Assessment of Ecotoxicity of Soils Contaminated by Heavy Metals

The experiment has shown that in soils contaminated by heavy metals, the boundary metal concentrations, above which ecotoxicity evidences are recorded, are different for the test plant and microbial community. Respiration inhibition in the studied soils occurs at higher doses of Pb, Zn, and Cd than a decrease in germination and length of white mustard ( Sinapis alba ) seedlings. Cd compounds and a complex of contaminants are the most toxic for both test plants and microorganisms. Concentrations of heavy metals, exerting a significant adverse impact on test plants and soil microbial community, have been revealed for soddy-podzolic, gray forest, leached chernozemic, and chestnut soils. With respect to the resistance to the contamination by heavy metals, the studied soils may be arranged in the following sequence: leached chernozem (Luvic Chernozem (Loamic, Aric, Pachic)) > gray forest soil (Eutric Retisol (Loamic, Aric, Cutanic, Ochric)) > chestnut soil (Haplic Kastanozem (Loamic, Aric)) > soddy-podzolic soil (Eutric Albic Retisol (Loamic, Aric, Cutanic, Differentic, Ochric)). At the contamination by Pb, Zn, and Cd acetates, the increase in the content of their mobile compounds is much greater as compared to their total content. The highest mobility of Pb, Zn, and Cd occurs at their simultaneous input to the soil.