Abstract
Eighty surface sediment samples taken in 1978 from Lake Geneva, together with two cores sampled in 1976 and 1980, and 30 samples (1978) from the Rhone River were analyzed for organochlorine compounds. DDT, its metabolites (DDE, TDE), HCB, and PCB were found. No other organochlorine compound was identified at the detection level of 0.5 ppb. DDT metabolites were widespread and indicated residual DDT sources in the Rhone watershed and other minor lake tributaries, particularly on the Swiss coast. DDT levels have declined since an apparent peak usage in 1957. HCB was found in almost all samples. It first appeared about 1962 with consistent usage to the present. Use is widespread with the major source being the Rhone River. PCB was found in all samples at levels comparable to levels in the North American Great Lakes. Sources appear to be diffuse urban/industrial, with major inputs on the Swiss shore between Vevey and Morges. Peak use of PCB occurred in 1972 and was followed by a decline to 1978, with some evidence for a second increase to 1980, the latest sample available. Both HCB and PCB were found at high levels in the most upstream samples of the Rhone River which may be indicative of substantial atmospheric loadings of these two compounds to the Lake Geneva Basin.
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