Distribution Characteristics,Source Analysis and Ecological Risk Assessment of Heavy Metals in Fluvial Sediments of Typical Manganese Ore Areas
Taking the river sediments of a representative manganese mining area in Rongxi Town,Chongqing,as the study subject,the contamination characteristics of heavy metals(Cd,Zn,Cr,Cu,Mn,Ni,Pb and As)in the sediments in this area were investigated,the potential ecological risks were evaluated,and the origins of these heavy metals were analyzed.The detection results revealed that the contents of Cd,Zn,Cu,Mn,Ni and As in the sediments of most of the sampling sites surpassed the background values for Chongqing soils and the background values for soil elements in China.The average content of each heavy metal in the sediments in spring and winter was higher than that in summer and fall.The single-factor pollution index values showed that Mn＞Zn＞As＞Ni＞Cd＞Cu＞Pb＞Cr,with Mn displaying extremely severe pollution and Zn and As presenting heavy pollution.The value of geoaccumulation index exhibited Mn＞Zn＞Cd＞As＞Ni＞Cu＞Cr＞Pb,of which Mn displayed heavy pollution.Meanwhile,the results of the potential ecological risk of heavy metals indicated a moderate ecological risk in this region,in which only the heavy metals Cd and Mn appeared as strong and moderate ecological risks,respectively,suggesting that Cd and Mn in sediments in the region are the main sources of local ecological risks.Furthermore,the findings of correlation and principal component analysis further revealed that Cd,Zn,Cu,Mn and Ni in the sediments have similar origins of pollution,mainly from manganese mining;the origins of Cr and Pb belong to natural sources;and As mainly comes from agricultural activities.Therefore,attention should be paid to the pollution of Mn,Zn,Cd and As in the sediments of this manganese mining area,and the source control and pollution prevention of heavy metals in the mining area should be emphasized.Simultaneously,efforts should be made to focus on the heavy metal pollution in the sediments of other similar manganese mining areas and to adopt corresponding pollution control strategies.The findings of this research can offer a reference for heavy metal pollution management in manganese mining areas.
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