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    宁夏固原市原州区土壤重金属分布特征及其生态风险评价

    Distribution characteristics and ecological risk assessment of soil heavy metal in Yuanzhou District of Guyuan City, Ningxia

    • 摘要:研究目的】通过研究宁夏固原市原州区表层土壤重金属含量及空间分布特征,对该地区进行生态风险评价,明确原州区表层土壤重金属累积情况。【研究方法】系统采集研究区表层土壤样品12988件,获取了As、Cd、Cr、Cu、Hg、Ni、Pb和Zn等8种重金属含量,采用单因子指数法、内梅罗综合污染指数法和潜在生态危害指数法进行土壤重金属生态风险评价。【研究结果】与宁夏自治区表层土壤元素背景值相比,原州区表层土壤8种重金属富集系数分别为As (1.01)、Cd(1.42)、Cr(1.04)、Cu(0.99)、Hg(1.03)、Ni(0.81)、Pb(1.01)和Zn(1.07)。土壤中8种重金属空间分布特征相似,高值区主要分布在六盘山东西两侧、固原市区、张易镇和黄铎堡镇等人类活动频繁区域,在东北部第四纪黄土覆盖区的炭山乡、寨科乡土壤重金属富集程度较低。单因子指数法评价结果显示,原州区土壤整体清洁,无污染。内梅罗综合污染指数法分析结果显示,土壤各重金属元素污染指数均小于0.7,属清洁水平,污染风险等级为安全。潜在生态危害指数法分析结果显示,Cd和Hg单元素潜在危害指数达到中等风险水平,重金属综合潜在生态危害指数为轻微风险。【结论】固原市原州区土壤重金属生态风险较低,受人类活动影响的区域,表层土壤重金属存在轻微富集。

       

      Abstract: Objective Through studying the content and spatial distribution characteristics of heavy metals in the surface soil of Yuanzhou District, Guyuan City, Ningxia, the ecological risk of this area was evaluated, and the accumulation of heavy metals in the surface soil of Yuanzhou District was clarified. Methods A total of 12,988 soil samples were collected and tested for the concentration of eight heavy metals, namely As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. The single-factor index, Nemerow comprehensive pollution index, and potential ecological hazard index methods were employed to estimate the ecological risks associated with heavy metal contamination in soils. Results Compared to the background values of Ningxia Autonomous Region, the average enrichment coefficients of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 1.01, 1.42, 1.04, 0.99, 1.03, 0.81, 1.01, and 1.07, respectively. We observed similar distributions of the eight heavy metals, with high concentration values primarily found in areas with frequent human activities, such as the east and west sides of Liupan Mountain, Guyuan City, Zhangyi Town, and Huangduobao Town. In contrast, low concentration values were observed in Tanshan Township and Zhaike Township in the northeast Quaternary areas with loess-covered soil. The single-factor index evaluation revealed that the soil was "clean" in the Yuanzhou area. The Nemerow comprehensive pollution index evaluation indicated that the soil pollution index of all heavy metals was less than 0.7, which is considered "clean." While the single-element potential hazard index of Cd and Hg reached moderate risk levels, the comprehensive potential ecological hazard index of heavy metals was at a slight risk level.Conclusion Overall, the soil quality in Yuanzhou District, Guyuan City is in good condition, but heavy metals were slightly enriched in the topsoil due to human activities in some areas.

       

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