Monitoring of organochlorine pesticides using PFU systems in Yunnan lakes and rivers, China.

Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean 0.11 microgl-1), and 0.24-21.95 microgl-1 (mean 7.39 microgl-1) respectively in lakes; and those in rivers were undetectable to 0.23 microgl-1 (mean 0.08 microgl-1), 0.68-2.93 microgl-1 (mean 1.70 microgl-1), and 2.71-37.56 microgl-1 (mean 17.01 microgl-1) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination.