**8. The phenomenon of hyperaccumulation**

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ signific antly) Figure 3. The effect of increasing EDTA doses introduced to soil (contaminated with 1.5 mg Cd dm-3) on cadmium content in leaves of *Tagetes erecta* 'Taishan Orange'

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not

**Figure 3.** The effect of increasing EDTA doses introduced to soil (contaminated with 1.5 mg Cd dm-3) on cadmium

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ signific antly) Figure 3. The effect of increasing EDTA doses introduced to soil (contaminated with 1.5 mg Cd dm-3) on cadmium content in leaves of *Tagetes erecta* 'Taishan Orange'

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ signific antly) Figure 3. The effect of increasing EDTA doses introduced to soil (contaminated with 1.5 mg Cd dm-3) on cadmium content in leaves of *Tagetes erecta* 'Taishan Orange'

16,89b 17,03b 17,67b

0 25 50 75 100

16,89b 17,03b 17,67b

**Doses EDTA (mg dm‐3)**

16,89b 17,03b 17,67b

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

33,23b 35,11b 39,78b

0 25 50 75 100

33,23b 35,11b 39,78b

33,23b 35,11b 39,78b

**Doses EDTA (mg dm‐3)**

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

111,25c

0 25 50 75 100

111,25c

**Doses EDTA (mg dm‐3)**

111,25c

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

0 25 50 75 100

**Doses EDTA (mg dm‐3)**

178,76d

178,76d

178,76d

34,21c

34,21c

34,21c

70,21c

70,21c

70,21c

268,34e

268,34e

268,34e

9,14a

9,14a

9,14a

15,31a

15,31a

15,31a

18,78a

18,78a

18,78a

**Ni (mg kg‐1 d.m.)**

in leaves of *Tagetes erecta* 'Taishan Orange'

**Ni (mg kg‐1 d.m.)**

**Ni (mg kg‐1 d.m.)**

**Pb (mg kg‐1 d.m.)**

**Pb (mg kg‐1 d.m.)**

**Pb (mg kg‐1 d.m.)**

content in leaves of *Tagetes erecta* 'Taishan Orange'

**Cd (mg kg‐1 d.m.)**

592 Environmental Risk Assessment of Soil Contamination

**Cd (mg kg‐1 d.m.)**

**Cd (mg kg‐1 d.m.)**

differ significantly)

differ significantly)

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 4. The effect of increasing EDTA doses introduced to soil (contaminated with 100 mg Pb dm-3) on lead content in leaves of *Tagetes erecta* 'Taishan Orange'

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 4. The effect of increasing EDTA doses introduced to soil (contaminated with 100 mg Pb dm-3) on lead content in leaves of *Tagetes erecta* 'Taishan Orange'

**Figure 4.** The effect of increasing EDTA doses introduced to soil (contaminated with 100 mg Pb dm-3) on lead content

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 4. The effect of increasing EDTA doses introduced to soil (contaminated with 100 mg Pb dm-3) on lead content in leaves of *Tagetes erecta* 'Taishan Orange'

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 5. The effect of increasing EDTA doses introduced to soil (contaminated with 50 mg Ni dm-3) on nickel content in leaves of *Tagetes erecta* 'Taishan Orange' Identification of compounds complexing toxic heavy metals and at the same time biodegradable in the soil medium is crucial for

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 5. The effect of increasing EDTA doses introduced to soil (contaminated with 50 mg Ni dm-3) on nickel content in leaves of *Tagetes erecta* 'Taishan Orange' Identification of compounds complexing toxic heavy metals and at the same time biodegradable in the soil medium is crucial for

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not differ significantly) Figure 5. The effect of increasing EDTA doses introduced to soil (contaminated with 50 mg Ni dm-3) on nickel content in leaves of *Tagetes erecta* 'Taishan Orange' Identification of compounds complexing toxic heavy metals and at the same time biodegradable in the soil medium is crucial for

\*homogeneous groups were identified using the Duncan test, p = 0.05 (values denoted with identical letters do not

**Figure 5.** The effect of increasing EDTA doses introduced to soil (contaminated with 50 mg Ni dm-3) on nickel content

57,21b

57,21b

57,21b

induced phytoremediation.

differ significantly)

induced phytoremediation.

induced phytoremediation.

in leaves of *Tagetes erecta* 'Taishan Orange'

