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 chromatogra phy with electron capture detector (GC-ECD). Pesticides were analyzed in di fferent horizons (upper 0-15, middle 15-30, lower 45-55 cm) of natural and horticultural soils, developed in highlands and lowlands. Physical and chem ical characteristics (organic matter content, pH, moisture, texture, etc.) were determined. Higher concentrations of total OCPs were found in highland s, 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 b ehaviours were found. Lindane could leach down to lower horizons, rich in c lays, while hydrophobic pesticides remain in the upper horizons, retained b y organic matter. Vegetables (carrots and potatoes) accumulated lindane wit h important contributions of DDTs and heptachlor. OCPs were taken up, accum ulated and metabolized efficiently by terrestrial invertebrates (earthworms and beetles). The results obtained testify the pollution by OCPs in "Los P adres" pond watershed. (C) 1999 Elsevier Science Ltd. All rights reserved.