Nanoplastics Found to Increase Greenhouse Gas Emissions in Wetland Ecosystems

Wetlands serve as crucial regulators of the global climate through carbon storage, but emerging research indicates their function may be compromised by plastic pollution. A study published in Frontiers of Environmental Science & Engineering demonstrates that nanoplastics—plastic particles smaller than 100 nanometers—can substantially intensify emissions of methane and nitrous oxide in plant-soil systems. These findings reveal an overlooked pathway through which plastic pollution may accelerate climate change by interfering with wetland ecosystems.

Methane and nitrous oxide are among the most potent greenhouse gases, with warming potentials far exceeding carbon dioxide. While natural wetlands contribute significantly to global methane emissions, they also function as long-term carbon sinks. Nanoplastics accumulate rapidly in aquatic and terrestrial environments as larger plastics degrade, yet their ecological consequences remain poorly understood. Previous research has shown microplastics alter soil chemistry and microbial activity, but the effects of smaller nanoplastics on greenhouse gas emissions were largely unexplored until this investigation.

Researchers from Tsinghua University and collaborating institutions report that nanoplastics significantly enhance methane and nitrous oxide emissions in wetland-like plant-soil systems. The study, published online on August 10, 2025, in Frontiers of Environmental Science & Engineering (DOI: 10.1007/s11783-025-2066-8), used controlled wetland simulations to examine how polystyrene nanoplastics affect greenhouse gas production. By combining gas flux measurements with microbial and plant analyses, the research provides mechanistic insight into how nanoplastics disrupt plant-soil interactions and alter carbon and nitrogen cycling.

Using simulated wetlands planted with reeds, researchers introduced increasing concentrations of polystyrene nanoplastics to soil and monitored greenhouse gas emissions over time. They found 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 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. 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.

Simultaneously, nanoplastics altered root exudate composition, sharply increasing release of L-phenylalanine—a compound convertible into substrates fueling methane production. Although some methane-oxidizing and nitrous oxide-consuming microbes also increased, their activity proved insufficient to offset elevated greenhouse gas generation. The corresponding author noted that nanoplastics are not just passive contaminants but active regulators of ecosystem processes that create conditions strongly favoring greenhouse gas production through multiple interconnected pathways.

The findings suggest 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.