*4.2.2 Electrical conductivity*

The most influential water quality guideline on crop productivity is the water salinity hazard as measured by electrical conductivity (ECw). EC measures salinity from all identified ions dissolved in a sample including negatively charged ions (e.g., Cl<sup>−</sup>, NO<sup>−</sup> 3) and positively charged ions (e.g., Ca++, Na+ ).

The values of electrical conductivity were determined by the concentration of ionic species contained in water. Using a standard of 84μS and a Crison multimeter (MM 41), water samples from Heidelberg (HB) recorded the highest electrical conductivity value of 1235 μS followed by (BS) 1040 μS, (WL) 948 μS and (SB) 488 μS.

A value of 132 μS was recorded for the tailing sediments. The higher electrical conductivity recorded could imply the presence of higher dissolved salt or ion concentration which suggests that the samples have higher conductivity.

The observed high ECw water on crop productivity will result in plants' inability to compete with ions in the soil solution for water (physiological drought). The higher EC implies less water is available to plants, despite the soil appearing wet, thus a reduced yield potential. This is because plants can only transpire "pure" water as usable plant water in soil solution decreases as EC increases.

#### *4.2.3 Total dissolved solids*

Using the expression 0.64 × EC, a measure of the total dissolved amount of substance was obtained. The lowest value was observed in the MT (84.48 mg/L) with HB recording the highest (790.40 mg/L). WL and BS both had 606.72 mg/L and 665.60 mg/L, respectively, while 312.32 mg/L was recorded in (SB). Crop yield can be adversely affected by the higher concentration of salt in water, thereby leading to soil degradation and pollution of groundwater. This parameter however did not deviate from the international standards, but the high concentrations of dissolved solids could result in some technical effects. Dissolved solids can produce hard water, which leaves deposits and films on fixtures and on the insides of irrigation pipes.

#### **4.3 Chemical composition of tailing sediments**

The energy-dispersive X-ray (EDX) microanalysis is a technique of elemental analysis associated to electron microscopy based on the generation of characteristic X-rays that reveal the presence of elements present in specimens. EDX technique is useful in the study of environmental pollution as it carries a huge vantage in the detection of heavy metals because they are nonbiodegradable and they can accumulate in ecological systems, thus resulting in pollution.

The scanning electron microscope (SEM) and EDX analyses (**Figure 2**) indicate homogenous distribution of granules throughout mining tailing samples with EDX analysis, further confirming elements such as Si (33.58%), Fe (19.12%), O (54.25%), Al (5.33%), K (1.76%) and Mg (0.44%) which could be compared to elemental composition revealed from X-ray fluorescence (XRF).

A typical mineralogical composition of the tailing sediments is shown in **Figure 3** as determined by XRD. The XRD results confirm the presence of silicate minerals which are quartz (SiO2), marcasite FeS2, dialuminium silicate Al(SiO4)O, pyrite (FeS2) and gupeite (Fe3Si). These could be linked with the elements identified from both XRF and ICP-OES.

**Table 3** reports the partial compositional analysis of the tailing sediments collected from the abandoned gold mine dump. SiO2 (81.82%) was shown to be the most abundant compound found in the tailing sediments. The oxides of Al, Fe and S were 6.93, 3.59 and 3.41%, respectively. Oxides of K were 1.98%, while those of Na, Mg, Ca, Mn, Zn, Pb and Cu were less than 1%.

ICP-OES analysis as illustrated in **Table 4** shows heavy metal concentrations in the sediments, wetland and surround streams. Filtrate from the tailing sediments showed very high concentration of various heavy metals with Cr recording the highest value of 43.13 mg/L, followed by Al 16.42 mg/L, As 10.17 mg/L, Pb 6.29 mg/L and Ni 1.34 mg/L, respectively. Considering the proximity and the fact that the artificial wetland and studied streams all get fed from the run-off water from the dump site during rainfall, it is not a coincidence that higher metal concentrations were observed. Many metal elements are essential nutrients for animals and crops but, in excess, may result in chronic or toxic effects.

Toxic substances are often in solution or as suspended solids in water which may affect the nutritional availability of toxic elements or substance in animals. Although short-term intake of toxic substance by animals has little or no noticeable effects, long-term exposure to those substances may result in serious damage. The extent of damage inflicted on animals by toxic elements may be determined by health status, age, and rate of consumption of toxic elements by the animals. However, the intake of toxic substances may not cause any measurable effect on growth, production, or reproduction yet may cause subcellular damage in farm animals which could be expressed as increased susceptibility to disease or to parasitic invasion.

