Ecological strategy for soil contaminated with mercury

Aims The paper presents results from plot experiments aimed at the development of an ecological strategy for soil contaminated with mercury. Meadow grass (Poa pratensis) was tested on mercury contaminated soil in a former chlor-alkali plant (CAP) in southern Poland for its phytoremediation potential. Methods The stabilisation potential of the plants was investigated on plots without additives and after the addition of granular sulphur. Biomass production, uptake and distribution of mercury by plants, as well as leachates and rhizosphere microorganisms were investigated, along with the growth and vitality of plants during one growing season. Results The analysed plants grew easily on mercury contaminated soil, accumulating lower amounts of mercury, especially in the roots, from soil with additive of granular sulphur (0.5 % w/w) and sustained a rich microbial population in the rhizosphere. After amendment application the reduction of Hg evaporation was observed. Conclusions The obtained results demonstrate the potential of using Poa pratensis and sulphur for remediation of mercury contaminated soil and reduction of the Hg evaporation from soil. In the presented study, methods of Hg reduction on “hot spots” were proposed, with a special focus on environmental protection. This approach provides a simple remediation tool for large areas heavily contaminated with mercury

Ecological strategy for soil contaminated with mercury

Aims The paper presents results from plot experiments aimed at the development of an ecological strategy for soil contaminated with mercury. Meadow grass (Poa pratensis) was tested on mercury contaminated soil in a former chlor-alkali plant (CAP) in southern Poland for its phytoremediation potential. Methods The stabilisation potential of the plants was investigated on plots without additives and after the addition of granular sulphur. Biomass production, uptake and distribution of mercury by plants, as well as leachates and rhizosphere microorganisms were investigated, along with the growth and vitality of plants during one growing season. Results The analysed plants grew easily on mercury contaminated soil, accumulating lower amounts of mercury, especially in the roots, from soil with additive of granular sulphur (0.5 % w/w) and sustained a rich microbial population in the rhizosphere. After amendment application the reduction of Hg evaporation was observed. Conclusions The obtained results demonstrate the potential of using Poa pratensis and sulphur for remediation of mercury contaminated soil and reduction of the Hg evaporation from soil. In the presented study, methods of Hg reduction on “hot spots” were proposed, with a special focus on environmental protection. This approach provides a simple remediation tool for large areas heavily contaminated with mercury

Diminishing the risk on lead and zinc ore regions by subtle modulation of soil properties

The negative effect of non-ferrous metal emission in Upper Silesian Industrial Region (Poland) on the quality of soil is continuously present. It poses a serious threat on living organisms and is an important factor influencing the level of metal load introduced to human organism. Easy way for diminishing the metal uptake by plants is the amendment application to the soil. Presented study was conducted to evaluate the effect of the introduction of sewage sludge and fly ashes from power station into the medium contaminated soil. Heavy metals in soil were stabilized with a mixture of sewage sludge and fly ashes from the local wastewater treatment plant and power plant. Previously the mixture was tested in terms of the probability of its ecotoxicological impact on plant growth and development. Even low doses of the mixture addition to the contaminated soil caused a observable reduction of lead, cadmium and zinc in leaves of grasses. Soil additives also increased the soil pH

Diminishing the risk on lead and zinc ore regions by subtle modulation of soil properties

The negative effect of non-ferrous metal emission in Upper Silesian Industrial Region (Poland) on the quality of soil is continuously present. It poses a serious threat on living organisms and is an important factor influencing the level of metal load introduced to human organism. Easy way for diminishing the metal uptake by plants is the amendment application to the soil. Presented study was conducted to evaluate the effect of the introduction of sewage sludge and fly ashes from power station into the medium contaminated soil. Heavy metals in soil were stabilized with a mixture of sewage sludge and fly ashes from the local wastewater treatment plant and power plant. Previously the mixture was tested in terms of the probability of its ecotoxicological impact on plant growth and development. Even low doses of the mixture addition to the contaminated soil caused a observable reduction of lead, cadmium and zinc in leaves of grasses. Soil additives also increased the soil pH

Environmental hazards related to Miscanthus x giganteus cultivation on heavy metal contaminated soil

