The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal ecosystems such as salt marsh, mangrove, seagrass, and kelp forests. The link between terrestrial and marine carbon cycles is an important yet poorly constrained component of the global carbon cycle. In general, the flow of terrestrial-derived carbon via surface waters (i.e., rivers) to the ocean is well quantified. However, increasing evidence suggest that significant dissolved carbon is transported to the coastal ocean through tidal water exchange and concealed subsurface pathways (i.e., submarine groundwater discharge (SGD), or porewater exchange (PEX)). This mechanism is commonly referred to as lateral carbon export or carbon ‘outwelling’, where dissolved carbon is laterally transferred from coastal ecosystems to adjacent estuarine and shelf waters. Outwelling represents an overlooked source of ‘blue carbon’, as the residence time of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) is sufficiently long within the ocean on time-scales of thousands of years. Carbon outwelling may rival or exceed rates of blue carbon burial, and yet, this pathway remains understudied to date.
Outwelling studies commonly focus on characterizing estuarine carbon tidal dynamics and flux, or focus on subsurface carbon cycling and flux. Groundwater flowing into coastal ecosystems can also play an important role in the productivity of blue carbon habitats by modulating salinity, increasing nutrient availability, and stimulating organic matter accumulation in above‐ground biomass. However, direct measurements quantifying lateral blue carbon exports from coastal ecosystems to the oceans are still limited due to a lack of robust, coherent sampling method and technology in highly dynamic coastal ecosystems. Measurements in these systems have been further hampered by the spatiotemporal scales of investigation (e.g., tidal vs. annual; in water vs. sediment). This limitation may underestimate the perceived sequestration capacity of blue carbon ecosystems, but pave the way for future work integrating mobile, dissolved carbon within the blue carbon framework.
This Research Topic welcomes original research work or comprehensive review related to the advances in understanding lateral blue carbon export carbon from coastal habitats (salt marsh, mangrove, seagrass) to adjacent estuarine and shelf waters.
The transport and transformation of blue carbon as it transits from terrestrial to oceanic biomes suffers from a lack of data from a variety of coastal ecosystems. In order to develop a better understanding of lateral blue carbon export, this collection invites contributions that:
1) Present and discuss innovative approaches related to the monitoring, sampling, and/or modeling of surface water-groundwater interactions in typical coastal ecosystems;
2) Investigate lateral blue carbon export forms, dynamics (i.e., reactivity and transformations) and export to the oceans over a variety of time scales;
3) Incorporate lateral blue carbon export within regional or global carbon budgets.
Potential topics include but are not limited to the following:
• Review and synthesis of lateral blue carbon export from coastal ecosystems
• New methods and technologies in assessing lateral blue carbon fluxes
• Distinguishing porewater exchange or bio-irrigation from groundwater discharge
• Exploring the impacts of stratigraphic heterogeneity and plant species on groundwater-derived blue carbon dynamics
• Uncertainties in the study of lateral blue carbon export
• Porewater and groundwater DOC, DIC and alkalinity cycling, reactivity and transformations
• Tracing and understanding the net fate of dissolved carbon exports
• Human or climatic influences on lateral blue carbon export and carbon conversion
The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal ecosystems such as salt marsh, mangrove, seagrass, and kelp forests. The link between terrestrial and marine carbon cycles is an important yet poorly constrained component of the global carbon cycle. In general, the flow of terrestrial-derived carbon via surface waters (i.e., rivers) to the ocean is well quantified. However, increasing evidence suggest that significant dissolved carbon is transported to the coastal ocean through tidal water exchange and concealed subsurface pathways (i.e., submarine groundwater discharge (SGD), or porewater exchange (PEX)). This mechanism is commonly referred to as lateral carbon export or carbon ‘outwelling’, where dissolved carbon is laterally transferred from coastal ecosystems to adjacent estuarine and shelf waters. Outwelling represents an overlooked source of ‘blue carbon’, as the residence time of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) is sufficiently long within the ocean on time-scales of thousands of years. Carbon outwelling may rival or exceed rates of blue carbon burial, and yet, this pathway remains understudied to date.
Outwelling studies commonly focus on characterizing estuarine carbon tidal dynamics and flux, or focus on subsurface carbon cycling and flux. Groundwater flowing into coastal ecosystems can also play an important role in the productivity of blue carbon habitats by modulating salinity, increasing nutrient availability, and stimulating organic matter accumulation in above‐ground biomass. However, direct measurements quantifying lateral blue carbon exports from coastal ecosystems to the oceans are still limited due to a lack of robust, coherent sampling method and technology in highly dynamic coastal ecosystems. Measurements in these systems have been further hampered by the spatiotemporal scales of investigation (e.g., tidal vs. annual; in water vs. sediment). This limitation may underestimate the perceived sequestration capacity of blue carbon ecosystems, but pave the way for future work integrating mobile, dissolved carbon within the blue carbon framework.
This Research Topic welcomes original research work or comprehensive review related to the advances in understanding lateral blue carbon export carbon from coastal habitats (salt marsh, mangrove, seagrass) to adjacent estuarine and shelf waters.
The transport and transformation of blue carbon as it transits from terrestrial to oceanic biomes suffers from a lack of data from a variety of coastal ecosystems. In order to develop a better understanding of lateral blue carbon export, this collection invites contributions that:
1) Present and discuss innovative approaches related to the monitoring, sampling, and/or modeling of surface water-groundwater interactions in typical coastal ecosystems;
2) Investigate lateral blue carbon export forms, dynamics (i.e., reactivity and transformations) and export to the oceans over a variety of time scales;
3) Incorporate lateral blue carbon export within regional or global carbon budgets.
Potential topics include but are not limited to the following:
• Review and synthesis of lateral blue carbon export from coastal ecosystems
• New methods and technologies in assessing lateral blue carbon fluxes
• Distinguishing porewater exchange or bio-irrigation from groundwater discharge
• Exploring the impacts of stratigraphic heterogeneity and plant species on groundwater-derived blue carbon dynamics
• Uncertainties in the study of lateral blue carbon export
• Porewater and groundwater DOC, DIC and alkalinity cycling, reactivity and transformations
• Tracing and understanding the net fate of dissolved carbon exports
• Human or climatic influences on lateral blue carbon export and carbon conversion