As it was stated by Brooks [28] the discovery and description of a phenomenon termed hyperaccumulation has contributed to the practical use of plants to remove metallic pollutants from soil. According to Boyd and Martens [25] and Brown et al. [29], plant species referred to as hyperaccumulators are genetically and physiologically capable of accumulating large amounts of heavy metals with no symptoms of toxicity. Threshold values of metal concentra‐ tions have been used to define metal hyperaccumulation, including 100 mg kg-1 dry weight of shoots for Cd, 1000 mg kg-1 for Cu, Ni, Pb and 10 000 mg kg-1 for Zn [10, 28, 86]. Cline et al. [34] stated that concentrations of heavy metals in tissues of hyperaccumulator plants should be 1 - 2%. Van der Ent et al. [120] recommend the following concentration criteria for different metals and metalloids in dried foliage:100 µg g-1 for Cd, Se and Ti; 300 µg g-1 for Co, Cu and Cr; 1000 µg g-1 for Ni, Pb and As; 3000 µg g-1 for Zn; 10000 µg g-1 for Mn, with plants growing in their natural habitats. There are over 400 known plant species from 45 families classified as hyperaccumulators. Most species belong to the families *Brasicaceae* and *Fabaceae* [103]. Ap‐ proximate numbers for various elements are as follows: Ni (450), Cu (32), Co (30), Se (20), Pb (14), Zn (12), Mn (12), As (5), Cd (2), Tl (2), [120]. Moreover, hyperaccumulators typically accumulate most efficiently one heavy metal and to date no plant has been identified which would be capable of accumulating in its tissues all toxic metals [37]. According to Vangrons‐ veld et al. [121] successful phytoremediation depends first of all on the selection of an appro‐ priate plant species. For this reason in the opinion of Baker et al. [10] it would be a practical solution to grow many different species at the same time.

Most natural hyperaccumulators are plants characterized by slow growth and production of low amounts of biomass. These traits result in a limited applicability of these plant species in phytoextraction of heavy metals from soil [37]. An example in this respect may be provided by *Thalspi caerulescens* L., producing only 5 ton dry matter per hectare [32], whereas it is costeffective to use plants, which yield 20 ton per hectare and the accumulation of metal in aboveground parts is over 1% [63].

Studies are being conducted worldwide on the use of plants producing large amounts of biomass (for energy generation purposes) in the phytoextraction of heavy metals from polluted soils. They include annual plants such as e.g. cereals and rape, and perennials e.g. willows, which capacity for phytoextraction of heavy metals was confirmed by Greger and Landberg [56] and Boyter et al. [26]. Other perennial species of energy crops include *Spartina pectinata, Sida Hermaphrodita, Rosa multiflora, Helianthus tuberosus, Populus spp.,* and *Robinia pseudoaca‐ cia.* The most significant parameters of these plants include high annual increment of biomass and its high calorific value [116].

Ociepa et al. [94] stated that plants grown for energy purposes may play a considerable role in view of the assumptions of the Common Agricultural Policy and the environmental protection policy of the European Union. One of such plant species is *Miscanthus × giganteus* Greef and Deu.

In the years 2008 – 2011 at the Department of Plant Nutrition, the Poznan University of Life Sciences, Poland, studies were conducted to assess applicability of *Miscanthus × giganteus* Greef and Deu. in phytoextraction of heavy metals from soil. The aim of the conducted analyses was to determine what amounts of cadmium and lead are transported to aboveground parts of *Miscanthus × giganteus* and whether *Miscanthus × giganteus* would be suitable for rapid phytoextraction of cadmium, lead from polluted soils.

#### **Material and methods**

The vegetation experiment was conducted in an unheated plastic tunnel with suspended sides, of 6 x 30 m in size. at the Marcelin Experimental Station of the Poznan University of Life Sciences.

Seedlings of *Miscanthus × giganteus* were produced at a tissue culture laboratory of Vitroflora. Plants were planted in the beginning of May in drainless containers (of 7 dm3) filled with previously prepared substrate. The experiment comprised 16 combinations (in each year of the study) and each combination consisted of six replications. A replication comprised one plant growing in pots.

Phytoremediation of cadmium and lead by *Miscanthus × giganteus* was investigated in two years of growth with the plants being grown in two substrates. at four levels of metal contents. Since light soils with low contents of organic matter predominate in Poland. such soil was selected for the experiment. Another substrate was a mixture of this mineral soil with highmoor peat. Highmoor peat was added to increase the amount of organic matter in the mineral soil.

