water bath. Samples were taken at various time intervals and were immediately vacuum-filtered through a 0.45-μm membrane filter [20, 21].

Atomic absorption spectrophotometry (Hitachi Z-6100) was used to determine the residual ion concentration in each filtrate. Five percent was estimated to be the analytical errors. To ensure the veracity of the experimental results, all experiments were duplicated [20, 21].

To understand the influence of pH on the considered ion adsorption, experiments were performed at various initial pH values within the range 2–7 with the initial Pb(II) ion concentration being maintained at 50 mg/l and from 2 to 11 for Ni(II) and PO4 <sup>3</sup><sup>−</sup> ions. For each test, 1 g of sorbent was added to 25 ml of all considered ion solution, with the suspensions being shaken for 4 h at 20 ± 1°C [20, 21].

#### **2.5 Adsorption isotherms**

#### *2.5.1 Isotherm determination*

Experiments were conducted at 10°C, 20°C, and 40°C, respectively. At each temperature, 5 g of sorbent were contacted for 4 h with 250 ml of ion solution of different initial concentration [20, 21]. The adsorption equilibrium data were analyzed in terms of the Langmuir and Freundlich isotherm models. The linear forms of the Langmuir and Freundlich isotherms [24] may be expressed, respectively, by the following equations [20, 21]:

$$\mathbf{\color{red}{Ce/qe=1/q\_0b}+Ce/q\_0} \tag{1}$$

$$
\log \mathbf{q}\_{\mathfrak{e}} = \begin{array}{c} \log \mathbf{K}\_{\mathbb{F}} \ \ \ + \quad \nwarrow \log \mathbf{C}\_{\mathfrak{e}} \end{array} \tag{2}
$$

where the Langmuir isotherm constants are q0 (mmol/g) and b (g/mmol) and the Freundlich isotherm constants are KF and n. The measure of the adsorption capacity of the sorbent value is q0 (maximum amount of ions adsorbed at the temperature under consideration) [20, 21].

#### *2.5.2 Determination of thermodynamic adsorption parameters*

The standard Gibbs free energy (ΔG0 ), the standard enthalpy (ΔH0 ), and the standard entropy (ΔS0 ) were determined to explain the effect of temperature on the adsorption parameters. It is known that the adsorption of metal ions is a reversible process corresponding to a heterogeneous equilibrium. The Gibbs free energy (ΔG0 ) was determined from the following relationship [25, 26]:

$$
\Delta \mathbf{G}\_0 = \text{RT} \ln \mathbf{K}\_\mathbf{L} \tag{3}
$$

with R being the gas constant, KL being equilibrium constant obtained from the Langmuir equation, and T being the absolute temperature (K). The enthalpy change (ΔH0 ) and the entropy change (ΔS0 ) were evaluated from Van't Hoff's equation:

$$
\log \text{K}\_{\text{L}} = \begin{array}{c c c} \text{\AA S}^{0} & - & \underline{\text{\Lambda H}^{0}} \\ \text{\text{2.303R}} & - & \underline{\text{2.303R}} \end{array} \tag{4}
$$

The values of ΔH0 and ΔS0 were calculated from the slope and intercept of the Van't Hoff plot of log KL versus 1/T.

The Gibbs free energy

$$
\Delta \mathbf{G}^0 = \Delta \mathbf{H}^0 - \mathbf{T} \Delta \mathbf{S}^0 \tag{5}
$$

indicates the degree of spontaneity of the adsorption process, with a higher negative value reflecting a more energetically favorable adsorption process.

#### *2.5.3 Kinetic parameters of adsorption*

In order to analyze the ion adsorption kinetics onto MOCS and MOCB, three kinetic models including the pseudo-first-order equation [27], the pseudo-secondorder equation [28], and the intraparticle diffusion model [29] were applied to the experimental data obtained for the time-dependent ion adsorption.

The pseudo-first-order kinetic model is given by the equation:

$$\log(\mathbf{q}\_{\varepsilon} \quad - \quad \mathbf{q}\_{\varepsilon}) \quad = \quad \log \mathbf{q}\_{\varepsilon} \quad - \quad \frac{\mathbf{k}\_{\mathrm{l}} \mathbf{t}}{2.303} \tag{6}$$

Similarly, the pseudo-second-order kinetic model may be written as.

$$\frac{\mathbf{u}\_{\mathbf{u}\_{\mathbf{u}}}}{\mathbf{q}\_{\mathbf{u}}} := \mathbf{u}\_{\mathbf{u}} \frac{1}{\mathbf{k}\_{\mathbf{u}} \mathbf{q}\_{\mathbf{u}}^{2}} \to \frac{\mathbf{u}\_{\mathbf{u}}}{\mathbf{q}\_{\mathbf{u}}} \tag{7}$$

while the intraparticle diffusion model may be written as:

$$\mathbf{q}\mathbf{t} = \mathbf{k}\mathbf{t}\mathbf{t}\mathbf{1}/\mathbf{2} + \mathbf{C} \tag{8}$$

**25**

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

the pseudo-second-order adsorption process [g/(mmol min)] is k2; the initial adsorption rate for the pseudo-second order adsorption process [mmol/(g min)] is k2qe2 = h; the intraparticle diffusion rate constant [mmol/(g min)] is kt; and C is a constant. Linear plots of log(qe – qt) versus t, t/qt versus t, and qt versus t1/2 suggest the applicability of the kinetic models to the system under consideration. The kinetic parameters can be determined from the slopes and intercepts

The activation energy for all considered ion adsorption was calculated via the

where k is the rate constant, k0 [g/(mmol min)] is a temperature-independent factor, Ea (J/mol) is the activation energy of the adsorption process, R is the gas constant [8.314 J/(mol K)], and T is the adsorption temperature (K). The linear

When ln k is plotted versus 1/T, a straight line of slope –Ea/R is obtained. In our case, the rate constant under consideration was k2, i.e., relating to the pseudo-

To observe the morphology of the uncoated and the manganese oxide-coated sand (MOCS) and manganese oxide-coated crushed brick (MOCB), SEM micrographs were taken. Obtained results from SEM images of acid-washed uncoated sand (US) and crushed brick (UB) (**Figure 1(a)** and **(c)**) showed that the US surface was characterized by a very ordered silica crystals, and for UB it was principally a regular aluminosilicate. The surfaces of the two virgin materials seem to be uniform and smooth with small cracks and light roughness, but these manganeseoxide-coated surfaces (MOCS **Figure 1(b)**, MOCB **Figure 1(d)**) were covered by newborn manganese oxides that were certainly obtained during the coating process. **Figure 1(b)** and **(d)** also showed manganese oxides formed in clusters, apparently on occupied surfaces. The amount of manganese on the surface of the MOCS and MOCB was determined by acid digestion analysis. Results obtained for the Mn deposits were approximately 1.5 mg Mn/g for sand and 2 mg Mn/g for crushed brick. It is to note also that the quantity of manganese deposit obtained in this work for the two sorbents was found to be higher than that generally mentioned in the literature, which is about 0.003–0.5 mg Mn/g of sand [28, 30]. This reflects the

The X-ray diffraction (XRD) patterns of the two coated sorbents (data not shown) revealed that the manganese oxides were amorphous, since no specific dif-

fraction ray indicative of any specific crystalline phase was detected.

k = k0 exp.(−Ea/RT) (9)

ln k = −Ea/RT + ln k0 (10)

*DOI: http://dx.doi.org/10.5772/intechopen.85318*

**2.6 Determination of the activation energy**

of these plots.

Arrhenius Equation [26]:

form of Eq. (9) is as follows:

**3. Results and discussion**

**3.1 Sorbent characterization**

*3.1.1 SEM micrographs and EDAX spectra*

effectiveness of the coating process used in this study.

second-order model.

qe and qt are the amounts of solute adsorbed per unit mass of adsorbent (mmol/g) at equilibrium and at any given time t, respectively; the pseudo-firstorder rate constant for the adsorption process (min<sup>−</sup><sup>1</sup> ) is k1; the rate constant for *Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

the pseudo-second-order adsorption process [g/(mmol min)] is k2; the initial adsorption rate for the pseudo-second order adsorption process [mmol/(g min)] is k2qe2 = h; the intraparticle diffusion rate constant [mmol/(g min)] is kt; and C is a constant. Linear plots of log(qe – qt) versus t, t/qt versus t, and qt versus t1/2 suggest the applicability of the kinetic models to the system under consideration. The kinetic parameters can be determined from the slopes and intercepts of these plots.

#### **2.6 Determination of the activation energy**

*Heavy Metal Toxicity in Public Health*

temperature under consideration) [20, 21].

The standard Gibbs free energy (ΔG0

) and the entropy change (ΔS0

Van't Hoff plot of log KL versus 1/T. The Gibbs free energy

*2.5.3 Kinetic parameters of adsorption*

and ΔS0

standard entropy (ΔS0

The values of ΔH0

(ΔG0

(ΔH0

*2.5.2 Determination of thermodynamic adsorption parameters*

) was determined from the following relationship [25, 26]:

ΔG0

experimental data obtained for the time-dependent ion adsorption. The pseudo-first-order kinetic model is given by the equation:

while the intraparticle diffusion model may be written as:

order rate constant for the adsorption process (min<sup>−</sup><sup>1</sup>

Similarly, the pseudo-second-order kinetic model may be written as.

qe and qt are the amounts of solute adsorbed per unit mass of adsorbent (mmol/g) at equilibrium and at any given time t, respectively; the pseudo-first-

= ΔH0

indicates the degree of spontaneity of the adsorption process, with a higher negative value reflecting a more energetically favorable adsorption process.

In order to analyze the ion adsorption kinetics onto MOCS and MOCB, three kinetic models including the pseudo-first-order equation [27], the pseudo-secondorder equation [28], and the intraparticle diffusion model [29] were applied to the

where the Langmuir isotherm constants are q0 (mmol/g) and b (g/mmol) and the Freundlich isotherm constants are KF and n. The measure of the adsorption capacity of the sorbent value is q0 (maximum amount of ions adsorbed at the

the adsorption parameters. It is known that the adsorption of metal ions is a reversible process corresponding to a heterogeneous equilibrium. The Gibbs free energy

with R being the gas constant, KL being equilibrium constant obtained from the Langmuir equation, and T being the absolute temperature (K). The enthalpy change

), the standard enthalpy (ΔH0

ΔG0 = RT ln KL (3)

) were evaluated from Van't Hoff's equation:

were calculated from the slope and intercept of the

qt = ktt1/2 + C (8)

) is k1; the rate constant for

−TΔS0 (5)

) were determined to explain the effect of temperature on

(2)

), and the

(4)

(6)

(7)

**24**

The activation energy for all considered ion adsorption was calculated via the Arrhenius Equation [26]:

$$\mathbf{k} = \mathbf{k}\_0 \exp.(-\mathbf{E}\mathbf{a}/\mathbf{R}\mathbf{T})\tag{9}$$

where k is the rate constant, k0 [g/(mmol min)] is a temperature-independent factor, Ea (J/mol) is the activation energy of the adsorption process, R is the gas constant [8.314 J/(mol K)], and T is the adsorption temperature (K). The linear form of Eq. (9) is as follows:

$$
\ln \mathbf{k} = -\mathbf{E}\mathbf{a}/\mathbf{R}\mathbf{T} + \ln \mathbf{k}\_0 \tag{10}
$$

When ln k is plotted versus 1/T, a straight line of slope –Ea/R is obtained. In our case, the rate constant under consideration was k2, i.e., relating to the pseudosecond-order model.

#### **3. Results and discussion**

#### **3.1 Sorbent characterization**

#### *3.1.1 SEM micrographs and EDAX spectra*

To observe the morphology of the uncoated and the manganese oxide-coated sand (MOCS) and manganese oxide-coated crushed brick (MOCB), SEM micrographs were taken. Obtained results from SEM images of acid-washed uncoated sand (US) and crushed brick (UB) (**Figure 1(a)** and **(c)**) showed that the US surface was characterized by a very ordered silica crystals, and for UB it was principally a regular aluminosilicate. The surfaces of the two virgin materials seem to be uniform and smooth with small cracks and light roughness, but these manganeseoxide-coated surfaces (MOCS **Figure 1(b)**, MOCB **Figure 1(d)**) were covered by newborn manganese oxides that were certainly obtained during the coating process. **Figure 1(b)** and **(d)** also showed manganese oxides formed in clusters, apparently on occupied surfaces. The amount of manganese on the surface of the MOCS and MOCB was determined by acid digestion analysis. Results obtained for the Mn deposits were approximately 1.5 mg Mn/g for sand and 2 mg Mn/g for crushed brick. It is to note also that the quantity of manganese deposit obtained in this work for the two sorbents was found to be higher than that generally mentioned in the literature, which is about 0.003–0.5 mg Mn/g of sand [28, 30]. This reflects the effectiveness of the coating process used in this study.

