Distribution and Sources of Organochlorine Pesticides in Taihu Lake, China

Thirty surface sediments, corresponding overlying water and porewater samples were collected for analysis of organochlorine pesticides (OCPs) from Taihu Lake, China in May 2010. Altogether six OCPs, i.e. hexachlorobenzene (HCB), β-hexachlorohexane (β-HCH), p,p′-DDE, p,p′-DDD, p,p′-DDT, and o,p′-DDT were detected, and the total OCPs varied from 7.84 to 32.23 ng g−1 in sediments, from 136.97 to 2,185.14 ng L−1 in porewater and from 24.27 to 154.07 ng L−1 in overlying water, respectively. The highest levels of contamination in sediment was observed in southeast of the lake, while in water and porewater samples highest levels were found in Zhushan Bay, the seriously polluted area in the north part of Taihu Lake. The partition coefficient of measured OCPs between sediment-overlying water was five and six fold higher than that between sediment-porewater, indicating the different distribution patterns of OCPs among sediment, overlying water and porewater matrices. The ratios of DDT/(DDD + DDE) ranged from 0.57 to 2.28 in sediments, 0.93–13.02 in porewater and 0.84–15.98 in overlying water, respectively, suggesting the potential new source of DDTs into the lake. The ratios of o,p′-DDT/p,p′-DDT in the three matrices were centered around 0.2–0.3, indicating the o,p′-DDT in the lake was originated from historical usage of technical DDTs.