Substrates: mineral soil (sand) and mineral soil with highmoor peat (1:1 v/v)

Doses of cadmium: control (native contents of cadmium), 3, 5 and 10 mg dm-3)

Doses of lead: control (native contents of cadmium), 250, 1000 and 5000 mg dm-3).

In mineral soil the method according to Mocek and Drzymała [88] was used to determine particle density (which amounted to 2.65 g cm-3) and bulk density (1.62 g cm-3). Total porosity of mineral soil was 38.9%. Moreover. grain size distribution of mineral soil was determined by the densimetric method according to Prószyński [88]. On the basis of the percentages of fractions the grain size class of soil was identified (according to the guidelines of the Polish Society of Soil Science) - sand.

Prior to the establishment of the experiment, Corg content in mineral soil was determined according to the Tiurin method [51]. Content of organic carbon in sand (the Tiurin method) was 0.55% (0.95% humus). while the percentage of organic matter in the mixture of sand and highmoor peat (from loss on ignition) was 10.05%. In the substrate composed of a mixture of mineral soil with highmoor peat (1:1 v/v) the percentage of organic substance was determined by loss on ignition the substrate by the direct method at high temperature in the presence of oxygen, under the influence of which organic substance is decomposed (carbon is released in the form of CO2. hydrogen in the form of H2O and nitrogen as N2, while the other elements remain in ash).

Experiments were conducted using highmoor peat by Hartmann (sphagnum peat. ground. fractional with acid reaction (pH 4.50). This peat has a high water capacity, at the same time retaining an elastic structure. The weight of 1 dm3 peat was 490 grams.

In order to obtain an appropriate pH for growing of *Miscanthus × giganteus* a neutralization curve was plotted for the analyzed substrates. On its basis the dose of CaCO3 required for the maintenance of pH within the range of 6.5-7.0 was established. The reaction of the substrate (mineral soil + highmoor peat) was regulated using 3 g dm-3 CaCO<sup>3</sup> (chemically pure reagent). The substrate composed of mineral soil did not require reaction control. Despite that fact 1 g dm-3 CaCO3 was applied in order to maintain pH at 6.5-7.0. An adequate amount of calcium carbonate was introduced to each experimental container with the substrate. Cadmium and lead contents in analyzed substrates after liming amounted: in mineral soil Cd 0.27, Pb 27.32 mg dm-3 and mineral soil with highmoor peat Cd 0.18, Pb

and Deu. in phytoextraction of heavy metals from soil. The aim of the conducted analyses was to determine what amounts of cadmium and lead are transported to aboveground parts of *Miscanthus × giganteus* and whether *Miscanthus × giganteus* would be suitable for rapid

**Material and methods** The vegetation experiment was conducted in an unheated plastic tunnel with suspended sides, of 6 x 30 m in size. at

Seedlings of *Miscanthus × giganteus* were produced at a tissue culture laboratory of Vitroflora. Plants were planted in the beginning of May in drainless containers (of 7 dm3) filled with previously prepared substrate. The experiment comprised 16 combinations (in each year of the study) and each combination consisted of six replications. A

Phytoremediation of cadmium and lead by *Miscanthus × giganteus* was investigated in two years of growth with the plants being grown in two substrates. at four levels of metal contents. Since light soils with low contents of organic matter predominate in Poland. such soil was selected for the experiment. Another substrate was a mixture of this mineral soil with highmoor peat. Highmoor peat was added to increase the amount of organic matter in the mineral

In mineral soil the method according to Mocek and Drzymała [88] was used to determine particle density (which amounted to 2.65 g cm-3) and bulk density (1.62 g cm-3). Total porosity of mineral soil was 38.9%. Moreover. grain size distribution of mineral soil was determined by the densimetric method according to Prószyński [88]. On the basis of the percentages of fractions the grain size class of soil was identified (according to the guidelines of the Polish Society

Prior to the establishment of the experiment, Corg content in mineral soil was determined according to the Tiurin method [51]. Content of organic carbon in sand (the Tiurin method) was 0.55% (0.95% humus). while the percentage of organic matter in the mixture of sand and highmoor peat (from loss on ignition) was 10.05%. In the substrate composed of a mixture of mineral soil with highmoor peat (1:1 v/v) the percentage of organic substance was determined by loss on ignition the substrate by the direct method at high temperature in the presence of oxygen, under the influence of which organic substance is decomposed (carbon is released in the form of CO2. hydrogen in the

