Abstract
Twenty-eight polychlorinated biphenyls (PCBs) in surface sediments collected from Dianchi Lake were analyzed. The objective was to provide a better understanding of the contamination levels, distributions, possible sources and environmental risk of PCBs. In the aquatic environment, PCBs were found ubiquitously. The concentrations of the total 28 PCBs ranged from 160 to 78,200 ng kg–1 dry weight. The contamination levels and distributions of PCBs among the samples were obviously different. The concentrations of PCBs decreased with the increase in distance from the sampling sites which were located in the northwest of Dianchi basin. Inflowing rivers carrying a large amount of untreated wastewater from industries were the major contributors to the high residual concentrations of PCBs. The main components of PCBs were tetrachlorobiphenyl (9.3 − 63.6%, mean: 30.8%), trichlorobiphenyl (8.7 − 49.3%, mean: 21.0%), hexachlorobiphenyl (2.7 − 36.4%, mean: 17.7%) and pentachlorobiphenyl (0 − 52.3%, mean: 14.9%). The distribution of PCBs was subject to the rivers flowing into the lake. Less chlorinated Aroclor mixtures containing 3 − 6 chlorinated atoms were the dominant components of PCBs. The northwest part of Dianchi Lake and its adjacent rivers had high contamination levels of PCBs, which could pose a potential risk to aquatic organisms.
