凤县某铅锌尾矿库周边土壤镉污染特征及风险评估

Cadmium pollution characteristics and risk assessment ofsoil around a lead-zinc tailings pond in Fengxian County

选取凤县某铅锌尾矿库周围土壤为研究对象,测定了土壤样品中镉(Cd)含量和形态分布,并利用潜在生态风险指数法和模糊数学综合评价法进行了风险评价.研究结果显示,该区域土壤pH为7.5~8.5,为碱性土壤.土壤中Cd含量为2.19~9.93 mg·kg-1,平均含量为4.62 mg·kg-1.所有采样点中土壤Cd含量均高于农用地土壤污染风险筛选值,超标倍数为3.65~16.5,而且56%的采样点中土壤Cd含量超过了农用地土壤污染风险管制值.土壤中Cd主要以弱酸提取态和残渣态为主,大部分土壤样品中这两种形态占50%以上,其中弱酸提取态Cd含量变化为12.45%~63.23%.潜在生态风险评估结果显示,73%的采样点Cd污染风险为IV及以上水平.模糊数学评估结果低于潜在生态风险评估结果,但该区域仍有80%的采样点为III级及以上水平,两种评估方法均显示出该区域土壤Cd污染风险较强,应采取有效措施进行土壤修复,降低Cd污染风险.该研究旨在为秦岭生态环境管理和恢复提供数据支撑.

Soil was taken around a lead-zinc tailings pond in Fengxian County as the research object,the content of cadmium(Cd)and species distribution were determined,risk assessment by potential ecological risk and fuzzy comprehensive evaluation were conducted.The results showed that the pH of the soil was 7.5~8.5,and the soil was alkaline.The Cd content in the soil was 2.19~9.93 mg·kg-1,and the average content of Cd was 4.62 mg·kg-1.The Cd content in all the soil samples was higher than the risk screening values for soil contamination of agricultural land,and the exceeding rate multiple to 3.65~16.5.In addition,the Cd content in 56%of the sample sites exceeded the risk intervention values for soil contamination of agricultural land.The Cd in the soil was mainly in the weak acid extracted state and residue state,which account for more than 50%in most soil samples,among which the weak acid extracted state content of Cd varied from 12.45%to 63.23%.The results of potential ecological risk assessment showed that 73%of the soil samples had a pollution risk of Cd above IV level.Although the results of fuzzy comprehensive evaluation were lower than the potential ecological risk assessment,80%of the soil samples had a pollution risk of Cd above III level.Hence,based on the risk assessment results,the pollution risk of Cd in the soil was strong,and effective remediation strategies should be consider to reduce the risk of Cd pollution.The aim of this study is to provide data support for Qinling eco-environmental management and restoration.