Organochlorine pesticides and polycyclic aromatic hydrocarbons in water and sediment of the Bosten Lake,Northwest China

We evaluated organic pollution in Bosten Lake, Xinjiang, China, by measuring the concentrations and distributions of organochlorine pesticides （OCPs） and polycyclic aromatic hydrocarbons （PAHs）. Water and sediment samples were collected from 19 sites 031-1319） in the lake for analysis. Our analytical results show that the concentrations of total OCPs in water ranges from 30.3 to 91.6 ng/L and the concentrations of PAHs ranges from undetectable （ND） to 368.7 ng/L. The concentrations of total OCPs in surface （i.e., lake bottom） sediment ranges from 6.9 to 16.7 ng/g and the concentrations of PAHs ranges from 25.2 to 491.0 ng/g. Hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） account for large proportions of the OCPs. Low α- to γ-HCH ratios in both water and sediment samples indicate possible contributions from both industrial products and lindane. DDTs in water are probably from historical input, whereas DDTs in sediments are from both historical and recent inputs. Moreover, DDT products in both water and sediments were from multiple sources in the northwestern part of the lake（B11, B12, B13, and B14）. Fugacity ratios for DDT isomers （p,p＇-DDE and p,p＇-DDT） at these sites were generally higher than equilibrium values. These results suggest that the input from the Kaidu River and diffusion of DDTs from the sediment to the water are responsible for DDT pollution in the water. Lower-molecular-weight PAHs, which originate primarily from wood and coal combustion and petroleum sources, represent the major fraction of the PAHs in both water and sediment samples. Our findings indicate that OCPs and PAHs in Bosten Lake can be attributed primarily to human activities. A risk assessment of OCPs and PAHs in water and sediment from Bosten Lake, however, suggests that concentrations are not yet high enough to cause adverse biological effects on the aquatic ecosystem.