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    北京近郊耕作土壤重金属状况评价分析

    Evaluation and analysis of heavy metals in cultivated soils in the suburbs of Beijing.

    • 摘要: 以北京市近郊昌平、通州、顺义、海淀和大兴5个区县耕作土壤为对象,在对74个样点土壤中Cr、Cu、Cd、Pb、As和Hg 6种重金属含量调查分析的基础上,利用GB 15618—1995《土壤环境质量标准》评价北京市近郊耕作土壤重金属污染现状,并参考北京市土壤重金属背景值,采用环境质量指数与Hakanson环境生态潜在风险指数相结合的方法,探讨土壤中6种重金属的累积污染现状及潜在生态风险。结果表明:土壤中6种重金属含量均低于GB 15618—1995中的二级标准,Cu、Cr、As、Cd、Pb和Hg的含量平均值分别为25.69、59.62、7.97、0.20、22.26和0.16 mg/kg;土壤中Pb、Cu和Cd 3种重金属有极大的同源可能性,但土壤Cr异源性明显;6种土壤重金属都表现出一定程度的累积效应,Cr的累积污染效应最大;土壤中Cd和Hg均处于较高的潜在风险等级,其中海淀部分样点土壤Hg含量已经达到极高潜在风险水平;17%左右的土壤样点已存在一定程度的潜在生态威胁。高累积污染和高风险潜在威胁区都集中在经济相对发达的海淀、通州、昌平。分析表明,近年来的人类生产活动已给北京市近郊耕作土壤的环境质量带来了负面影响,故应依照属地管理原则立即采取区域化重点监测管理措施。

       

      Abstract: The cultivated soils in Changping, Tongzhou, Shunyi, Haidian and Daxing districts in the suburbs of Beijing were selected with 74 sampling points to assess the accumulation status and potential ecological risk of six heavy metals of As, Cd, Cr, Cu, Hg and Pb. The individual pollution index, synthetical pollution index and potential ecological risk index were calculated with National Soil Heavy Metals Standards (GB15618-1995 Grade Ⅱ) and with the background level of heavy metals in Beijing as the assessment criteria to explore the accumulation degree and the pollution status of soil heavy metals. Results showed that heavy metal concentration in the cultivated soils did not exceed the national standards Grade Ⅱ and could satisfy the safety qualification. Lead, Cu and Cd might have homology, but Cr had not similar source as the others. The six heavy metals in soils showed certain accumulation effects. Cadmium and Hg were in a higher potential risk grade, and especially Hg in Haidian District reached a very high potential risk level. About 17% of the soil samples had potential ecological threat to a certain degree. The high accumulation degree and potential ecological risk grade occurred in relatively developed districts like Haidian, Tongzhou and Changping. Analyses showed that human activities had influenced soil environmental quality in recent years. Therefore, we should take immediate regional monitoring management and related measures in accordance with the principles of territorial administration.

       

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