Distribution of organic contaminants in Lake Taihu

Water contamination in Lake Taihu and Lake Wulihu poses a threat to water supply and recreation. Water samples were collected during 1988–1989 for analysis of organic contaminants in the two lakes. Over 800 organic contaminants were detected by GC and GC-MS, and 84 of them were screened by a scoring system as priority contaminants. Results showed that the average concentration was one order of magnitude higher in Lake Wulihu than in Lake Taihu, although the number of contaminants in Lake Wulihu was only double those in Lake Taihu. Concentrations of phthalates, halohydrocarbons, and alkanes in Lake Taihu were close to those in Lake Wulihu, whereas the concentrations of alkylaromatics, anilines, phenols, alcohols, ketones, and polynuclear aromatics in Lake Taihu were lower than in Lake Wulihu by 2–3 orders of magnitude. The average concentration of contaminants in Lake Taihu reaches the highest during the rainy season while this occurs in Lake Wulihu during the dry season because of differences in water flow patterns in the lakes, conditions of the water environment, and physico-chemical properties of contaminants.