According to recent estimates reaching the target of a 20% share of renewable energy sources (RES) in the final energy balance in Poland by 2020 will result in the demand for more than 8 million tons of biomass, which, in turn, will entail the necessity of creating large-scale energy crop plantations. According to EU assumptions the most effective way to produce biomass for energy purposes is cultivation of energy crops in agricultural areas. It is particularly vital for Poland, because these areas constitute a relatively large part of the country (59%), 76% of them being used as farmlands. In Silesia, the most industrialized region of the country, 5-10% of agricultural soils are contaminated with cadmium, lead and zinc. The main objective of the presented study was to estimate the accumulation of heavy metals in the tissues of Miscanthus x giganteus grown on contaminated soils and calculate concentrations of Pb, Cd and Zn in crops. It was shown that the large intake of heavy metals by that species could cause high emissions of pollutants into the atmosphere during its improper combustion. As a side effect, winter harvesting led to the loss of even 30% of biomass. Plant residues (leaves) can be the source of pollution after decomposing and releasing metals back into the soil. Moreover, miscanthus leaves can be transferred by wind to the surrounding areas. It is very likely that ash coming from the combustion of contaminated biomass cannot be used as a fertilizer

Environmental hazards related to

According to recent estimates reaching the target of a 20% share of renewable energy sources (RES) in the final energy balance in Poland by 2020 will result in the demand for more than 8 million tons of biomass, which, in turn, will entail the necessity of creating large-scale energy crop plantations. According to EU assumptions the most effective way to produce biomass for energy purposes is cultivation of energy crops in agricultural areas. It is particularly vital for Poland, because these areas constitute a relatively large part of the country (59%), 76% of them being used as farmlands. In Silesia, the most industrialized region of the country, 5-10% of agricultural soils are contaminated with cadmium, lead and zinc. The main objective of the presented study was to estimate the accumulation of heavy metals in the tissues of Miscanthus x giganteus grown on contaminated soils and calculate concentrations of Pb, Cd and Zn in crops. It was shown that the large intake of heavy metals by that species could cause high emissions of pollutants into the atmosphere during its improper combustion. As a side effect, winter harvesting led to the loss of even 30% of biomass. Plant residues (leaves) can be the source of pollution after decomposing and releasing metals back into the soil. Moreover, miscanthus leaves can be transferred by wind to the surrounding areas. It is very likely that ash coming from the combustion of contaminated biomass cannot be used as a fertilizer

The use of indigenous plant species and calcium phosphate for the stabilization of highly metal-polluted sites in southern Poland

Highly metal-polluted (Pb, Cd, Zn) soil from a non-ferrous mine and smelter site in southern Poland, further referred to as Waryski soil, was used to test indigenous plant species for stabilization effectiveness of heavy metals in soils. Results of pilot investigations with commercially available cultivars of plant species showed that these cultivars could not grow on this highly polluted soil even with the application of soil amendments to stabilize the heavy metals. Based on these results, mesocosm and field experiments with an indigenous, metal-tolerant ecotype of Deschampsia cespitosa from the Waryñski site were carried out. The mesocosm experiment showed that applications of calcium phosphate (3.8% w/w) as a heavy metal-stabilizing amendment decreased Cd and Zn concentrations 2 and 3-fold respectively in leachates, whereas lead content was not significantly changed. This decrease in the concentration of heavy metals in leachates was correlated with a lower accumulation of Pb, Cd and Zn in the roots and shoots of D. cespitosa, ecotype Waryñski. In the field experiment, lower accumulations of Cd in roots and shoots and Zn in shoots in the amendment added plot were observed during the second year of investigations. In the first growing season, D. cespitosa plant cover in the amendment enriched mesocosms ranged from 95 to 100%, compared to 10% in mesocosms without calcium phosphate. In the second year of the experiment, in non-amendment enriched mesocosms D. cespitosa was substituted with Cardaminopsis arenosa(95% cover). C. arenosa is an undesirable species for phytostabilization, as it accumulates high amounts of zinc and cadmium in its shoots, even thought it provided better growth cover in not amended soils. However, in amended mesocosms, soil surface cover by D. cespitosa was still very high (90%). Similar results were obtained in field experiments. Addition of calcium phosphate to the soil also resulted in excellent D. cespitosa root system development when compared to soils without amendment. In amended mesocosms, high plant cover and root system development significantly decreased the volume of leachates and improved water retention. These results indicate that the use of D. cespitosa, ecotype Waryski in combination with calcium phosphate as a heavy metals immobilizing agent is sufficient to restore a dense vegetative cover to highly heavy metal-polluted soil