海南岛琼中黎母山—湾岭地区土壤重金属元素分布特征及生态风险评价

    Spatial distribution and ecological risk assessment of heavy metal pollution in the soil of Limu Mountain- Wanling Town, Qiongzhong, Hainan Province

    • 摘要: 为了解琼中黎母山—湾岭地区土壤重金属元素分布特征及其潜在生态风险,采集了表层(0~20 cm)土壤样品2682件,对应中层(80~100 cm)及深层(180~200 cm)土壤样品各304件。分析测定Cu、Pb、Zn、Cr、Ni、Cd、As、Hg八种重金属元素。对8种重金属元素空间分布特征进行多元统计分析,并采用地累积指数法、潜在生态危害指数法对该区土壤重金属污染程度、生态风险进行评估。结果显示,表层土壤中8种重金属元素均值均高于海南岛土壤重金属背景值,表现出不同程度的积累;不同土地利用类型及种植类型对表层土壤重金属富集影响较大;垂向上,由表层至深层,土壤Pb、Zn、Cu、Cr、Ni五种重金属元素含量依次降低,但差异不大;Cd、As、Hg在垂向上表现出明显的表聚性。Pearson相关性分析与因子分析结果显示,Cu、Cr、Ni主要受地质背景影响,其余5种元素均受地质背景及人为因素影响。地累积指数结果显示,8种金属元素均值除Hg(0.08)外,均小于0,总体为无污染-轻微污染;生态风险评价显示,Cd和Hg为主要危害元素,Cd以轻微-中等危害为主,Hg以中等-强风险为主,其余元素危害指数均为轻微级,96%的土壤总体潜在生态危害指数在中等以下。

       

      Abstract: In order to understand the spatial distribution and ecological risk assessment of heavy metal pollution in the soil of Limu Mountain-Wanling Town, Qiongzhong, 2682 topsoil samples(0~20 cm) and 304 middle-soil layer samples(80~100 cm) and subsoil samples(180~200 cm) were respectively collected to analyze for 8 heavy metal elements(Cu, Pb, Zn, Cr, Ni, Cd, As and Hg).Based on the metals' distribution, geoaccumulation index and potential ecological hazard index, multivariate statistics was conducted to evaluate the potential ecological risks.Results show that the mean values of 8 heavy metal elements in topsoils are higher than the soil background values of Hainan, showing different degree of accumulation effect.The accumulation of heavy metal in topsoils is associated with different land-use types and various planting patterns.Vertically, the contents of Pb、Zn、Cu、Cr、Ni decrease a little with depth, but contents of Cd, As and Hg are characterized by surface accumulation.Pearson correlation analysis and factor analysis suggest that Cu, Cr and Ni in the topsoils are mainly controlled by geological background, others are controlled by geological background and human activities.The mean geoaccumulation indexes of other heavy metal elements except for Hg(0.08) are less than 0.The ecological risk assessment show that Cd and Hg are the main hazard elements, Cd is mainly of slight to medium hazard, Hg is of medium to strong risk, and the hazard indexes of the other elements are all slight.The overall potential ecological hazard index of 96% of the soil is below medium hazard.

       

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