粤北某矿区横石河流域耕作土壤剖面重金属空间分布及生态风险评价

Spatial distribution and potential ecological risk assessment of heavy metals in cultivated soil profiles of Hengshi River Basin in the sulfide mine, Northern Guangdong

通过对粤北某矿尾矿库下游农耕区土壤剖面重金属含量及其理化性质进行分析测试,探讨农耕区剖面土壤重金属的分布特征及其与理化性质之间的关系,采用Hakanson潜在生态风险指数法对剖面土壤污染进行评价。结果显示,研究区各剖面中Cd含量的平均值均超过国家二级土壤标准,最大超标倍数达9.37,Cu、Pb和Zn含量的平均值最大超标倍数分别为23.10、2.82和3.15倍;随着与尾矿库距离的增加,各剖面中重金属含量逐渐降低,Cd、Cu、Pb、Zn的迁移累积受到土壤理化性质参数的影响;潜在生态风险评价显示剖面中重金属生态风险程度排序为Cd、Cu、Pb、Zn,华屋、凉桥和水楼剖面综合潜在生态风险指数达到中度至重度的生态风险。研究结果可为研究区农用地的安全利用及土壤改良提供理论依据。

Heavy metals of agricultural region soil profiles and the pH value, organic matter of the soils from sulfide mining of northern Guangdong were analyzed. The distribution of heavy metals and the relationship between pH value, organic matter in soil profiles were investigated. The pollution and ecological risk of heavy metals were evaluated by Hakanson potential ecological risk index method. The results showed that the average content of Cd was higher than national soil secondary standard in each soil profiles; the contents of Cd, Cu, Pb and Zn were beyond the national soil secondary standard as high as 9.51, 23.10, 2.82 and 3.20 times. With the increase of distance from the tailings, the content of heavy metals in soil profiles reduced gradually, and the migration and accumulation of heavy metals were affected by pH and organic matter. The potential ecological risk assessment showed ecological risk degree of heavy metals was Cd 〉 Cu 〉 Pb 〉 Zn; the potential ecological risk indexes of soil profiles of Huawu, Liangqiao and Shuilou were moderate to severe ecological risk. The results of this study provided a theoretical basis for the security of agricultural land and soil improvement.