Vanessa Katherine Kalero

The effect of polymer soil amendments on changes in toxicity of agro-sod-podzolic soil spiked with a complex of heavy metals (HM) has been characterized. Hydrolyzed polyacrylonitrile (HYPAN) and a binary composition of HYPAN+potassium humate (HYPAN+PH, 1:10) were applied at a rate of 0.2% (on a dry matter basis) to soils with model contamination by Cu, Zn, Pb, and Cd at levels of 2, 4, and 6 approximate permissible concentrations (APC). Samples without ameliorant treatment served as a control for all soil pollution levels. The effect of polymer formulations on reducing the toxicity of heavy metals manifested to varying degrees depending on the level of soil contamination. The bacterial standard bioluminescent biotest and phytotesting on the seedlings of higher plants Sinapis alba L. showed a positive effect of the HYPAN+PH composition at the highest contamination level, 6 APC. Bioindication of the functional state of soil microbiota showed that ameliorants lowered the microbial metabolic coefficient (to an acceptable level of 2 µg C-CO₂ mg⁻¹·Cmic·h⁻¹), which is important evidence of their positive effect on the soil microbial community. Laboratory biotesting of uncontaminated soil, as well as at relatively low levels of HM contamination, revealed the toxicity of the aqueous extract of samples with ameliorants (inhibiting root growth and quenching bioluminescence in bacterial bioassay). In light of the findings of this study, it is recommended that further analyses should be conducted before suggesting the use of tested ameliorants for the detoxification of polluted soils.