**43**

**Table 3.**

**Figure 3.**

*XRD patterns of the filtered sediments.*

*Mobility of Trace Element Contaminants from Abandoned Gold Mine Dump to Stream Waters…*

With agricultural activities taking place around the vicinity of the tailing dump, farmers employ water from the streams in irrigation and feeding of animals despite the high heavy metal concentrations that apparently exceed the maximum permissible level of the US Environmental Protection Agency water composition [23, 24]. Al, As, Zn, Cd, Ni, Cu, Pb and Cr were all above the required standard. There is a strong likelihood of the run-off water from the tailing dumps and fine particles being blown during severe windstorm introducing heavy metals such as Al, As,

*Results of XRF analysis detailing composition of tailing sediments.*

**Oxides MT1 conc. (%) MT2 conc. (%) MT3 conc. (%) MT4 conc. (%) MTAve. conc. (%)** SiO2 69.42 86.87 86.35 84.63 81.82 Al2O3 9.09 6.03 5.18 7.42 6.93 Fe2O3 5.87 2.37 2.60 3.53 3.59 SO3 8.94 1.44 2.32 0.92 3.41 K2O 2.71 1.61 1.64 1.96 1.98 MgO 1.49 0.38 0.30 0.33 0.63 TiO2 0.58 0.49 0.51 0.49 0.52 CaO 0.90 0.23 0.55 0.13 0.45 Na2O 0.27 0.14 0.14 0.16 0.18 Cr2O3 0.15 0.17 0.15 0.14 0.52 PbO 0.04 0.03 0.04 0.04 0.04 NiO 0.11 0.01 0.02 0.01 0.04

*DOI: http://dx.doi.org/10.5772/intechopen.90818*

**Figure 2.** *SEM micrograph of tailing sediments.*

*Mobility of Trace Element Contaminants from Abandoned Gold Mine Dump to Stream Waters… DOI: http://dx.doi.org/10.5772/intechopen.90818*

**Figure 3.** *XRD patterns of the filtered sediments.*


**Table 3.**

*Trace Metals in the Environment - New Approaches and Recent Advances*

elemental composition revealed from X-ray fluorescence (XRF).

fied from both XRF and ICP-OES.

Mg, Ca, Mn, Zn, Pb and Cu were less than 1%.

crops but, in excess, may result in chronic or toxic effects.

The scanning electron microscope (SEM) and EDX analyses (**Figure 2**) indicate

homogenous distribution of granules throughout mining tailing samples with EDX analysis, further confirming elements such as Si (33.58%), Fe (19.12%), O (54.25%), Al (5.33%), K (1.76%) and Mg (0.44%) which could be compared to

A typical mineralogical composition of the tailing sediments is shown in **Figure 3** as determined by XRD. The XRD results confirm the presence of silicate minerals which are quartz (SiO2), marcasite FeS2, dialuminium silicate Al(SiO4)O, pyrite (FeS2) and gupeite (Fe3Si). These could be linked with the elements identi-

**Table 3** reports the partial compositional analysis of the tailing sediments collected from the abandoned gold mine dump. SiO2 (81.82%) was shown to be the most abundant compound found in the tailing sediments. The oxides of Al, Fe and S were 6.93, 3.59 and 3.41%, respectively. Oxides of K were 1.98%, while those of Na,

ICP-OES analysis as illustrated in **Table 4** shows heavy metal concentrations in the sediments, wetland and surround streams. Filtrate from the tailing sediments showed very high concentration of various heavy metals with Cr recording the highest value of 43.13 mg/L, followed by Al 16.42 mg/L, As 10.17 mg/L, Pb 6.29 mg/L and Ni 1.34 mg/L, respectively. Considering the proximity and the fact that the artificial wetland and studied streams all get fed from the run-off water from the dump site during rainfall, it is not a coincidence that higher metal concentrations were observed. Many metal elements are essential nutrients for animals and

Toxic substances are often in solution or as suspended solids in water which may affect the nutritional availability of toxic elements or substance in animals. Although short-term intake of toxic substance by animals has little or no noticeable effects, long-term exposure to those substances may result in serious damage. The extent of damage inflicted on animals by toxic elements may be determined by health status, age, and rate of consumption of toxic elements by the animals. However, the intake of toxic substances may not cause any measurable effect on growth, production, or reproduction yet may cause subcellular damage in farm animals which could be expressed as increased susceptibility to disease or to parasitic

**42**

**Figure 2.**

*SEM micrograph of tailing sediments.*

invasion.

