摘要：Blue carbon ecosystems (BCEs; figure), comprising tidal marshes, mangrove forests, and seagrass meadows, contribute more than 50% of the total organic carbon buried in global marine sediments, despite occupying only 0·5% of the sea floor. 1 The ability of BCEs to sequester carbon dioxide into large amounts of stored sediment carbon 1 makes them important nature- based solutions for climate adaptation and mitigation. 2 The features that make BCEs important carbon sinks (ie, their global distribution and capacity to trap and preserve a large amount of carbon dioxide at the land and ocean interface) also make them an important sink of plastic-carbon. As of 2015, about 8300 million metric tonnes of virgin plastics were produced globally, 3 which is equivalent to 6900 million metric tonnes of plastic-carbon. Approximately 50–80 million metric tonnes of plastic-carbon accumulate within natural systems each year due to plastic mismanagement. 4 By comparison, BCEs accumulate about 100 million metric tonnes of blue carbon each year. 5 The current stocks of plastic-carbon in the global coastal systems are about 3–10 million metric tonnes, 5 with growing reports of plastic-carbon within BCEs. 6–8 If the present cubic growth trend for plastic accumulation and uncertain socioeconomic factors continue, amounts of plastic- carbon stock within the Earth system are projected to rise to 14 000 million metric tonnes by 2035, meaning that the amount of plastic-carbon will be equivalent to global blue carbon stock.
