| 崔罗肖,胡启智,李蒙,吴家龙,范慧中,陈思思,任宗玲.清远电子垃圾拆解区土壤重金属污染空间分布特征及风险评价[J].农业环境科学学报,2022,41(10):2200-2211. |
| 清远电子垃圾拆解区土壤重金属污染空间分布特征及风险评价 |
| Spatial distribution and risk assessment of heavy metals in the soils of Qingyuan e-waste dismantling area， China |
| 投稿时间：2022-06-23 修订日期：2022-08-29 |
| DOI：10.11654/jaes.2022-0630 |
| 中文关键词: 电子垃圾拆解区 重金属 风险评价 空间分布 |
| 英文关键词: e-waste dismantling area heavy metal risk assessment spatial distribution |
| 基金项目:广东省基础与应用基础研究基金项目(2021A1515011283,2020A1515010556);国家自然科学基金项目(41811530277) |
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| 中文摘要: |
| 为探究清远市龙塘镇电子垃圾拆解区内土壤重金属污染扩散程度及其潜在生态风险，本研究在白鹤塘、大坑寮、松源塘、对面岗4个村庄，采集荒地、旱地、水田土样共44个，分析土壤样品中As、Cd、Cr、Cu、Ni、Pb、Zn、Hg的含量，采用单项污染指数法、综合污染指数法和潜在生态危害指数法对土壤重金属污染状况进行风险评估，采用反距离权重法对土壤重金属地累积指数进行插值分析，解析土壤重金属污染空间扩散特征及可能来源。结果表明：研究区域内土壤重金属污染程度依次为荒地>水田>旱地；荒地土壤达到重污染水平，Cd、Cu、Pb、Zn的平均含量分别为34.63、5 536.27、10 602.38、7 421.82 mg·kg-1，是其主要污染元素；水田土壤主要存在Cu的轻度污染及Cd、Pb的轻微污染；旱地土壤仅存在Cd、Cu的轻微污染。荒地、旱地、水田的重金属综合潜在生态危害指数分别为22 527.03、415.00、499.36；荒地土壤处于极高等潜在生态风险水平，Cd是最重要的生态危害元素；旱地和水田土壤为高等潜在生态风险水平，主要生态危害元素为Cd和Hg。除Hg之外，土壤重金属均呈现出由污染源中心向周边不同程度扩散的趋势；随着与污染源距离的增加，土壤重金属污染程度逐渐降低；形成了西南-东北对角线方向上的白鹤塘及大坑寮污染严重、东南角和西北部的对面岗及松源塘污染较轻的空间分布格局。土壤重金属含量之间的相关性及其空间扩散分布特征反映了其污染来源及扩散时间的不同。土壤中Cd、Cu、Pb、Zn污染面积大及污染程度高，可能与电子垃圾拆解活动造成的污染随大气、水流等扩散直接相关； Ni、Cr污染面积较小且程度低，可能以自然成土来源为主； As和Hg污染程度低但扩散面积大，其来源可能包括电子垃圾焚烧产生的烟尘沉降、灌溉水和自然成土来源。因此，要加强防控研究区域内的污染源及荒地土壤中重金属的迁移扩散，并提防由于当地土壤重金属污染带来的农产品安全问题。 |
| 英文摘要: |
| To investigate the diffusion level and potential ecological risk of soil heavy metal pollution in the electronic waste dismantling area of Longtang Town, Qingyuan City, 44 soil samples were collected from wastelands, drylands, and paddy fields in four villages, such as Baihetang, Dakengliao, Songyuantang, and Duimiangang. The As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg contents in the soil samples were analyzed. Single pollution index, comprehensive pollution index, and potential ecological hazard index methods were used to assess the risk of soil heavy metal pollution. Inverse distance weight method was used to determine the spatial dispersion characteristics and possible sources of soil heavy metal pollution by interpolating the geo-accumulation index of the soil heavy metals. The results showed that the degree of soil heavy metal pollution in the study area was in the order as follows： wasteland>paddy field>dryland. Cd, Cu, Pb, and Zn were the major pollutants in the wasteland soils, with average contents of 34.63, 5 536.27, 10 602.38 mg · kg-1, and 7 421.82 mg · kg-1, respectively. The paddy soils were mainly slightly contaminated by Cu, Cd, and Pb, whereas the dryland soils were only slightly contaminated by Cd and Cu. Potential ecological hazard index showed that the risk index（RI）values of wasteland, dryland, and paddy soils were 22 527.03, 415.00, and 499.36, respectively. The wasteland soils reached an extremely high potential ecological risk level, and Cd was identified as the most important risk factor. For dryland and paddy soils, a high potential ecological risk level was reached, and Cd and Hg were the main ecological risk factors. Except for Hg, the spatial distribution of the other soil heavy metals showed the same pattern of diffusion from the center of the pollution source to the surrounding areas, that is, the degree of soil heavy metal pollution decreased with increasing distance from the pollution source. Soil contamination was severe in the southwest and northeast areas（Baihetang and Dakengliao） , whereas contamination in the southeast and northwest areas（Duimiangang and Songyuantang）was mild. The correlation between soil heavy metal contents and their spatial distribution reflected the different pollution sources and diffusion durations. The large pollution area and high pollution degree of Cd, Cu, Pb, and Zn in the soil might be directly related to the dispersion of pollutants caused by ewaste dismantling activities via air and water. In contrast, smaller areas were contaminated with much lower concentrations of Ni and Cr, indicating that they might mainly come from natural sources. The contents of As and Hg in the soil were not high, but they were widespread. Therefore, they might originate from atmospheric deposition from e-waste incineration, sewage irrigation, and natural sources. The results highlight the significance of controlling pollution sources in the study area and migration of heavy metals in wasteland soils. Moreover, it is necessary to take precautions against the contamination of agricultural products due to serious contamination of local soils with heavy metals. |
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