The X-ray diffraction (XRD) patterns of the two coated sorbents (data not shown) revealed that the manganese oxides were amorphous, since no specific diffraction ray indicative of any specific crystalline phase was detected.

#### **Figure 1.**

*SEM micrographs of samples: (a) US, (b) MOCS, (c) uncoated crushed brick, and (d) MOCB.*

**Figure 2(a)** of the EDAX spectra of MOCS shows that Mn, O, and Si are the main constituents. These had been expected to be the principal elements of MOCS. In fact, EDAX the important peak of Si occurring in EDAX spectrum was apparently related to the too thin coating, or manganese oxides did not cover the full surface of the MOCS, allowing the X-ray to reach the sand support. From the EDAX spectrum of MOCB illustrated in **Figure 2(b)**, it was shown that Mn, O, Si, Al, Ca, and K are the dominant constituents. The presence of the Mn peak indicates the effectiveness of the adopted coating process.

#### *3.1.2 Specific surface area*

It is to note that specific surface areas of the two sorbents increased after coating. The obtained values of surface area were 1.36 and 1.86 m2 /g, for uncoated sand and uncoated crushed brick, respectively, after coating with manganese oxide the surface area of sorbents increased to 3.81 and 4.64 m<sup>2</sup> /g, respectively. We can conclude that the addition of the manganese oxides contributes to the increase in both inner and surface porosities.

**27**

**Figure 3.**

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

ent initial concentration was used: 10 mg/l and 50 mg/l for PO4

ensure that the equilibrium time was practically attained (**Figure 3**).

To study the effect of contact time on the sorption of all different ions, a differ-

Adsorption process is strongly related to pH and to the charge on both the adsorbate and the adsorbent. The surface charge on a manganese oxide surface varies with the solution pH due to the exchange of H+ ions. The surface groups on manganese oxide are amphoteric and can act as either an acid or a base. Consequently, the oxide surface can undergo protonation and deprotonation in response to changes in

The optimal pH was obtained at around pH 4. It is to note that the removal decreases continuously for pH values ranging between around 4 and 10 according to other works dealing with sorption of phosphate ions on hematite and Al2O3 [31], ion-exchange fiber [32], alunite [33], and bauxite [34]. The decrease in the phosphate ion uptake, occurring beyond pH 5, could be probably attributed in one hand to a competition between phosphate ions and hydroxyl ions for the sorption on the surface Lewis acid sites of the sorbent [21] and in another hand by considering a zero point of charge of the sorbent. In fact, above the zero point of charge, the positive charge density on the surface of the sorbents increases which disfavors the sorption of phosphate ions. The sorption of phosphate onto hydroxylated mineral surface can be described by a ligand exchange mechanism [35, 36], which causes an increase in pH due to the hydroxyl ions released from the oxidic sorbent. Concerning nickel sorption is negligible at the low pH values probably due to the competition

from pH 4. A maximum is reached at around pH 7–8; then, above pH 8 the amount of adsorbed nickel decreases as the pH increases. According to the simple species, diagrams, which were constructed for Ni(II), up to pH 8, nickel is present in the

*Effect of contact time on all considered ions removal at pH 5 onto (a) phosphorus ions and (b) lead and nickel ions.*

ion and the considered species while increases progressively

Ni(II), respectively, and a fixed pH solution of 5.0. The data showed that the sorption on MOCB and MOCS was very fast at the initial stages of the contact period, and thereafter it becomes slower near the equilibrium. The difference between the surface areas of each adsorbent can explain the differences in their sorption capacities. The sorption of all elements on the two sorbents was very fast too in the first few minutes and sharply reached a 80% removal after only 10–15 min. When the sorption process approached completion, the sorption slowed down. In this work, subsequent experiments were carried out at a contact time of 2 h for all sorbents to

<sup>3</sup><sup>−</sup> and for Pb(II) and

*DOI: http://dx.doi.org/10.5772/intechopen.85318*

**3.2 Batch adsorption experiments**

*3.2.1 Kinetic study*

*3.2.2 Effect of initial pH*

the solution pH [20].

effects between H3O+

**Figure 2.** *EDAX spectrum of (a) MOCS and (b) MOCB.*

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

#### **3.2 Batch adsorption experiments**

#### *3.2.1 Kinetic study*

*Heavy Metal Toxicity in Public Health*

**Figure 2(a)** of the EDAX spectra of MOCS shows that Mn, O, and Si are the main constituents. These had been expected to be the principal elements of MOCS. In fact, EDAX the important peak of Si occurring in EDAX spectrum was apparently related to the too thin coating, or manganese oxides did not cover the full surface of the MOCS, allowing the X-ray to reach the sand support. From the EDAX spectrum of MOCB illustrated in **Figure 2(b)**, it was shown that Mn, O, Si, Al, Ca, and K are the dominant constituents. The presence of the Mn peak indicates

*SEM micrographs of samples: (a) US, (b) MOCS, (c) uncoated crushed brick, and (d) MOCB.*

It is to note that specific surface areas of the two sorbents increased after coat-

and uncoated crushed brick, respectively, after coating with manganese oxide

conclude that the addition of the manganese oxides contributes to the increase in

/g, for uncoated sand

/g, respectively. We can

the effectiveness of the adopted coating process.

ing. The obtained values of surface area were 1.36 and 1.86 m2

the surface area of sorbents increased to 3.81 and 4.64 m<sup>2</sup>

*3.1.2 Specific surface area*

**Figure 1.**

both inner and surface porosities.

*EDAX spectrum of (a) MOCS and (b) MOCB.*

**26**

**Figure 2.**

To study the effect of contact time on the sorption of all different ions, a different initial concentration was used: 10 mg/l and 50 mg/l for PO4 <sup>3</sup><sup>−</sup> and for Pb(II) and Ni(II), respectively, and a fixed pH solution of 5.0. The data showed that the sorption on MOCB and MOCS was very fast at the initial stages of the contact period, and thereafter it becomes slower near the equilibrium. The difference between the surface areas of each adsorbent can explain the differences in their sorption capacities. The sorption of all elements on the two sorbents was very fast too in the first few minutes and sharply reached a 80% removal after only 10–15 min. When the sorption process approached completion, the sorption slowed down. In this work, subsequent experiments were carried out at a contact time of 2 h for all sorbents to ensure that the equilibrium time was practically attained (**Figure 3**).

#### *3.2.2 Effect of initial pH*

Adsorption process is strongly related to pH and to the charge on both the adsorbate and the adsorbent. The surface charge on a manganese oxide surface varies with the solution pH due to the exchange of H+ ions. The surface groups on manganese oxide are amphoteric and can act as either an acid or a base. Consequently, the oxide surface can undergo protonation and deprotonation in response to changes in the solution pH [20].

The optimal pH was obtained at around pH 4. It is to note that the removal decreases continuously for pH values ranging between around 4 and 10 according to other works dealing with sorption of phosphate ions on hematite and Al2O3 [31], ion-exchange fiber [32], alunite [33], and bauxite [34]. The decrease in the phosphate ion uptake, occurring beyond pH 5, could be probably attributed in one hand to a competition between phosphate ions and hydroxyl ions for the sorption on the surface Lewis acid sites of the sorbent [21] and in another hand by considering a zero point of charge of the sorbent. In fact, above the zero point of charge, the positive charge density on the surface of the sorbents increases which disfavors the sorption of phosphate ions. The sorption of phosphate onto hydroxylated mineral surface can be described by a ligand exchange mechanism [35, 36], which causes an increase in pH due to the hydroxyl ions released from the oxidic sorbent. Concerning nickel sorption is negligible at the low pH values probably due to the competition effects between H3O+ ion and the considered species while increases progressively from pH 4. A maximum is reached at around pH 7–8; then, above pH 8 the amount of adsorbed nickel decreases as the pH increases. According to the simple species, diagrams, which were constructed for Ni(II), up to pH 8, nickel is present in the

**Figure 3.** *Effect of contact time on all considered ions removal at pH 5 onto (a) phosphorus ions and (b) lead and nickel ions.*

solution mainly in the form of Ni2+ ions. Neutral Ni(OH)2 particles start to precipitate at pH 8 and become predominant at pH 11 [37].

The adsorption of Pb(II) ions onto both adsorbents was markedly dependent on the pH value. When the initial solution pH increased from 2 to 7, the removal of Pb (II) ion was possibly inhibited following the competition between metal ions and H+ for the available adsorption locations, while the uptake of H+ ions was more preponderant. However, the adsorption of Pb (II) ions increased with the deprotonation of the binding sites caused by the negative charge density of each adsorbent and this with the increase of the pH [20].

From our previous work [20], we have attributed this increase in adsorption with decreasing H+ ion concentration (relatively high pH values), which indicates that ion exchange is one of the major adsorption processes. Due to the equal of positive and negative groups, the total surface charge is zero, which can explain the effect of pH in terms of pHpzc value of the adsorbent. The pHpzc of MOCS and MOCB was investigated and determined to be 4.5 and 4.3, respectively [20]. If the pH was below the pHpzc, the surface charge on the adsorbent was positive; however when it is above the pHpzc value, the surface charge was negative, so the two considered adsorbents (MOCS and MOCB) have positive surface charge, and this is below the respective pH values of 4.3 and 4.5; therefore, the absorption of Pb (II) ions was low. However, the surface charges of the two adsorbents MOCS and MOCB were negative when the pH was increased above 4.3 and 4.5, respectively. The uptake is going to increase if the Pb (II) species count were either neutral or positively charged. Also, at higher pH values than pHpzc, the cation removal would be favored, and for anion, the adsorption was favored at pH values lower than pHpzc.

#### **3.3 Sorption isotherm**

The sorption of all considered ions increases as its initial concentration in the solution increases, until a maximum value (saturation state) is reached.

The maximum sorption capacity, Q0, calculated from the Langmuir equation at 20°C, is indicated in **Table 1**.

As seen, sorption on the two coated sorbents is greater than that on virgin sand. The coatings significantly increase adsorption capacity, resulting in higher interactions between sorbents and sorbate. The values of sorption constants, derived from the Freundlich model (**Table 2**), show that the KF constant—which is a measure of sorption capacity—remains higher for MOCB than for MOCS. Values obtained of 1 < n < 10 imply favorable sorption of all ions on the two sorbents [20, 21].

