DDT CONTAMINATION OF FISH AND SEDIMENTS FROM LAKE-ORSJOEN, SOUTHERN NORWAY - COMPARISON OF DATA FROM 1975 AND 1994

Long term DDT contamination is reported of a small lake which previous ly was recipient of the insecticide wastes from a plant nursery. 19 ye ars after closing down of the outfall sum-DDT in perch and pike exceed s an assumed ''high background level'' by about 5-10 times. Gradient s tudies of sediments and perch indicated that deposits in the close vic inity of the former outfall still acted as a source for contamination of the more distant parts of the lake. Comparison with 1975 data never theless showed that DDT levels in fish had been reduced by about 90% a nd a rough estimate indicated a ''half life'' of DDT of 5-7 years. Cop yright (C) 1996 Elsevier Science Ltd