Auswaschung einiger Insektizide aus landwirtschaftlich genutzten Böden im Lysimeterversuch

Six lysimeters filled with loam and seven lysimeters filled with sand, having an area of 1 m² and a depth of 1 m, were agriculturally used and in July of 1976, 1977, 1979 they were treated with the following agents (g/m²): Toxaphen (0.73, 0.36), Lindan (0.05), Butonat (0.09), Trichlorphon (0.07), Methylparathion (0.045, 0.03) and Dimethoat (0.17). The percolates having accumulated on the lysimeter bottom were drained off monthly and investigated in the toxicological test with Poecilia and Daphnia. The lasting precipitation in 1978 and 1977 resulted in 1978 in percolates with a toxic effect for several months. The July-applications of 1979 resulted in toxic percolates from December 1979 to May 1980. Compared with sand, loamy soils have shown only a time delay of toxicity, but no decrease of it. To assess the results, the theoretical average maximum concentration = quantity used: annual runoff is compared with the LC₅₀ of the substances, solved in percolates of untreated lysimeters. For the organophosphorus insecticides either other substances contained in the percolates act synergistically or toxicity is increased by degradation products as Paraoxon. In general, a toxipotent penetration of the insecticides into the ground water is possible.