The Release Regularities And Pollution Controlling Of Polychlorinated Biphenyls Of Sediments In Qiantang River

Qiantang River is the largest river in Zhejiang Province, about 85% of surface water of Hangzhou City is from Qiantang river, which is the important lifeline to Hangzhou。We analyzed the pollution characteristics of PCBs of sediments in Qiantang River, and found it's potential environmental risk. So the release rules and their affecting factors of PCBs in sediments and LDPE were discussed, and then we developed several zerovalent iron materials to control the pollution of PCBs. The main conclusions emerging from the study were as follows:2006-2010, PCBs of sediments from Qiantang River were summarized, PCBs were significantly correlated with the sediment organic contents(O.M), also correlated with the hydrological conditions of Qiantang river. So dry period, PCBs pollution of sediments was more serious.The organic matter content of sediments of Qiantang River in Fuyang was 7.71 % to 12.24%, the PCBs concentration ranged from 57.9155μg/kg dw to 76.7846μg/kg dw, tetrachlorobiphenyl and pertachlorobiphenyl were the main. The release of PCBs in sediments met the first-order reaction kinetics, which illustrated that the mail release of PCBs may be the diffusion mechanism. PCBs release rate constant of sediment was positively correlated with octanol partition coefficient Kow of PCBs, also with the solubility, the release quantity were negatively correlated with octanol partition coefficient Kow and solubility of PCBs.Dissolved organic matters (DOM) were extracted form sediment of Fuyang bridge, and then we got Hydrophilic organic matters (HY) and hydrophobic organic compounds (HON) from DOM. The infrared characterization showed that several functional groups such as polysaccharide, carboxyl, phenol structure, and aromatic structure, C=C, C=O, C-O, aliphatic, aromatic ring, Si-O,-NH4+ were existed in DOM.The transfer rate of PCBs in LDPE were significantly improved by DOM, HY, HON, as same as release qulities from solid phase transfered to the liquid. The release effections of PCBs in LDPE was influenced by different pH and temperatures, and logKmw of PCBs in LDPE and logKow were linear relation, correlation coefficient R =0.97(20C), R=0.95 (30C).Several materials such as activated carbon (AC), zerovalent iron (Fe0), activated carbon loading by Fe0(AC-Fe0), montmorillonite loading by Fe0 (MMT-Fe0) and organic modified montmorillonite loading by Fe0 (CTMAB-MMT-Fe0) were prepared and SAXS characterization indicated that all materials were nanometer scale. SAFS characterization results showed that 90.4% iron of Fe0 was zero-valent iron. Existing forms of iron of AC-Fe0, CTMAB-MMT-Fe0 were zero and trivalent iron. Zero valence iron was not existed on MMT.The capability of removing PCBs was AC,AC-Fe0> CTMAB-MMT-Fe0>>Fe0>MMT-Fe0. The study on reduction of concentration of PCBs in sediment by Fe0, we found that adding 1% mass fraction of sediment, the concentration of PCBs reduced to 14.22 ug/kg before 15.18 ug/kg, the average reduction rate was 6.32%. High chlorinated biphenyls in sediments were changed to low chlorinated biphenyls by using Fe0.