Chai Bing-Wen, Yin Hua, Wei Qiang, Lu Gui-Ning, Dang Zhi
School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
Medical Devices Research and Testing Center, South China University of Technology, Guangzhou 510006, China.
Huan Jing Ke Xue. 2021 Mar 8;42(3):1073-1080. doi: 10.13227/j.hjkx.202007245.
Microplastic pollution is ubiquitous and has attracted significant public attention. Recent research on microplastic has focused on aquatic environments, but its impacts on soil ecosystems remain poorly understood, especially in e-waste dismantling zones. The objective of this study was to investigate the relationships between microplastic and surrounding soil in abandoned e-waste disassembling plots with different dismantling methods focusing on ecotoxicology and microbiology in Guiyu, Shantou District, Guangdong Province. The surface morphology of collected microplastics showed signs of aging and degradation, possibly due to their long-term exposure in the soil and the original disassembling methods. In addition, there were diverse metal elements at different surface positions of the same microplastic sample based on SEM-EDS analyses, indicating that some metal elements carried by microplastics are derived from the surrounding soil rather than being inherent to the microplastic. Moreover, seven heavy metals (Pb, Cd, Cr, As, Ba, Co, and Ni) inherent in microplastic were identified using ICP-OES, revealing that the concentrations varied in different sampling plots were typically higher than in the surrounding soil. In particular, the concentration of Ba in microplastic was 10 orders of magnitude higher than in soil. Indeed, Ba in the form of BaSO is widely used as a filler in numerous plastics. Furthermore, microplastic-associated microorganisms were examined using 16S rRNA sequencing, and the relationships between the top 50 genera of microplastic-bound bacteria and soil environmental factors were analyzed using the Spearman's rank correlation coefficient. Microorganisms primarily originated from the surroundings of microplastics; therefore, environmental factors could directly affect the microbial communities associated with this type of pollutant. Importantly, different dismantling methods were associated with distinct soil environmental factors, and their correlations with microplastic-associated microorganisms also varied.
微塑料污染无处不在，已引起公众广泛关注。近期关于微塑料的研究主要集中在水生环境，但人们对其对土壤生态系统的影响仍知之甚少，尤其是在电子垃圾拆解区。本研究的目的是调查广东省汕头市贵屿区不同拆解方式的废弃电子垃圾拆解场地中微塑料与周边土壤之间的关系，重点关注生态毒理学和微生物学。收集的微塑料表面形态显示出老化和降解的迹象，这可能是由于它们长期暴露在土壤中以及原始的拆解方法所致。此外，基于扫描电子显微镜-能谱分析（SEM-EDS），同一微塑料样品不同表面位置存在多种金属元素，这表明微塑料携带的一些金属元素来自周边土壤，而非微塑料本身固有。此外，使用电感耦合等离子体发射光谱仪（ICP-OES）鉴定出微塑料中含有的七种重金属（铅、镉、铬、砷、钡、钴和镍），结果显示不同采样场地中这些重金属的浓度通常高于周边土壤。特别是，微塑料中钡的浓度比土壤中高10个数量级。实际上，硫酸钡形式的钡在众多塑料中被广泛用作填充剂。此外，利用16S rRNA测序检测了与微塑料相关的微生物，并使用斯皮尔曼等级相关系数分析了与微塑料结合的细菌中排名前50的属与土壤环境因素之间的关系。微生物主要源自微塑料周边环境；因此，环境因素可直接影响与这类污染物相关的微生物群落。重要的是，不同的拆解方法与不同的土壤环境因素相关，它们与微塑料相关微生物的相关性也各不相同。
