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Funded Research

The Carbon Budget of Tidal Wetlands and Estuaries of the Contiguous United States: A Synthesis Approach (WETCARB = Wetland-Estuary Transports and CARbon Budgets)

Najjar, Raymond (Ray): Pennsylvania State University (Project Lead)
Bianchi, Thomas: University of Florida (Co-Investigator)
Cai, Wei-Jun: University of Delaware (Co-Investigator)
Feagin, Rusty: Texas A&M University (Co-Investigator)
Fuentes, Jose: Pennsylvania State University (Co-Investigator)
Herrmann, Maria: Penn State University (Co-Investigator)
Kroeger, Kevin: USGS (Co-Investigator)
Tzortziou, Maria: CCNY City University of New York/ Columbia University LDEO (Co-Investigator)
Alin, Simone: NOAA Pacific Marine Environmental Laboratory (Participant)
Evans, Wiley: Hakai Institute (Participant)
Hu, Chuanmin: University of South Florida (Participant)

Project Funding: 2014 - 2017

NRA: 2013 NASA: Carbon Cycle Science   

Funded by NASA, Other US Funding:

Tidal wetlands and estuaries play key roles in the global carbon cycle because of their high rates of carbon burial and processing of riverine carbon. A NASA-supported coastal carbon data synthesis activity, which led to the development of preliminary coastal carbon budgets for North America, identified carbon fluxes in tidal wetlands and estuaries as an area of particularly large uncertainty. The main objective of the proposed work is to develop a carbon budget for tidal wetlands and estuaries of the contiguous US using existing field observations, remote sensing products, and statistical models. The great spatial and temporal heterogeneity of tidal systems demands novel techniques for extrapolating limited in situ data to regional scales. We propose to use NASA remote sensing products as a key resource for spatially interpolating and scaling up in situ carbon data. We seek to determine the carbon fluxes across and between the head of tide and the seawater boundary for 139 of the estuarine-wetland systems delineated and catalogued by NOAA, which account for >90% of estuarine surface area within the contiguous US. Mass-balance equations describing the steady-state organic and inorganic carbon budgets applied to tidal wetlands and estuaries are the theoretical underpinning of the analysis. The relevant carbon fluxes are the net carbon dioxide uptake from the atmosphere by tidal wetlands; the net evasion of carbon dioxide from estuaries; input from land to tidal wetlands and estuaries; burial in tidal wetland soils and estuarine sediments; the net advective transport from tidal wetlands to estuaries, tidal wetlands to the ocean, and estuaries to the ocean; and net ecosystem production in tidal wetlands and estuaries. Specifically, we propose to develop estuarine and tidal wetland databases on carbon fluxes or measurements that allow the computation of carbon fluxes. Those fluxes will be modeled using NASA remote sensing products, data from the National Wetlands Inventory, and estuarine characteristics compiled by NOAA. These models, with well-determined error estimates, will be used to extend flux estimates to all 139 systems of interest, thereby enabling the development of regional and national coastal carbon budgets. Particular research questions we will answer with our synthesis are: Is the oxidation of organic carbon in estuaries largely supported by wetland production and export or by the respiration of riverine organic carbon? How do flux processes vary between climatic zones, and between passive margins (Atlantic, Gulf) and active margins (Pacific)? What estuaries have the highest potential for 'blue carbon' projects to conserve net CO2 uptake by tidal wetlands? Is the combined system (tidal wetlands and estuaries) a net source or sink of CO2 to the atmosphere? Our research team has extensive expertise in remote sensing, wetland biogeochemistry, and estuarine biogeochemistry. Multiple team members have a history of successful collaboration through the participation in a coastal carbon synthesis activity initiated by the Ocean Carbon and Biogeochemistry Program and the North American Carbon Program. Furthermore, the team has requisite regional expertise, with research experience on the Atlantic, Gulf, and Pacific coasts, which will facilitate access to and synthesis of relevant datasets. The proposed work will result in the development of improved remote sensing retrievals is coastal systems. Results from this work will be particularly useful for targeting optimal remote sensing design and maximizing the return of future NASA ocean color missions, including the Climate Initiative mission PACE (Pre-Aerosol, Cloud and Ecosystems) and the Decadal Survey mission recommended by the National Research Council, GEO-CAPE (GEOstationary for Coastal and Air Pollution Events). Results will also be useful for future parameterization of MODIS algorithms, specific to tidal wetlands, by NASA, NACP, and the MODIS Land Team.


