| Autor: |
Deng S; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Duan JH; Chongqing Institute of Geological Survey, Chongqing 401120, China., Ning MH; Chongqing Institute of Geological Survey, Chongqing 401120, China., Tan L; Chongqing Institute of Geological Survey, Chongqing 401120, China., Pu G; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Chen JX; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Qi XB; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Jiang SZ; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Xie TY; No. 205 Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 401120, China., Liu YZ; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China. |
| Abstrakt: |
Soil polluted by heavy metals (HMs) is an important environmental issue in China, and regional geological background is a vital factor that influences the enrichment of HMs in soils. Previous studies have shown that soils derived from black shales are commonly enriched in HMs and present high potential eco-environmental risks. However, few studies have investigated the HMs in different agricultural products, which inhibit the safe use of land and safe production of food crops in black shale regions. This study investigated the concentrations, pollution risks, and speciation of HMs in soils and agricultural products from a typical black shale region in Chongqing. The results showed that the study soils were enriched in Cd, Cr, Cu, Zn, and Se but not in Pb. Approximately 98.7% of total soils exceeded the risk screening values, and 47.3% of total soils exceeded the risk intervention values. Cd had the highest pollution level and potential ecological risks and was the primary pollutant in soils of the study area. Most of the Cd resided in ion-exchangeable fractions (40.6%), followed by residual fractions (19.1%) and weak organic matter combined fractions (16.6%), whereas Cr, Cu, Pb, Se, and Zn were dominated by residual fractions. Additionally, organic combined fractions contributed to Se and Cu, and Fe-Mn oxide combined fractions contributed to Pb. These results indicated that Cd had higher mobility and availability than those of other metals. The agricultural products presented a weak ability to accumulate HMs. Approximately 18.7% of the collected samples with Cd exceeded the safety limit, but the enrichment factor was relatively low, indicating low pollution risks of the heavy metals. The findings of this study could provide guidelines for safe use of land and safe production of food crops in black shale regions with high geological background. |
