Article Dans Une Revue Science of the Total Environment Année : 2025

The impact of polyvinyl chloride microplastics on carbon and nitrogen cycling in peatforming environments: relevance of the filler additive calcium carbonate (CaCO3 )

Résumé

Peat-forming wetlands (PFW) are crucial in the global C-cycle, yet they are increasingly threatened by various anthropogenic pressures, including microplastic (MP) pollution. We investigate the impacts of polyvinyl chloride (PVC) and its additive, calcium carbonate (CaCO3) on organic matter (OM) degradation in PFW. We conducted two experiments: first, by mixing peat soil with increasing concentrations of crushed sanitary PVC-MP (0.3%, 3%, and 30%) and second, by assessing the role of CaCO₃ in modulating these impacts. Our findings revealed significant alterations in peat chemical properties largely mediated by CaCO3 (i.e. increased pH, and Ca2+, Mg2+, K+ concentrations). PVC-MP increased carbon dioxide (CO2) and methane (CH4) production, as well as dissolved organic carbon release. CaCO3 may have enhanced CO2 release through its dissolution and contributed to CH4 production as a C source for a more diverse and active metagenomic community (higher mcrA gene abundance). Shifts in microbial community composition (e.g. reduction of Acidobacteriae and increase in active fermenters, such as Clostridia) and metabolism (higher lignin-like compounds degradation and P-uptake activity but lower C-degrading enzyme activity) also contributed in the C-cyle alterations. PVC-MP enhanced denitrification (narG gene abundance) but reduced relative proportion of the ammonia-oxidizing archaea Nitrososphaeria, leading to inhibition of nitrification. The effects of PVC-MP were concentration-dependent, with CaCO₃ strongly influencing the C cycle but only partially affecting the N cycle, suggesting potential effect of other additives, such as plasticisers. Overall, our results highlight a significant disruption of microbial processes due to MP pollution, leading to increased greenhouse gas emissions and significant implications on the role of PFW as global C-sinks.

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insu-05033070 , version 1 (14-04-2025)

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Juanita Mora Gomez, Adrien Jacotot, Nicolas Freslon, Hela Ben Zeineb, Michael Charron, et al.. The impact of polyvinyl chloride microplastics on carbon and nitrogen cycling in peatforming environments: relevance of the filler additive calcium carbonate (CaCO3 ). Science of the Total Environment, 2025, 977, pp.179341. ⟨10.1016/j.scitotenv.2025.179341⟩. ⟨insu-05033070⟩
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