Fate of organochlorine pesticides in soils and terrestrial biota of "Los Padres" pond watershed, Argentina

Concentrations of organochlorine pesticides (OCPs) in soils and associated biota around "Los Padres" pond watershed were determined by gas chromatography with electron capture detector (GC-ECD). Pesticides were analyzed in different horizons (upper 0-15, middle 15-30, lower 45-55 cm) of natural and horticultural soils, developed in highlands and lowlands. Physical and chemical characteristics (organic matter content, pH, moisture, texture, etc.) were determined. Higher concentrations of total OCPs were found in highlands, because of the high content of clay material and organic matter. Lindane, heptachlor, aldrin, DDT and metabolites were found in soils. Depending on physical and chemical characteristics of pesticides and soils, different behaviours were found. Lindane could leach down to lower horizons, rich in clays, while hydrophobic pesticides remain in the upper horizons, retained by organic matter. Vegetables (carrots and potatoes) accumulated lindane with important contributions of DDTs and heptachlor. OCPs were taken up, accumulated and metabolized efficiently by terrestrial invertebrates (earthworms and beetles). The results obtained testify the pollution by OCPs in "Los Padres" pond watershed. (C) 1999 Elsevier Science Ltd. All rights reserved.