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Purpose <p>Microplastics (MPs), as emerging agricultural soil contaminants, exert distinct impacts on soil organic carbon (SOC) sequestration. However, the specific regulatory mechanisms of non-biodegradable MPs (NBMPs) versus biodegradable MPs (BMPs) remain poorly understood.</p> Methods <p>The impacts of a typical NBMP (polyethylene, PE) and a typical BMP (polylactic acid, PLA) at different levels (0, 0.1%, and 0.5% w/w) on SOC distribution at the aggregate level were investigated.</p> Results <p>The results showed that PLA significantly reduced the content of easily oxidizable organic carbon (EOC) compared to the control (CK), whereas PE exhibited a weaker effect. Specifically, under the 0.5% PLA treatment, EOC decreased by up to 39.68%, with consistent reductions observed across all aggregate sizes (ranging from 32.07% to 35.05%). In contrast, PE promoted a sustained, concentration-dependent accumulation of SOC, and this promoting effect was most prominent in the 0.25–0.5&#xa0;mm aggregates, which rose by 13.50%–29.55% under 0.1% and 0.5% PE, respectively. Conversely, 0.5% PLA caused a significant reduction in SOC by 6.79% in bulk soil. Both MPs significantly enhanced urease and β-glucosidase activities in bulk soil relative to the CK, with 0.5% PLA showing the greatest increases of 25.21% and 47.46%, respectively. Partial least squares path modeling and correlation analyses confirmed that PE enhances aggregate stability to provide physical protection and directly contributes its own carbon as an exogenous source to the soil carbon pool, whereas PLA accelerates carbon transformation by stimulating microbial enzyme activity and supplies its degradation products as a new labile carbon source that promotes labile carbon turnover.</p> Conclusion <p>This study reveals distinct pathways through which NBMPs and BMPs regulate soil carbon stability, informing agricultural risk assessment and carbon management strategies.</p> Graphical Abstract <p></p>

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Differential regulation of organic carbon distribution in soil aggregates by non-biodegradable and biodegradable microplastics

  • 期刊论文

  • 发表日期：

    2026年6月20日

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  • Yue Li,
  • Hongwen Yu,
  • Quanying Wang,
  • Yunjiang Liang

摘要

Purpose

Microplastics (MPs), as emerging agricultural soil contaminants, exert distinct impacts on soil organic carbon (SOC) sequestration. However, the specific regulatory mechanisms of non-biodegradable MPs (NBMPs) versus biodegradable MPs (BMPs) remain poorly understood.

Methods

The impacts of a typical NBMP (polyethylene, PE) and a typical BMP (polylactic acid, PLA) at different levels (0, 0.1%, and 0.5% w/w) on SOC distribution at the aggregate level were investigated.

Results

The results showed that PLA significantly reduced the content of easily oxidizable organic carbon (EOC) compared to the control (CK), whereas PE exhibited a weaker effect. Specifically, under the 0.5% PLA treatment, EOC decreased by up to 39.68%, with consistent reductions observed across all aggregate sizes (ranging from 32.07% to 35.05%). In contrast, PE promoted a sustained, concentration-dependent accumulation of SOC, and this promoting effect was most prominent in the 0.25–0.5 mm aggregates, which rose by 13.50%–29.55% under 0.1% and 0.5% PE, respectively. Conversely, 0.5% PLA caused a significant reduction in SOC by 6.79% in bulk soil. Both MPs significantly enhanced urease and β-glucosidase activities in bulk soil relative to the CK, with 0.5% PLA showing the greatest increases of 25.21% and 47.46%, respectively. Partial least squares path modeling and correlation analyses confirmed that PE enhances aggregate stability to provide physical protection and directly contributes its own carbon as an exogenous source to the soil carbon pool, whereas PLA accelerates carbon transformation by stimulating microbial enzyme activity and supplies its degradation products as a new labile carbon source that promotes labile carbon turnover.

Conclusion

This study reveals distinct pathways through which NBMPs and BMPs regulate soil carbon stability, informing agricultural risk assessment and carbon management strategies.

Graphical Abstract