The Xiangjiang River (XR), the second largest tributary of the Yangtze River, is mainly located in Hunan province in south-central China. Nineteen surface sediment samples (the top 3-cm layer) collected from XR were analyzed to determine the concentrations, distribution, sources, and ecological risk of organochlorine pesticides (OCPs). The concentrations of OCPs were 3.0-29.8 ng/g (dry weight) with a mean of 12.6 +/- 7.7 ng/g. The widely detected compounds included HCHs, DDTs, HCB, and dieldrin. Overall, the dominant OCPs in the sediments were mainly composed of residual and degradation products, e.g., beta-HCH with a mean of 42.2 % in HCHs and p,p'-DDE with a mean of 43.5 % in DDTs, implying that OCPs in the sediments had suffered from long-term aging without fresh inputs in XR. However, there was a high proportion of p,p'-DDT to DDTs in three sites, suggesting that there was use of technical DDT from their surrounding areas at present. The ratios of alpha-HCH/gamma-HCH and p,p'-DDD + p,p'-DDE/DDTs increase from the upper reaches to the lower reaches of XR, suggesting sediments enriched with alpha-HCH and metabolites DDD and DDE during sediment transport process and could be attributed to the transformation of gamma-HCH to alpha-HCH and DDT to DDE or DDD. The assessment of the ecological risk indicates that the OCPs in the sediments of XR have a moderate adverse biological effect on organisms.

Publication name	ENVIRONMENTAL MONITORING AND ASSESSMENT Volume: 185 Issue: 11 Pages: 8861-8871 Published: NOV 2013
Author(s)	Li, Yuanyuan; Lin, Tian; Qin, Yanwen; Zhang, Lei; Guo, Zhigang
Corresponding author	GUO Zhigang  guozgg@fudan.edu.cn  Fudan Univ, Dept Environm Sci & Engn, 220 Handan Rd, Shanghai 200433, Peoples R China
Author(s) from IGCAS	LIN Tian

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