Cao, F., Tzortziou, M., Hu, C., Mannino, A., Fichot, C. G., Del Vecchio, R., Najjar, R. G., Novak, M. 2018. Remote sensing retrievals of colored dissolved organic matter and dissolved organic carbon dynamics in North American estuaries and their margins. Remote Sensing of Environment. 205, 151-165. DOI: 10.1016/j.rse.2017.11.014

Chen, S., Hu, C., Barnes, B. B., Wanninkhof, R., Cai, W., Barbero, L., Pierrot, D. 2019. A machine learning approach to estimate surface ocean pCO2 from satellite measurements. Remote Sensing of Environment. 228, 203-226. DOI: 10.1016/j.rse.2019.04.019

Fennel, K., Alin, S., Barbero, L., Evans, W., Bourgeois, T., Cooley, S., Dunne, J., Feely, R. A., Hernandez-Ayon, J. M., Hu, X., Lohrenz, S., Muller-Karger, F., Najjar, R., Robbins, L., Shadwick, E., Siedlecki, S., Steiner, N., Sutton, A., Turk, D., Vlahos, P., Wang, Z. A. 2019. Carbon cycling in the North American coastal ocean: a synthesis. Biogeosciences. 16(6), 1281-1304. DOI: 10.5194/bg-16-1281-2019

Herrmann, M., Najjar, R. G., Kemp, W. M., Alexander, R. B., Boyer, E. W., Cai, W., Griffith, P. C., Kroeger, K. D., McCallister, S. L., Smith, R. A. 2015. Net ecosystem production and organic carbon balance of U.S. East Coast estuaries: A synthesis approach. Global Biogeochemical Cycles. 29(1), 96-111. DOI: 10.1002/2013GB004736

Hinson, A. L., Feagin, R. A., Eriksson, M. 2019. Environmental Controls on the Distribution of Tidal Wetland Soil Organic Carbon in the Continental United States. Global Biogeochemical Cycles. 33(11), 1408-1422. DOI: 10.1029/2019GB006179

Hinson, A. L., Feagin, R. A., Eriksson, M., Najjar, R. G., Herrmann, M., Bianchi, T. S., Kemp, M., Hutchings, J. A., Crooks, S., Boutton, T. 2017. The spatial distribution of soil organic carbon in tidal wetland soils of the continental United States. Global Change Biology. 23(12), 5468-5480. DOI: 10.1111/gcb.13811

Najjar, R. G., Herrmann, M., Alexander, R., Boyer, E. W., Burdige, D. J., Butman, D., Cai, W., Canuel, E. A., Chen, R. F., Friedrichs, M. A. M., Feagin, R. A., Griffith, P. C., Hinson, A. L., Holmquist, J. R., Hu, X., Kemp, W. M., Kroeger, K. D., Mannino, A., McCallister, S. L., McGillis, W. R., Mulholland, M. R., Pilskaln, C. H., Salisbury, J., Signorini, S. R., St-Laurent, P., Tian, H., Tzortziou, M., Vlahos, P., Wang, Z. A., Zimmerman, R. C. 2018. Carbon Budget of Tidal Wetlands, Estuaries, and Shelf Waters of Eastern North America. Global Biogeochemical Cycles. 32(3), 389-416. DOI: 10.1002/2017GB005790

Signorini, S. R., Mannino, A., Friedrichs, M. A. M., St-Laurent, P., Wilkin, J., Tabatabai, A., Najjar, R. G., Hofmann, E. E., Da, F., Tian, H., Yao, Y. 2019. Estuarine Dissolved Organic Carbon Flux From Space: With Application to Chesapeake and Delaware Bays. Journal of Geophysical Research: Oceans. DOI: 10.1029/2018JC014646

2015 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

  • Spatial quantification of blue carbon at landscape and continental scales   --   (Rusty A Feagin, R Wasantha Kulawardhana, Audra L Hinson, Sorin C Popescu, Thomas S Bianchi, Kevin M Yeager, Raymond G Najjar, Kevin D Kroeger, Lisa Windham-Myers)   [abstract]   [poster]
  • The carbon budget of tidal wetlands and estuaries of the contiguous United States: a synthesis approach   --   (Raymond Najjar, Tom Bianchi, Jose D. Fuentes, Maria Herrmann, Wei-Jun Cai, Rusty A Feagin, William Michael Kemp, Kevin Kroeger, Maria A. Tzortziou, Simone Alin, Chuanmin Hu, Wiley Evans)   [abstract]
  • Net ecosystem production and organic carbon balance of U.S. east coast estuaries: A synthesis approach   --   (Maria Herrmann, Raymond Najjar, William Michael Kemp, Richard Alexander, Elizabeth W Boyer, Wei-Jun Cai, Peter Griffith, Kevin Kroeger, S. Leigh McCallister, Richard Smith)   [abstract]

More details may be found in the following project profile(s):