Research And Evaluation On Heavy Metal Contamination And Biodiversity Of Rivers In Tongling Of Anhui Province

Tongling area of Anhui province is rich in mineral resources. It’s an important mineral concentration of copper, iron, gold and sulfur in our country. Abundant of heavy metal pollutants produced by long-term mining activities were disposed into rivers. The river ecosystem health was badly infective affected. In this paper, the quality of the water and sediment in rivers and the diverse of aquatic organisms was studied. The content heavy metal and other physicochemical properties of the rivers(including overlying water and sediment) and the community structure and diversity of phytoplankton and benthos were analyzed, based on field investigation and laboratory analysis. The diversity of sediment microbe and attached microbe were analyzed by the method of PCR-DGGE. The pollution status of overlying and sediment of the rivers was analyzed. The influence that environmental factors had on the bacterial diversity and community compositon were discussed. And the multi-variable assessment of river ecosystem health was undertook. The results indicated that:(1) Cd was the primary metal pollution factor of overlying water. As and Zn caused serious water pollution, too. The heavy metal pollution of overlying water in three rivers, Shunan river, Xinqiao river and Huanghu river, which flowed through the mining area was more seriously than other rivers. TN was the primary nonmetallic pollution factor of overlying water, and COD caused serious pollution, too. There are altogether82.26%sections that had suffered pollution of different degree, according to the synthesis pollution index’s gardening. Among them, there were8.06%sections that had suffered serious pollution,11.29%sections that had suffered heavy pollution,62.90%sections that had suffered light pollution. Among them, there were17.74%sections that its water quality was somewhat clean, none were clean.(2) The heavy metal contents in sediments were far higher than that in overlying water, the metal contents of the two phase observed higher levels of synchrony. The heavy metal in sediments all indicated the same distribution regularity that the heavy metal contents in sediments of the river flowed through the mining area were much higher than that in other rivers, except Cr. Heavy metal elements As, Cd, Cu, Pb, Zn and Fe in sediments, had high correlation between each other. Cr had low correlation with other elements, and had a unique way of accumulation. The content of TP in sediments had high correlation with the contents of all heavy metal elements, while the contents of other normal normal physicochemical properties had low correlation with the contents of heavy metal elements. Hankanson potential ecological risk index and geoaccumulation index were used conducting environmental risk assessment, and the results of two methods were similar. The heavy metal elements Cd, As and Cu were the main polluted elements, Cr was less polluted.(3) The diversity of sediment microbe in Shunan river and Xinqiao river were much lower, while the diversity of sediment microbe in Zhongcang river is the highest. According to the analysis by CCA, the sediments environment factors C, NH3-N, Zn and Cr had an significance level influence to the bacteria community in sediments. The diversity of attached microbe in Zhongcang river and Northwestern river were much lower. According to the analysis by CCA, the overlying water environment factors NH3-N, TN,COD and TP had an significance level influence to the attached bacteria community, and the sediments environment factors NO3-N, Cd, Zn, C and NH3-N had an significance level influence to the attached bacteria community.(4)A total of203phytoplankton species were identified, belonging to96genera of8phyla. The main phylum were Bacillariophyta and Chlorophyta. A total of11species of zoobenthos were identified, belonging to7families of4classes. The dominant species were Bellamya aeruginosa. The phytoplankton cell densities in Huanghu river, Xinqiao river and Shunan river were much lower, while the phytoplankton cell density in Zhongcang river was the highest. The diversities of phytoplankton in Huanghu river, Xinqiao river and Shunan river were much lower, while diversity of phytoplankton in Northeast river were the highest. According to the analysis by CCA, the overlying water environment factors COD, TN and NH3-N had an significance level influence to the phytoplankton community. (5) The multi-variable assessment of river ecosystem health in Tongling area showed that2of60sites were "healthy" level,16were "sub-healthy" level,33were "poor" level, and last9were "sick" level, suggesting the serious degradation of river ecosystem in Tongling. The weights of habitat quality indicator and biological indicator which were the most influential indicators of the assessment index system were0.4027and0.3409. Among the physicochemical properties of overlying water, the weight of TNWwas the highest, and TPW, Cu w and Zn wwere important influential indices to the river ecosystem. Among the physicochemical properties of sediments, the weight of TCS was the highest, and Zn s, Crs and TNs were important influential indices to the river ecosystem.