Abstract：
The impact of microplastics and their additives on soil nutrient cycling, particularly through microbial mechanisms, remains underexplored. This study investigated the effects of polyethylene microplastics, polyethylene resin, and plastic additives on soil nitrogen content, physicochemical properties, nitrogen cycling functional genes, microbial composition, and nitrogen transformation rates. Results showed that all amendments increased total nitrogen but decreased dissolved total nitrogen. Polyethylene microplastics and additives increased dissolved organic nitrogen, while polyethylene resin reduced it and exhibited higher microbial biomass. Amendments reduced or did not change inorganic nitrogen levels, with additives showing the lowest values. Polyethylene resin favored microbial nitrogen immobilization, while additives were more inhibitory. Amendment type and content significantly interacted with nitrogen cycling genes and microbial composition. Distinct functional microbial biomarkers and network structures were identified for different amendments. Polyethylene microplastics had higher gross ammonification, nitrification, and immobilization rates, followed by polyethylene resin and additives. Nitrogen transformation was driven by multiple functional genes, with Proteobacteria playing a significant role. Soil physicochemical properties affected nitrogen content through transformation rates, with C/N ratio having an indirect effect and water holding capacity directly impacting it. In summary, plastic additives, compared to polyethylene microplastics and resin, are less conducive to nitrogen degradation and microbial immobilization, exert significant effects on microbial community structure, inhibit transformation rates, and ultimately impact nitrogen cycling.
摘要：
微塑料及其添加剂对土壤养分循环的影响，特别是通过微生物机制，仍未充分开发。这项研究调查了聚乙烯微塑料的影响，聚乙烯树脂,和塑料添加剂对土壤氮含量的影响，物理化学性质，氮循环功能基因，微生物组成，和氮转化率。结果表明，所有改良剂都增加了总氮，但降低了溶解的总氮。聚乙烯微塑料和添加剂增加了溶解的有机氮，而聚乙烯树脂降低了它，并表现出更高的微生物生物量。修正降低或不改变无机氮水平，添加剂显示最低值。聚乙烯树脂有利于微生物固氮，而添加剂的抑制性更强。修正类型和含量与氮循环基因和微生物组成显著相互作用。针对不同的修正,鉴定了不同的功能性微生物生物标志物和网络结构。聚乙烯微塑料具有较高的总氨化率，硝化，和固定率，其次是聚乙烯树脂和添加剂。氮转化是由多个功能基因驱动的，变形杆菌发挥了重要作用。土壤理化性质通过转化率影响氮含量，C/N比具有间接影响，持水能力直接影响它。总之,塑料添加剂,与聚乙烯微塑料和树脂相比，不利于氮降解和微生物固定化，对微生物群落结构产生显著影响，抑制转化率，并最终影响氮循环。
