Organochlorinated compounds in waters of the Pearl River Delta region

Samples of river water and sewage water were analysed for ten PCB congeners, chlorobenzenes and chlorinated pesticides (BHCs and DDT) in three cities (Guangzhou, Shenzhen and Zhaoqing) in the Pearl River Delta, The results showed that the sewage water in Shengzhen had the highest concentration of total PCBs at about 10ng/L, and Dasha River (Shengzhen), the lowest at about 1.Ong/L. In general, the sewage waters in the three cities had higher concentrations of PCBs than river waters. Chlorobenzenes were investigated in the water samples. The total concentrations of chlorobenzenes ranged from 0.02 similar to 0.13 mu g/L, the Dasha River had the highest level of chlorobenzenes, and the sewage water in Zhaoqing had the next highest. The result may be related to the discharges production factories nearby the sampling sections of the Dasha River (Shenzhen) water in Zhaoqing. The concentrations of organochlorinated pesticides (alpha-BHC, gamma-BHC, delta-BHC, DDT and DDE) changed little in all water samples except for the sewage water in Guangzhou. It seemed that these pesticides are more a residual signal than a direct discharge from point sources.