Wetlands, crucial ecosystems for carbon storage and climate regulation, face a hidden threat from plastic pollution that could transform their role in the global climate system. A study published in Frontiers of Environmental Science & Engineering reveals that nanoplastics—plastic particles smaller than 100 nanometers—substantially intensify emissions of two powerful greenhouse gases, methane and nitrous oxide, in plant-soil systems. These findings highlight an overlooked pathway through which plastic pollution may accelerate climate change, with implications for environmental policy and climate modeling.
Researchers from Tsinghua University and collaborating institutions conducted controlled wetland simulations to examine how polystyrene nanoplastics affect greenhouse gas production. The study, published online on August 10, 2025, 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, suggesting climate change could exacerbate the impact.
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.
"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. These effects operate through multiple interconnected pathways, which helps explain why even small particles can have outsized impacts on climate-relevant processes in wetlands."
The implications are significant for climate policy and environmental management. Methane and nitrous oxide are among the most potent greenhouse gases, with warming potentials far exceeding that of carbon dioxide. Wetlands are widely recognized as nature-based solutions for carbon sequestration, yet nanoplastic contamination could undermine their climate-mitigation potential. The findings suggest that plastic pollution may contribute to climate change in ways not currently accounted for in greenhouse gas models, necessitating incorporation of nanoplastics into environmental risk assessments and greenhouse gas inventories.
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. With nanoplastics rapidly accumulating in aquatic and terrestrial environments as larger plastics degrade, their ecological consequences—particularly their role in climate feedback loops—require greater attention from researchers and policymakers alike.
