Distribution, sources, and risk assessment of polychlorinated biphenyls in surface waters and sediments of rivers in Shanghai, China

The distribution, sources, and potential risks of polychlorinated biphenyl （PCB） contamination in the rivers of Shanghai, China were investigated. Fourteen PCB congeners in surface waters and sediments, which were collected from 53 sampling sites, were quantified by gas chromatography-mass spectrometer （GC-MS）. The total concentrations of PCBs in the dissolved phase, in particulates, and in sediments ranged from not detected （nd） to 34.8 ng.L^-1, from 0.76 to 39.71 ng.L^-1, and from 1.46 to 46.11 ng.g^-1 （dry weight, dw）, respectively. The corresponding WHO toxic equivalents （TEQs） of dioxin-like polychlorinated biphenyls （dl-PCBs） ranged between nd-1135.63 pg TEQ-L^-1, 0.02-605.94 pg TEQ.L^-1, and 0.05-432.12 pg TEQ-g^-1 dw, respectively. Thepenta-CBs, especially PCB 118 and PCB 105, were the dominant congeners in all samples. Principle Component Analysis （PCA） indicated that the PCBs were mainly influenced by a historical accumulation of commercial PCB products, the burning of house coal, and emissions from municipal solid waste incineration （MSWI） and secondary metallurgy industries. The center of Shanghai was significantly affected by PCB contamination, followed by the industrial parklands and suburban towns, while the farmland of Chongming Island was the least affected area. Adverse biological and health effects would be likely in the central urban areas, industrial parks, and residential towns of Shanghai.

Atmospheric deposition of polycyclic aromatic hydrocarbons （PAHs） in Shanghai： the spatio-temporal variation and source identification

This study investigated the dry and wet deposition fluxes of atmospheric polycyclic aromatic hydrocarbons （PAHs） in Shanghai, China. The flux sources were traced based on composition and spatio-temporal variation. The results show that wet deposition concentrations of PAHs ranged from 0.07 to 0.67 μg·L-1 and were correlated with temperature （P 〈 0.05）. Dry deposition of PAHs concentrations ranged from 3.60-92.15 μg·L-1 and were higher in winter and spring than in summer and autumn. The annual PAH average fluxes were 0.631 μg·m-2·d-1 and 4.06 μg.m·d-1 for wet and dry deposition, respectively. The highest wet deposition of PAH fluxes was observed in summer, while dry deposition fluxes were higher in winter and spring. Atmospheric PAHs were deposited as dry deposition in spring and winter, yet wet deposition was the dominant pathway during summer. Total atmospheric PAH fluxes were higher in the northern areas than in the southern areas of Shanghai, and were also observed to be higher in winter and spring. Annual deposition of atmospheric PAHs was about 10.8 t in across all of Shanghai. Wet deposition of PAHs was primarily composed of two, three, or four rings, while dry deposition of PAHs was composed of four, five, or six rings. The atmospheric PAHs, composed of four, five, or six rings, primarily existed in the form of particulates. Coal combustion and vehicle emissions were the dominant sources of PAH in the observed area of downtown Shanghai. In suburban areas, industrial pollution, from sources such as coke oven, incinerator, and oil fired power plant, was as significant as vehicle emissions in contributing to the deposition of PAHs.