典型硫铁矿区农田土壤-作物系统重金属生态风险及迁移富集特征

为揭示硫铁矿区地质高背景和人为活动影响叠加区下土壤-作物系统重金属生态风险，分析测试了某硫铁矿区农田土壤-作物系统中重金属含量及其赋存形态，利用生物富集系数(BFC)、潜在生态风险指数(RI)、风险评估指数(RAC)和相关分析等方法开展了重金属生态风险评估及迁移富集影响因素研究.结果表明，土壤中Cd、 Cu、 Pb和Zn含量均值均显著高于浙江省和全国表层土壤背景值.土壤中Cd单指标潜在生态风险危害最大，其次是Hg;重金属综合潜在生态风险(RI)以轻微等级为主，占比为52%.土壤中Cd的生物有效组分和潜在生物有效组占比分别为46%和33%,生物有效性相对较高；Cu和Pb以潜在生物有效组分为主，占比分别为60%和73%; As、 Cr、 Hg、 Ni和Zn均以残渣态为主(残渣态占比>60%).RAC评价显示，元素风险等级大小依次为：Cd>Zn>Cu>Pb>Ni>As>Cr>Hg,土壤Cd潜在生态风险最大，以高和极高风险等级为主，其他各元素RAC均为无风险或低风险.与土壤中Cd含量相比，研究区作物中Cd含量超标率明显较低，仅8件水稻籽实样品Cd...

Ecological Risk Assessment and Migration and Accumulation Characteristics of Heavy Metals in Farmland Soil-crop System from Typical Pyrite Mining Area

To evaluate the ecological risk of heavy metals in the soil-crop system in the superimposed high background and human activities from pyrite mining, the heavy metal contents and chemical speciation in soil and crop samples were analyzed, and these data were used to assess the potential ecological risk and factors affecting the migration ability of heavy metals using bioconcentration factors(BCF), potential ecological risk index(RI), risk assessment code(RAC), and correlation analysis. The results indicate that the average Cd, Cu, Pb, and Zn concentrations exceeded the background values of soils in Zhejiang Province and China. Cd had the greatest potential ecological harm, followed by that of Hg. The bioactive components and potential bioactive components of Cd accounted for 46% and 33%, respectively, indicating relatively high bioavailability. Cu and Pb were mainly in potential bioactive components accounting for 60% and 73%, respectively. The As, Cr, Hg, Ni, and Zn were predominantly residual and accounted for >60%, which indicated low biological activity. The RAC levels were in the following order:Cd>Zn>Cu>Pb>Ni>As>Cr>Hg; soil Cd had the highest ecological risk, mainly with high and extremely high levels, whereas other elements had no risk or low risk. Compared with Cd content in soil, only eight rice samples had Cd contents exceeding the safety limit, and sweet potato samples did not exceed the standard. The migration and enrichment capability of rice in order from strong to weak was s follows:Cd>Zn>Cu>Hg>As>Ni>Cr>Pb; the bioactive component of Cd played a significant role in promoting Cd absorption by rice. Soil OM had a bi-directional effect on Cd bioavailability, whereas soil texture had an indirect effect. This comprehensive study shows that the total amount of heavy metals in soil, chemical speciation, biological activities, absorption, and enrichment of heavy metals by crops should be taken into consideration when assessing the ecological risks in the superimposed areas affected by high background and human activities, such as the pyrite mining area.