State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China; School of the Environment, Nanjing University, Nanjing 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China; School of the Environment, Nanjing University, Nanjing 210023, China.
J Hazard Mater. 2024 Oct 5;478:135443. doi: 10.1016/j.jhazmat.2024.135443. Epub 2024 Aug 6.
Microplastics (MPs) are widespread in agroecosystems and profoundly impact soil microbiome and nutrient cycling. However, the effects of MPs on soil autotrophic ammonium oxidization processes, including nitrification, complete ammonium oxidation (comammox), anaerobic ammonium oxidation (anammox), and anaerobic ammonium oxidation coupled to iron reduction (Feammox), remain unclear. These processes are the rate-limiting steps of nitrogen cycling in agroecosystems. Here, our work unveiled that exposures of polyethylene (PE), polypropylene (PP), polylactic acid (PLA), and polybutylene adipate terephthalate (PBAT) MPs significantly modulated ammonium oxidization pathways with distinct type- and dose-dependent effects. Nitrification remained the main contributor (56.4-70.7 %) to soil ammonium removal, followed by comammox (11.7-25.6 %), anammox (5.0-20.2 %) and Feammox (3.3-11.6 %). Compared with conventional nonbiodegradable MPs (i.e., PE and PP), biodegradable MPs (i.e., PLA and PBAT) exhibited more pronounced impacts on soil nutrient conditions and functional microbes, which collectively induced alterations in soil ammonium oxidation. Interestingly, low-dose PLA and PBAT remarkably enhanced the roles of anammox and Feammox in soil ammonium removal, contributing to the mitigation of soil acidification in agroecosystems. This study highlights the diverse responses of ammonium oxidization pathways to MPs, further deepening our understanding of how MPs affect biogeochemical cycling and enriching strategies for agricultural managements amid increasing MPs pollution.
微塑料（MPs）广泛存在于农业生态系统中，对土壤微生物组和养分循环有深远影响。然而，MPs 对土壤自养氨氧化过程的影响，包括硝化、完全氨氧化（comammox）、厌氧氨氧化（anammox）和厌氧氨氧化耦合铁还原（Feammox），仍不清楚。这些过程是农业生态系统氮循环的限速步骤。在这里，我们的工作揭示了聚乙烯（PE）、聚丙烯（PP）、聚乳酸（PLA）和聚丁二酸丁二醇酯对（PBAT） MPs 的暴露显著调节了氨氧化途径，具有不同的类型和剂量依赖性效应。硝化仍然是土壤铵去除的主要贡献者（56.4-70.7%），其次是 comammox（11.7-25.6%）、anammox（5.0-20.2%）和 Feammox（3.3-11.6%）。与传统的不可生物降解 MPs（即 PE 和 PP）相比，可生物降解 MPs（即 PLA 和 PBAT）对土壤养分条件和功能微生物表现出更显著的影响，这些因素共同导致了土壤氨氧化的变化。有趣的是，低剂量的 PLA 和 PBAT 显著增强了 anammox 和 Feammox 在土壤铵去除中的作用，有助于减轻农业生态系统中的土壤酸化。本研究强调了氨氧化途径对 MPs 的不同反应，进一步加深了我们对 MPs 如何影响生物地球化学循环的理解，并为农业管理中日益增加的 MPs 污染提供了丰富的策略。
