The Distribution And Fate Of Organochlorine Pestricites In Mainstream Of Haihe River

In this paper, organochlorine pestricites, which were listed as'priority persistent organic pollutants'by the US EPA and China, were selected as representative contaminations. The organochlorine pestricites studied in this work included hexachlorocyolohexane(HCH)isomers, 2,2-bis(4-Chlorophenyl)-1,1,1-trichloroethane(DDT)and its metabolites. The water index, settling particle fluxes, concentrations of HCHs and DDTs in water (surface water and overlying water) and in sediment (including porewater) were measured. The distribution and fate of organochlorine pestricites in Haihe River were analyzed. Modeling of the transport behaviours of organochlorine pestricites between water and sediment was carried out by a fugacity model.The results showed that the eutrophic status of Haihe River was serious and the water index changed significantly with time.The concentrations of HCHs and DDTs in surface water of Haihe river were 4.02~25.29 ng/L (mean 12.94 ng/L) and 6.88~78.82 ng/L (mean 28.54 ng/L), respectively. The concentrations of HCHs and DDTs in overlying water were 4.95~36.47 ng/L (mean 14.17ng/L) and 3.35~99.23 ng/L (mean 34.53 ng/L), respectively. The concentrations of HCHs and DDTs in porewater were 8.96~85.75 ng/L (mean 33.06ng/L) and 47.63~339.17 ng/L (mean 158.86ng/L), respectively. In samples of surface water, overlying water and porewater, the concentrations of DDTs were significantly higher than those of HCHs. The concentrations of HCHs and DDTs in porewater were significantly higher than those in surface water and overlying water. Composition of HCH isomers, DDT and its metabolites was dominant byβ-HCH and p,p'-DDT, respectively. This showed that residues of HCHs in water of Haihe River mainly from the large usage in the history, while there was still a recent use of DDT.The concentrations of HCHs and DDTs in surface sediments of Haihe river were 2.77~5.96 ng/g (mean 4.25 ng/g) and 5.82~45.5 ng/g (mean 21.55 ng/g), respectively. The concentrations of DDTs were significantly higher than those of HCHs. Composition of HCH isomers, DDT and its metabolites was dominant byβ-HCH and DDE, respectively. Concentrations of HCHs and DDTs were related well to TOC. DDTs were mainly aerobic biodegraded in water and surface sediment in Haihe River. Sediment trap fluxes of HCHs and DDTs were related well to TOC fluxes, which indicated vertical transport of HCHs and DDTs in water was significantly influenced by organic carbon content in settling particles.A multimedia (including water and sediment) fugacity model for the steady state conditions was established and successfully applied to the field data forγ-HCH in Haihe River. It is indicated that biodegradation of pollutants in sediment and suspended particle deposition played important roles in transport of pollutants between water and sediment.