ИСТИНА

The search for effective remedies for metal-contaminated soils is one of the important environmental problems in the areas of metallurgical enterprises. In this research we investigated the effectiveness of biochar and Fe-containing sorbents in modeling the remediation effects of Eutric Histosol peat soil contaminated by copper-nickel complex emissions (Kola Peninsula, Russia). To samples of contaminated soil, we added biochar (2%), sorbents (2%), or their combination by background addition of dolomite (20%, to neutralize acidity). The sorbents were represented by both macro- (Iron powder, Fe-Mn-Concretions) and nanoparticles of iron (Fe-NP). In total, the toxicity of 7 variants of soil samples was analyzed. Soil without sorbents was considered a control. To assess the toxicity of the samples, we used a standard aqueous extract biotesting method for the survival rate of Сeriodaphnia after 48 hours of exposure to the sample. Biochar at a dose of 3% reduced soil toxicity, which manifested itself in an increase in crustacean survival rate from 0% (control) to 85% (Biochar). Iron-containing sorbents were more effective in reducing toxicity than biochar: with Fe-Mn-Concretions the survival rate was 90%, with Iron powder - 100%. The compositions of Fe-containing drugs with biochar did not improve the effect of the sorbents individually for all drugs. In the variant Biochar + Fe-Mn-Concretions, the survival rate is 10% higher than when only Fe-Mn-Concretions are added, when Biochar + Fe-NP is also 10% higher than when only Biochar is added. But when adding Biochar + Iron powder, the test-culture survival rate is only 85%, which is noticeably lower than with Iron powder (100%). Thus, more detailed studies of the mechanism of detoxifying action of biochar in the presence of different forms of Fe-containing sorbents of toxic cations in the soil are needed.