| Zhalong Wetland is one of the most important ecological regions located in the northern part of China. Organochlorine pesticides（OCPs） have been detected in sediments from different regions in China, but little is known about Zhalong Wetland. This study investigated OCPs concentrations and risk levels in the surface sediments from Zhalong wetland. Seven-teen OCPs of 12 samples were determined by gas chromatography with electron capture detector（GC-ECD）, and the distribution patterns and sources of OCPs were analyzed. The total concentrations of 17 OCPs ranged from 0.41 ng·g-1 to 19.32 ng·g-1（with a mean value of 4.82 ng·g-1 based on dry weight）. Compared with the surface sediments of other lakes both in China and other countries, the levels of OCPs in Zhalong were lower. OCPs were dominated by DDTs and HCHs, while chlordane were detected in all surface sediment samples. The analysis of OCPs compositions indicated that DDT and HCH mainly came from the early residues in the environment, and chlordane mainly originated from atmospheric deposition. Correlations between OCPs and total organic carbon（TOC） demonstrated that TOC content strongly influenced the levels and distributions of OCPs. Meanwhile, the results of ecological risk evaluation showed that OCPs in sediments from Zhalong wetland had a certain ecological risk, which would have potential toxic effects on sediment-dwelling organisms. |
