The Effectiveness of Remediation Agents for Detoxification of Heavy-Metal-Contaminated Soils according to Experimental Results

Abstract

The effectiveness of remediation agents in detoxification of soils contaminated with heavy metals is studied in a laboratory experiment. The objects of the study are southern tundra soils functioning under conditions of anthropogenic impacts: haplic gleysols gelic and histic fluvisols oxyaquic. The chemical ability of remediation agents to bind metals (Ni and Cu), transferring them to a sedentary state compared to the reference variants (without adding a remediation agent), is evaluated. In the experiments, remediation agents are used in three doses (D1–D3): carbonaceous (shungite), of biological origin (diatomite), and mineral remediation agents (glauconite and bentonite). To assess the immobilization of Ni and Cu in soils, acid-soluble (AS) forms (extraction of 1 N HNO₃), mobile forms (ammonium acetate buffer with pH 4.8), and water-soluble forms of Ni and Cu (1 : 20 aqueous extract) are determined by inductively coupled plasma mass spectrometry. The effectiveness of soil detoxification during the application of remediation agents is evaluated by the phytotoxic effect in an express test, a response of standardized test plants (Brassica rapa CrGC and Avena sativa) represented by higher plants. A decrease in the proportion of mobile forms of Ni and Cu by 50% or more in haplic gleysols gelic is revealed when any dose of remediation agents is added. The greatest effect of reducing mobility is exerted by shungite and diatomite at a dose of D1, up to 15% Ni and Cu in histic fluvisols oxyaquic. The use of the selected remediation agents in the indicated amounts did not have a phytotoxic effect on the test plants in the experiment.