电子废物拆解区微塑料与周围土壤环境之间的关系

微塑料污染无处不在，并受到了社会各界的关注.近年来，关于微塑料在水生态系统中的报道越来越多，而关于陆地生态环境，尤其在电子废物拆解区土壤微塑料污染的研究还十分匮乏.以广东省汕头地区贵屿镇废弃的以不同拆解方式所造成的电子废物拆解样地为研究对象，从生态毒理学和微生物学角度探讨了微塑料与其周围土壤环境之间的关系.通过SEM-EDS对微塑料表面进行表征，发现其表面具有老化和降解的迹象；这可能是由于微塑料长期暴露在土壤中，以及原始的拆解方法造成其表面形态及性质发生了变化.另外，在同一微塑料样品的不同表面位置，金属元素类型存在较大差异；说明微塑料所携带的一些金属元素并非本身固有，而是从周围土壤环境中吸附的.利用ICP-OES对微塑料内载固有的7种重金属（Pb、Cd、Cr、As、Ba、Co和Ni）进行分析发现，由于微塑料主要来源于各类电子废物，其所含各重金属含量在不同样地中有所不同，且几乎均高于周围土壤，尤其Ba在微塑料中的含量比在土壤中高出10³数量级.Ba在塑料中主要以BaSO₄的形式存在，常作为填料广泛添加于各种塑料中.此外，对微塑料表面微生物进行16S rRNA测序，并采用Spearman等级相关系数分析了微塑料表面细菌群落平均丰度前50的属与土壤环境因子之间的关系.这些微生物主要来源于微塑料所处的周围环境，因此环境因子的差异会直接影响微塑料表面微生物群落.由不同拆解方式所导致的电子废物污染场地具有不同的土壤环境因素，这些因素与微塑料表面微生物的相关性也存在差异.

Relationships Between Microplastic and Surrounding Soil in an E-Waste Zone of China

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 10³ orders of magnitude higher than in soil. Indeed, Ba in the form of BaSO₄ 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.