Wetlands, which play a crucial role in climate regulation by storing carbon, may have their function compromised by nanoplastics, according to a new study. Research published in Frontiers of Environmental Science & Engineering demonstrates that plastic particles smaller than 100 nanometers can substantially increase emissions of methane and nitrous oxide, two potent greenhouse gases, in plant-soil systems. The findings, available at https://doi.org/10.1007/s11783-025-2066-8, suggest plastic pollution may accelerate climate change through previously overlooked pathways.
Researchers from Tsinghua University and collaborating institutions used controlled wetland simulations planted with reeds to examine how polystyrene nanoplastics affect greenhouse gas production. The study found that nanoplastics increased methane emissions by 20% to nearly 100%, while nitrous oxide emissions approximately doubled under higher concentrations. These effects became more pronounced as plants matured and environmental temperatures rose.
Mechanistic analyses revealed that nanoplastics inhibited plant growth, reduced chlorophyll content, and weakened antioxidant defenses, impairing photosynthesis and stress resistance. Crucially, nanoplastics reduced oxygen release from plant roots, creating more anaerobic conditions in the rhizosphere that favored methane-producing microorganisms and enhanced denitrification processes responsible for nitrous oxide formation.
Metagenomic analyses showed increased abundance of genes involved in acetoclastic methanogenesis and denitrification pathways, particularly in rhizosphere soils. Simultaneously, nanoplastics altered root exudate composition, sharply increasing the release of L-phenylalanine—a compound that can be converted into substrates fueling methane production. Although some methane-oxidizing and nitrous oxide–consuming microbes also increased, their activity was insufficient to offset the elevated greenhouse gas generation.
The corresponding author noted that nanoplastics are not just passive contaminants but active regulators of ecosystem processes. By simultaneously impairing plant physiological functions and reshaping microbial communities in the rhizosphere, nanoplastics create conditions that strongly favor greenhouse gas production through multiple interconnected pathways.
The findings suggest that plastic pollution may contribute to climate change in ways not currently accounted for in greenhouse gas models. Wetlands are widely recognized as nature-based solutions for carbon sequestration, yet nanoplastic contamination could undermine their climate-mitigation potential. Incorporating nanoplastics into environmental risk assessments and greenhouse gas inventories may therefore be essential. More broadly, the study underscores the urgency of controlling plastic pollution at its source, as continued accumulation of nanoplastics could amplify greenhouse gas emissions across sensitive ecosystems worldwide.