#### **3.4 Thermodynamic adsorption parameters**

Thermodynamic parameters were evaluated using the data obtained at the temperatures of 10, 20, and 40 °C. The values of ΔG0 were calculated using the


**29**

**Table 3.**

*Thermodynamic parameters.*

**Table 2.**

*Freundlich parameters.*

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

tion by the two adsorbents was confirmed by the negative values of ΔG0

the slope and intercept of the plot of ln b versus 1/T. **Table 3** illustrates the calculated parameters for the two adsorbents. The spontaneous nature of all ions adsorp-

The pseudo-first-order and pseudo-second-order kinetic equations as well as the intraparticle diffusion model were applied to predict the kinetics of the adsorption of all ions onto the two adsorbents. The values, which are founded for the kinetic model, were excessively high (> 0.998); this result decreases for the intraparticle

Lead 3.53 0.26 0.997 2.97 0.33 0.97 Phosphate ions 0.58 0.39 0.98 0.78 0.36 0.98 Nickel 0.32 0.22 0.98 0.61 0.26 0,91

**Temperature (°C) 10 20 40** MOCS Lead ΔG° (kJ/mol) −30.948 −32.042 −34.229

Nickel ΔG° (kJ/mol) −23.35 −24.17 −25.82

Phosphate ions ΔG° (kJ/mol) −24.827 −25.704 −27.459

Nickel ΔG° (kJ/mol) −24.78 −25.68 −27.44

Phosphate ions ΔG° (kJ/mol) −27.703 −28.862 −30.640

MOCB Lead ΔG° (kJ/mol) −28.432 −29.437 −31.446

**Element SCM BCM**

and ΔS0

show that the adsorption process was endothermic

**Kf 1/n R2 Kf 1/n R2**

ΔH° (kJ/mol) 42.776 42.776 42.776 ΔS° (kJ/(kmol)) 0.252 0.252 0.252

ΔH° (kJ/mol) 17.63 17.63 17.63 ΔS° (kJ/(kmol)) 0.14 0.14 0.14

ΔH° (kJ/mol) 12.342 12.342 12.342 ΔS° (kJ/(kmol)) 0.129 0.129 0.129

ΔH° (kJ/mol) 32.753 32.753 32.753 ΔS° (kJ/(kmol)) 0.211 0.211 0.211

ΔH° (kJ/mol) 22.78 22.78 22.78 ΔS° (kJ/(kmol)) 0.16 0.16 0.16

ΔH° (kJ/mol) 24.693 24.693 24.693 ΔS° (kJ/(kmol)) 0.182 0.182 0.182

show the increasing randomness at solid/

were obtained from

. On the

*DOI: http://dx.doi.org/10.5772/intechopen.85318*

in nature, while the positive values of ΔS0

**3.5 Determination of kinetic parameters**

liquid interface during the adsorption process.

contrary, positive values of ΔH0

Langmuir isotherm constant, b. The values of ΔH0

**Table 1.** *Langmuir parameters.* *Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

Langmuir isotherm constant, b. The values of ΔH0 and ΔS0 were obtained from the slope and intercept of the plot of ln b versus 1/T. **Table 3** illustrates the calculated parameters for the two adsorbents. The spontaneous nature of all ions adsorption by the two adsorbents was confirmed by the negative values of ΔG0 . On the contrary, positive values of ΔH0 show that the adsorption process was endothermic in nature, while the positive values of ΔS0 show the increasing randomness at solid/ liquid interface during the adsorption process.

#### **3.5 Determination of kinetic parameters**

The pseudo-first-order and pseudo-second-order kinetic equations as well as the intraparticle diffusion model were applied to predict the kinetics of the adsorption of all ions onto the two adsorbents. The values, which are founded for the kinetic model, were excessively high (> 0.998); this result decreases for the intraparticle


#### **Table 2.**

*Heavy Metal Toxicity in Public Health*

tate at pH 8 and become predominant at pH 11 [37].

and this with the increase of the pH [20].

**3.3 Sorption isotherm**

20°C, is indicated in **Table 1**.

**3.4 Thermodynamic adsorption parameters**

solution mainly in the form of Ni2+ ions. Neutral Ni(OH)2 particles start to precipi-

From our previous work [20], we have attributed this increase in adsorption with decreasing H+ ion concentration (relatively high pH values), which indicates that ion exchange is one of the major adsorption processes. Due to the equal of positive and negative groups, the total surface charge is zero, which can explain the effect of pH in terms of pHpzc value of the adsorbent. The pHpzc of MOCS and MOCB was investigated and determined to be 4.5 and 4.3, respectively [20]. If the pH was below the pHpzc, the surface charge on the adsorbent was positive; however when it is above the pHpzc value, the surface charge was negative, so the two considered adsorbents (MOCS and MOCB) have positive surface charge, and this is below the respective pH values of 4.3 and 4.5; therefore, the absorption of Pb (II) ions was low. However, the surface charges of the two adsorbents MOCS and MOCB were negative when the pH was increased above 4.3 and 4.5, respectively. The uptake is going to increase if the Pb (II) species count were either neutral or positively charged. Also, at higher pH values than pHpzc, the cation removal would be favored, and for anion, the adsorption was favored at pH values lower than pHpzc.

The sorption of all considered ions increases as its initial concentration in the

The maximum sorption capacity, Q0, calculated from the Langmuir equation at

As seen, sorption on the two coated sorbents is greater than that on virgin sand. The coatings significantly increase adsorption capacity, resulting in higher interactions between sorbents and sorbate. The values of sorption constants, derived from the Freundlich model (**Table 2**), show that the KF constant—which is a measure of sorption capacity—remains higher for MOCB than for MOCS. Values obtained of

solution increases, until a maximum value (saturation state) is reached.

1 < n < 10 imply favorable sorption of all ions on the two sorbents [20, 21].

**Element SCM BCM**

Thermodynamic parameters were evaluated using the data obtained at the temperatures of 10, 20, and 40 °C. The values of ΔG0 were calculated using the

Lead 6 2.56 0.98 6.25 3.36 0.97 Phosphate ions 1.96 0.41 0.97 2.08 1.38 0.98 Nickel 3.33 0.34 0.99 3.7 0.62 0.99

**Q 0 (mg/g) b (l/mg) R2 Q 0 (mg/g) b (l/mg) R2**

The adsorption of Pb(II) ions onto both adsorbents was markedly dependent on the pH value. When the initial solution pH increased from 2 to 7, the removal of Pb (II) ion was possibly inhibited following the competition between metal ions and H+ for the available adsorption locations, while the uptake of H+ ions was more preponderant. However, the adsorption of Pb (II) ions increased with the deprotonation of the binding sites caused by the negative charge density of each adsorbent

**28**

**Table 1.**

*Langmuir parameters.*

*Freundlich parameters.*


#### **Table 3.** *Thermodynamic parameters.*

diffusion equation and also for the pseudo-first-order equation. Furthermore, the quantity of all considered elements adsorption at equilibrium (qe) compared to the experimental data concluded the pseudo-second-order link was more reasonable than that of the pseudo-first order model. This proposed that the removal operation move forward via a pseudo-second-order rather than a pseudo-first-order kinetic model. For this model, the initial adsorption rate, h, and the rate constant K2 diminished with the increase of the initial concentration of all considered ions; then, a limiting step may involve chemisorption [20].

#### **4. Conclusions**

Results obtained from this work showed that the deposited oxides were essentially amorphous and corresponded to 1.5 mg Mn(II)/g sand and 2 mg Mn(II)/g crushed brick.

The optimal pH adsorption for all considered ions was 5, and adsorption capacities were higher onto MOCB than MOCS.

The activation energy values for the two adsorbents found from Arrhenius plots and the kinetics which found pseudo-second order suggested that the limiting step of adsorption of all ions could be chemisorption. The results obtained in the present study suggest that manganese oxide-coated adsorbents are potentially suitable for removing of cations and anions from aqueous solution.

#### **Author details**

Nesrine Boujelben

Water Energy and Environment Laboratory, Geology Department, National Engineering School of Sfax, Sfax, Tunisia

\*Address all correspondence to: nesrine.boujelben@tunet.tn

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**31**

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

[8] Mohan D, Singh KP. Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse—An agricultural waste. Water Research.

[9] Han RP, Zhu L, Zou WH, Wang DT, Shi J, Yang JJ. Removal of copper(II) and lead(II) from aqueous solution by manganese oxide coated sand— II. Equilibrium study and competitive adsorption. Journal of Hazardous Materials. 2006;**137**(1):480-488

[10] Ghaedi M, Biyareh MN, Kokhdan

[11] Sun YB, Yang SB, Chen Y, Ding CC, Cheng WC, Wang XK. Adsorption and desorption of U(VI) on functionalized

[12] Ma MH, Gao HY, Sun YB, Huang MS. The adsorption and desorption of Ni(II) on Al substituted goethite. Journal of Molecular Liquids.

2015;**201**:30-35. International Journal of Environmental Research Public Health.

[13] Sounthararajah DP, Loganathan P, Kandasamy J, Vigneswaran S. Effects of humic acid and suspended solids on the removal of heavy metals from water by adsorption onto granular activated carbon. International Journal of Environmental Research and Public

graphene oxides: A combined experimental and theoretical study. Environmental Science & Technology.

SN, Shamsaldini S, Sahraei R, Daneshfar A, et al. Comparison of the efficiency of palladium and silver nanoparticles loaded on activated carbon and zinc oxide nanorods loaded on activated carbon as new adsorbents for removal of Congo red from aqueous solution: Kinetic and isotherm study. Materials Science and Engineering: C.

2012;**32**(4):725-734

2015;**49**:4255-4262

2017, 14, 1145 10 of 11

Health. 2015;**12**:10475-10489

2002;**36**(9):2304-2318

*DOI: http://dx.doi.org/10.5772/intechopen.85318*

[1] Rao MM, Rao GPC, Seshaiah K, Choudary NV, Wang MC. Activated carbon from Ceiba pentandra hulls, an agricultural waste, as an adsorbent in the removal of lead and zinc from aqueous solutions. Waste Management

(Oxford). 2008;**28**(5):849-858

2018;**43**:2155-2165

[2] Liu Z, Zhong X, Wang Y, Ding Z, Wang C, Wang G, et al. An efficient adsorption of manganese oxides/ activated carbon composite for lead(II) ions from aqueous solution. Arabian Journal for Science and Engineering.

[3] Sreejalekshmi KG, Krishnan KA, Anirudhan TS. Adsorption of Pb(II) and Pb(II)-citric acid on sawdust activated carbon: Kinetic and equilibrium isotherm studies. Journal of Hazardous Materials. 2009;**161**(2-3):1506-1513

[4] Aziz HA, Adlan MN, Ariffin KS. Heavy metals (Cd, Pb, Zn, Ni, Cu and Cr(III)) removal from water in Malaysia: Post treatment by high quality limestone. Bioresource Technology.

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electrochemical method with a stainless steel net electrode coated with single wall carbon nanotubes. Chemical Engineering Journal. 2013;**218**:81-88

[6] Al-Othman ZA, Naushad Inamuddin M. Organic–inorganic type composite cation exchanger poly-o-toluidine Zr(IV) tungstate: Preparation, physicochemical characterization and its analytical application in separation of heavy metals. Chemical Engineering

Journal. 2011;**172**(1):369-375

[7] O'Connell DW, Birkinshaw C, O'Dwyer TF. Heavy metal adsorbents prepared from the modification of cellulose: A review. Bioresource Technology. 2008;**99**:6709-6724

2008;**99**(6):1578-1583

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

#### **References**

*Heavy Metal Toxicity in Public Health*

**4. Conclusions**

crushed brick.

then, a limiting step may involve chemisorption [20].

removing of cations and anions from aqueous solution.

ties were higher onto MOCB than MOCS.

**30**

**Author details**

Nesrine Boujelben

provided the original work is properly cited.

Engineering School of Sfax, Sfax, Tunisia

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Water Energy and Environment Laboratory, Geology Department, National

diffusion equation and also for the pseudo-first-order equation. Furthermore, the quantity of all considered elements adsorption at equilibrium (qe) compared to the experimental data concluded the pseudo-second-order link was more reasonable than that of the pseudo-first order model. This proposed that the removal operation move forward via a pseudo-second-order rather than a pseudo-first-order kinetic model. For this model, the initial adsorption rate, h, and the rate constant K2 diminished with the increase of the initial concentration of all considered ions;

Results obtained from this work showed that the deposited oxides were essentially amorphous and corresponded to 1.5 mg Mn(II)/g sand and 2 mg Mn(II)/g

The optimal pH adsorption for all considered ions was 5, and adsorption capaci-

The activation energy values for the two adsorbents found from Arrhenius plots and the kinetics which found pseudo-second order suggested that the limiting step of adsorption of all ions could be chemisorption. The results obtained in the present study suggest that manganese oxide-coated adsorbents are potentially suitable for

\*Address all correspondence to: nesrine.boujelben@tunet.tn

[1] Rao MM, Rao GPC, Seshaiah K, Choudary NV, Wang MC. Activated carbon from Ceiba pentandra hulls, an agricultural waste, as an adsorbent in the removal of lead and zinc from aqueous solutions. Waste Management (Oxford). 2008;**28**(5):849-858

[2] Liu Z, Zhong X, Wang Y, Ding Z, Wang C, Wang G, et al. An efficient adsorption of manganese oxides/ activated carbon composite for lead(II) ions from aqueous solution. Arabian Journal for Science and Engineering. 2018;**43**:2155-2165

[3] Sreejalekshmi KG, Krishnan KA, Anirudhan TS. Adsorption of Pb(II) and Pb(II)-citric acid on sawdust activated carbon: Kinetic and equilibrium isotherm studies. Journal of Hazardous Materials. 2009;**161**(2-3):1506-1513