Experiments were conducted using highmoor peat by Hartmann (sphagnum peat. ground. fractional with acid reaction (pH 4.50). This peat has a high water capacity, at the same time retaining an elastic structure. The weight of 1

In order to obtain an appropriate pH for growing of *Miscanthus × giganteus* a neutralization curve was plotted for the analyzed substrates. On its basis the dose of CaCO3 required for the maintenance of pH within the range of 6.5-7.0 was established. The reaction of the substrate (mineral soil + highmoor peat) was regulated using 3 g dm-3 CaCO<sup>3</sup> (chemically pure reagent). The substrate composed of mineral soil did not require reaction control. Despite that fact 1 g dm-3 CaCO3 was applied in order to maintain pH at 6.5-7.0. An adequate amount of calcium carbonate was introduced to each experimental container with the substrate. Cadmium and lead contents in analyzed substrates after liming amounted: in mineral soil Cd 0.27, Pb 27.32 mg dm-3 and mineral soil with highmoor peat Cd 0.18, Pb

phytoextraction of cadmium, lead from polluted soils.

the Marcelin Experimental Station of the Poznan University of Life Sciences.

Substrates: mineral soil (sand) and mineral soil with highmoor peat (1:1 v/v) Doses of cadmium: control (native contents of cadmium), 3, 5 and 10 mg dm-3) Doses of lead: control (native contents of cadmium), 250, 1000 and 5000 mg dm-3).

form of H2O and nitrogen as N2, while the other elements remain in ash).

replication comprised one plant growing in pots.

594 Environmental Risk Assessment of Soil Contamination

soil.

of Soil Science) - sand.

dm3 peat was 490 grams.

12.03 mg dm-3. Two weeks after liming nutrients cadmium and lead were introduced to the substrate. Cadmium and lead was introduced only in the first year of the experiment in the form of chemically pure reagents (C.P.): cadmium sulfate (3CdSO4 8H2O), lead acetate [(CH3COO)2Pb∙3H2O]. Pre-vegetation fertilization (in the first year) with macroand micronutrients was determined taking into consideration initial nutrient contents in substrates. after liming reaching the following levels (in mg dm-3): N 200, P 120, K 250, Mg 100, Fe 50, Mn 20, B 1.5 and Mo 1.5. All macroand micronutrients were introduced in the form of solutions using chemically pure reagents (potassium monophosphate, potassium nitrate, ammonium nitrate, magnesium saltpeter, magnesium sulfate, iron sulfate, copper sulfate, zinc sulfate, manganese sulfate, ammonium molybdate, borax). In the second year of the experiment an identical experimental design was used as in the first year. After plant cutting in the first year of the experiment containers with polluted substrates were stored in an unheated tunnel to the next vegetation year (the second year of the study). In the second year of the study in March - prior to the beginning of vegetation substrate samples were collected and chemical analyses were performed to determine nutrient contents. On this basis nutrient fertilization was established (leading to nutrient contents at the same levels. which were applied in the first year of the experiment). Nutrients in substrates were determined using the *"Universal"* method [78] in CH3COOH solution at a concentration of 0.03 mol dm-3, pH in water was determined by potentiometry (the substrate to water ratio of 1:2), while conductometry was applied to determine EC (mS cm-1), (the substrate to water ratio of 1:2), [50]. The following nutrient determination techniques were applied: N – NH4 and N – NO3 by microdistillation (Bremner modified by Starck), P by colorimetry using the vanadium-molybdenum method, K, Ca and Na by flame photometry, Mg by atomic absorption (AAS), Cl and S – SO4 by nephelometry [78].

In October in each year of the study prior to harvesting plant height was measured. Dry weight of plants was recorded and samples of plant material were collected for analyses.

Harvested plant material (entire aboveground mass) was dried in an extraction drier at a temperature of 105ºC for 48 h. Next the material was ground and at 2.5 g from each sample it was digested in a mixture of concentrated HNO3 (ultra pure) and HClO4 (analytically pure) at a 3:1 ratio [18]. Content of cadmium and lead in the plant material were determined by flame atomic absorption spectrophotometry (FAAS), AAS-3 spectrophotometer by Zeiss. Moreover, content of metals in the reference material (*Pseudevernia furfuracea* BCR®-482/2009) was determined. In the first and second year of the study samples of substrate were collected after harvest, from which metals were extracted using the Lindsey's solution containing in 1 dm3: 5 g EDTA (ethylenediaminetetraacetic acid), 9 cm3 25% NH4OH solution, 4 g citric acid and 2 g Ca(CH3COO)2 2H2O. Next this metal was assayed by flame atomic absorption spectrophotometry (FAAS), AAS-3 spectrophotometer by Zeiss.

