Priority organic pollutants in soil of arboretum of the Botanical Garden of Moscow State University: Report 3. Specific features of vertical distribution pattern of organochlorine pesticide in profile of urbanozem

Abstract

The vertical distribution pattern of dichlorodiphenyltrichloroethane (DDT) and its metabolites (hexachlorocyclohexane (HCH) isomers and hexachlorobenzene (HCB)) in the urbanozem of the arboretum of the Botanical Garden of Moscow State University at Vorob’evy Gory is studied. The highest contents of DDT, dichlorodiphenyldichloroethylene (DDE), and HCH isomers in the soil profile are found in the Au humus horizon and/or in the top part of the U technogenic 10–20-cm-thick layer. The greatest HCB content is typical of the U technogenic 20–30-cm-thick layer. The total content of DDT and its metabolites (156.2 mg/kg) in the surface layer is within the range typical of soils of old parks and recreational zones. The residual DDT content in the soil profile is 0.336–1.47 of the maximum permissible content. The ratio between metabolites and isomers of DDT points to its slight transformation (5.67–37.6%) and application as an industrial chemical. The contents of HCB (2.479–5.868 μg/kg) and the total content of HCH isomers (α + β + γ) in the profile of the urbanozem are 1–2 orders of magnitude lower than the maximum permissible contents or approximate permissible contents (0.3824–0.9863 μu/kg) and correspond to their background levels. The ratio between the HCH isomers shows that the transformation rate of the pesticide is rather high and that in the preceding period it was mainly used in the form of lindane.