Groundwater Carbon Exports Exceed Sediment Carbon Burial in a Salt Marsh

Salt marshes can sequester large amounts of carbon in sediments, but the relation between carbon storage and exportation remains poorly understood. Groundwater exchange can flush sediment carbon to surface waters and potentially reduce storage. In this study, we estimated groundwater fluxes and associated carbon fluxes using a radon (Rn-222) mass balance and sediment carbon burial rates using lead (Pb-210) in a pristine salt marsh (North Inlet, SC, USA). We used delta C-13 to trace carbon origins. We found that groundwater releases large amounts of carbon to the open ocean. These groundwater fluxes have the potential to export 7.2 +/- 5.5 g m(-2) of dissolved inorganic carbon (DIC), 0.2 +/- 0.2 g m(-2) of dissolved organic carbon (DOC) and 0.7 +/- 0.5 g m(-2) of carbon dioxide (CO2) per day. The fluxes exceed the average surface water CO2 emissions (0.6 +/- 0.2 g m(-2) day(-1)) and the average sediment carbon burial rates (0.17 +/- 0.09 g m(-2) day(-1)). The delta C-13 results suggest that groundwater carbon originated from salt marsh soils, while the sediment carbon source is derived from salt marsh vegetation. We propose that the impact of salt marshes in carbon cycling depends not only on their capacity to bury carbon in sediments, but also on their high potential to export carbon to the ocean via groundwater pathways.

NATURVETENSKAP Geovetenskap och miljövetenskap Oceanografi, hydrologi och vattenresurser hsv//swe
NATURAL SCIENCES Earth and Related Environmental Sciences Oceanography, Hydrology and Water Resources hsv//eng
Submarine groundwater discharge
Blue carbon
Coastal carbon
Radioactive tracers
Coastal wetland
estuarine research reserve
north inlet estuary
south-carolina
inorganic carbon
nutrient inputs
organic-carbon
porewater exchange
discharge sgd
gas-exchange
time-series
Environmental Sciences & Ecology
Marine & Freshwater Biology

Xiao, K. (författare)
Conrad, S. R. (författare)
Wadnerkar, P. D. (författare)
Wilson, A. M. (författare)
Sanders, C. J. (författare)
Santos, Isaac R.Gothenburg University,Göteborgs universitet,Institutionen för marina vetenskaper,Department of marine sciences(Swepub:gu)xsanis (författare)
Göteborgs universitetInstitutionen för marina vetenskaper (creator_code:org_t)

Ingår i:Estuaries and Coasts: Springer Science and Business Media LLC45, s. 1545-611559-27231559-2731

Av författaren/redakt...: Correa, R. E.; Xiao, K.; Conrad, S. R.; Wadnerkar, P. D.; Wilson, A. M.; Sanders, C. J.; visa fler...; Santos, Isaac R.; visa färre...

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