The pollution of Lake Ladoga by organochlorine pesticides and petroleum products
According to information available from scientific literature, Europe's largest lake, Lake Ladoga, is heavily polluted by organochlorine pesticides (OCPs) and petroleum products. Our studies (1992–1999) were conducted over the entire lake, and at various depths, throughout the year. The substances detectable by gas chromatography were natural compounds, most of which are the product of planktonic algae metabolism. For each phytoplankton group, the use of multivariate statistics has revealed a complex of low molecular weight (LMW) haloid-organic compounds. Studies revealed that OCPs are not detectable, even in extremely high concentrations of hexane extracts. Investigations showed that OCPs could not be identified in Lake Ladoga even at concentrations of 0.0001–0.000025 µg L−1(that is, 100 and 400 times lower than the maximum permissible concentrations for fisheries). It was discovered that the chromatographic retention times of some detected LMW haloid-organic metabolites of phytoplankton coincide with the retention times of some OCPs and of hydrocarbons from petroleum products. The distribution of different hydrocarbons in the lake is also related to the distribution of planktonic algae, which is the main source of hydrocarbons in Lake Ladoga.
Document Type: Research Article
Publication date: September 1, 2003