Influence Of Mining Area Heavy Metal Pollution On Soil Microbial Community Structure

Since microorganism plays an important role in the processes of material circle and energy flow of ecological system, its diversity, variation laws of its community structure and its driving factors have become the hot topics in ecological study. In this experiment, the river sediment in Guangdong Dabaoshan area was taken as a research object, the variation laws of diversity and community structure of sediment microbes in different river reaches was surveyed and the functions exerted by sediment's physical and chemical properties in the variation process was analyzed, due to which the ecological effect of heavy metal pollution of river sediment was deeply understood in its theoretical basis. The research results are as follows:(1) The abundance and diversity of microbial species set types among the 10 sampling points in the main rivers in Dabaoshan area are differentiated; and the variation laws of microbial species set types are similar in abundance and diversity among the sampling points. The abundance and diversity of sediment microbial species set types are lowest among the 2 sampling points nearest to the outfall of Dabaoshan tailings pond, and the 2 points have no remarkable difference; the abundance and diversity of species set types are highest among the 4 sampling points farthest from the pollution sources, and no obvious difference was found among these 4 points. As for the abundance and diversity of sediment microbial species set types, they have no obvious difference in the three sampling points which are in the Chengong River before running into the Hengshi River, in the Hengshi River before flowing into the Wengjiang River, and in the Wengjiang River before mingling with the Hengshi River, but such difference are remarkably higher than that in the sampling point in the Chengong River after it runs into the Hengshi River.(2) It can be known from the relevant analysis of sediment physical and chemical characteristics and of sediment microbial community characteristics, consistent correlation was indicated between the abundance and diversity of sediment microbial community species set types and the sediment physical and chemical characteristics; both of the abundance and diversity and the physical and chemical characteristics showed negative correlation with sediment Pb content, Fe content, Cu content, Zn content, moisture content, full phosphorus content and total sulphur content and showed positive correlation with sediment p H value and rapid available phosphorus content.(3) In this research, analysis at category classification level was conducted on the valid sequences of the 20 sediment samples. In a result, there are 15 main class groups were obtained, which are mainly formed by proteobacteria, cyanophyta, Bacteroidetes, acidobacteria, chloroflexi, euryarchaeota, crenarchaeota, verrucomicrobia, nitrospirae, actinobacteria, firmicutes, spirochaeta, gemmatimonadetes, chlorobi, planctomycetes and species unknown in classification. The formation of sediment microbial community and advantageous class groups are roughly the same, but the relative abundance of each category among different sampling points is remarkably different. In addition, some special rare class groups with low relative abundance respectively exist among different sampling points.(4) It can be seen from the redundancy analysis(RDA) of among the physical and chemical factors in the mining area river's sediment and the sediment microbial community that, the similitude of the 2 microbial community formations in the same sampling point is relatively high, while the microbial community formations in different sampling points have relatively large difference. Sulfate radical content in sediment is the leading environmental factor in differentiating sediment microbial community structure.To sum up, the microbial diversity and community structure in different river reaches are different, and such difference is remarkably related with environmental factor, among which sediment sulfate radical content is the leading environmental factor in differentiating sediment microbial community structure.