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. Research published in Frontiers of Environmental Science & Engineering demonstrates that nanoplastics—plastic particles smaller than 100 nanometers—substantially intensify emissions of methane and nitrous oxide, two powerful greenhouse gases with warming potentials far exceeding carbon dioxide.
The study, available at https://doi.org/10.1007/s11783-025-2066-8, reveals that nanoplastics increase methane emissions by 20% to nearly 100% and approximately double nitrous oxide emissions in wetland-like plant-soil systems. These effects become more pronounced as plants mature and environmental temperatures rise, suggesting climate change could amplify the impacts of nanoplastic contamination.
Researchers from Tsinghua University and collaborating institutions used controlled wetland simulations planted with reeds to examine how polystyrene nanoplastics affect greenhouse gas production. By combining gas flux measurements with microbial and plant analyses, the study provides mechanistic insight into how nanoplastics disrupt plant-soil interactions and alter carbon and nitrogen cycling.
Nanoplastics inhibit plant growth, reduce chlorophyll content, and weaken antioxidant defenses, impairing photosynthesis and stress resistance. Crucially, they reduce oxygen release from plant roots, creating more anaerobic conditions in the rhizosphere that favor methane-producing microorganisms and enhance 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 alter 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.
This research matters because it identifies an overlooked pathway through which plastic pollution may accelerate climate change. Wetlands are widely recognized as nature-based solutions for carbon sequestration, yet nanoplastic contamination could undermine their climate-mitigation potential. The findings suggest plastic pollution contributes to climate change in ways not currently accounted for in greenhouse gas models or environmental risk assessments.
As nanoplastics rapidly accumulate in aquatic and terrestrial environments from the degradation of larger plastics, their ecological consequences remain poorly understood. This study demonstrates they are not just passive contaminants but active regulators of ecosystem processes that create conditions strongly favoring greenhouse gas production through multiple interconnected pathways.
Incorporating nanoplastics into environmental risk assessments and greenhouse gas inventories may therefore be essential for accurate climate modeling. More broadly, the research underscores the urgency of controlling plastic pollution at its source, as continued accumulation of nanoplastics could amplify greenhouse gas emissions across sensitive ecosystems worldwide, potentially transforming wetlands from carbon sinks into significant emission sources.
