Editorial: Advances in understanding lateral blue carbon export from coastal ecosystems

Abstract

‘Blue Carbon’ refers to the carbon captured by the coastal systems or ocean and was coined about a decade ago (Nellemann et al., 2009), emphasizing the carbon sequestration capacity of coastal vegetated ecosystems (e.g., macroalgae/kelp, seagrass beds, saltmarshes, and mangroves). These blue carbon systems only cover <0.1% of the ocean area, but may account for >50% of the carbon storage in marine environments, representing a large carbon sink comparable to the global river input (Alongi, 2014). The fluxes of terrestrial-derived carbon including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and particulate organic carbon (POC) transported through surface river runoff to the ocean were well known and quantified (Ludwig et al., 1996; Regnier et al., 2022). However, increasing evidence suggests that tidal exchange dominates the transport of significant dissolved carbon from coastal ecosystems to adjacent estuarine and shelf waters (e.g., Maher et al., 2013; Tait et al., 2016; Wang et al., 2016; Chen et al., 2021). This mechanism is commonly named as carbon ‘outwelling’ or lateral carbon export (e.g., Teal, 1962; Odum, 1968; Wang and Cai, 2004; Sippo et al., 2017; Cabral et al., 2021; Santos et al., 2021; Tamborski et al., 2021).