电子垃圾拆解区不同用地类型土壤重金属空间分布特征与风险评价

Spatial distribution characteristics and risk assessment of heavy metals for different land-use types in electronic waste disposal area

为了探究电子垃圾拆解区不同用地类型土壤重金属的空间分布特征及潜在生态风险,对广东某电子垃圾拆解区稻田、菜地、荒地和拆解地土壤重金属Cu、Zn、Cd和Pb的质量分数及形态空间分布特征进行了研究,并采用地累积指数法和潜在生态风险指数法分别评价重金属潜在的生态风险。结果表明,4种用地类型土壤的Cd质量分数全部超标,超标倍数为1.42~94.2倍,Cd是4种用地类型土壤潜在危害最大的重金属。拆解地土壤的4种重金属质量分数远远超过土壤环境质量标准限值,Cu、Zn、Cd和Pb质量分数分别为标准限值的8.79、1.38、27.6和6.20倍。各用地类型土壤的潜在生态风险指数介于165(荒地)~2 587(拆解地),拆解地土壤达到极强风险水平,其它用地类型土壤为中等风险水平。本研究结果可为电子垃圾拆解区土壤重金属污染防治与修复实践提供理论参考。

In order to investigate the spatial distribution characteristics and potential ecological risks of soil heavy metals for different land-use types in the e-waste dismantling area, the spatial distribution characteristics of heavy metals, including Cu, Zn, Cd, and Pb, were studied for different land-use types in the e-waste disposal area located Guangdong province, such as paddy field, vegetable plot, barren land, and disposal site. The mass fraction and speciation of these heavy metals had been also examined for the four different land-use types,whose potential environmental risks were further assessed by geo-accumulation index(Igeo) and Hankanson potential ecological risk index(RI), respectively. The results showed that mass fraction of Cd in four land-use types have exceeded Soil Environmental Quality Standard, in which the exceed multiple ranged from 1.42 to94.2, highlighting the Cd pollution was the most significant among these heavy metals. For disposal site, the content of four heavy metals far exceeded the standards, increasing about 8.79, 1.38, 27.6 and 6.20-fold of the standard values for Cu, Zn, Cd, and Pb, respectively. Furthermore, the ecological risk of different land-use types ranged from 165(barren land) to 2 587(disposal site), with the disposal site reaching a very strong risk and the others reaching at a medium risk, respectively. These results could provide scientific basis and theoretical reference for the prevention and remediation of heavy metal pollution in the soil, especially for the electronic waste disposal area.