Biological risk, source and pollution history of organochlorine pesticides (OCPs) in the sediment in Nansha mangrove, South China.

In the last century, organochlorine pesticides (OCPs) have been extensively used, especially in South China, to promote crop yield. In view of their toxicity, persistence and bioavailability, however, the Chinese government has attempted to regulate their production and use. We aimed to examine the biological risk, source and pollution history of OCPs in the sediment in Nansha mangrove which is located in the industrial region in South China. Results showed that HCHs and DDTs, mainly originating from lindane and technical DDT respectively, were the dominant OCPs, but their concentrations were too low to cause adverse effects on biota. In the last decade, the total concentration of HCHs showed a decreasing trend, whereas DDTs remained stable, despite their limited input. This suggests that management of HCHs was effective, while more management efforts should be put on DDTs, especially the use of dicofol and technical DDT, in future.