中南某废弃铅冶炼场地土壤剖面重金属污染成因及风险评估

Formation and risk assessment of heavy metal contamination in soil profiles of an abandoned lead smelting site in south-central China

城镇化和产业升级在中南地区形成了大量废弃冶炼场地,这些场地的环境污染风险已严重制约了当地社会可持续发展。为厘清废弃冶炼场地重金属的污染特征及成因,以中南某废弃铅冶炼场地为例,采集不同冶炼功能区和周边农田的土壤剖面样品,分析其重金属含量、分布和迁移特征,采用主成分分析和风险评估编码法等方法进行污染源解析和风险评估。结果显示,该场地土壤重金属污染严重,主要来源有冶炼源、交通源和自然源;场地重金属污染的空间异质性强且受来源控制显著;场地土壤Pb、Zn、Cu、Cd和As含量超过筛选值,Pb、Cd和As是最主要的生态风险因子,土壤Cd的迁移能力沿剖面从表层向下逐渐增强,存在危害地下水和场地周边农作物的风险。

Many abandoned smelting sites with unclear pollution characteristics and environmental risks formed in the process of urbanization and industrial upgrading have become a serious constraint to the sustainable development in southcentral China.To clarify the pollution characteristics and formation of heavy metals(HMs)at abandoned smelting sites,soil profile samples were collected from different smelting functional areas and surrounding farmlands at an abandoned lead smelting site in south-central China as an example.The content,distribution,and migration characteristics of HMs were analyzed,and principal component analysis and risk assessment code were used for source apportionment and risk assessment.The results show that the main sources of HMs in soils of the site are smelting,traffic,and natural sources.The spatial heterogeneity of HMs is strong and significantly controlled by the sources.The contents of Pb,Zn,Cu,Cd,and As in soils exceed their screening values,and Pb,Cd,and As are the most important ecological risk factors.The migration ability of Cd gradually increases along the profile,posing a risk of contamination to groundwater and crops around the site.