Results of content of cadmium and lead in substrates and aboveground parts of *Miscanthus × giganteus* were elaborated statistically in the Statobl program applying a one-way analysis of variance for orthogonal factorial experiments, with differences between means determined at a significance level p=0.05.

*Miscanthus × giganteus* Greef and Deu. (Figure 6) is an interspecies hybrid of a diploid Chinese silver grass [*Miscanthus sinensis* (Thunb.) Anderss.] and a tetraploid Amus silver grass [*Miscanthus sacchariflorus* (Maxim.) Benth], belonging to the family *Poaceae* [54, 55, 61]. After three years of culture the yield of dry matter is 20 to 35 t and plant height is 3 - 4 m [102]. *Miscanthus × giganteus* originates from South-Eastern Asia and it has been grown in Europe, initially as an ornamental plant, for over 50 years. In Poland it still is not a popular crop. In the nearest future interest in growing of this plant in Poland will be increasing. This abundant grass forms new shoots stretching outwards from rhizomes (underground runners), forming an increasingly bigger rounded cluster [102].

Analyses conducted by physiologists classify *Miscanthus* to the group of plants of the C-4 pathway, which are characterised by a highly efficient photosynthesis process, ensuring a rapid and high increase in biomass, at a simultaneous lower transpiration coefficient, i.e. lower water consumption [58, 89].

Proposed methods to manage Miscanthus after phytoextraction of heavy metals from soil include combustion (ashes – hazardous waste), bio-ore, paper and pulping industry, produc‐ tion of particleboards as well as chemical industry (packaging plastics).

**Figure 6.** *Miscanthus × giganteus* Greef and Deu. in the third year of growth

The aim of the conducted analyses was to determine the effect of increasing doses of cadmium, lead introduced to mineral soil (sand) and to mineral soil with an addition of highmoor peat (at a 1:1 ratio, v/v), on the tolerance index of *Miscanthus x giganteus*. The tolerance index (Ti ) was calculated, i.e. the ratio of the yield (dry biomass) obtained in metal-polluted soil to the yield (dry biomass) produced in unpolluted soil. This index is considered as the most reliable indicator of the toxic effect of heavy metals contained in soils and substrates exercised on plants.


In the first year of growth of *Miscanthus × giganteus* the tolerance index greater than one was recorded in plants in mineral soil polluted with 3 mg Cd dm-3 and 1000 mg Pb dm-3 (Table 6). In the second year of growth the tolerance index greater than one was found in plants in mineral soil contaminated with all the used cadmium pollution rates and in soil, to which 250 and 1000 mg Pb dm-3 were introduced. The tolerance index greater than one was also recorded in the substrate constituting a mixture of mineral soil with highmoor peat contaminated with 3 mg Cd dm-3 (in the first year of growth) and 5 mg Cd dm-3 (in the second year of growth).


**Table 6.** The tolerance index (Ti) in *Miscanthus x giganteus*

Analyses conducted by physiologists classify *Miscanthus* to the group of plants of the C-4 pathway, which are characterised by a highly efficient photosynthesis process, ensuring a rapid and high increase in biomass, at a simultaneous lower transpiration coefficient, i.e. lower

Proposed methods to manage Miscanthus after phytoextraction of heavy metals from soil include combustion (ashes – hazardous waste), bio-ore, paper and pulping industry, produc‐

The aim of the conducted analyses was to determine the effect of increasing doses of cadmium, lead introduced to mineral soil (sand) and to mineral soil with an addition of highmoor peat (at a 1:1 ratio, v/v), on the tolerance index of *Miscanthus x giganteus*. The tolerance index (Ti

was calculated, i.e. the ratio of the yield (dry biomass) obtained in metal-polluted soil to the yield (dry biomass) produced in unpolluted soil. This index is considered as the most reliable indicator of the toxic effect of heavy metals contained in soils and substrates exercised on

)

tion of particleboards as well as chemical industry (packaging plastics).

