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| Spatial distribution and risk assessment of heavy metals in the soils of Qingyuan e-waste dismantling area， China |
| Received:June 23, 2022 Revised:August 29, 2022 |
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| KeyWord:e-waste dismantling area;heavy metal;risk assessment;spatial distribution |
| Author Name | Affiliation | E-mail | | CUI Luoxiao | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | 1493984626@qq.com | | HU Qizhi | Guangdong Geological Bureau, Guangdong Hydrogeology Battalion, Guangzhou 510510, China | | | LI Meng | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | WU Jialong | Land Development and Reclamation Center of Guangdong Province, Guangzhou 510635, China | | | FAN Huizhong | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | CHEN Sisi | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | REN Zongling | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | |
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| Abstract: |
| 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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