Effect Of Paper Mill And Pesticides On Environmental Microbial Communities In Daling River Area

A great number of pollutants were discharged into rivers, which resultedin severe environment pollution. Thus, studying their effect on the river ecosystem is important for environmental protection and environmental remediation. In the research, we studied the bacterial communities of Daling River area, which was polluted by paper mill (point pollution) and pesticides pollution (non-point pollution) using denaturing gradient gel electrophoresis (DGGE) and next-generation sequencing (NGS). We explored the bacterial community structure in soil, water and sediment of Daling River and their explanatory factors such as pesticides. Furthurmore, we studied the effect of historical residual hexachlorocyclohexanes and dichlorodiphenyltrichloroethane on bacterial communities in sediment core collected from an estuary in northeastern China, which was formed during 1960-2011. The results of this work were as shown below:1) Bacterial communities in different media were all affected by paper mill pollution (PMP) with different ways. In the soil, bacterial community was influenced by PMP closely related with pollutants transmission affected by monsoon; in the water, bacterial community was shaped by habitat type; in the sediment, bacterial community in the samples in the downstream was severely affected by PMP owing to long term pollution history.2) Main pesticides in the surface sediment and sediment core were HCHs and DDTs. We found that HCHs and DDTs can significantly affect Shannon’s index both in the surface sediment and sediment core. However, we found the explanatory pesticide of bacterial community in the surface sediment wasHCHs and the explanatory pesticide of bacterial community in the sediment core was DDTs. Furthermore, we found historical residual HCHs and DDTs resulted in increase of abundance of Flavobacteria and Clostridia, which accounted for 40% of all the bacteria.3) We selected Clostridia and Epsilonproteobacteria at the class level and Fusibacter and Desulfobulbus at the genus level as bacterial indicators of paper mill pollution. We also propose Sphingobacteria, Alphaproteobacteria, Actinobacteria, Subdivision3, Planctomycetacia and Verrucomicrobiae at the class level and Bacillus, Steroidobacter, Nocardioides, Terrimonas, Pirellula and Methylibium at the genus levelto monitor the remediation of polluted sediment environments.4) In the study, we found theabundance of bacteria at the genus level is suited to the sceening process ofindicated bacteria. Furthermore, we proposed that we should use bacterial datawhich accounted for 50% the total bacteriafor bacterial diversity analysis including Shannon’s index and Pielou index using next generation sequencing in future. We also found the standardiszed effect size of the mean nearest taxon distancecouldwell reveal the historical pollution, such as paper mill pollution and historical pesticide pollution.