Coastal Habitats Trap Microplastics, Offering a Surprising Climate Co-benefit

China’s vital coastal habitats are acting as unexpected sinks for microplastic pollution, a new study reveals. These ‘blue carbon ecosystems’ (BCEs) – environments like mangrove forests and seagrass beds – are exceptionally effective at trapping tiny plastic particles in their sediment.

Researchers investigating the Chinese coastline discovered that these ecosystems store between 1.3 and 3.8 times more microplastics than adjacent bare mudflats. The density of these particles in the top 12 cm of sediment was found to range from 2,170 to a staggering 42,240 particles per square metre.

While the plastic’s contribution to the overall organic carbon stocks is negligible, its burial has a surprising co-benefit. By locking away microplastics that might otherwise decompose, these habitats help avoid greenhouse gas emissions, estimated at 0.3 to 45.3 Gg of CO₂ equivalent across the nation. The study also found that this plastic accumulation has accelerated in recent decades, especially in mangroves, and is strongly linked to factors like the size of nearby urban areas and distance from the shore.