Distribution characteristics,sources and potential ecological risks of heavy metals in summer surface sediments of Keluke Lake in Qaidam Basin
In order to identify the pollution status of heavy metals in lake sediments in the Qinghai-Tibet Plateau,enrich the relevant studies on heavy metals in the plateau in environmentally sensitive and vulnerable areas,and protect the ecological environment of special regional units according to local conditions,this study takes typical freshwater lakes in the Qinghai-Tibet Plateau as an example,the physical and chemical characteristics of 10 kinds of heavy metals(Al,Cr,Mn,Fe,Ni,Cu,Zn,As,Cd,Pb),sediment pH and organic matter in surface sediments of Keluke Lake and some nearby wetlands,which are widely existing and have significant impact on the environment,will be analyzed in May 2021.The possible sources were analyzed by principal component analysis,and the ecological risk assessment was carried out by the method of land accumulation index and potential ecological risk index.The results show that the physical and chemical characteristics of surface sediments in Keluke Lake are spatially uneven except pH.The content and distribution characteristics of organic matter are the main factors affecting the spatial distribution of heavy metals such as Cr,Mn and Ni.The average concentrations of heavy metals in sediments are Fe>Al>Mn>Zn>Ni>Cu>Pb>Cr>As>Cd from high to low,all of which are lower than the soil background values of Qinghai Province.The average accumulation index of heavy metals is less than 0,the potential ecological risk of heavy metals is slight,and only Cd has a moderate ecological risk,indicating that Cd is the main element causing the ecological risk of heavy metals in the surface sediments of Keluke Lake in summer.Correlation and principal component analysis results show that Cr,Ni,Cu,As,Cd and Pb have similar pollution sources,and the heavy metal sources in surface sediments may be mainly natural sources,which are affected by natural processes such as endogenous deposition and rock weathering.This study will provide a theoretical basis for revealing the migration and transformation of heavy metals in surface sediments in highly sensitive areas.
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