[4] Aziz HA, Adlan MN, Ariffin KS. Heavy metals (Cd, Pb, Zn, Ni, Cu and Cr(III)) removal from water in Malaysia: Post treatment by high quality limestone. Bioresource Technology. 2008;**99**(6):1578-1583

[5] Liu YX, Yan JM, Yuan DX, Li QL, Wu XY. The study of lead removal from aqueous solution using an electrochemical method with a stainless steel net electrode coated with single wall carbon nanotubes. Chemical Engineering Journal. 2013;**218**:81-88

[6] Al-Othman ZA, Naushad Inamuddin M. Organic–inorganic type composite cation exchanger poly-o-toluidine Zr(IV) tungstate: Preparation, physicochemical characterization and its analytical application in separation of heavy metals. Chemical Engineering Journal. 2011;**172**(1):369-375

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[23] Lo SL, Jengh T, Lai CH. Characteristics and adsorption properties of an ironcoated sand. Water Science and Technology. 1997;**35**:63-70

[24] Seader JD, Herley EJ. Separation Process Principles. New York: Wiley; 1998

[25] Aksu Z. Determination of the equilibrium, kinetic and thermodynamic parameters of the batch biosorption of nickel (II) ions onto chlorella vulgaris. Process Biochemistry. 2002;**38**(1):89-99

[26] Namasivayam C, Ranganathan K. Waste Fe(III)/Cr(III) hydroxide as adsorbent for the removal of Cr(VI) from aqueous solution and chromium plating industry waste water. Environmental Pollution. 1993;**82**:255-261

[27] Panday KK, Prasad G, Singh VN. Copper(II) removal from aqueous solutions by fly ash. Water Research. 1985;**19**:869-873

[28] Selvaraj R, Younghun K, Cheol KJ. Removal of copper from aqueous solution by aminated and protonated mesoporous aluminas: Kinetics and equilibrium. Journal of Colloid and Interface Science. 2004;**273**:14-21

[29] Chiron N, Guilet R, Deydier E. Adsorption of Cu(II) and Pb(II) onto a grafted silica: Isotherms and kinetic models. Water Research. 2003;**37**(13):3079-3086

[30] Chang YY, Kim KS, Jung JH, Yang JK, Lee SM. Application of iron-coated sand and manganese-coated sand on the treatment of both As(III) and

**33**

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese…*

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As(V). Water Science and Technology.

[31] Hu P-Y, Hsieh Y-H, Chen J-C, Chang C-Y. Characteristics of manganesecoated sand using SEM and EDAX analysis. Journal of Colloid and Interface Science. 2004;**274**:308-312

[32] Horanyi G, Joo P. Some peculiarities in the specific adsorption of phosphate ions on hematite c-Al2O3 as reflected by radiotracer studies. Journal of Colloid and Interface Science. 2002;**247**:12-17

[33] Xia LR, Jinlong G, Hongxiao T. Adsorption of fluoride, phosphate, and arsenate ions on a new type of ion exchange fiber. Journal of Colloid and Interface Science. 2002;**248**:268-274

[34] Ozacar M. Phosphate adsorption characteristics of alunite to be used as a cement additive. Cement and Concrete

[35] Altundogan HS, Tumen F. Removal of phosphates from aqueous solutions by using bauxite. I: Effect of pH on the adsorption of various phosphates. Journal of Chemical Technology & Biotechnology. 2001;**77**:77-85

[36] Goldberg S, Sposito G. On the mechanism of specific phosphate adsorption by hydroxylated mineral surfaces: A review. Communications in Soil Science and Plant Analysis.

[37] Mavros P, Zouboulis AI, Lazaridis NK. Removal of metal ions from wastewaters the case of nickel.

Journal of Environmental Technology.

Research. 2003;**2372**:1-5

1985;**16**:801-821

1993;**14**:83-91

2007;**55**:69-75

*Sorption of Phosphorus, Nickel, and Lead from Aqueous Solution Using Manganese… DOI: http://dx.doi.org/10.5772/intechopen.85318*

As(V). Water Science and Technology. 2007;**55**:69-75

*Heavy Metal Toxicity in Public Health*

[14] Lee SM, Laldawngliana C, Tiwari D. Iron oxide nano-particlesimmobilized-sand material in the treatment of Cu(II), Cd(II) and Pb(II) contaminated waste waters. Chemical Engineering Journal. 2012;**195**:103-111

[22] Bajpai S, Chaudhuri M. Removal of arsenic from ground water by manganese dioxide–coated sand. Journal of Environmental Engineering. 1999;**125**(8):782-784

sand. Water Science and Technology.

[24] Seader JD, Herley EJ. Separation Process Principles. New York: Wiley;

thermodynamic parameters of the batch biosorption of nickel (II) ions onto chlorella vulgaris. Process Biochemistry.

[26] Namasivayam C, Ranganathan K. Waste Fe(III)/Cr(III) hydroxide as adsorbent for the removal of Cr(VI) from aqueous solution and chromium plating industry waste water. Environmental Pollution.

[27] Panday KK, Prasad G, Singh VN. Copper(II) removal from aqueous solutions by fly ash. Water Research.

[28] Selvaraj R, Younghun K, Cheol KJ. Removal of copper from aqueous solution by aminated and protonated mesoporous aluminas: Kinetics and equilibrium. Journal of Colloid and Interface Science. 2004;**273**:14-21

[29] Chiron N, Guilet R, Deydier E. Adsorption of Cu(II) and Pb(II) onto a grafted silica: Isotherms and kinetic models. Water Research.

[30] Chang YY, Kim KS, Jung JH, Yang JK, Lee SM. Application of iron-coated sand and manganese-coated sand on the treatment of both As(III) and

2003;**37**(13):3079-3086

[25] Aksu Z. Determination of the equilibrium, kinetic and

[23] Lo SL, Jengh T, Lai CH. Characteristics and adsorption properties of an ironcoated

1997;**35**:63-70

2002;**38**(1):89-99

1993;**82**:255-261

1985;**19**:869-873

1998

[15] Tani Y, Miyata N, Ohashi M, Ohnuki T, Seyama H, Iwahori K, et al. Interaction of inorganic arsenic with biogenic manganese oxide produced by a Mn-oxidizing fungus, strain KR21-2. Environmental Science & Technology.

[16] Kennedy C, Smith DS, Warren LA. Surface chemistry and relative Ni sorptive capacities of synthetic hydrous Mn oxyhydroxides under variable wetting and drying regimes. Geochimica et Cosmochimica Acta.

[17] Villalobos M, Bargar J, Sposito G. Mechanisms of Pb(II) sorption on a biogenic manganese oxide. Environmental Science & Technology.

[18] Benjamin MM, Slatten RS, Bailey RP, Bennett T. Sorption and filtration of metals using iron oxide coated sand. Water Research. 1996;**30**:2609-2620

[19] Sharma SK, Petrusevski B, Schippers JC. Characterisation of coated sand from iron removal plants. Journal of Water Supply: Research and

Technology. 2002;**2**:247-257

[20] Boujeben N, Bouzid J, Elouear Z. Removal of Lead(II) ions from aqueous solutions using manganese oxide-coated adsorbents: Characterization and kinetic study. Adsorption Science & Technology.

[21] Boujelben N, Bouhamed F, Elouear Z, Bouzid J, Feki M. Removal of

phosphorus ions from aqueous solutions using manganese-oxide-coated sand and brick. Desalination and Water Treatment. 2014;**52**:2282-2292

2004;**38**:6618-6624

2004;**68**:443-454

2005;**39**:569-576

**32**

2009;**27**:2

[31] Hu P-Y, Hsieh Y-H, Chen J-C, Chang C-Y. Characteristics of manganesecoated sand using SEM and EDAX analysis. Journal of Colloid and Interface Science. 2004;**274**:308-312

[32] Horanyi G, Joo P. Some peculiarities in the specific adsorption of phosphate ions on hematite c-Al2O3 as reflected by radiotracer studies. Journal of Colloid and Interface Science. 2002;**247**:12-17

[33] Xia LR, Jinlong G, Hongxiao T. Adsorption of fluoride, phosphate, and arsenate ions on a new type of ion exchange fiber. Journal of Colloid and Interface Science. 2002;**248**:268-274

[34] Ozacar M. Phosphate adsorption characteristics of alunite to be used as a cement additive. Cement and Concrete Research. 2003;**2372**:1-5

[35] Altundogan HS, Tumen F. Removal of phosphates from aqueous solutions by using bauxite. I: Effect of pH on the adsorption of various phosphates. Journal of Chemical Technology & Biotechnology. 2001;**77**:77-85

[36] Goldberg S, Sposito G. On the mechanism of specific phosphate adsorption by hydroxylated mineral surfaces: A review. Communications in Soil Science and Plant Analysis. 1985;**16**:801-821

[37] Mavros P, Zouboulis AI, Lazaridis NK. Removal of metal ions from wastewaters the case of nickel. Journal of Environmental Technology. 1993;**14**:83-91

**35**

**1. Introduction**

**Chapter 3**

**Abstract**

Tract Cancers

carcinogenesis in a number of cancer models.

benzo[a]pyrene, respiratory tract cancers

conditions rapidly change on the planet.

*Chanda Siddoo-Atwal*

A Role for Heavy Metal Toxicity

and Air Pollution in Respiratory

Cigarette smoke and air pollution have been associated with lung cancer and naso pharyngeal and laryngeal cancer, respectively. Significant concentrations of select heavy metals including lead and cadmium have been isolated in popular cigarette brands, and these heavy metals can be inhaled via smoking. Lead is able to mimic the activity of calcium in the human body, thereby leading to toxic effects in a variety of target organs. Lead perturbs and alters the release of intracellular calcium stores from organelles like the endoplasmic reticulum (ER) and mitochondria. A rise in mitochondrial calcium stimulates the generation of reactive oxygen species (ROS) and free fatty acids which can further promote calcium release and, ultimately, result in cell death. In the case of cadmium, the renal proximal tubule of the kidney accumulates freely filtered and metallothionein-bound metal, which is degraded in endosomes and lysosomes. This results in the release of free cadmium into the cytosol where it can generate reactive oxygen species and activate cell death pathways. In developing countries, indoor air pollution due to the domestic use of unprocessed biomass fuels such as wood, dung, and coal is another cause of respiratory tract cancers in humans. In some developed countries such as Australia and Canada, the alarming increase in forest fire frequency due to climate change and the associated smoke released into the environment is also likely to pose a future human health risk. Polycyclic organic particles in biomass and forest fire smoke can include carcinogens such as benzo[a]pyrene, which is also found in cigarette smoke. Benzo[a]pyrene can induce apoptosis in mammalian cells by initiating mitochondrial dysfunction, activating the intrinsic caspase pathway (caspase-3 and caspase-9), and via p53 activation. The constitutive activation of apoptotic pathways has been linked to

**Keywords:** cigarette smoke, indoor and outdoor air pollution, lead, cadmium,

"Smoking is hazardous to the health" is a phrase that is commonly used and understood in many parts of the world. In actuality, "smoke" is the hazard. The inhalation of smoke from cigarettes, indoor air pollution, and forest fires currently constitutes a serious public health issue of increasing importance as environmental **Chapter 3**

## A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers

*Chanda Siddoo-Atwal*

#### **Abstract**

Cigarette smoke and air pollution have been associated with lung cancer and naso pharyngeal and laryngeal cancer, respectively. Significant concentrations of select heavy metals including lead and cadmium have been isolated in popular cigarette brands, and these heavy metals can be inhaled via smoking. Lead is able to mimic the activity of calcium in the human body, thereby leading to toxic effects in a variety of target organs. Lead perturbs and alters the release of intracellular calcium stores from organelles like the endoplasmic reticulum (ER) and mitochondria. A rise in mitochondrial calcium stimulates the generation of reactive oxygen species (ROS) and free fatty acids which can further promote calcium release and, ultimately, result in cell death. In the case of cadmium, the renal proximal tubule of the kidney accumulates freely filtered and metallothionein-bound metal, which is degraded in endosomes and lysosomes. This results in the release of free cadmium into the cytosol where it can generate reactive oxygen species and activate cell death pathways. In developing countries, indoor air pollution due to the domestic use of unprocessed biomass fuels such as wood, dung, and coal is another cause of respiratory tract cancers in humans. In some developed countries such as Australia and Canada, the alarming increase in forest fire frequency due to climate change and the associated smoke released into the environment is also likely to pose a future human health risk. Polycyclic organic particles in biomass and forest fire smoke can include carcinogens such as benzo[a]pyrene, which is also found in cigarette smoke. Benzo[a]pyrene can induce apoptosis in mammalian cells by initiating mitochondrial dysfunction, activating the intrinsic caspase pathway (caspase-3 and caspase-9), and via p53 activation. The constitutive activation of apoptotic pathways has been linked to carcinogenesis in a number of cancer models.

