Time effect on the stabilization of technogenic copper compounds in solid phases of Haplic Chernozem.

We studied the regularities of Cu stabilization in Haplic Chernozem contaminated with easily soluble (acetates, nitrates, sulfates, chlorides) and poorly soluble (acetates, nitrates, sulfates, chlorides) metal compounds in a five-year model experiment were studied. A low contents of Cu loosely bound compounds (LBC) (no >5% of total content) unchanging over time were revealed in the uncontaminated soil, which is indicative of the stability of soil processes. The Cu LBC content decreased over time in the soils contaminated with easily soluble compounds and increased in the soils contaminated with poorly soluble compounds. In both cases, the contents of Cu LBCs after 5 years of incubation remained higher than in the original uncontaminated soil. The effect of the attendant anions on the Cu LBC content was more apparent under the Cu application of 2000 mg kg-1 than at 300 mg kg-1. An inverse process characterized by an increase in the concentration of Cu LBCs over time was observed in the soil contaminated with Cu orthophosphate and oxide. Soil contaminated with different Cu compounds results in soil acidification. According to the effect on the decrease in soil pH, the attendant anions form the following series: SO42- ≈ Cl- > NO3- > Ac- > PO42- > O2-, which correlates with the Cu LBC content. Thus, the stabilization of Cu compounds in the soil is affected by the attendant anions and the interaction time of the metal with the soil solid phases.