重庆市万州区农村土壤重金属污染及生态风险研究

Heavy metal pollution in rural soil and ecological risk in Wanzhou District, Chongqing

  • 摘要:
    目的 分析和评估重庆市万州区农村土壤中铅(Pb)、镉(Cd)、铬(Cr)污染水平,为提出相关措施建议提供数据支撑。
    方法 以 2017—2021年土壤监测数据为基础,应用GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准(试行)》、污染指数法和潜在生态风险法等进行生态风险评估。
    结果 共采集100份土壤样品,pH值为3.50~8.30,均值6.10。土壤中Pb、Cd、Cr的均值分别为25.2、0.310和68.6 mg·kg-1。除Cr外,其他元素均值均超过土壤背景值。Cd变异系数最大,空间分布不均匀,总体超标率为30.0%。Pb和Cr元素总体均处于警戒级,Cd总体处于轻污染水平。Cd污染水平点位占比较Pb、Cr高,差异有统计学意义(χ2=15.015,P=0.001)。不同乡镇内梅罗综合污染指数为0.70~2.07,中位数为1.10,总体处于轻污染水平。Cd潜在生态危害风险较高,整体处于轻度危害。综合潜在生态危害指数中Cd的贡献率最高为84.1%。
    结论 万州区农村土壤中存在一定程度的镉污染且具有轻度生态风险,应加强万州区农村土壤镉污染的监测治理。

     

    Abstract:
    Objective To analyze and assess the pollution levels of lead (Pb), cadmium (Cd), and chromium (Cr) in rural soils of Wanzhou District, Chongqing Municipality, and to provide data support for proposing relevant measures and suggestions.
    Methods Based on the soil monitoring data from 2017 to 2021, the ecological risk assessment was conducted by applying the Soil Pollution Risk Control Standard for Agricultural Land of Soil Environmental Quality (for trial implementation) (GB 15168‒2018), the pollution index method and the potential ecological risk method.
    Results A total of 100 soil samples were collected, with pH values ranged from 3.50 to 8.30, and a mean value of 6.10. The mean values of Pb, Cd, and Cr in the soil were 25.2 mg·kg-1, 0.310 mg·kg-1, and 68.6 mg·kg-1, respectively. Except for Cr, the mean values of other elements exceeded the soil background values. Cd level had the largest coefficient of variation and uneven spatial distribution, with an overall exceedance rate of 30.0%. Pollution levels of Pb and Cr were generally at the alert level, while Cd was generally at a light pollution level. The proportion of Cd pollution levels was higher than that of Pb and Cr, and the difference was statistically significant (χ2 =15.015, P=0.001). The Nemerow comprehensive pollution index in different townships ranged from 0.70 to 2.07, with a median value of 1.10, and was generally at a light pollution level. The potential ecological hazard risk of Cd was relatively high, and was generally at a mild level of hazard. The highest contribution rate in the comprehensive potential ecological hazard index was Cd, accounting for 84.1%.
    Conclusion There is a certain degree of Cd pollution and mild ecological risk in rural soils of Wanzhou District. Monitoring and management of Cd pollution in rural soils of Wanzhou District, Chongqing Municipality, should be strengthened.

     

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