**Keywords:** cigarette smoke, indoor and outdoor air pollution, lead, cadmium, benzo[a]pyrene, respiratory tract cancers

#### **1. Introduction**

"Smoking is hazardous to the health" is a phrase that is commonly used and understood in many parts of the world. In actuality, "smoke" is the hazard. The inhalation of smoke from cigarettes, indoor air pollution, and forest fires currently constitutes a serious public health issue of increasing importance as environmental conditions rapidly change on the planet.

The presence of heavy metals and other toxic and trace elements in tobacco smoke is a major concern. Notably, lead (Pb), arsenic (As), chromium (Cr), nickel (Ni), and cadmium (Cd) are usually associated with its adverse health effects. Heavy metals can pass from tobacco to the smoke and smoke condensate [1]. Although cigarette filters remove a portion of these elements, environmental smoke pollution occurs via the smoke exhaled by the smoker and the sidestream smoke emitted by the burning cigarette. The sidestream smoke inhaled by nonsmokers can contain a relatively high concentration of heavy metals. This process of passive smoking can result in the deposition of heavy metals deep in the lung tissue [2].

Lead and cadmium, particularly, both of which have long half-lives (10–12 years), accumulate in tissues and fluids following smoke exposure. Biomonitoring studies reveal that smokers have substantially higher lead and cadmium levels than nonsmokers. Bioaccumulation of metals has also been demonstrated in nonsmokers, who are chronically exposed to secondhand smoke [3]. Smoking-related diseases can be attributed to the inhalation of many different toxins including heavy metals. Heavy metals like lead have been shown to affect various biochemical processes in the human body including calcium metabolism and the activation of cell death pathways which are involved in carcinogenesis [4].

A significant percentage of people in developing countries utilize coal and biomass fuels like wood and dung for domestic energy. These materials are often burnt in simple stoves resulting in incomplete combustion. Consequently, women and young children are exposed to high levels of indoor air pollution daily. Many substances in biomass smoke are hazardous to the health including carbon monoxide, nitrous oxides, sulfur oxides (principally from coal), formaldehyde, and polycyclic organic matter (notably carcinogens such as benzo[a]pyrene [BaP]). Particles, particularly with diameters below 10 microns (PM10), especially those less than 2.5 microns in diameter (PM2.5), can penetrate deeply into the lungs to cause damage to these delicate organs. Epidemiological evidence suggests that indoor air pollution increases the risk of chronic obstructive pulmonary disease and of acute respiratory infections in childhood, which are the most important cause of death among preschool children in developing nations. Biomass smoke is also associated with low birth weight, increased infant and perinatal mortality, pulmonary tuberculosis, nasopharyngeal and laryngeal cancer, cataracts, and lung cancer (specifically, in the case of coal) [5].

The incidence of forest fires is strongly linked to climatic conditions. In fact, climate change is predicted to affect forests in the following ways: increased growth rates, tree-line movements, changes to forest species assemblages, increased fire incidence, more severe droughts in some areas, increased storm damage, and increased insect and pathogen damage [6]. Specifically, predicted impacts of climate change in Australia include increased fuel loadings, drier fuels, and increased dangerous fire weather [7, 8]. Model predictions for Canada have found expectations of decreased fire frequency in parts of the eastern boreal forest, while dramatic increases are expected elsewhere in the country [9]. In fact, over recent decades, the area burned by wildland fires in Canada has steadily increased and is predicted to double by the end of the century accompanied by an increase in length of the fire season [10]. At the same time, it is important to note that several climatic and non-climatic factors besides increased temperatures determine forest fire frequency including ignition sources, fuel loads, vegetation characteristics, rainfall, humidity, wind, topography, landscape fragmentation, and management policies [11]. Currently, research on the health effects of forest and wild fire smoke

**37**

**2. Lead [Pb]**

**Figure 1.**

(EPA) and other regulatory agencies [16, 17].

*A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers*

is limited [12]. However, smoke from these conflagrations contains the same kind of particles as indoor combustion from wood smoke. Similar to the situation of indoor air pollution from biomass smoke, forest fires generate polycyclic aromatic hydrocarbons (PAHs), which can include carcinogens such as benzo(a)pyrene [BaP] [13]. Polycyclic aromatic hydrocarbons (PAH) like BaP can stimulate various biochemical processes in the body including the continuous activation of apoptotic (cell death) pathways that have been linked to the initiation of carcinogenesis [14]. It is of interest that this chemical compound (BaP) is also found in cigarette smoke (**Figure 1**).

*The same view of the Olympic Mountains in Washington State, USA, before (left) and during (right) forest* 

Generally, elemental lead use and exposure have decreased significantly since the 1970s due to the innovation of unleaded gasoline and lead-free plumbing and paints. However, lead poisoning is still a serious problem. Lead is very toxic and specifically targets the kidneys, liver, central nervous system, hematopoietic system, and endocrine and reproductive systems. It can be absorbed by women during pregnancy and transferred to the developing fetus. Prenatal lead exposure has been linked to reduced birth weight, preterm delivery, and neurodevelopmental abnormalities in offspring. Exposure occurs mostly as a result of deteriorating house paints, contact at the workplace, hobbies, leaching from lead-containing vessels into food and water, cigarette smoke, and the use of lead in certain traditional medicines and cosmetics. Routes of exposure mainly include inhalation of lead-containing dust particles and ingestion of lead-contaminated food and water [15]. Lead has been classed as a probable carcinogen by the Environmental Protection Agency

Lead is able to mimic the activity of calcium in the human body, thereby leading to toxic effects in a variety of target organs [15]. These biochemical effects include the calcium-dependent inhibition of release of several neurotransmitters [18] and augmentation of calcium-dependent events involving protein kinase C and calmodulin [19, 20]. Lead can also be incorporated into the human skeleton instead of calcium. Moreover, lead perturbs and alters the release of intracellular calcium stores from organelles like the endoplasmic reticulum (ER) and mitochondria [19, 21]. Mitochondria can accumulate large amounts of calcium, for example, in the presence of inorganic phosphate. The rise in calcium results in an upregulation of energy metabolism and an increase in mitochondrial membrane potential. Then, the release of this accumulated calcium through a special channel, permeability transition pore (PTP), can cause mitochondrial depolarization. According to the

*DOI: http://dx.doi.org/10.5772/intechopen.90092*

*fire season (2018) in British Columbia, Canada.*

*A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers DOI: http://dx.doi.org/10.5772/intechopen.90092*

**Figure 1.**

*Heavy Metal Toxicity in Public Health*

tissue [2].

carcinogenesis [4].

cancer (specifically, in the case of coal) [5].

The presence of heavy metals and other toxic and trace elements in tobacco smoke is a major concern. Notably, lead (Pb), arsenic (As), chromium (Cr), nickel (Ni), and cadmium (Cd) are usually associated with its adverse health effects. Heavy metals can pass from tobacco to the smoke and smoke condensate [1]. Although cigarette filters remove a portion of these elements, environmental smoke pollution occurs via the smoke exhaled by the smoker and the sidestream smoke emitted by the burning cigarette. The sidestream smoke inhaled by nonsmokers can contain a relatively high concentration of heavy metals. This process of passive smoking can result in the deposition of heavy metals deep in the lung

Lead and cadmium, particularly, both of which have long half-lives (10–12 years), accumulate in tissues and fluids following smoke exposure. Biomonitoring studies reveal that smokers have substantially higher lead and cadmium levels than nonsmokers. Bioaccumulation of metals has also been demonstrated in nonsmokers, who are chronically exposed to secondhand smoke [3]. Smoking-related diseases can be attributed to the inhalation of many different toxins including heavy metals. Heavy metals like lead have been shown to affect various biochemical processes in the human body including calcium metabolism and the activation of cell death pathways which are involved in

A significant percentage of people in developing countries utilize coal and biomass fuels like wood and dung for domestic energy. These materials are often burnt in simple stoves resulting in incomplete combustion. Consequently, women and young children are exposed to high levels of indoor air pollution daily. Many substances in biomass smoke are hazardous to the health including carbon monoxide, nitrous oxides, sulfur oxides (principally from coal), formaldehyde, and polycyclic organic matter (notably carcinogens such as benzo[a]pyrene [BaP]). Particles, particularly with diameters below 10 microns (PM10), especially those less than 2.5 microns in diameter (PM2.5), can penetrate deeply into the lungs to cause damage to these delicate organs. Epidemiological evidence suggests that indoor air pollution increases the risk of chronic obstructive pulmonary disease and of acute respiratory infections in childhood, which are the most important cause of death among preschool children in developing nations. Biomass smoke is also associated with low birth weight, increased infant and perinatal mortality, pulmonary tuberculosis, nasopharyngeal and laryngeal cancer, cataracts, and lung

The incidence of forest fires is strongly linked to climatic conditions. In fact, climate change is predicted to affect forests in the following ways: increased growth

rates, tree-line movements, changes to forest species assemblages, increased fire incidence, more severe droughts in some areas, increased storm damage, and increased insect and pathogen damage [6]. Specifically, predicted impacts of climate change in Australia include increased fuel loadings, drier fuels, and increased dangerous fire weather [7, 8]. Model predictions for Canada have found expectations of decreased fire frequency in parts of the eastern boreal forest, while dramatic increases are expected elsewhere in the country [9]. In fact, over recent decades, the area burned by wildland fires in Canada has steadily increased and is predicted to double by the end of the century accompanied by an increase in length of the fire season [10]. At the same time, it is important to note that several climatic and non-climatic factors besides increased temperatures determine forest fire frequency including ignition sources, fuel loads, vegetation characteristics, rainfall, humidity, wind, topography, landscape fragmentation, and management policies [11]. Currently, research on the health effects of forest and wild fire smoke

**36**

*The same view of the Olympic Mountains in Washington State, USA, before (left) and during (right) forest fire season (2018) in British Columbia, Canada.*

is limited [12]. However, smoke from these conflagrations contains the same kind of particles as indoor combustion from wood smoke. Similar to the situation of indoor air pollution from biomass smoke, forest fires generate polycyclic aromatic hydrocarbons (PAHs), which can include carcinogens such as benzo(a)pyrene [BaP] [13]. Polycyclic aromatic hydrocarbons (PAH) like BaP can stimulate various biochemical processes in the body including the continuous activation of apoptotic (cell death) pathways that have been linked to the initiation of carcinogenesis [14]. It is of interest that this chemical compound (BaP) is also found in cigarette smoke (**Figure 1**).

#### **2. Lead [Pb]**

Generally, elemental lead use and exposure have decreased significantly since the 1970s due to the innovation of unleaded gasoline and lead-free plumbing and paints. However, lead poisoning is still a serious problem. Lead is very toxic and specifically targets the kidneys, liver, central nervous system, hematopoietic system, and endocrine and reproductive systems. It can be absorbed by women during pregnancy and transferred to the developing fetus. Prenatal lead exposure has been linked to reduced birth weight, preterm delivery, and neurodevelopmental abnormalities in offspring. Exposure occurs mostly as a result of deteriorating house paints, contact at the workplace, hobbies, leaching from lead-containing vessels into food and water, cigarette smoke, and the use of lead in certain traditional medicines and cosmetics. Routes of exposure mainly include inhalation of lead-containing dust particles and ingestion of lead-contaminated food and water [15]. Lead has been classed as a probable carcinogen by the Environmental Protection Agency (EPA) and other regulatory agencies [16, 17].

Lead is able to mimic the activity of calcium in the human body, thereby leading to toxic effects in a variety of target organs [15]. These biochemical effects include the calcium-dependent inhibition of release of several neurotransmitters [18] and augmentation of calcium-dependent events involving protein kinase C and calmodulin [19, 20]. Lead can also be incorporated into the human skeleton instead of calcium.

