Distribution features and potential ecological risk assessment of heavy metal elements in the surface sediment of Liuye Lake in Changde City
The situation of heavy metals in the surface sediments of Liuye Lake has a significant impact on the ecological environment of the Dongting Lake basin.The contents and forms of heavy metals in the surface sediments of 31 sampling points in the area were monitored and analyzed,and the risk assessment was carried out using the potential ecological risk index method and the health risk assessment model.The results indicated that:(1)the average values of heavy metals were higher than the background values of heavy metal elements in the sediment of the Dongting Lake water system.According to"Soil environmental quality risk control standard for soil contamination of agricultural land"(GB 15618-2018),Cd could pose a pollution risk.(2)Cd,Cr,Pb,Cu,Zn and Ni had similar sources,Mn had single source,and As had multiple sources.(2)As,Cr,Cu,Zn and Ni in the surface sediments were mainly in residual state,Cd and Mn were mainly in weakly acid extractable and reducible states,and Pb was mainly in reducible state.(3)The single potential ecological risk index of Cd was 57.0,which belonged to moderate risk,while the other seven heavy metals were all considered mild risk.The comprehensive potential ecological risk index of 8 heavy metals was 100.8,which was considered mild risk.(4)The total carcinogenic and non-carcinogenic risk in adults and children were within an acceptable range,and the total risk index of cancer and non-cancer in children were higher than that in adults.The carcinogenic risk index of As was greater than that of Cd.The non-carcinogenic risk index of Zn was the lowest,while Cr was the highest.
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