矿粮复合区土壤-作物系统重金属污染风险性评价

Risk assessment of heavy metal contamination in soil-plant system of the overlapped areas of crop and mineral production

为分析矿区污染农田农作物生产的生态安全性,以焦作市中马村矿区的典型农田为例,对矿区农田土壤及植物中Zn、Cr、Cd、Cu和Pb等重金属的质量分数进行了测定,并对重金属污染风险进行了评价。结果表明,根据重金属的单项污染指数,在矿井水污灌农田(F1样地)土壤中Zn和Cd的质量分数达到中度污染水平,Cr的质量分数达到轻微污染水平,Cu和Pb元素质量分数未达到污染水平。在煤矸石污染农田(F2样地)土壤中Zn、Cr和Cd的质量分数达到轻度污染水平,Cu和Pb元素质量分数未达到污染水平。在矿区公路侧农田(F3样地)土壤中各元素质量分数均未达到污染水平。采用潜在生态风险指数法对土壤重金属污染的生态风险进行评价,F1和F2样地综合生态风险指数分别为239.60和178.42,达到中等水平,F3样地土壤达到轻微生态风险水平。采用单项污染指数和综合污染指数法对小麦(Triticum aestivum)籽粒中重金属风险进行评价,在F1和F2样地中,小麦籽粒中Cu质量分数均未达到污染水平,Pb、Cd和Cr质量分数均达到重度污染水平。Zn质量分数在F1样地中达到轻度污染水平,在F2样地中达到中度污染水平。在F3样地中,小麦籽粒中Cd和Cu质量分数未达到污染水平,Zn质量分数达到轻度污染水平,Pb、Cr质量分数达到重度污染水平。从综合污染指数评价来看,F1、F2和F3 3个样地小麦籽粒中重金属污染综合指数均达到重度污染水平。评价结果对科学治理矿区污染土壤,确保矿区农田生态安全、粮食生产安全具有重要意义。

In this study, to study the ecological safety of crops production in the overlapped areas of crop and mineral production, the contents of Zn, Cr, Cd, Cu and Pb in wheat and soil were investigated and pollution risk of heavy metals were evaluated in Zhongmacun mining area of Jiaozuo, China. The results showed that, according to single contamination index of heavy metal, the contents of Zn and Cd in the mine water contaminated soil （F1 sample plot） reached middle contamination level, the content of Cr reached slight contamination level, and but the contents of Cu and Pb were under contamination level. The contents of Zn, Cr and Cd in the coal waste rock contaminated soil （F2 sample plot） reached slight contamination level, and but the contents of Cu and Pb under contamination level. The contents of Zn, Cr, Cu, Pb and Cd in soil close to the highway （F3 sample plot） were all under contamination level. Potential ecological risk index was used to evalaued the ecological risk of heavy metals polluted soil. The assessment results showed that the comprehensive ecological risk index was 239.60 for F1 sample plot, and 178.42 for F2 sample plot, they both reached midddle risk level; the comprehensive ecological risk index of soil in F3 sample plot reached slight risk level. The single contamination index and comprehensive contamination index methods were used to evaluate the heavy metal polluted risk of wheat grain. The assessment results showed that the contents of Cu of wheat grain were under contamination level, but the contents ofPb, Cd and Cr of wheat grain reached the severe risk level in F1 and F2 sample plots. The content of Zn of wheat grain reached the slight risk level in F1 sample plot and middle risk level in F2 sample plot. The contents of Cd and Cu of wheat grain were under contamination level, but the content of Zn of wheat grain reached the sligh risk level in F1 and F2 sample plots. The contents of Pb and Cr of wheat grain reached the severe risk level in F3 sample plot. The comprehensive contamination indexes of wheat grain all reached the severe risk level in F1, F2 and F3 sample plots. The assessment results above had important practical value for managing the polluted soil and ensuring farmland ecological safety and food production safety.