| With the development of society. Rubber dam has been used by more and more countries and regions, for its low cost, simple structure, short construction period, perfect shock resistance, water resistance and good sealing effects. Studies showed that Rubber dam could increase upstream water surface area and water retention time, thereby increased the river light effect and purification time, and increased the content of dissolved oxygen in water, even improved the microclimate and so on. However, the rubber dam construction on water environment effect has been seldom payed close attention. Extension water retention time made pollutant difficult to quickly rule out, heavy metals content increase in short distance of upstream, even be accumulated in the sediment. When water environment conditions changed, the heavy metals bound to the sediment would be released back into the water and then polluted the overlying water. The purpose of the study is to explore the retention of rubber dam on the river environment effects of heavy metals pollution, and carried on thorough analysis to heavier pollution of sediment, to hope for play a certain reference role to the future construction and environment management work.This paper made monitoring analysis and evaluation to rubber dam upstream and downstream water. The results show that, the heavy metals content of rubber dam for upstream is different from that of downstream. The highest content is As, whose pollution share rate was maximum, followed by Cr6+, and the correlation between Cr6+and As reaches0.9166, between Hg and Cd reaches0.8563. The other heavy metal elements have shown a positive correlation, which indicated that it had similar pollution sources. Secondly, the RI of rubber dam upstream was higher than that of downstream, and heavy metals content tested roughly showed the same trend. In January, the RI was higher than that in July, showing that river polluted degree during the dry season was greater than that during the wet period river.Monitoring analysis and evaluation were made on the rubber dam upstream and downstream sediment, the results showed that the content of heavy metals in sediment close to the rubber dam was much higher. The lowest point was in the upstream of the350m, and the highest point was in the upstream of the5m. After analysis, the result should have some relation to the rubber dam on sediment barrier function. Secondly, with the soil environment background of Ganzhou city, all sampling points of Cd and Hg on the potential ecological risk coefficient was greater than40, so the harm degree for Cd and Hg was medium. The potential ecological risk coefficient of Pb, Cr, As was less than40, so the harm degree was slight.Monitoring analysis to the fish in the rubber dam upstream and downstream, the results showed that the other four elements content were lower than food contamination limit except from As. By the metal difference analysis, the effect of the rubber dam construction on fish was slight or not at all.According to the river sediment heavy metals leaching toxicity test and form distribution characteristics test study, among the five heavy metals in sediment, As leaching proportion was the largest. The heavy metal elements of rivers lead to second pollution, ranking as As>Cd>Cr>Hg>Pb. Pb was higher in the form of Fe-Mn oxidation phase, and Cd and Cr were mainly associated with residual phase, Hg exists in the form of organic combination, As was mainly associated with organic combination and Fe-Mn oxidation phase. |
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