Moreover, lead perturbs and alters the release of intracellular calcium stores from organelles like the endoplasmic reticulum (ER) and mitochondria [19, 21]. Mitochondria can accumulate large amounts of calcium, for example, in the presence of inorganic phosphate. The rise in calcium results in an upregulation of energy metabolism and an increase in mitochondrial membrane potential. Then, the release of this accumulated calcium through a special channel, permeability transition pore (PTP), can cause mitochondrial depolarization. According to the

model of glutamate toxicity, mitochondrial calcium accumulation and resultant membrane depolarization are clearly linked to the initiation of a cell death pathway in mitochondria [22, 23].

A rise in mitochondrial calcium also stimulates the generation of reactive oxygen species (ROS) and free fatty acids which can further promote opening of the PTP, resulting in calcium release and, ultimately, in cell death [23]. Many genes and proteins that respond to conditions of oxidative stress stimulated by ROS release within the cell subsequently trigger apoptosis. Because mitochondria are important regulators of cellular redox status, the induction of oxidative stress exhibits its effects upon these organelles by triggering the intrinsic apoptotic pathway via cytochrome c release and caspase cascade activation [24, 25].

In this regard, it has been reported in various experiments that lead poisoning results in cellular damage mediated by the formation of reactive oxygen species (ROS) [26]. An elevation in the relative activities of certain antioxidant enzymes such as glutathione peroxidase has also been reported in the erythrocytes of leadexposed workers [27].

In one large epidemiological study in Eastern Europe spanning several years, an elevated risk of renal cell carcinoma was observed in the category of highest cumulative occupational lead exposure [28]. Lead has been found to induce renal tumors in rats and mice [29, 30]. Lead causes DNA strand breakage and 8-hydroxy-deoxyguanosine adduct formation in calf thymus DNA [31]. It induces sister chromatid exchanges in Chinese hamster ovary cells [32]. Lead-induced cytotoxicity and apoptosis have been demonstrated in human cancer cells via various cellular and molecular processes including oxidative stress induction and caspase-3 activation [15]. Finally, mitochondrial alterations appear to play a central role in lead-induced rod photoreceptor cell apoptosis [33].

Taken together, the above data point to the activation of apoptotic pathways as a possible mechanism of lead carcinogenesis. It clearly has the potential to initiate cancer as described in a new approach to cancer risk assessment based on an apoptotic model of tumor formation. In this two-stage model of tumor formation, Step I exposure to a carcinogen (Pb in this case), possibly facilitated by a genetic predisposition, results in an epigenetic or genetic event causing continuous apoptotic activation of cells in the target tissue. In Step II, when the carcinogen may or may not be present, resistance to apoptosis and continuous cell proliferation result due to another genetic or epigenetic event [4, 14].

#### **3. Cadmium [Cd]**

Cadmium is a heavy metal that is widely distributed in the earth's crust, while the highest level of cadmium compounds is found in sedimentary rocks and marine phosphates. Human exposure to this element can occur through employment in primary metal industries, eating contaminated food, smoking cigarettes (a major contributor), and working in cadmium-contaminated places. Other sources of cadmium include emissions from mining, smelting, manufacturing batteries, pigments, stabilizers, and alloys. The main routes of cadmium exposure are via inhalation or cigarette smoke and ingestion of food. It is a severe pulmonary and gastrointestinal irritant, which can prove fatal when inhaled or ingested in extreme cases [15].

Cadmium levels in the body can be measured in the blood or urine. Typically, blood and urine cadmium levels are higher in cigarette smokers, intermediate in former smokers, and lower in nonsmokers. The circulatory system is an important distribution route of cadmium toxicity, and blood vessels are considered to be the

**39**

provides [39].

*A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers*

primary target. Chronic cadmium inhalation exposure is associated with changes in pulmonary function and chest radiographs consistent with emphysema. Chronic low-level cadmium exposure can also cause decreases in olfactory function and

Cadmium compounds have been classified as human carcinogens by certain regulatory agencies including the International Agency for Research on Cancer and the US National Toxicology Program based on repeated findings of a correlation between occupational cadmium exposure and lung cancer in humans. In addition, there is strong experimental evidence that the pulmonary system is the main target site for carcinogenesis in rodents [17]. Such rodent studies reveal that chronic cadmium inhalation results in pulmonary adenocarcinomas. Oral cadmium exposure in rats is also associated with tumors of the prostate, testes, and

Cadmium is a weak mutagen and the mechanisms of its toxicity are poorly understood. It has been reported to affect signal transduction pathways, induce inositol phosphate formation, increase cytosolic free calcium levels in a variety of cell types, and block calcium channels. At lower micromolar concentrations, cadmium can induce the expression of antioxidant enzymes such as glutathione transferases and metallothioneins suggesting that it causes cellular damage via the generation of

Specifically, receptor-mediated endocytosis of freely filtered and metallothionein-bound cadmium causes it to accumulate in the renal proximal tubule of the kidney. Following internalization and degradation of metallothionein-cadmium complexes in endosomes and lysosomes in this kidney model, free cadmium is released into the cytosol, where it can generate ROS and activate cell death path-

**4. Polycyclic aromatic hydrocarbons [PAHs] and benzo(a)pyrene [BaP]**

Polycyclic aromatic hydrocarbons and their derivatives are a major class of organic compounds that are produced as a result of incomplete combustion of fossil fuels and other organic matter. Consequently, they are prevalent in the human environment and include a number of potent carcinogens. Some of the major sources of these emissions are wood and coal burning, automobiles and other fossilfuel propelled modes of transportation, heat and power plants, and refuse burning. PAHs are not only present in the air, but are found in many common foods and drinking water and form a significant component of tobacco smoke [38].

Levels of PAHs are routinely measured in the atmosphere for air quality assess-

PAH-DNA adducts have been compared in the peripheral leukocytes of nonsmall cell lung cancer patients and in controls. Adduct formation has been found to be significantly higher in lung cancer cases than in controls. Further, in the cancer patients, adducts were more strongly correlated with lung tumor tissue than with non-tumor lung tissue consistent with a genetic susceptibility to lung cancer as a result of adduct-induced DNA damage [40]. More specifically, BPDE-DNA adducts have been observed in the white blood cells of occupationally exposed workers and cigarette smokers. BaP is metabolically activated to its carcinogenic form benzo(*a*) pyrene diol epoxide (BPDE), and this is an important step in BaP carcinogenicity

ment, in sediments and mollusks for environmental monitoring, in biological tissues for monitoring of health effects, and in foodstuffs for safety reasons. Gas chromatography is often chosen for analyzing (separating, identifying, and quantifying) PAHs due to the high degree of selectivity and resolution this method

ROS, which can initiate DNA damage and activate apoptotic pathways.

*DOI: http://dx.doi.org/10.5772/intechopen.90092*

bone mineral density and osteoporosis.

hematopoietic system [34–36].

ways [37] implicated in cancer.

#### *A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers DOI: http://dx.doi.org/10.5772/intechopen.90092*

primary target. Chronic cadmium inhalation exposure is associated with changes in pulmonary function and chest radiographs consistent with emphysema. Chronic low-level cadmium exposure can also cause decreases in olfactory function and bone mineral density and osteoporosis.

Cadmium compounds have been classified as human carcinogens by certain regulatory agencies including the International Agency for Research on Cancer and the US National Toxicology Program based on repeated findings of a correlation between occupational cadmium exposure and lung cancer in humans. In addition, there is strong experimental evidence that the pulmonary system is the main target site for carcinogenesis in rodents [17]. Such rodent studies reveal that chronic cadmium inhalation results in pulmonary adenocarcinomas. Oral cadmium exposure in rats is also associated with tumors of the prostate, testes, and hematopoietic system [34–36].

Cadmium is a weak mutagen and the mechanisms of its toxicity are poorly understood. It has been reported to affect signal transduction pathways, induce inositol phosphate formation, increase cytosolic free calcium levels in a variety of cell types, and block calcium channels. At lower micromolar concentrations, cadmium can induce the expression of antioxidant enzymes such as glutathione transferases and metallothioneins suggesting that it causes cellular damage via the generation of ROS, which can initiate DNA damage and activate apoptotic pathways.

Specifically, receptor-mediated endocytosis of freely filtered and metallothionein-bound cadmium causes it to accumulate in the renal proximal tubule of the kidney. Following internalization and degradation of metallothionein-cadmium complexes in endosomes and lysosomes in this kidney model, free cadmium is released into the cytosol, where it can generate ROS and activate cell death pathways [37] implicated in cancer.

#### **4. Polycyclic aromatic hydrocarbons [PAHs] and benzo(a)pyrene [BaP]**

Polycyclic aromatic hydrocarbons and their derivatives are a major class of organic compounds that are produced as a result of incomplete combustion of fossil fuels and other organic matter. Consequently, they are prevalent in the human environment and include a number of potent carcinogens. Some of the major sources of these emissions are wood and coal burning, automobiles and other fossilfuel propelled modes of transportation, heat and power plants, and refuse burning. PAHs are not only present in the air, but are found in many common foods and drinking water and form a significant component of tobacco smoke [38].

Levels of PAHs are routinely measured in the atmosphere for air quality assessment, in sediments and mollusks for environmental monitoring, in biological tissues for monitoring of health effects, and in foodstuffs for safety reasons. Gas chromatography is often chosen for analyzing (separating, identifying, and quantifying) PAHs due to the high degree of selectivity and resolution this method provides [39].

PAH-DNA adducts have been compared in the peripheral leukocytes of nonsmall cell lung cancer patients and in controls. Adduct formation has been found to be significantly higher in lung cancer cases than in controls. Further, in the cancer patients, adducts were more strongly correlated with lung tumor tissue than with non-tumor lung tissue consistent with a genetic susceptibility to lung cancer as a result of adduct-induced DNA damage [40]. More specifically, BPDE-DNA adducts have been observed in the white blood cells of occupationally exposed workers and cigarette smokers. BaP is metabolically activated to its carcinogenic form benzo(*a*) pyrene diol epoxide (BPDE), and this is an important step in BaP carcinogenicity

*Heavy Metal Toxicity in Public Health*

in mitochondria [22, 23].

exposed workers [27].

**3. Cadmium [Cd]**

in extreme cases [15].

rod photoreceptor cell apoptosis [33].

due to another genetic or epigenetic event [4, 14].

model of glutamate toxicity, mitochondrial calcium accumulation and resultant membrane depolarization are clearly linked to the initiation of a cell death pathway

cytochrome c release and caspase cascade activation [24, 25].

A rise in mitochondrial calcium also stimulates the generation of reactive oxygen species (ROS) and free fatty acids which can further promote opening of the PTP, resulting in calcium release and, ultimately, in cell death [23]. Many genes and proteins that respond to conditions of oxidative stress stimulated by ROS release within the cell subsequently trigger apoptosis. Because mitochondria are important regulators of cellular redox status, the induction of oxidative stress exhibits its effects upon these organelles by triggering the intrinsic apoptotic pathway via

In this regard, it has been reported in various experiments that lead poisoning results in cellular damage mediated by the formation of reactive oxygen species (ROS) [26]. An elevation in the relative activities of certain antioxidant enzymes such as glutathione peroxidase has also been reported in the erythrocytes of lead-

In one large epidemiological study in Eastern Europe spanning several years, an elevated risk of renal cell carcinoma was observed in the category of highest cumulative occupational lead exposure [28]. Lead has been found to induce renal tumors in rats and mice [29, 30]. Lead causes DNA strand breakage and 8-hydroxy-deoxyguanosine adduct formation in calf thymus DNA [31]. It induces sister chromatid exchanges in Chinese hamster ovary cells [32]. Lead-induced cytotoxicity and apoptosis have been demonstrated in human cancer cells via various cellular and molecular processes including oxidative stress induction and caspase-3 activation [15]. Finally, mitochondrial alterations appear to play a central role in lead-induced

Taken together, the above data point to the activation of apoptotic pathways as a possible mechanism of lead carcinogenesis. It clearly has the potential to initiate cancer as described in a new approach to cancer risk assessment based on an apoptotic model of tumor formation. In this two-stage model of tumor formation, Step I exposure to a carcinogen (Pb in this case), possibly facilitated by a genetic predisposition, results in an epigenetic or genetic event causing continuous apoptotic activation of cells in the target tissue. In Step II, when the carcinogen may or may not be present, resistance to apoptosis and continuous cell proliferation result

Cadmium is a heavy metal that is widely distributed in the earth's crust, while

Cadmium levels in the body can be measured in the blood or urine. Typically, blood and urine cadmium levels are higher in cigarette smokers, intermediate in former smokers, and lower in nonsmokers. The circulatory system is an important distribution route of cadmium toxicity, and blood vessels are considered to be the

the highest level of cadmium compounds is found in sedimentary rocks and marine phosphates. Human exposure to this element can occur through employment in primary metal industries, eating contaminated food, smoking cigarettes (a major contributor), and working in cadmium-contaminated places. Other sources of cadmium include emissions from mining, smelting, manufacturing batteries, pigments, stabilizers, and alloys. The main routes of cadmium exposure are via inhalation or cigarette smoke and ingestion of food. It is a severe pulmonary and gastrointestinal irritant, which can prove fatal when inhaled or ingested

**38**

in experimental animal studies [41]. Moreover, using a specially developed assay on peripheral blood lymphocytes, it has been determined that there is a significant association between the level of in vitro BPDE-induced DNA adducts and risk for lung cancer in humans [42]. In another molecular epidemiologic hospital-based study, DNA repair capacity was measured in cultured lymphocytes from lung cancer patients and controls. It cleverly utilized the host-cell reactivation assay with a reporter gene damaged by the known activated tobacco carcinogen, benzo[*a*] pyrene diol epoxide. It was observed that reduced DNA repair capacity was associated with increased risk of lung cancer in a dose-dependent fashion [43]. In addition, the frequency of BPDE-induced chromosomal aberrations is significantly higher in lymphocyte cultures from lung cancer patients than in controls. These chromosomal aberrations tend to be predominantly single chromatid breaks with few exchanges or isochromatid breaks [44].

