Ecological Risk Assessment On Heavy Metals In Soils Of Momoge Wetland

Wetland has important ecological functions and social and economic value.In the process of urbanization and development of various industrial and agricultural,there are some acts ofdestroyingwetland such as reclaiming wetlands for farmland,over fishing,building encroaching on wetlands,blind development of tourism whichhave brought about a multi-faceted adverse impact on wetlandecosystem.Soil is the carrier of the lives of wetland ecosystem.The unreasonable application of chemical fertilizers and pesticides,free disposal of domestic wastes and other human activities may make the content of heavy metals in wetland soil rising.Therefore,carrying out soil heavy metals pollution and risk assessment regularly has important scientific significance in wetland protection and rational utilization.This article takes Momoge wetland as the research object and learns on the content characteristics and sources of heavy metals in the soil of this area by field sampling,indoor experiment,using the methods of multivariate statistical analysis and GIS.Thepollution and potential ecological risk degree of Momoge wetland soil heavy metalsare evaluated with a variety of soil environmental quality and potential ecological risk assessment methods.The main results are as follows:The order of 6 soil heavy metals in Momoge wetland is Zn>Cr>Pb>Ni>Cu>Cd.The mean contents of Cu,Zn,and Cd are higher than the local background values.The mean contents of Pb,Cr and Ni are basically equal to the local environmental background values for soils.The contents of six soil heavy metals,except Cd is slightly higher than the national environmental quality standard for soils,are in the standard range.The accumulation of Cd in Momoge wetland is obvious.The results of source apportionment based on multivariate statistical analysis show that all results of descriptive statistical analysis,correlation analysis,principal component analysis,and cluster analysis are consistent and can verify each other.The results show that Pb,Ni,Cu,Cr and Zn are significantly related to TP and organic matter in the soil of the study area.And thecorrelation between Cd and TN is significant.Pb,Ni,Cu,Cr and Zn are mainly influenced by the geochemical background values,while Cd is mainly derived from anthropogenic sources and greatly influenced by human activities.By using single factor index method,Nemerow index,geoaccumulation index and potential ecological risk index method,this paperevaluates the status and potential ecological risk of heavy metal pollution in the soil of the Momoge wetland based on the reference value of the local soil background values and the environmental quality standard for soils.The results show that the accumulation ofPb,Niand Cr in the region is relatively light,and Cu,Zn and Cd accumulate in a certain degree,especially Cd.The Nemero index evaluation resultindicates that the pollution level of whole studyarea is atthe alert level.The pollution level of soil heavy metals by the evaluation of geoaccumulation index method is lowerthan the single factor pollution index method.In the perspective of ecological risk,the whole study area is in a slight ecological risk degree,but the individual potential ecological risk of Cd is in astrong ecological risk level,which needs to be paid attention.In view of the ecological risk of Cd,this study discusses the remediation countermeasures of soil heavy metals,especially Cd and provides some references for the prevention and management of heavy metal pollution in wetland soil.