The spatial variation of heavy metals in the soils in Shuikoushan mining-smelting area,Hunan Province,China,was investigated using multivariate and geo-statistic analysis.A total of 106 composite soil samples were collected in an area of about 100 km2. Concentrations of total As,Cd,Pb,Zn,Cu and Cr were measured using inductively coupled plasma mass spectrometry(ICP-MS) . Arsenic and Pb were found to have a common source,indicating the same sources and spreading processes,such as aerosols and airborne particulates from smelting chimneys.Airborne sources from smelting chimneys contributed greatly to Cd in the area,which demonstrated the same dispersion pattern as As and Pb.However,two hot spots of Cd around smelters were possibly enlarged by wastewaters,demonstrating another important source of Cd in Shuikouhsan.Geo-statistic interpolated mapping demonstrated that hotspots of Zn were only found proximal to the large smelters,suggesting that Zn primarily came from the chimneys of larger smelters. The major Cu hot-spots appeared closely to the tailing dam,indicating that weathering and leaching of tailings were the major sources of Cu contamination in Shuikoushan.Our findings indicated that airborne volatile particles and aerosols contributed the most to As,Cd,Pb,Zn and Cu contamination,while Cd and Cu may also derive from the discharge of wastewater from smelters and the leaching of tailings,respectively.
土壤砷污染是当今全球十分严重的环境与健康问题之一。土壤砷形态及生物有效性研究是开展污染诊断、评估环境健康风险及开展砷污染土壤修复的重要依据。目前土壤砷形态的研究方法包括化学选择性提取操作定义法、溶剂提取仪器测定或吸附材料选择性分离法和同步辐射X射线近边能谱(XANES)直接测定法,这些方法相互结合在土壤砷的形态转化研究中发挥着重要作用。目前关于生物有效性研究存在多种方法并存的局面,化学提取法相对经济、方便,但存在很大的局限性,往往不能真实反映土壤砷的有效态含量,只能作为环境危害程度识别的参考;植物指示法需选择敏感性植物方能有效地指示土壤砷对环境与健康的潜在危害;土壤动物与微生物指示法代表了未来开展砷污染早期预警的发展方向,具有广阔的应用前景。模拟肠胃液提取法(In V itroGastrointestinalMethod)比较接近动物或人体对土壤砷污染的真实吸收状态,在环境健康风险评价中发挥着重要作用。目前国外已发展出采用兔、仔猪和猴的动物模型以研究经口摄入的生物有效性砷,但尚不清楚哪种动物模型更能准确反映砷对人体的生物有效性。
