微塑料参与下的土壤碳循环过程评述

Review of soil carbon cycling processes involving microplastics

  • 摘要: 土壤有机碳固定是驱动土壤肥力演变和陆地生态系统碳平衡的关键过程。鉴于微塑料在土壤生态系统中的持久性和生态环境风险, 其对土壤性质和过程的影响日益受到关注, 但基于土壤碳循环视角关注微塑料介导作用的研究仍相对匮乏。赋存于土壤中的微塑料能够通过间接影响土壤理化性质和直接参与碳循环的方式影响土壤有机碳固存、矿化与消长, 这进一步加剧了土壤有机碳循环过程的不确定性, 也突出了相关研究的迫切性。以此为背景, 本文概述了土壤有机碳固定途径的理论发展, 总结了土壤中微塑料的来源特征, 阐述了微塑料对不同土壤碳库的影响, 并深入探讨了微塑料调控土壤碳循环的可能机制, 最后对微塑料参与下的土壤有机碳循环相关研究进行了展望。结果表明微塑料能够通过影响土壤物理结构、微生物群落结构多样性、酶活性与功能基因、生物膜的形成、动物的繁殖与生长、植物的生长和根系沉积等对土壤碳的平衡起到介导作用, 同时通过自身参与到土壤全链条生物地球化学循环中而直接影响土壤有机碳循环。但相关研究仍处于起步阶段, 如何选取科学方法将微塑料周转与有机碳循环过程进行区分与耦合是未来研究的难点。因此, 在现有研究基础上, 通过先进土壤学研究手段的嵌套与改良, 以及研究思路的革新与交叉, 可进一步精准区分微塑料源碳在不同有机碳库中的贡献潜力, 探明微塑料直接和间接影响土壤有机碳循环的耦合作用机制, 并推进多因素影响下微塑料参与土壤碳循环过程的研究。

     

    Abstract: Soil organic carbon (SOC) sequestration is a pivotal process that drives soil fertility evolution and carbon (C) balance in terrestrial ecosystems. Microplastics, due to their persistence and ecological risks in soil ecosystems, are increasingly gaining attention for their impacts on soil properties and processes. However, the influence of microplastics on SOC cycling remains uncertain. Microplastics can indirectly affect SOC sequestration and mineralization by influencing soil physical and chemical properties. Moreover, they can directly participate in the soil C cycle, further complicating our understanding of the SOC cycle. In light of this context, this study outlines the development of SOC sequestration pathways, summarizes the sources of soil microplastics, explains how microplastics affect different soil C pools, and delves into the potential mechanisms through which microplastics regulate the soil C cycle. Finally, we provide an overview and prospects for research on the SOC cycle and microplastics. Our findings revealed that microplastics impact SOC balance by influencing the formation and degradation of soil physical structures, microbial community structure diversity, enzyme activity and functional genes, biofilm formation, animal reproduction and growth, plant growth, and root deposition. Additionally, microplastics directly participate in the SOC cycle as part of the broader soil biogeochemical cycle. However, it is important to note that research in this area is still in its early stages, and differentiating and linking microplastic turnover with the SOC cycle using scientific methods presents challenges. Future research should aim to distinguish the potential contribution of microplastic-derived C in various SOC pools, explore the mechanisms through which microplastics directly and indirectly affect the SOC cycle, and examine the role of microplastics in the SOC cycle under the influence of multiple factors. This will require the integration of advanced soil study methods as well as innovative interdisciplinary approaches.

     

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