浙北环太湖平原耕地土壤重金属的空间变异特征及其风险评价研究

SPATIAL VARIABILITY AND RISK EVALUATION OF SOIL HEAVY METALS IN TAIHU LAKE REGION OF NORTH ZHEJIANG PROVINCE

研究了浙北环太湖平原10个区县市耕地土壤Hg、Cd、Cr、Pb、Cu、As六种重金属的空间变异特征及其环境风险。结果表明,土壤Hg和Cd含量在总体分布上显现出较强的各区县市空间异质性,且这种变异更多与外界人为因素的影响密切相关。鉴于Hg在研究区域超标率高达10.34%,为该区土壤环境质量的主要限制因子,对土壤Hg用超过国家规定的土壤环境质量二级标准(0.3 mg kg-1)的离析克里格法(Disjunc-tive kriging)进行了风险评价,结果表明超标区域主要集中在各区县市的城镇和工矿企业周边,说明其与人为活动造成的大量大气粉尘、工业固废和城市垃圾的长期累积密切相关。研究认为在加快城市化和工业、农业现代化的同时,还应该考虑土壤污染与农产品质量、生态安全和人体健康的关系。

A total of 2 631 soil samples were collected from 10 counties of the Taihu Lake region of North Zhejiang Province, China, in the study to characterize spatial variability and environmental risks of Hg, Cd, Cr, Pb, Cu and As. Results clearly, show strong spatial variability of Hg and Cd, suggesting its close relationship with anthropogenic factors. Meanwhile, statistical analysis of the test results indicate that concentrations of the heavy metals in the soils were in the range of the safety values of the national soil quality criteria with the exception of Hg and Cd. Compared with Cd （2.62 % ） slight in risk, Hg in 10.34 % of the soil samples exceeded the environmental safety criteria of the national soil quality standard, suggesting that Hg might be considered as a dominant element causing soil heavy metal pollution in the study area. The disjunctive kriging technique was thus used to quantify the risk of Hg pollution, and revealed that polluted areas were concentrated around cities and towns and industri- al plants and mining, suggesting that the pollution is closely related to air-particle deposition as well as discharge of industrial solid waste and urban garbage. The results of this study provide some insight into risk assessment of environmental pollution and decision-making for agriculture and industry.