*Results of XRF analysis detailing composition of tailing sediments.*

With agricultural activities taking place around the vicinity of the tailing dump, farmers employ water from the streams in irrigation and feeding of animals despite the high heavy metal concentrations that apparently exceed the maximum permissible level of the US Environmental Protection Agency water composition [23, 24]. Al, As, Zn, Cd, Ni, Cu, Pb and Cr were all above the required standard. There is a strong likelihood of the run-off water from the tailing dumps and fine particles being blown during severe windstorm introducing heavy metals such as Al, As,


#### **Table 4.**

*Results of ICP-OES analysis on stream water samples and filtrate from tailing sediments showing heavy metal concentration.*

Cd, Pb, Ni, Zn, Cr and Cu into nearby rivers. Direct consumption of such waters by humans and animals such as cattle gets into the gastrointestinal system, leaving some adverse effects by increasing the gastrointestinal pH, resulting in surficial coating on the stomach [25]. In addition, some of the trace metals get leached into the water table through percolation and are absorbed by plants which the animals feed from.

In humans, several forms of cancer have been linked to arsenic, and chronic exposure to arsenic through drinking water has been associated to health effects such as nervous disorders, high blood pressure, diabetes and hyperkeratosis [26]. However, there are little or no reports on the effect of arsenic in drinking water on the health and/or effect of farm animals. Arsenic availability in soil can disturb normal functioning of plant metabolism, consequently leading to stunted growth and low crop productivity [27]. Previous studies indicated arsenic to be responsible for reduction in gas exchange attributes (photosynthetic rate, transpiration rate, stomatal conductance) and chlorophyll concentrations [28].

The total aluminium concentration in a human body is approximately 9 ppm (dry mass) with an approximately daily intake of 5 mg, of which only a small fraction is absorbed. The high aluminium content of the various water sources observed may have negative impacts on plants, humans and animals. Various ailments of the nervous system, such as Parkinson's disease, amyotrophic lateral sclerosis (Lou Gehrig's disease) and Alzheimer's disease as well as functional lung disorder, may be experienced in humans [29]. There are currently no reports on aluminium toxicity to ruminants. However, there are indications about the risks of inducing either a phosphorus deficiency or a condition known as grass tetany when ruminants consume large amounts of aluminium from soil, aluminium-rich forages or water high in aluminium content [30]. In general, more soluble forms of aluminium in plants may pose some risk such as the inhibition of root elongation [31].

Plant growth and development is often affected adversely by cadmium, a non-essential element due to its high toxicity and large solubility in water [32]. The uptake of minerals by plants has been reported to be altered by cadmium which impacts on the availability of minerals from the soil as well as a reduction in the population of soil microbes [33]. Stomatal opening, transpiration and photosynthesis have been reported to be affected by cadmium in nutrient solutions, but the metal is taken up into plants more readily from nutrient solutions than from soil [34]. The accumulation of cadmium in humans could lead to renal failure,

**45**

*Mobility of Trace Element Contaminants from Abandoned Gold Mine Dump to Stream Waters…*

decreased vitamin D synthesis and consequently osteoporosis. The high concentration of cadmium may adversely interfere with the metabolism of essential trace elements which in farm animals such as cattle could result in an unthrifty appearance; rough coat hair; dry scaly skin; dehydration; loss of hair from the legs, thighs, ventral chest, and brisket; mouth lesions; oedematous, shrunken scaly scrotum; sore and enlarged joints; impaired sight; extreme emaciation; and some atrophy of

Despite plants being able to take up high levels of lead of up to 500 ppm from soils, as toxic pollutants, lead and some of its compounds can limit the synthesis of plant chlorophyll [36]. The growth of plants is often retarded by higher concentrations of lead. Crops cultivated in the study area stand a risk of suffering damage and

Besides gaining access into the food chain via plant uptake, humans, through water intake, consume more lead. With the alarming concentrations of lead shown in **Table 4**, inhabitants are likely to have excess lead intake which could, over time, result in paralysis, skin pigmentation and colic. Females may experience menstrual disorder, infertility and spontaneous abortion, while children may suffer lower IQs, behavioural changes and concentration disorder. Lead is the most common cause of cattle poisoning. Animals die or perform poorly after inadvertently ingesting lead either through feed or water. Gradual poisoning of the areas cannot be ruled out as evidenced from the tailing sediments. Lead when consumed by ruminants end up in the reticulum (fore stomach) which provides a reservoir from which it is absorbed into the bodies of cattle, sheep and goats. In older cattle and sheep, subacute lead poisoning is characterised by anorexia, rumen stasis, colic, dullness and transient constipation, frequently followed by diarrhoea, blindness, head pressing, bruxism,

Chromium (Cr) occurs in the environment primarily in two valence states, trivalent chromium (Cr III) and hexavalent chromium (Cr VI), with the latter being

