设施菜地土壤重金属污染特征及其潜在生态风险评价

    Specificity and potential ecological risk of heavy metals pollution in greenhouse vegetable soils--A case study of Lanzhou city

    • 摘要: 以兰州市设施菜地土壤为研究对象,研究土壤中重金属污染的特征,并采用潜在生态危害指数法对土壤中重金属的潜在生态危害进行评价。结果表明,不同种植年限下,Cd、Pb、Cr、Hg、As5种重金属的平均含量均超过兰州市土壤背景值,种植年限越长,重金属累积越明显,含量越高。潜在生态风险评估表明,以国家土壤环境质量域级标准为评价标准,不同种植年限下,5种重金属的耘蚤则值和RI值均处于轻度风险水平;以本地土壤背景值为评价标准,不同种植年限下,Cd和Hg达到中等危害,≥10年的土壤中5种重金属的综合潜在生态风险指数为157.73,属中度危害,≤5年和6~9年的RI值也已接近中等危害。

       

      Abstract: Specificity of heavy metals pollution index of greenhouse vegetable soils in Lanzhou city was studied for the potential ecological risk. The potential ecological risk was used to assess the ecological hazards of heavy metals in greenhouse vegetable soils. The results showed that the average concentration of Cd, Pb, Cr, Hg and As were higher than the local background soil value with different planting years. With the increase of planting years, the test heavy metals contents in the soil profiles all had increasing trend, and the contents were obviously higher in facility vegetable fields. The potential ecological risks results of these heavy metals showed that,compared to the National Soil Quality Standard(Grade Ⅱ) evaluation standard, the E¹and RI value of five heavy metals were all less than 40 and 150, posing little ecological hazard. If the local background soil value was used as evaluation standard, with different planting years Cd and Hg were at a higher level that posing Grade域hazard. The five kinds of heavy metals comprehensive potential ecological risk index (RI) was 157.73 in equal or greater than 10-year planting soil, that posing the secondary hazard. In addition, their RI value closed to the secondary hazards in less than or equal to 5-year and 6~9 years planting years of soil.

       

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