Characteristics Of Sediment Pollution And Its Influence On Microbial Community Structure In Water Area Of Villages Located In The Lake

Villages located in the lake,as an important part of the whole area of Baiyangdian Lake,is one of the main endogenous pollution problems of the environmental pollution in Baiyangdian Lake,and the surrounding water area of Dianzhong village is the main carrying area of pollution,so it is of great significance to study the pollution characteristics of this area for the pollution control of Baiyangdian Lake.The pollution characteristics of overlying water and surface sediments were systematically analyzed,the risk assessment of the pollution level was carried out.The vertical distribution of pollutants in the sediment column was further analyzed,reveals the depositional characteristics of pollutants.At the same time,the structural characteristics of the main microbial communities in the sediments of villages located in the lake and their relationships with the environmental factors were discussed,which provides a scientific basis for the ecological restoration of the waters around the villages.The main results of this study are as follows:1.The current water quality of villages located in the lakewas moderately polluted,and the comprehensive nitrogen and phosphorus pollution index of surface sediments showed the mild pollution.The horizontal distribution of organic matter was significantly different.The content of organic matter in the southeast was higher than that in the northwest.Total nitrogen and total phosphorus showed relatively similar spatial distribution characteristics to organic matter.The average concentration of Cd was much higher than that of other heavy metals,The potential ecological risk index shows that the ecological hazards of heavy metals were in the order of Cd>Hg>Pb>Cu>As>Cr>Zn,the surface sediments in the waters of villages located in the lake belong to a moderate ecological risk level as a whole.2.The pH range of the columnar sediments in villages located in the lake was relatively small,and the whole was slightly alkaline.Most of villages' TN and organic matter showed a trend of gradually decreasing from the surface layer to the bottom;More than half of the 7heavy metals,including Cr,Cu,and Zn,were mainly enriched at a depth of 10 cm,indicating that the influence of human activities in recent years was an important reason for the accumulation of heavy metal.The geoaccumulation index showed that Cd in the sediments of villages located in the lake had different pollution risks.The potential ecological risk index showed that the comprehensive potential ecological risk index RI=154.96,which means there was a moderate heavy metal pollution risk.3.The organic matter in the sediments of villages located in the lake had a very significant positive correlation with TN,but showed a poor correlation with TP.This might be due to the difference in the deposition process of nitrogen and phosphorus.As,Cu,Zn,Pb,Cd,and Cr had a very significant positive correlation(P<0.01),and showed certain homology or similar geological accumulation process,while Hg and As had weak homology with other heavy metals.Organic matter had extremely significant or significant correlation with elements such as Hg,Zn,Cu,Cd,etc.,indicating that organic matter in columnar sediments affects the distribution and enrichment of heavy metals.4.The main bacterial groups based on the phylum level of the 0 ? 5 cm sediments were Proteobacteria,Chloroflexi,Bacteroidetes and Firmicutes.The predominant flora at the sediment based on phylum level of the 0 ? 55 cm sediments were Proteobacteria,Chloroflexi and Firmicutes.The microbial community structure between different depths and sampling points had certain hierarchical differences.The first dominant phylum Proteobacteria in sediments showed the characteristics of vertical changes with decreasing depth.There were higher microbial diversity and abundance in the 9?1(Guolikou)and 6?1(Caiputai)regions.5.The effects of physical and chemical factors on the distribution of sediment microbial communities were in the order of pH>TN>OM>TP.The abundance of the first dominant phylum Proteobacteria was positively correlated with TN and OM,and significantly positively correlated with pH.The influence of OM and TN on all 0 ? 5 cm sediments as well as the 0 ? 25 cm upper layer sediments were much greater than that of the bottom layer 40 ?55 cm sediments.Spearman and RDA analysis showed that heavy metals play a significant role in driving the evolution of sediment microbial communities.Cd had the greatest impact on the distribution of sediment microbial communities,followed by Pb,As,Hg,etc.PICRUSt predicted and analyzed the function of microbial communities and found that the COG function composition of all samples was similar.