南京地区农田土壤和蔬菜重金属污染状况研究

采集了南京市5县4郊5个环境单元（矿冶区、交通干线、工厂周边、污灌地、农产品基地）共100个样点的农田土壤及部分蔬菜样品，测定了重金属（Pb、Cu、Zn、Cd）的质量分数。结果表明，土壤Pb、Cu、Zn、Cd 质量分数的变化范围分别为26.1~4 138.8、16.5 ~3 375.1、46.0~3 587.6、0.09~17.61 mg/kg。不同功能区土壤重金属含量存在明显差异，以矿区周边农田污染最为严重，其次为污灌地和公路沿线农田, 部分农产品基地存在轻度Cd污染，工厂周边农田土壤污染相对较小。19个样点的青菜地上部重金属Pb、Cu、Zn、Cd质量分数的变化范围分别为0.11~7.11、5.04~76.42、36.8~364.3、0.04~2.96 mg/kg，同样以矿区周边污染农田的青菜样本重金属含量最高。青菜重金属含量与土壤重金属生物有效性含量和总量之间呈极显著相关。不合理的矿业开采和冶炼是导致南京地区农田土壤和蔬菜重金属污染的重要原因。

STUDY OF THE HEAVY METAL CONTAMINATION IN SOILS AND VEGETABLES IN NANJING AREA

Heavy metal contamination in soils and vegetables in five environmental units,i.e.mining and smelting area,arterial traffic,factory,sewage irrigation plot and farm produce base,in 5 counties and 4 suburbs of Nanjing City were investigated.The results shown that the scope of total soil Pb,Cu,Zn and Cd concentrations of 100 soil samples was 26.1~4 138.8,16.5~3 375.1,46.0~3 587.6 and 0.09~(17.61) mg/kg,respectively.There were significant differences among different environmental units.Soils sampled from mining and smelting areas were the most seriously contaminated with heavy metals,followed by soils from sewage irrigation plots and highway.Soils from farm produce bases were slightly polluted by Cd.Among 5 environmental units,soils from peripheral farmlands of factories had the least contamination by heavy metals.The scope of Pb,Cu,Zn and Cd concentrations in the shoot of 19 Chinese cabbage(Brassica chinensis L.)samples was 0.11~7.11,5.04~76.42,36.8~364.3 and 0.04~2.96 mg/kg,respectively.The samples from mining and smelting areas had the highest shoot heavy metal concentration,and also the highest in the soils of these areas.The heavy metal concentration in the shoot of cabbage had a significantly positive correlation with the total and bio-available concentrations of soil heavy metals.Non-rational mining and smelting activities have been the major cause of heavy metal contamination in soils and vegetables in Nanjing Area.