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上海市某大型再开发场地土壤重金属污染特征、评价及来源分析
陈展1,2, 吴育林1,2, 张刚1,2
1.上海勘察设计研究院有限公司, 上海 200093;2.上海环境岩土工程技术研究中心, 上海 200093
摘要:
[目的] 研究土壤中重金属污染与生态风险状况,为保障城市更新改造过程中土地的合理利用提供科学依据。[方法] 以上海市某大型再开发利用场地为研究对象,采集了102个点位的表层(0-0.5 m)和下层(1.5-2.0 m)土壤样品,测定10种重金属(As,Be,Cu,Pb,Ni,TI,Zn,Cd,Cr和Hg)浓度,采用地累积指数、内梅罗指数和潜在生态风险指数进行土壤重金属污染和生态风险评价,并进一步利用多元统计分析方法揭示土壤中重金属的来源情况。[结果] ①测试土壤中重金属均未超过《土壤环境质量建设用地土壤污染风险管控标准(试行)》(GB36600-2018)第二类用地风险筛选值,但6.9%,24.5%,25.5%,37.3%和63.7%的采样点土壤中As,Cu,Pb,Zn和Hg浓度超过土壤元素背景值,存在不同程度的累积现象。内梅罗指数评价结果表明研究区域土壤整体处于尚清洁到轻度污染状态,分别有11.8%和3.84%的表层区域与2.64%和0.63%的下层区域土壤呈中度污染和重度污染状态。②表层土壤综合潜在生态风险指数均值为89.91,处于中等风险水平,Hg为研究区域主要的生态风险因子。③土壤中Ni,Cr,Be和TI浓度主要受成土母质风化作用的自然源控制,Pb,Zn,Cu,As和Hg主要受交通运输源和历史农业活动源的影响,其中自然源对表层土壤中的As和下层土壤中Cu也有相当比例的贡献,而表层土壤中Hg更多受到除交通运输源以外的其他人类活动源影响。[结论] 后续土地利用过程应注重Hg的生态风险管控,并提高对外来交通源引起的重金属累积效应的关注。
关键词:  再开发利用  土壤  重金属  污染评价  生态风险评价
DOI:10.13961/j.cnki.stbctb.2021.01.032
分类号:X53;X826
基金项目:上海市科学技术委员会项目“上海环境岩土工程技术研究中心”(15DZ2251300);上海市科学技术委员会项目“原位水力循环修复与风险管控全过程智能监控技术研究与数字化评价系统开发”(18DZ1204302)
Pollution Characteristics, Assessment, and Source Analysis of Soil Heavy Metals in Large-scale Redevelopment Site in Shanghai City
Chen Zhan1,2, Wu Yulin1,2, Zhang Gang1,2
1.SGIDI Engineering Consulting (Group) Co., Ltd, Shanghai 200093, China;2.Shanghai Engineering Research Center of Geo-Environment, Shanghai 200093, China
Abstract:
[Objective] The heavy metal pollution characteristics and ecological risk for soil were studied to provide a scientific basis for the proper land use in the process of urban renewal.[Methods] Samples of topsoil (0-0.5 m) and subsoil (1.5-2.0 m) were collected from 102 point locations in a large-scale redevelopment site in Shanghai City, and the concentration levels of 10 heavy metals (As, Be, Cu, Pb, Ni, Ti, Zn, Cr, Cd, and Hg) were tested and measured. The heavy metal contamination and ecological risk were evaluated with geo-accumulation, Nemerow, and potential ecological risk indices. The sources of heavy metals were further identified and revealed by multivariate statistical analysis.[Results] ① The contents of the heavy metals in soil were lower than the type Ⅱ land soil risk screening values stipulated in the "Soil Environmental Quality-Risk Control Standard for Soil Contamination of Development Land, Pilot Version" (GB36600, 2018), but the contents of As, Cu, Pb, Zn, and Hg in soil from 6.9%, 24.5%, 25.5%, 37.3%, and 63.7% sampling points exceed the background values of soil elements, which indicated different degrees of accumulation. The soil in the entire study area generally varies from clean to slightly polluted, with 11.8% and 3.84% of the topsoil and 2.64% and 0.63% of the subsoil moderately and heavily contaminated, respectively. ② The mean value of the comprehensive potential ecological risk index for topsoil was 89.91, representing a medium risk level. Hg in topsoil was the main ecological risk factor in the study area. ③ The concentrations of Ni, Cr, Be, and TI in the soil were mainly controlled by natural sources of weathering of the soil parent material. Pb, Zn, Cu, As, and Hg contents in soil were mostly affected by sources of transportation and historical agricultural production activities. Natural sources also contributed a considerable proportion to the contents of As in topsoil and Cu in subsoil as well as man-made sources. Hg in topsoil was more affected by other human activity sources than transportation sources.[Conclusion] During subsequent land use processes, more attention should be paid to the ecological risk control of Hg and the cumulative effect of heavy metals caused by external traffic sources.
Key words:  redevelopment  soil  heavy metals  pollution assessment  ecological risk assessment