[Distribution and Potential Risk of Organochlorine Pesticides in the Soil of a Submerged Area Around Miyun Reservoir]

Soil samples collected from a submerged area around Miyun Reservoir were analyzed for organochlorine pesticide (OCP) residues using GC-MS. The distribution characteristics and possible sources of OCPs were studied, as well as the potential ecological risk. The results showed the following:① the residuals of OCPs in the surface soil were mainly hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), and the average contents of HCHs and DDTs were 1.74 ng·g^-1 and 1.01 ng·g^-1, respectively. In comparison with other lakes and reservoirs in China, the mean value of DDT content of the soil samples from Miyun Reservoir was slightly less, whereas the mean value of HCH content was similar to other waterbodies. ② There was a distinct spatial distribution of OCPs in soils of the submerged area. Specifically, the OCP content in the water-land interlaced soil was generally higher, with distinct differences to the water or in land. In the eastern region of the reservoir and in the Chaohe River inflow area, the residues of OCPs were mainly DDTs, as was the case for the submerged soils of small isolated watersheds. The OCPs in the submerged area of the northern reservoir and the western central reservoir were mainly γ-HCH residues, while HCH and DDT residues were found in high proportions in the flooded area where the Baihe River inflows. These patterns were related to sources of pollutants; ③ the source analysis showed that sources of HCHs could be related to lindane input, while DDTs mainly derived from the early residues in the environment; ④ there was low ecological risk from OCPs in most of the samples, and a potential risk from DDT in the Baihe inflow area and in the central submerged zone of the western reservoir.