Effects of heavy metal pollution on microbial community and diversity in lake-river ecotone of Lake Poyang

Abstract

The lake-river ecotone of Lake Poyang is an interfacial area between lake ecosystem and river ecosystem in Lake Poyang basin. The region is rich in species diversity, and it is an important buffer and purification zone of pollution, because the water is coming from the five major rivers. This paper analyzed the effect of heavy metal pollution on the microbial community structure and diversity in lake-river ecotone of Lake Poyang. Moreover, the heavy metals have been measured by atomic absorption spectrometry and atomic fluorescence spectrometry. Our results show that these trace metals (Hg, Cu, Zn, Pb and Cd) exhibited different degrees of pollution and the pollution of lead and mercury were the most serious. The concentrations of Pb and Hg reached IV in quality standard for ground water, the others reached II. High throughput sequencing results show that the microbial communities were mainly composed of 4 categories: Proteobacteria, Actinobacteria, Bacteriodetes and Verrucomicrobia, the average abundance were 58.31%, 13.63%, 9.69% and 1.33% in lake-river ecotone of Lake Poyang, respectively. The results of diversity index analysis show that, the index (Chao 1, Shannon and Simpson indexes) of R9 site (the interchange between Changjiang River and Lean River) and H11 site (the estuary of Lake Poyang flows to Yangtze River) was the highest, the index of N2 site (Wanjiaqiao) and W6 site (the estuary of the Ganjiang River flows into Lake Poyang) was the lowest. This study shows that microbial community abundance decreased in those badly-contaminated areas. The heavy metal pollution in R9 and H11 sites were serious, but the microbial diversity was rich, suggesting that the factors affecting the microbial diversity were multiple.