**Figure 6.** *Miscanthus × giganteus* Greef and Deu. in the third year of growth

< 1 value lower than one - inhibition of growth or plant death

> 1 value greater than one - positive effect of metal on yielding.

= 1 value equal one - no effect of increased metal contents on yielding

plants.

Ti

Ti

Ti

water consumption [58, 89].

596 Environmental Risk Assessment of Soil Contamination

In the opinion of Arduini et al. [8] and Kozak et al. [77], *Miscanthus* is a less tolerant species to high concentrations of heavy metals in comparison to osier and it is necessary to conduct further tests on the applicability of varieties of this species in the phytoextraction of heavy metals.

Kalembasa and Malinowska [72], when testing different clones of *Miscanthus* found differences in their capacity to accumulate individual heavy metals, particularly cadmium. Iżewska [65] in the third year of *Miscanthus* culture recorded a greater content of cadmium and a lower content of lead in its biomass. In the opinion of Kalembasa and Malinowska [71], contents of cadmium and lead in biomass are also dependent on the harvest date of Miscanthus. The highest cadmium concentration was recorded in *Miscanthus* biomass at the begining of June, lead at the beginning of September and October. Those authors stated that the triploid Miscanthus species was characterized by higher contents of cadmium and lead in its biomass in comparison to the diploid species. According to those authors, nitrogen, phosphorus and potassium fertilization has an effect on cadmium content in biomass of diploid Miscanthus genotypes.

Based on studies conducted by the authors of this chapter it was found that cadmium applied at 3 and 5 mg dm-3 mineral soil in the first year of growth of *Miscanthus × giganteus* had no significant effect on the content of this metal in aboveground parts of plants in comparison to those growing in soil with no addition of this metal (Table 7). In the second year of growth in mineral soil to which 5 mg Cd dm-3 were introduced a significantly greater content of this metal was detected in aboveground parts of plants in comparison to plants growing in unpolluted soil. In plants growing in mineral soil the greatest Cd content was found in the second years of growth of *Miscanthus × giganteus* growing in soil polluted with 10 mg Cd dm-3 .

In a mixture of mineral soil with highmoor peat, to which 3 mg Cd dm-3 were introduced both in the first and second year of growth of *Miscanthus × giganteus* no significant differences were observed in the contents of this metal in aboveground parts. The greatest cadmium content was recorded in plants growing in the substrate polluted with 10 mg Cd dm-3 in the first and second years of growth.


\*homogeneous groups were identified using the Duncan test, p=0.05 (values denoted with identical letters do not differ significantly)

**Table 7.** Contents of Cd (mg kg-1 dry weight) in aboveground parts of *Miscanthus × giganteus* growing in substrates polluted with cadmium

A significantly greater lead content in aboveground parts of *Miscanthus × giganteus* in com‐ parison to the control was found in plants growing in all tested substrates contaminated with this metal (Table 8). In plants growing in mineral soil contaminated with 10 mg Pb dm-3 a higher content of this metal was detected in the first year of growth and it was the highest content recorded in the analyses. No differences were observed in lead contents in aboveground parts of *Miscanthus × giganteus* in the first and second year of growth in a mixture of mineral soil with highmoor peat.


\*homogeneous groups were identified using the Duncan test, p=0.05 (values denoted with identical letters do not differ significantly)

**Table 8.** Contents of Pb (mg kg-1 dry weight) in aboveground parts of *Miscanthus × giganteus* growing in lead-polluted substrates

In the conducted analyses the cadmium and lead concentration indexes were calculated for aboveground parts of *Miscanthus × giganteus*. The metal concentration index was caluclated from the formula

#### C = a : b

mineral soil to which 5 mg Cd dm-3

598 Environmental Risk Assessment of Soil Contamination

second years of growth.

**Dose of metal (mg dm-3)**

**Substrate**

Mineral soil

Mineral soil + highmoor peat

differ significantly)

polluted with cadmium

with highmoor peat.

