Soil, the earth's largest pool of active carbon, is critical for carbon neutrality efforts. However, against the backdrop of intensifying plastic pollution, microplastics have become integrated into the soil carbon cycle. To accurately evaluate the impact of microplastics on the global terrestrial soil organic carbon (SOC) pool and carbon emissions, a comprehensive understanding of the transformation, fate, and influence of microplastic-derived carbon on soil carbon dynamics is indispensable.

Researchers from the Wuhan Botanical Garden of the Chinese Academy of Sciences and Freie Universität Berlin delve into the potential pathways through which microplastics affect SOC dynamics from biological, geochemical, and physical perspectives. They also identify the key priorities for future research.

The authors assert that microplastics, often accompanied by other pollutants, can modify the content and quality of SOC. This occurs by leaching dissolved organic matter (DOM) into soil and affecting the natural mineralization process of existing SOC. These changes may influence the 'microbial carbon pump' - a mechanism critical for converting organic matter into stable forms, and the formation of mineral - associated organic carbon, which offers long-term carbon storage.

Moreover, microplastic surfaces act as critical interfaces. They can adsorb DOM for long - term preservation and transport, and serve as 'hotspots' for interactions between minerals and organic matter. Additionally, microplastics alter the physical storage of SOC by disrupting soil aggregate structure and carrying carbon sources.

Finally, researchers anticipate that future studies should strive to comprehensively understand the role of microplastics in the dynamics of SOC pools across scales ranging from local to global, particularly against the backdrop of escalating plastic pollution. This is crucial for both addressing microplastic pollution and achieving carbon neutrality.

Results entitled "Impacts of microplastics on terrestrial soil carbon dynamics", are published in Nature Geoscience. HE Gang is the first author, while Prof. LIU Wenzhi and YANG Yuyi serve as the corresponding authors. This work was funded by the National Natural Science Foundation of China, the Joint Fund of the National Natural Science Foundation of China and the China Postdoctoral Science Foundation.

Fate of microplastic-derived carbon and its influence on SOC storage (Black lines represent carbon flow, with dashed lines highlighting underexplored pathways through which microplastics may affect microbial carbon transformations and SOC fractions. Red lines indicate the toxic effects of microplastics and co-occurring contaminants)(Image by HE Gang)