The high concentration levels of Cr as contained in **Table 4** are worrisome as it is known from previous studies to be a toxic metal that can cause severe harm to plants depending on its oxidation state. Some of the toxic effects of Cr on plant growth and development include alterations in the process of germination and growth of roots, stem, and leaves, which may affect total dry matter production and yield [38]. Excessive Cr also impacts adversely on plant's physiological processes such as photosynthesis, water relations, mineral nutrition, oxidative imbalance and inhibition of enzymatic activities. Chromium can affect antioxidant metabolism in plant. The corrosive nature of some chromium (VI) compounds, when in excess, results in ulcerations, dermatitis and allergic skin reactions in humans. When inhaled on the other hand, it could lead to ulceration and perforation of the mucous membranes of the nasal septum, irritation of the pharynx and larynx, asthmatic bronchitis, bronchospasms and oedema [39]. In mammals, chromium (III) is an essential trace element involved in lipid and glucose metabolism [40]. Chromium (VI) as reported from previous studies adversely affected the developing embryo, causing retarded foetal development in cattle during gestation, resulting in reductions in the number of foetuses and foetal weight and a higher incidence of stillbirth

This study revealed that the tailing sediments were largely comprised of fine sands that are loosely packed and prone to erosion, thus supporting the migration

*DOI: http://dx.doi.org/10.5772/intechopen.90818*

hyperesthesia and incoordination [37].

and post-implantation loss [41].

**5. Conclusion**

hindlimb muscles [35].

reduced growth.

more toxic.

*Mobility of Trace Element Contaminants from Abandoned Gold Mine Dump to Stream Waters… DOI: http://dx.doi.org/10.5772/intechopen.90818*

decreased vitamin D synthesis and consequently osteoporosis. The high concentration of cadmium may adversely interfere with the metabolism of essential trace elements which in farm animals such as cattle could result in an unthrifty appearance; rough coat hair; dry scaly skin; dehydration; loss of hair from the legs, thighs, ventral chest, and brisket; mouth lesions; oedematous, shrunken scaly scrotum; sore and enlarged joints; impaired sight; extreme emaciation; and some atrophy of hindlimb muscles [35].

Despite plants being able to take up high levels of lead of up to 500 ppm from soils, as toxic pollutants, lead and some of its compounds can limit the synthesis of plant chlorophyll [36]. The growth of plants is often retarded by higher concentrations of lead. Crops cultivated in the study area stand a risk of suffering damage and reduced growth.

Besides gaining access into the food chain via plant uptake, humans, through water intake, consume more lead. With the alarming concentrations of lead shown in **Table 4**, inhabitants are likely to have excess lead intake which could, over time, result in paralysis, skin pigmentation and colic. Females may experience menstrual disorder, infertility and spontaneous abortion, while children may suffer lower IQs, behavioural changes and concentration disorder. Lead is the most common cause of cattle poisoning. Animals die or perform poorly after inadvertently ingesting lead either through feed or water. Gradual poisoning of the areas cannot be ruled out as evidenced from the tailing sediments. Lead when consumed by ruminants end up in the reticulum (fore stomach) which provides a reservoir from which it is absorbed into the bodies of cattle, sheep and goats. In older cattle and sheep, subacute lead poisoning is characterised by anorexia, rumen stasis, colic, dullness and transient constipation, frequently followed by diarrhoea, blindness, head pressing, bruxism, hyperesthesia and incoordination [37].

Chromium (Cr) occurs in the environment primarily in two valence states, trivalent chromium (Cr III) and hexavalent chromium (Cr VI), with the latter being more toxic.

The high concentration levels of Cr as contained in **Table 4** are worrisome as it is known from previous studies to be a toxic metal that can cause severe harm to plants depending on its oxidation state. Some of the toxic effects of Cr on plant growth and development include alterations in the process of germination and growth of roots, stem, and leaves, which may affect total dry matter production and yield [38]. Excessive Cr also impacts adversely on plant's physiological processes such as photosynthesis, water relations, mineral nutrition, oxidative imbalance and inhibition of enzymatic activities. Chromium can affect antioxidant metabolism in plant. The corrosive nature of some chromium (VI) compounds, when in excess, results in ulcerations, dermatitis and allergic skin reactions in humans. When inhaled on the other hand, it could lead to ulceration and perforation of the mucous membranes of the nasal septum, irritation of the pharynx and larynx, asthmatic bronchitis, bronchospasms and oedema [39]. In mammals, chromium (III) is an essential trace element involved in lipid and glucose metabolism [40]. Chromium (VI) as reported from previous studies adversely affected the developing embryo, causing retarded foetal development in cattle during gestation, resulting in reductions in the number of foetuses and foetal weight and a higher incidence of stillbirth and post-implantation loss [41].
