Distribution of organochlorine pesticides in surface water and sediments from Qiantang River, East China

The levels of 13 organochlorine pesticides (OCPs) in surface water and sediments from Qiantang River in East China were investigated to evaluate their potential pollution and risks. A total of 180 surface water samples at 45 sampling sites and 48 sediment samples at 19 sampling stations were collected along the river in four seasons of 2005. Soil samples and wet deposition samples were also collected to provide evidence on the source of OCPs pollution. The total OCPs concentrations in surface water and sediments were 7.68-269.4 ng/L and 23.11-316.5 ng/g-dry weight (dw), respectively. The concentrations of OCPs in sediments were in the range of 8.22-152.1 ng/g-dw for HCHs (alpha-, beta-, gamma-, delta-HCH), 1.14-100.2 ng/g-dw for DDTs (p,p'-DDD, p,p'-DDE, p,p'-DDT o,p'-DDD), 9.41-69.66 ng/g-dw for other OCPs (aldrin, diedrin, endrin, heptachlor, heptachlor epoxide). The total OCPs concentrations in soils and wet deposition were 5.04-214.9 ng/g-dw and 16.18-242.4 ng/L, respectively. Among the OCPs, HCHs, DDTs and heptachlor were the most dominant compounds in the sediments. The dominant OCPs in water were gamma-HCH among HCHs, heptachlor among other OCPs and p,p'-DDE among DDTs. Also, different contamination patterns among sampling seasons were found. The concentrations of OCPs in sediment collected in spring were higher than those in summer and autumn. In contrast, the concentrations of OCPs in surface water in summer and autumn were higher among four sampling seasons. Distribution of HCHs, DDTs and other OCPs were different indicating their different contamination sources. The notable contamination was found in Fuchun reservoir. Composition analyses in sediments indicated a recent usage or discharge of lindane into the river.