Study On AVS And SEMHg In Sediments Of Urban Rivers

This research sellect three urban rivers:Liwa river, Caoyang river and Yinchu river as the research object by the principle of the time gradient of ecological restoration of aquatic vegetation. It focus on the relationship of the change of the spatial distribution of AVS and SEMHg, by the way of field survey sampling methods and indoor simulated experiments. The main conclusions as follows:The results of field survey shows that:The concentration of THg in sediments of these three rivers. Caoyang river 952.39ug/kg> Liwa river 416.55ug/kg> Yinchu river 296.18ug/kg. They are 9.5times、4times and 3times higher than the the background values of Shanghai soils. The concentration of AVS has close rerationship with the concentration of TOC in sediments.The result of indoor simulated experiments shows that:under different temperature of 4 ℃、15℃ and 30℃, the pH of sediments and the pH of water are become lower and lower, but the concenration of AVS become higher and higher with the time release and temperature. Because the concenration of SEMHg is very low, so different temperatures effect the move of SEMHg slightly, but it can effect the different form of Hg’s translation to the SEMHg. The sediments which has been developed under the aerobic conditions, the change of concenration of AVS in sedimnts has been affected obviousy by the oxidation. before indoor simulated experiments it was 165.06±24.95umol/g, but after indoor simulated experiments, it was97±39.6umol/g, SEMHg has been droped from 15.83±2.29ug/kg to 13.8±1.49ug/kg. The sediments which has been developed under anaerobic conditions, the concenration of AVS in sediments didn’t changed too much. it changed around 184.72±14.07umol/g～199.77±13.38umol/g. the concentration of SEMHg has raisen from 9.29±1.13ug/kg to 23.84±1.79ug/kg. there is no obvious disciplinarian has been found.