There is overwhelming evidence in the scientific literature for BaP-induced lung and respiratory tract carcinogenesis in experimental animals. Highly sensitive immunoassays using antiserum specific for benzo(a)pyrene have revealed a dose-related increase in levels of BaP-DNA adducts in the lung tissue of mice and rabbits following intraperitoneal injection with this chemical carcinogen [45]. In the past, respiratory tract tumors have been induced in Syrian golden hamsters following intratracheal injections of benzo(a)pyrene and benzo(a)pyrene-ferric oxide [46, 47]. In fact, BaP-induced lung cancer in mice is so reproducible that it has become a popular model for studying the potential role of natural products in ameliorating the effects of BaP [48]. It is known that lung carcinogenesis can be induced in Swiss albino mice following biweekly treatment with BaP (50 mg/kg b. wt.) over a period of 16 weeks [49]. Supplementation with hesperidin, a naturally occurring flavonoid in citrus fruits, has been reported to have a chemopreventive activity during BaPinduced lung cancer in Swiss albino mice. It appears to attenuate the accompanying loss in tissue antioxidant function and to have an antiproliferative effect as revealed by histopathological analysis involving proliferating cell nuclear antigen (PCNA) immunostaining [50]. In another interesting chemopreventive study, BaP-induced neoplasia of mouse forestomach was inhibited by a principal component of Japanese soy sauce, 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone, suggesting that this *Saccharomyces cerevisiae* metabolite is a potent anticarcinogen [51].

In mouse hepatoma cells, treatment with micromolar concentrations of BaP results in caspase-3 activation, followed by apoptosis. However, caspase-3 activity is blocked and BaP-induced apoptosis attenuated by pretreatment of the cells with a specific inhibitor of caspase-3-like proteases, acetyl-Asp-Glu-Val-Asp-aldehyde [52]. It has also been demonstrated that BaP treatment of mouse hepatoma cells causes apoptosis via the catalytic activation of caspase-9, mitochondrial dysfunction including a loss in membrane potential and cytosolic release of cytochrome c, and phosphorylation of p53 (Ser15) [53]. In BaP-treated human Hep3B (p53-null) cells, necrosis is induced at 12 hours and apoptosis at 24 h, respectively, due to a dramatic increase in oxidative stress [54].

Although many epidemiological studies have been carried out on smokers with lung cancer, there is also evidence to suggest that people living in urban areas have an increased risk of lung cancer due to higher levels of air pollution in these areas. A number of studies have indicated a correlation between lung cancer risk and exposure to urban air pollutants, particularly inhalable and fine particulate matter [55]. In animal experiments, lung toxicity, inflammatory effects, genotoxicity, and rodent carcinogenicity have been demonstrated for diesel exhaust and urban air particulates. In vitro*,* both can cause oxidative DNA damage, mainly single-strand breaks and 8-oxo-dG (8-oxo-7,8-dihydro-2′-deoxyguanosine)*.* In vivo*,* even at low-dose levels, diesel exhaust particles can induce oxidative DNA damage in

**41**

from the same treatment [61].

*A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers*

rodent lung tissue [55]. BaP is currently used as the main indicator of PAH levels in air pollution. However, recently, there has been some concern that there may be PAHs with a higher potency of carcinogenicity like dibenz[*a*, *h*]anthracene (DBA) and dibenzo[*a*, *l*]pyrene in air/PAH mixtures that pose even a greater health risk to

Inside the cell, the harmful effects of free radicals are balanced by the antioxidant action of antioxidant enzymes and nonenzymatic antioxidants that help in the

Metallothioneins (MTs) are small, cysteine-rich proteins that bind heavy metals

Cytosolic glutathione S-transferases (GSTs) are a supergene family of dimeric enzymes that detoxify a number of carcinogens including polycyclic aromatic hydrocarbons which are some of the principal substrates. The enzyme, GSTM1-1, appears to be particularly effective in dealing with certain PAH derivatives, and at least one large epidemiological study has found a highly significant correlation between the absence of GSTM1–1 activity and adenocarcinoma of the lung in smokers [58]. GSTs require the presence of glutathione in order to fulfill their function of conjugating glutathione (GSH) to cytotoxic and genotoxic lipophilic compounds for their removal from the cell. Interestingly, the presence of intracellular zinc appears to boost glutathione levels in certain cell types [59], and, thus, zinc supplementation may be a useful measure for the prevention of lung cancer from tobacco smoke and environmental factors such as heavy metals by boosting both MT and GST

Vitamin C (ascorbic acid) and vitamin E (DL-α-tocopherol) treatment together has been reported to result in a significant reduction in smoking-related BaP-DNA adducts in women and suggests that antioxidant supplementation may help to mitigate some of the carcinogenic effects of BaP exposure. It is particularly effective in females with the GSTM1 null genotype, whereas males do not seem to benefit

Black tea polyphenols (theaflavins and epigallocatechin gallate) have been observed to suppress cell proliferation and induce apoptosis during BaP-induced lung carcinogenesis in mice. The occurrence of carcinoma in situ was effectively

activities [60]. Glutathione supplementation may also be helpful.

reduced as a result of this treatment [62] (**Figure 2**).

and participate in an array of protective stress responses. MTs are found in bacteria, plants, invertebrates, and vertebrates. There are four main mammalian MT isoforms (MT-1 to MT-4) with distinct roles in different tissues. Aerobic organisms are susceptible to damage by reactive oxygen species (ROS) and reactive nitrogen species (RNS). MT protects cells from exposure to various free radical species like the hydroxyl, peroxyl, alkoxyl, and superoxide anion radical and the nitric oxide and nitric dioxide radicals, which react readily with sulfhydryl groups. MT is also important for the regulation of zinc levels and the distribution of this metal in the extracellular space. Since zinc cannot pass easily through membranes, zinctransporting proteins, Zrt-Irt-like protein or zinc iron permease (ZIPs) and zinc transporters (ZnTs), help to facilitate this process. The presence of Zinc(II) within the cell causes an increase in the major zinc-binding protein metallothionein, and it binds to MTs forming a thermodynamically stable complex. MT can be activated by various stimuli including heavy metal ions, cytokines, growth factors, and oxidative stress within the cell. Cells that display high MT production are resistant to heavy metal toxicity by cadmium, whereas cell lines that cannot synthesize MTs are

*DOI: http://dx.doi.org/10.5772/intechopen.90092*

**5. Antioxidants and detoxification**

sensitive to the toxic effects of cadmium [57].

process of detoxification.

humans [56].

#### *A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers DOI: http://dx.doi.org/10.5772/intechopen.90092*

rodent lung tissue [55]. BaP is currently used as the main indicator of PAH levels in air pollution. However, recently, there has been some concern that there may be PAHs with a higher potency of carcinogenicity like dibenz[*a*, *h*]anthracene (DBA) and dibenzo[*a*, *l*]pyrene in air/PAH mixtures that pose even a greater health risk to humans [56].

#### **5. Antioxidants and detoxification**

*Heavy Metal Toxicity in Public Health*

few exchanges or isochromatid breaks [44].

dramatic increase in oxidative stress [54].

in experimental animal studies [41]. Moreover, using a specially developed assay on peripheral blood lymphocytes, it has been determined that there is a significant association between the level of in vitro BPDE-induced DNA adducts and risk for lung cancer in humans [42]. In another molecular epidemiologic hospital-based study, DNA repair capacity was measured in cultured lymphocytes from lung cancer patients and controls. It cleverly utilized the host-cell reactivation assay with a reporter gene damaged by the known activated tobacco carcinogen, benzo[*a*] pyrene diol epoxide. It was observed that reduced DNA repair capacity was associated with increased risk of lung cancer in a dose-dependent fashion [43]. In addition, the frequency of BPDE-induced chromosomal aberrations is significantly higher in lymphocyte cultures from lung cancer patients than in controls. These chromosomal aberrations tend to be predominantly single chromatid breaks with

There is overwhelming evidence in the scientific literature for BaP-induced lung and respiratory tract carcinogenesis in experimental animals. Highly sensitive immunoassays using antiserum specific for benzo(a)pyrene have revealed a dose-related increase in levels of BaP-DNA adducts in the lung tissue of mice and rabbits following intraperitoneal injection with this chemical carcinogen [45]. In the past, respiratory tract tumors have been induced in Syrian golden hamsters following intratracheal injections of benzo(a)pyrene and benzo(a)pyrene-ferric oxide [46, 47]. In fact, BaP-induced lung cancer in mice is so reproducible that it has become a popular model for studying the potential role of natural products in ameliorating the effects of BaP [48]. It is known that lung carcinogenesis can be induced in Swiss albino mice following biweekly treatment with BaP (50 mg/kg b. wt.) over a period of 16 weeks [49]. Supplementation with hesperidin, a naturally occurring flavonoid in citrus fruits, has been reported to have a chemopreventive activity during BaPinduced lung cancer in Swiss albino mice. It appears to attenuate the accompanying loss in tissue antioxidant function and to have an antiproliferative effect as revealed by histopathological analysis involving proliferating cell nuclear antigen (PCNA) immunostaining [50]. In another interesting chemopreventive study, BaP-induced neoplasia of mouse forestomach was inhibited by a principal component of Japanese soy sauce, 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone, suggesting that

this *Saccharomyces cerevisiae* metabolite is a potent anticarcinogen [51].

In mouse hepatoma cells, treatment with micromolar concentrations of BaP results in caspase-3 activation, followed by apoptosis. However, caspase-3 activity is blocked and BaP-induced apoptosis attenuated by pretreatment of the cells with a specific inhibitor of caspase-3-like proteases, acetyl-Asp-Glu-Val-Asp-aldehyde [52]. It has also been demonstrated that BaP treatment of mouse hepatoma cells causes apoptosis via the catalytic activation of caspase-9, mitochondrial dysfunction including a loss in membrane potential and cytosolic release of cytochrome c, and phosphorylation of p53 (Ser15) [53]. In BaP-treated human Hep3B (p53-null) cells, necrosis is induced at 12 hours and apoptosis at 24 h, respectively, due to a

Although many epidemiological studies have been carried out on smokers with lung cancer, there is also evidence to suggest that people living in urban areas have an increased risk of lung cancer due to higher levels of air pollution in these areas. A number of studies have indicated a correlation between lung cancer risk and exposure to urban air pollutants, particularly inhalable and fine particulate matter [55]. In animal experiments, lung toxicity, inflammatory effects, genotoxicity, and rodent carcinogenicity have been demonstrated for diesel exhaust and urban air particulates. In vitro*,* both can cause oxidative DNA damage, mainly single-strand breaks and 8-oxo-dG (8-oxo-7,8-dihydro-2′-deoxyguanosine)*.* In vivo*,* even at low-dose levels, diesel exhaust particles can induce oxidative DNA damage in

**40**

Inside the cell, the harmful effects of free radicals are balanced by the antioxidant action of antioxidant enzymes and nonenzymatic antioxidants that help in the process of detoxification.

