[Pollution Characteristics and Ecological Risk Assessment of Organochlorine Pesticides in Water Source Areas of Guangdong and Guangxi]

The concentrations of 16 organochlorine pesticides (OCPs) in 7 water samples collected from different sites of water source areas of Guangdong and Guangxi were detected by SPE-GC-MS, and then the pollution characteristics were analyzed. This study established species sensitivity distribution(SSD) curves with BurrⅢ distribution model. In the meantime, HC₅ values were calculated by BurrliOZ software, which were used to evaluate the toxicity effects of OCPs towards aquatic organisms. Finally, margin of safety concentration values were calculated to assess the ecological risk. The results showed that the concentration of OCPs varied from 6.64 to 34.19 ng·L^-1, with a mean value of 16.76 ng·L^-1, while HCHs and DDTs contributed a lot. HCHs were predominately originated from lindane, which is a component in household insecticide, while DDTs were from dicofol contamination or historical residues. Vertebrates could stand severer toxicity in comparison with invertebrates. α-endosulfan showed a greater toxicity towards aquatic plants and microorganisms than others, while p, p'-DDT turned out to be the most hazardous pollutant to vertebrates and invertebrates among the 16 OCPs studied. Generally speaking, OCPs in study areas didn't show conspicuous ecological risks towards aquatic organisms, DDTs and α-endosulfan, however, are still worth paying close attention due to their high potential risks.