Estimation of Organochlorine Pesticides (DDT and HCH) in Surface Sediments from Baihua Lake

Baihua Lake, a man-made reservoir located in a typical plateau karstic area, is one of the five drinking water sources for Guiyang city. In the present research, contents of organochlorine pesticides (including o,p'-DDT, p,p'-DDT, p,p'-DDD, p,p'-DDE, alpha-HCH, beta-HCH, gamma-HCH and delta-HCH) in eight surface sediment samples collected from Baihua Lake were estimated by gas chromatography-electron capture detector (GC-ECD). The results showed that the concentration of DDTs was in the range from 1.0 to 16.3 ng g(-1) (thy weight), and that of HCHs varied from 0.3 to 7.6 ng g(-1) p, p'-DDE and p, p'-DDD were the most significant contaminants in sediments, with the average concentrations up to 2900 pg g(-1) and 3700 pg g(-1), respectively. A high value of (DDD+DDE)/DDT revealed that there is no recent use of DDT in the surrounding areas. The alpha/gamma ratio of HCH implied the input of both technical HCH and lindane. Principle component analysis (PCA) of the results implicated that the distribution characteristics of these OCPs were primarily affected by two potential factors. Hierarchical cluster analysis (RCA) demonstrated that these eight samples could be divided into three groups and there was a distinct difference in the pollution degree of sediment samples.