**Table 7.** Contents of Cd (mg kg-1

were introduced a significantly greater content of this metal

**Year of culture**

**1st year 2nd year**

**range**

**range R**

**SD mean min.-max.**

Control 0.98-1.29 0.31 0.12 **1.17 ab** 1.29-1.52 0.23 0.10 **1.39 ab**

Cd 3 1.31-1.99 0.68 0.24 **1.70 bc** 1.14-2.59 1.45 0.51 **2.06 a-d**

Cd 5 1.33-3.69 2.36 0.78 **2.61 bcd** 1.78-4.69 2.91 0.97 **3.52 d**

Cd 10 3.56-8.34 4.78 1.62 **5.51 e** 6.16-12.62 6.46 2.81 **9.30 g**

Control 0.64-1.33 0.69 0.25 **0.97 a** 0.95-1.46 0.51 0.19 **1.20 ab**

Cd 3 1.34-1.93 0.59 0.22 **1.60 abc** 1.38-1.90 0.52 0.20 **1.66 abc**

Cd 5 2.39-3.96 1.57 0.67 **2.97 cd** 2.68-4.78 2.10 0.97 **3.41 d**

Cd 10 5.23-9.34 4.11 1.55 **7.46 f** 5.54-11.17 5.63 2.48 **8.66 fg**

dry weight) in aboveground parts of *Miscanthus × giganteus* growing in substrates

\*homogeneous groups were identified using the Duncan test, p=0.05 (values denoted with identical letters do not

A significantly greater lead content in aboveground parts of *Miscanthus × giganteus* in com‐ parison to the control was found in plants growing in all tested substrates contaminated with

content of this metal was detected in the first year of growth and it was the highest content recorded in the analyses. No differences were observed in lead contents in aboveground parts of *Miscanthus × giganteus* in the first and second year of growth in a mixture of mineral soil

this metal (Table 8). In plants growing in mineral soil contaminated with 10 mg Pb dm-3

.

were introduced both

in the first and

**SD mean**

a higher

was detected in aboveground parts of plants in comparison to plants growing in unpolluted soil. In plants growing in mineral soil the greatest Cd content was found in the second years

in the first and second year of growth of *Miscanthus × giganteus* no significant differences were observed in the contents of this metal in aboveground parts. The greatest cadmium content

of growth of *Miscanthus × giganteus* growing in soil polluted with 10 mg Cd dm-3

was recorded in plants growing in the substrate polluted with 10 mg Cd dm-3

**range R**

In a mixture of mineral soil with highmoor peat, to which 3 mg Cd dm-3

**min.-max. range**

a - content in a plant growing in polluted substrate

b - content in a plant growing in unpolluted substrate.

The greatest concentration index was recorded for lead in the first year of growth in the case of plants growing in mineral soil (Table 9). Plants growing in mineral soil were characterized by a greater concentration index for cadmium and lead in the first year of growth. An identical dependence was found in plants growing in a mixture of soil and peat, except for plants growing in a substrate contaminated with 5000 mg Pb dm-3, in which a higher lead concen‐ tration index was found in the second year of growth.

Miscanthus sp. was tested on heavy metal contaminated arable soil in Southern Poland [110]. The authors concluded that this species accumulates high amounts of metals what may cause high emission of contaminants during biomass combustion.

According to Kalembas [70] in ash of *Miscanthus sinensis* Thumb. the content of individual heavy metals ranks in the following decreasing levels: Zn>Cd>Pb>Ni>Cu>Cr.


**Table 9.** Metal concentration indexes in aboveground parts of *Miscanthus x giganteus*

Both in soil and in a mixture of soil and peat a lower cadmium content was recorded after the second year of culture except for substrates contaminated with 10 mg Cd dm-3, in which this dependence was not observed (Table 10).

When analyzing lead content in tested substrates after the completion of growth a lower Pb content was found also in the second year except for a mixture of mineral soil with peat, to which lead was not introduced (table 11).

In the substrate being a mixture of soil with peat lower contents of cadmium and lead were observed in comparison to those recoded in mineral soil in all the experimental variants (Tables 10 and 11).


\*homogeneous categories were identified with the Duncan test, p=0.05 (values denoted with identical letters do not differ significantly)

**Table 10.** Cadmium contents (extracted with Lindsey's solution) in substrates (in mg dm-3) after the completion of plant growth in the first and the second year of analyses

Continuous and Induced Phytoextraction — Plant-Based Methods to Remove Heavy Metals from Contaminated Soil http://dx.doi.org/10.5772/57257 601


\*homogeneous groups were identified with the Duncan test, p=0.05 (values denoted with identical letters do not dif‐ fer significantly)

**Table 11.** Contents of lead (extracted with Lindsey's solution) in substrates (in mg dm-3) after the completion of plant growth in the first and the second years of analyses
