南京江北地区菜地土壤有效态重金属的含量及空间分异特征

在南京市浦口和大厂的5大主要功能区（工业区、交通干线、居民区、蔬菜生产基地和风景区）内共采集了75个菜地表层土壤样品,以Cd、Cu、Pb和Zn等典型污染重金属的有效态含量为基础,运用经典统计分析、主成分分析和地统计分析相结合的方法对菜地土壤重金属污染进行了评估。结果表明,菜地有效态Cd、Cu、Pb和Zn的平均含量以交通干线沿线（宁六公路泰山新村-南信大段）最低,工业区（南钢或扬子石化）最高,其他功能区的均介于两者之间。主成分分析将菜地土壤有效态重金属大致分为农业源和工业、生活源。从功能区菜地土壤污染总得分排序结果可以看出,宁六公路沿线（泰山新村-南信大段）菜地土壤环境质量最高,以下依次是龙王山风景区、盘城蔬菜基地和盘城镇,老工业区的扬子石化和南钢周边菜地土壤环境质量较差。研究区内菜地土壤有效态Cd、Cu、Pb和Zn的空间分布均具有中等强度空间相关性,不同有效态重金属在空间上具有明显的各向异性,其空间变异主要发生在北-南方向。有效态Pb的空间分布较离散,有效Cd、Cu和Zn的高值区大致都位于老工业区内。

Concentrations and Spatial Distribution Characteristics of Available Heavy Metals in Vegetable Soils in Jiangbei Area of Nanjing City

75 surface samples were collected from vegetable soils located in or nearby 5 contrasting zones：industry, arterial highway, resident, vegetable production base and scenery site, across Pukou and Dachang districts of Nanjing City. Pollution characteristics of available heavy meta（lCd, Cu, Pb and Zn）in soils were assessed by methods of normal statistical analysis, principal components analysis and geostatistical analysis. The results showed that the average concentrations of available heavy metals in vegetable soils was the lowest along arterial highway （Ningliu Road from Village Taishan to Nanjing University of Information Science Technology）and the highest in industrial area（Nanjing steel group or Sinopec Yangzi Petrochemical Company Ltd.）while those of other functional areas were between the two above. Two main sources of available heavy metals, agriculture and industry-resident, were obtained, by principal components analysis. The order of heavy metals pollution in vegetable soils in the functional areas was：Ningliu Road（from Village Taishan to Nanjing University of Information Science Technology）Longwang Mountain scenery sitePancheng vegetable production base and Pancheng Townthe old industrial area（including Nanjing steel group and Sinopec Yangzi Petrochemical Company Ltd.）. Available Cu, Cd, Pb and Zn exhibited moderate spatial dependence in vegetable soil in the studied area. The geostatistical analysis also showed a significant anisotropy in distribution of soil available heavy metals which demonstrated an azimuth angle in the long axis direction（N-S）. The spatial distribution of available Pb was more discrete. The high-value area of available Cd, Cu and Zn was generally located in the old industrial area.