雷州半岛土壤重金属分布特征及其污染评价

在雷州半岛采集了106个土壤表层样品,分析了其中8种重金属元素(Cu、Pb、Zn、Cr、Ni、Cd、Hg和As)的全量.结果表明,雷州半岛土壤重金属污染由高到低排序为Ni＞Cr＞Hg＞Cu＞Zn＞Cd＞As＞Pb,Zn、Cd、As和Pb质量浓度均没有超标,Hg和Cu质量浓度超标率亦不高,但Ni和Cr平均质量浓度达49.81、87.13 mg/kg,高于国内外其他对照区域,超标率分别为25.47%和24.53%;重金属元素在雷州半岛各土壤利用类型中分布规律不明显,按4种主要土壤利用类型受重金属污染程度大小排序为甘蔗地＞果园土＞水田＞菜地;雷州半岛土壤综合污染指数总平均为0.970,土壤总体上尚清洁,重金属污染处于警戒水平;雷州半岛各区域中,徐闻、雷州两地土壤重金属质量浓度明显高于其他地区,其主要原因是徐闻、雷州两地成土母质主要为玄武岩,造成土壤Cr、Ni及其他重金属背景值较高.

Distribution and pollution assessment of heavy metals in soil samples of Leizhou Peninsula

Concentrations of 8 heavy metals in 106 topsoil samples collected from 4 functional areas of Leizhou Peninsula were determined, and the data were analyzed for a pollution assessment of their presence. Relative to the national standards for heavy metals in soil, the order in decreasing pollution potential was Ni, Cr, Hg, Cu, Zn, Cd, As and Pb. Zn, Cd, As and Pb in those samples were below the respective national soil standards; Hg and Cu in some of the samples were modestly above the standards. Average concentrations of Ni (49.81 mg/kg) and Cr (87.13 mg/kg) exceeded the standards by 25.47% and 24.53% respectively; they were higher than the same in most domestic and foreign soil samples. Although distribution of heavy metals in the samples was not well defined, the data suggested the order in declining pollution potential of sugarcane soil, orchard soil, paddy field and pot garden. The average combined pollution index was 0.970, indicating that most of the soil samples were clean and that pollution of heavy metal for some areas was at the alert level. Heavy metal contents for soil samples taken in Xuwen and, to a less extent, Leizhou were notably higher than the rest due possibly to fact that those soils were originally from basalt which could have resulted in higher background concentrations, especially Ni and Cr, as observed.