某氧化铜矿尾矿区重金属污染特征及农作物健康风险评价

为了探究氧化铜矿尾矿区重金属的环境风险,以云南省某典型铜尾矿库为研究对象,在尾矿库及周边区域采集表层样品和主要农作物,分析样品中重金属含量(Cd、As、Pb、Cu、Ni和Zn);运用单因子指数法、综合污染指数法和地累积指数法评价尾矿及周边土壤的污染状况,基于潜在生态风险指数法评估重金属生态风险程度,并利用目标危害商数法对农作物健康风险进行评价。结果表明:尾矿pH在9左右,属高碱性尾矿,尾矿区及周边区域受Cu污染最严重,其平均CF值达到高度污染水平,Cd达到中度及以上污染水平,少部分采样点中As达到中度至重度污染。根据潜在生态风险分析,Cu和Cd均具有较高潜在生态风险,为主要特征污染物。农田玉米粒的健康风险指数中,Cu具有最大贡献率,且植物叶片中铜富集较其它部位高。因此尽管表现为碱性尾矿,不易造成酸性废水排放污染,但该氧化铜矿尾矿周边仍然存在Cu、Cd等重金属污染的生态风险,同时该尾矿闭库修复后,应避免种植食用叶片的作物,避免重金属污染及Cu等重金属的摄入累积。

Heavy metals pollution characteristics and crop health risk assessment around a copper oxide tailing pond

In order to explore the environmental risks of heavy metals in the tailings of oxidized copper mines, a typical copper tailings pond in Yunnan Province was collected from the tailing pond and surrounding areas, and the heavy metals content (Cd, As, Pb, Cu, Ni and Zn); single factor pollution index method, comprehensive pollution index method and geo-accumulation index method were used to evaluate the pollution degree of tailings and surrounding soils, based on potential ecological risk index method to evaluate the ecological risk of heavy metals, and used the target hazard quotient method to evaluate the health risks of crop. The results show that the pH of tailings is about 9, which is a highly alkaline tailings. The tailings area and surrounding areas are most polluted by Cu, and the average CF value reaches a high pollution level. The Cd reaches a moderate or above pollution level, and a small number of sampling points of As reaches moderate to severe pollution. According to the analysis of potential ecological risks, both Cu and Cd have high potential ecological risks and are the main characteristic pollutants. In the health risk index of farmland corn kernels, Cu has the largest contribution rate, and the copper concentration in plant leaves is higher than the other parts. Therefore, although the alkaline tailings is not easy to cause pollution from AMD, there are still ecological risks of Cu, Cd and other heavy metal pollution around the copper oxide tailings. At the same time, after the tailing pond is closed and repaired, edible leaves should be avoided, and to avoid heavy metal pollution and Cu and other heavy metal intake accumulation.