经济发达县域耕地土壤重金属污染评价及其影响因素分析

通过对昆山市14个区镇91个土壤样品中As、Cd、Cr、Cu、Pb、Ni、Hg、Zn 8种重金属测定分析，对该市耕地土壤重金属污染进行评价并进行重金属污染的影响因素分析。结果表明，昆山市耕地土壤存在不同程度的轻微污染，重金属Cd、Cr、Cu、Pb、Hg、Zn均超过国家土壤背景值，旱地、水田中均以Hg污染范围较广、变异系数较大。综合污染指数表现为水田（115）>旱地（100）。区镇耕地重金属污染评价表明千灯、陆扬、石浦、锦溪、石牌处于警戒值之内，蓬朗、周庄、张浦、正仪、周市、巴城、淀山湖、花桥、陆家轻度污染；昆山市耕地土壤中重金属元素均未超过土壤环境基本容量，能够保证作物品质和农业持续发展。同时，研究表明区域重金属轻微污染具有复合污染的特性，Cd、Pb相关性最高(〖WTBX〗P〖WTBZ〗=0621 0)， Pb与Hg、Cu、Zn、Cu与Cr也有相关性（0438 7、0426 0、0350 9、0394 0），区域重金属的轻微污染受人为因素影响显著，研究指出应加强对区域优先控制污染物Hg、次优先控制污染物Pb、Cd、Zn、Cu、Cr的控制与治理。

ANALYSIS OF HEAVY METAL POLLUTION AND ASSESSMENT OF ITS ENVIRONMENTAL EFFECT IN DEVELOPED AREAS

The distribution of heavy mentals，i.e.As，Cd，Cr，Cu，Pb，Ni，Hg and Zn in cultivated soils in Kunshan City were studied in the present investigation.Statistical results showed that the cultivated soil in Kunshan City was polluted by heavy metals.Among the eight types of heavy metal elements，the element Hg had the highest level exceeding the national background level and the largest variability in the cultivated soil.Meanwhile，heavy metals of As，Cd，Cr，Cu，Pb，Ni，Zn all exceeded the national heavy metal background value of soils.The Synthetic Pollution Index was in the following order：paddy field (115) > dry land (100).Heavy metals in five towns，i.e.Qiandeng，Luyang，Shipu，Jinxi，Shipai were in the precaution domain，while other towns (Penlang，Zhouzhuang，Zhangpu，Zhengyi，Zhoushi，Bacheng，Dianshanhu，Huaqiao，Lujia) were all subtly polluted.Regional heavy metal pollution had the characteristics of combined pollution because there was a significant positive correlation among Cd and Pb (〖WTBX〗P〖WTBZ〗=06210)，Pb and Hg，Cu，Zn (04387，04260，03509) and Cu and Cr (03940).It was also found that the regional heavy metal pollution was influenced by artificial factors.Consequently，Hg which was the regional priority control pollutant and Pb，Cd，Zn，Cu，Cr which were the regional inferior priority control pollutants，should be frequently monitored and closely regulated in cultivated soils in Kunshan of Suzhou City，Jiangsu Province.