A study published in Frontiers of Environmental Science & Engineering has uncovered a novel pathway through which nanoplastic pollution could accelerate climate change. Researchers from Tsinghua University and collaborating institutions found that polystyrene nanoplastics—particles smaller than 100 nanometers—can substantially increase emissions of methane and nitrous oxide in wetland plant-soil systems. The findings, published online on August 10, 2025 (DOI: 10.1007/s11783-025-2066-8), suggest that plastic pollution may undermine the climate-mitigation potential of wetlands, which are typically recognized as natural carbon sinks.
In controlled experiments simulating wetland conditions with reeds, the team introduced increasing concentrations of polystyrene nanoplastics and monitored greenhouse gas fluxes. They observed that methane emissions rose by 20% to nearly 100%, while nitrous oxide emissions approximately doubled at higher concentrations. These effects became more pronounced as plants matured and temperatures increased, indicating that seasonal and growth factors may exacerbate the impact.
Mechanistic analyses revealed that nanoplastics inhibited plant growth, reduced chlorophyll content, and weakened antioxidant defenses, impairing photosynthesis and stress resistance. Crucially, the particles reduced oxygen release from plant roots, creating more anaerobic conditions in the rhizosphere. This shift 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. Additionally, nanoplastics altered root exudate composition, sharply increasing the release of L-phenylalanine—a compound that can be converted into substrates fueling methane production.
"This work demonstrates that nanoplastics are not just passive contaminants but active regulators of ecosystem processes," said the corresponding author. "By simultaneously impairing plant physiological functions and reshaping microbial communities in the rhizosphere, nanoplastics create conditions that strongly favor greenhouse gas production."
The findings suggest that current greenhouse gas models may overlook the contribution of plastic pollution to climate change. As nanoplastics continue to accumulate in sensitive ecosystems worldwide, their potential to amplify emissions from wetlands—which are major natural sources of methane and nitrous oxide—could have significant implications. The study underscores the urgency of controlling plastic pollution at its source and incorporating nanoplastics into environmental risk assessments and greenhouse gas inventories.
The research was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China. The full study is available at https://doi.org/10.1007/s11783-025-2066-8.
