Accumulation of Heavy Metals in Agricultural Soils and Crops in the Permian Gufeng Formation Siliceous Rock Distribution Region in Three Gorges Reservoir Area
The agricultural soils and crops in the siliceous rock distribution area of the Permian Gufeng Formation in the Three Gorges Reservoir Area are characterized by enrichment of heavy metals.This paper studied concentration of heavy metals,the chemical specia-tion of Cd in the agricultural soils and crops in the typical Gufeng Formation distribution region in the Three Gorges Reservoir Area,to reveal the environmental impacts on the migration and enrichment process of heavy metals in soils-crops system.The results showed that the enrichment degree of heavy metals in the soil of the study area was Cd＞Mo＞Hg＞Cr＞Ni＞Cu＞Zn＞As＞Pb,with all elements higher than the background values of soil in China.The pollution degree of Cd in soil of the study area is the highest,with an average concentration of 12.98 mg/kg,and all the samples exceeded the official standard concentration.Both the single factor pollution index and geoaccumulation index of Cd present a serious pollution grade.The average ecological risk factor(Er)was 4 929,indicating a ver-y high ecological risk.Cd was mainly occurred as exchangeable,residual,and reducible state.The content of Cd in crops from the study area followed an order of lettuce stem＞lettuce leaf＞bean＞cabbage＞potato＞rape seeds,with Cd,Cr and other elements exceeding the safety threshold of agriculture products.The transport capacity of heavy metals varies significantly in different plant types.Lettuce stems and leaves are prone to enriched in Cd.The occurrence forms of elements,soil pH values and crop types are positively correlated with the migration of heavy metals in crops and crops system.
Three Gorges reservoir areasoilsheavy metalsagricultural crops
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