Occurrence Characteristics And Biological Toxicity Of Persistent Organic Pollutants In Strategic Water Sources Of The Yangtze Estuary

The Yangtze Estuary is one of the current water sources of Shanghai City. Research on persistent organic pollution in water sources of the Yangtze Estuary has significant meaning for safety drinking water supply in Shanghai City. In order to investigate the status of persistent organic pollution, this study collected water and sediment samples in strategic water sources of the Yangtze Estuary and its around areas, and analyzed organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs) by chemical and biological methods.In this study, GC-μECD and GC-MS were used for qualitative and quantitative analyses of OCPs, PAHs and PCBs. The results for surface sediment samples showed that the total concentrations of 20 OCPs ranged from 0.46 ng/g to 12.09 ng/g, in which HCHs and DDTs were. the predominant components. The compositions of HCHs and DDTs indicated that they were mainly the early residues in the environment. The sum of 20 PAHs concentrations in surface sediments ranged from 59.66 ng/g to 4175.94 ng/g, which were mainly low molecular weight PAHs. Source analysis by molecular indices and ratio methods implied PAHs originated from petroleum leakage and petroleum combustion process. Compared with other areas, the levels of OCPs and PAHs in surface sediments of this study were low to moderate. PCBs pollution in surface sediments was lower, and only in 5 sampling sites were lower concentrations and less kinds of PCBs detected. Moreover, the effects range low (ERL) and effects range median (ERM) values were employed to assess ecological risk of OCPs and PAHs in surface sediments. It was found that the total 16 priority PAHs and most of individual PAH concentrations in Wusong Mouth and p,p'-DDT concentrations in most sites were above ERL but below ERM values, indicating potential adverse biological impacts.The spatial distribution of OCPs and PAHs concentrations of surface sediments varied significantly among sampling sites in this study, following the sequence: the south coast > the south waterway > the north waterway. The entries of urban sewage discharges and tributary river runoff along the south coast were the main sources of OCPs and PAHs; while the strategic water source sites had rarely been affected by discharging and had the lowest OCPs and PAHs concentrations in surface sediments. In addition, strong correlations were found between both OCPs and PAHs concentrations and organic matter content in surface sediments, which indicated organic matter content played an important role in distributing organic pollutants to study areas.OCPs and PAHs in water were analyzed in three strategic water sources of the Yangtze Estuary including Qingcaosha, Biandansha and Meimaosha. It was found that OCPs and PAHs concentrations were lower; the runoff of the Yangtze River was the source of pollutants; and sediment resuspension might aggravate organic pollution of water.Moreover, in this study sediment extracts were analyzed by a battery of in vitro bioassays including EROD bioassay, recombinant gene yeast bioassay and SOS/umu bioassay. It was found that samples in the entries of urban sewage discharges and tributary river runoff along the south coast showed significant Ah-receptor response, estrogenic response and genotoxicity response, of which PAHs was a main risk stressor. In addition, OCPs was a main risk stressor of estrogenic response. While samples of the strategic water source sites showed no significant bio-toxicity effects.