Metallothioneins (MTs) are small, cysteine-rich proteins that bind heavy metals and participate in an array of protective stress responses. MTs are found in bacteria, plants, invertebrates, and vertebrates. There are four main mammalian MT isoforms (MT-1 to MT-4) with distinct roles in different tissues. Aerobic organisms are susceptible to damage by reactive oxygen species (ROS) and reactive nitrogen species (RNS). MT protects cells from exposure to various free radical species like the hydroxyl, peroxyl, alkoxyl, and superoxide anion radical and the nitric oxide and nitric dioxide radicals, which react readily with sulfhydryl groups. MT is also important for the regulation of zinc levels and the distribution of this metal in the extracellular space. Since zinc cannot pass easily through membranes, zinctransporting proteins, Zrt-Irt-like protein or zinc iron permease (ZIPs) and zinc transporters (ZnTs), help to facilitate this process. The presence of Zinc(II) within the cell causes an increase in the major zinc-binding protein metallothionein, and it binds to MTs forming a thermodynamically stable complex. MT can be activated by various stimuli including heavy metal ions, cytokines, growth factors, and oxidative stress within the cell. Cells that display high MT production are resistant to heavy metal toxicity by cadmium, whereas cell lines that cannot synthesize MTs are sensitive to the toxic effects of cadmium [57].

Cytosolic glutathione S-transferases (GSTs) are a supergene family of dimeric enzymes that detoxify a number of carcinogens including polycyclic aromatic hydrocarbons which are some of the principal substrates. The enzyme, GSTM1-1, appears to be particularly effective in dealing with certain PAH derivatives, and at least one large epidemiological study has found a highly significant correlation between the absence of GSTM1–1 activity and adenocarcinoma of the lung in smokers [58]. GSTs require the presence of glutathione in order to fulfill their function of conjugating glutathione (GSH) to cytotoxic and genotoxic lipophilic compounds for their removal from the cell. Interestingly, the presence of intracellular zinc appears to boost glutathione levels in certain cell types [59], and, thus, zinc supplementation may be a useful measure for the prevention of lung cancer from tobacco smoke and environmental factors such as heavy metals by boosting both MT and GST activities [60]. Glutathione supplementation may also be helpful.

Vitamin C (ascorbic acid) and vitamin E (DL-α-tocopherol) treatment together has been reported to result in a significant reduction in smoking-related BaP-DNA adducts in women and suggests that antioxidant supplementation may help to mitigate some of the carcinogenic effects of BaP exposure. It is particularly effective in females with the GSTM1 null genotype, whereas males do not seem to benefit from the same treatment [61].

Black tea polyphenols (theaflavins and epigallocatechin gallate) have been observed to suppress cell proliferation and induce apoptosis during BaP-induced lung carcinogenesis in mice. The occurrence of carcinoma in situ was effectively reduced as a result of this treatment [62] (**Figure 2**).

**Figure 2.** *A crop of BC apples covered with a layer of fine particulate matter from forest fire smoke.*

#### **6. Conclusions**

Lead and cadmium are two of the heavy metals that are expelled in cigarette smoke. In epidemiological studies, lead and cadmium have been correlated with human cancers including renal and lung, respectively. In animal studies, lead has been found to induce renal tumors in rats and mice, while cadmium inhalation is associated with pulmonary adenocarcinomas in rodents. In addition, oral cadmium in the diet of rats results in tumors of the prostate, testes, and hematopoietic system. Apoptosis or oxidative stress, which can signal cell death, has been observed and reported in cell cultures in response to both metals. As such, these two heavy metals have the potential to cause cancer independently.

The polycyclic aromatic hydrocarbon, benzo(a)pyrene, which is a prominent component of indoor/outdoor air pollution and cigarette smoke, is a well-established carcinogen. BaP-DNA adducts have been observed in lung cancer patients and in experimental animals following BaP exposure. BPDE-DNA adducts have been reported in the white blood cells of occupationally exposed workers and cigarette smokers. There is a strong positive correlation between this type of BaP/BaP metabolite DNA adduct formation and risk for lung cancer in humans. An elevated frequency of BPDE-induced chromosomal aberrations has also been observed in lymphocyte cultures from lung cancer patients. Moreover, animal studies have revealed a highly reproducible association between BaP exposure and respiratory tract tumors in Syrian golden hamsters and lung cancer in mice. BaP treatment of mouse hepatoma cells can cause apoptosis via caspase-3 and caspase-9 activation, mitochondrial dysfunction including a loss in membrane potential and cytosolic release of cytochrome c, and phosphorylation of p53 (Ser15). In a BaP-treated human hepatocellular carcinoma cell line, necrosis is induced at 12 hours and apoptosis at 24 hours, respectively, due to a dramatic increase in oxidative stress. Thus, these results are consistent with a mechanism of carcinogenesis based on an apoptotic model.

Zinc supplementation may be useful for heavy metal detoxification in mammals. Certain antioxidants including vitamin C, vitamin E, black tea polyphenols (theaflavins and epigallocatechin gallate), and flavonoids have been reported to help in mitigating some of the toxic effects of polycyclic aromatic hydrocarbons. Thus, antioxidant supplementation may prove to be an effective measure in reducing the risk of respiratory tract cancers in smokers and from air pollution in developing nations where there is still a significant use of biomass fuels.

In recent years, great progress has been made in banning cigarette smoking from public places around the world due to the proven hazards of secondhand

**43**

**Author details**

Canada

Chanda Siddoo-Atwal

*A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers*

smoke. Some developing nations have also instituted economic and educational programs to discourage the general use of biomass fuels and seasonal burning of paddy fields. Certain countries have legislated stricter laws to deal with irresponsible cigarette smokers, who often start large blazes by discarding their cigarettes and matches outdoors, and, professional arsonists. In places like British Columbia, where there are so many forests and the incidence of forest fires is increasing due to climate change, one extreme solution may be to close public parks during the

Nevertheless, despite these local actions, nothing short of an international effort is required to tackle climate change effectively on a global scale. If countries are to truly cooperate in combatting the rapidly changing conditions on the planet, general goodwill among nations and the cessation of all hostilities embodied in a World Peace Treaty (WPT) seem to be necessary. A ban on the use of nuclear weapons and nuclear testing should also be included in such an agreement since there is already evidence to suggest that atmospheric nuclear explosions have contributed to climate change in addition to greenhouse gases. Economic benefits are likely to be a positive outcome of "green" eco-friendly policies in the long run as awareness about their

President and Primary Biochemist of Moondust Cosmetics Ltd, West Vancouver,

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: moondustcosmetics@gmail.com

provided the original work is properly cited.

*DOI: http://dx.doi.org/10.5772/intechopen.90092*

importance is raised among the general public.

peak fire season.

#### *A Role for Heavy Metal Toxicity and Air Pollution in Respiratory Tract Cancers DOI: http://dx.doi.org/10.5772/intechopen.90092*

smoke. Some developing nations have also instituted economic and educational programs to discourage the general use of biomass fuels and seasonal burning of paddy fields. Certain countries have legislated stricter laws to deal with irresponsible cigarette smokers, who often start large blazes by discarding their cigarettes and matches outdoors, and, professional arsonists. In places like British Columbia, where there are so many forests and the incidence of forest fires is increasing due to climate change, one extreme solution may be to close public parks during the peak fire season.

Nevertheless, despite these local actions, nothing short of an international effort is required to tackle climate change effectively on a global scale. If countries are to truly cooperate in combatting the rapidly changing conditions on the planet, general goodwill among nations and the cessation of all hostilities embodied in a World Peace Treaty (WPT) seem to be necessary. A ban on the use of nuclear weapons and nuclear testing should also be included in such an agreement since there is already evidence to suggest that atmospheric nuclear explosions have contributed to climate change in addition to greenhouse gases. Economic benefits are likely to be a positive outcome of "green" eco-friendly policies in the long run as awareness about their importance is raised among the general public.

#### **Author details**

*Heavy Metal Toxicity in Public Health*

**6. Conclusions**

**Figure 2.**

Lead and cadmium are two of the heavy metals that are expelled in cigarette smoke. In epidemiological studies, lead and cadmium have been correlated with human cancers including renal and lung, respectively. In animal studies, lead has been found to induce renal tumors in rats and mice, while cadmium inhalation is associated with pulmonary adenocarcinomas in rodents. In addition, oral cadmium in the diet of rats results in tumors of the prostate, testes, and hematopoietic system. Apoptosis or oxidative stress, which can signal cell death, has been observed and reported in cell cultures in response to both metals. As such, these two heavy

*A crop of BC apples covered with a layer of fine particulate matter from forest fire smoke.*

The polycyclic aromatic hydrocarbon, benzo(a)pyrene, which is a prominent component of indoor/outdoor air pollution and cigarette smoke, is a well-established carcinogen. BaP-DNA adducts have been observed in lung cancer patients and in experimental animals following BaP exposure. BPDE-DNA adducts have been reported in the white blood cells of occupationally exposed workers and cigarette smokers. There is a strong positive correlation between this type of BaP/BaP metabolite DNA adduct formation and risk for lung cancer in humans. An elevated frequency of BPDE-induced chromosomal aberrations has also been observed in lymphocyte cultures from lung cancer patients. Moreover, animal studies have revealed a highly reproducible association between BaP exposure and respiratory tract tumors in Syrian golden hamsters and lung cancer in mice. BaP treatment of mouse hepatoma cells can cause apoptosis via caspase-3 and caspase-9 activation, mitochondrial dysfunction including a loss in membrane potential and cytosolic release of cytochrome c, and phosphorylation of p53 (Ser15). In a BaP-treated human hepatocellular carcinoma cell line, necrosis is induced at 12 hours and apoptosis at 24 hours, respectively, due to a dramatic increase in oxidative stress. Thus, these results are consistent with a mechanism of carcinogenesis based on an

Zinc supplementation may be useful for heavy metal detoxification in mammals. Certain antioxidants including vitamin C, vitamin E, black tea polyphenols (theaflavins and epigallocatechin gallate), and flavonoids have been reported to help in mitigating some of the toxic effects of polycyclic aromatic hydrocarbons. Thus, antioxidant supplementation may prove to be an effective measure in reducing the risk of respiratory tract cancers in smokers and from air pollution in devel-

In recent years, great progress has been made in banning cigarette smoking from public places around the world due to the proven hazards of secondhand

oping nations where there is still a significant use of biomass fuels.

metals have the potential to cause cancer independently.

**42**

apoptotic model.

Chanda Siddoo-Atwal

President and Primary Biochemist of Moondust Cosmetics Ltd, West Vancouver, Canada

\*Address all correspondence to: moondustcosmetics@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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**46**

*Heavy Metal Toxicity in Public Health*

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Bosken CH, Spitz MR, Hong WK, et al. Sensitivity to DNA damage induced by benzo(*a*)pyrene diol epoxide and risk of lung cancer: A case-control analysis. Cancer Research. 2001;**61**(4):1445-1450

[43] Wei Q, Cheng L, Amos CI, Wang L-E, Guo Z, Hong WK, et al. Repair of tobacco carcinogen-induced DNA adducts and lung cancer risk: A

molecular epidemiologic study. Journal of the National Cancer Institute. 2000;**92**(21):1764-1772. DOI: 10.1093/

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jnci/92.21.1764

1996;**56**(17):3975-3979

carcin/3.12.1405

1974;**34**(4):689-698

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samples: A critical review of gas chromatographic (GC) methods. Analytical and Bioanalytical Chemistry.

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[41] Shamsuddin AKM, Sinopoli NT, Hemminki K, Boesch RR, Harris CC. Detection of benzo(a)pyrene: DNA

2006;**386**(4):859-881

[40] Tang D, Santella RM,

Biomarkers & Prevention.

1995;**4**(4):341-346

2010;**23**(5):783-792

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**49**

Section 2

Health Risks, Toxicological

and Cellular Tissue Effects

of Heavy Metals

### Section 2
