Carbon budget of tidal wetlands, estuaries, and shelf waters of eastern north America




Najjar, Raymond
Herrmann, Maria
Alexander, Richard
Boyer, Elizabeth
Burdige, David
Butman, David
Cai, Wei-Jun
Canuel, E. A.
Chen, Robert
Friedrichs, Marjorie


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Carbon cycling in the coastal zone affects global carbon budgets and is critical for understanding the urgent issues of hypoxia, acidification, and tidal wetland loss. However, there are no regional carbon budgets spanning the three main ecosystems in coastal waters: tidal wetlands, estuaries, and shelf waters. Here we construct such a budget for eastern North America using historical data, empirical models, remote sensing algorithms, and process-based models. Considering the net fluxes of total carbon at the domain boundaries, 59 ± 12% (± 2 standard errors) of the carbon entering is from rivers and 41 ± 12% is from the atmosphere, while 80 ± 9% of the carbon leaving is exported to the open ocean and 20 ± 9% is buried. Net lateral carbon transfers between the three main ecosystem types are comparable to fluxes at the domain boundaries. Each ecosystem type contributes substantially to exchange with the atmosphere, with CO2 uptake split evenly between tidal wetlands and shelf waters, and estuarine CO2 outgassing offsetting half of the uptake. Similarly, burial is about equal in tidal wetlands and shelf waters, while estuaries play a smaller but still substantial role. The importance of tidal wetlands and estuaries in the overall budget is remarkable given that they, respectively, make up only 2.4 and 8.9% of the study domain area. This study shows that coastal carbon budgets should explicitly include tidal wetlands, estuaries, shelf waters, and the linkages between them; ignoring any of them may produce a biased picture of coastal carbon cycling.



eastern north america, shelf waters


This research was supported by theNASA Interdisciplinary Science program(grant NNX14AF93G), the NASA CarbonCycle Science Program (grantNNX14AM37G), the NASA OceanBiology and Biogeochemistry Program(grant NNX11AD47G), and the NationalScience Foundation’s ChemicalOceanography Program (grantOCE-1260574). Comments from ananonymous reviewer helped to improvethis paper. This study was part of theNorth American Carbon Program. Thedata supporting the analysis andconclusions in this paper can be foundin the supporting information. Any useof trade,firm, or product names is fordescriptive purposes only and does notimply endorsement by the U.S.Government.



Najjar, R.G., Herrmann, M., Alexander, R., Boyer, E.W., Burdige, D.J., Butman, D., Cai, W.J., Canuel, E.A., Chen, R.F., Friedrichs, M.A. and Feagin, R.A., 2018. Carbon budget of tidal wetlands, estuaries, and shelf waters of Eastern North America. Global Biogeochemical Cycles, 32(3), pp.389-416.