Authors

Ariane Arias-Ortiz, Universitat Autònoma de Barcelona
Jaxine Wolfe, Smithsonian Environmental Research Center
Scott D. Bridgham, University of Oregon
Sara Knox, The University of British Columbia
Gavin McNicol, The University of Illinois at Chicago
Brian A. Needelman, University of Maryland at College Park
Julie Shahan, Stanford University
Ellen J. Stuart-Haëntjens, U.S. Geological Survey
Lisamarie Windham-Myers, U.S. Geological Survey
Patty Y. Oikawa, California State University, East Bay
Dennis D. Baldocchi, University of California, Berkeley
Joshua S. Caplan, Temple University
Margaret Capooci, University of Delaware
Kenneth M. Czapla, University of California, Riverside
R. Kyle Derby, Chesapeake Bay National Estuarine Research Reserve
Heida L. Diefenderfer, Pacific Northwest National Laboratory
Inke Forbrich, Marine Biological Laboratory
Gina Groseclose, Louisiana State University
Jason K. Keller, Chapman UniversityFollow
Cheryl Kelley, University of Missouri
Amir E. Keshta, Tanta University
Helena S. Kleiner, Smithsonian Environmental Research Center
Ken W. Krauss, U.S. Geological Survey
Robert R. Lane, Comite Resources
Sarah Mack, Tierra Resources LLC
Serena Moseman-Valtierra, University of Rhode Island
Thomas J. Mozdzer, Bryn Mawr College
Peter Mueller, University of Münster
Scott C. Neubauer, Virginia Commonwealth University
Genevieve Noyce, Smithsonian Environmental Research Center
Katrina V. R. Schäfer, Rutgers University Newark
Rebecca Sanders-DeMott, U.S. Geological Survey
Charles A. Schutte, Rowan University
Rodrigo Vargas, University of Delaware
Nathaniel B. Weston, Villanova University
Benjamin Wilson, Florida International University
J. Patrick Megonigal, Smithsonian Environmental Research Center
James R. Homquist, Smithsonian Environmental Research Center

Document Type

Article

Publication Date

9-5-2024

Abstract

Methane (CH4) is a potent greenhouse gas (GHG) with atmospheric concentrations that have nearly tripled since pre-industrial times. Wetlands account for a large share of global CH4 emissions, yet the magnitude and factors controlling CH4 fluxes in tidal wetlands remain uncertain. We synthesized CH4 flux data from 100 chamber and 9 eddy covariance (EC) sites across tidal marshes in the conterminous United States to assess controlling factors and improve predictions of CH4 emissions. This effort included creating an open-source database of chamber-based GHG fluxes (https://doi.org/10.25573/serc.14227085). Annual fluxes across chamber and EC sites averaged 26 ± 53 g CH4 m−2 year−1, with a median of 3.9 g CH4 m−2 year−1, and only 25% of sites exceeding 18 g CH4 m−2 year−1. The highest fluxes were observed at fresh-oligohaline sites with daily maximum temperature normals (MATmax) above 25.6°C. These were followed by frequently inundated low and mid-fresh-oligohaline marshes with MATmax ≤25.6°C, and mesohaline sites with MATmax >19°C. Quantile regressions of paired chamber CH4 flux and porewater biogeochemistry revealed that the 90th percentile of fluxes fell below 5 ± 3 nmol m−2 s−1 at sulfate concentrations >4.7 ± 0.6 mM, porewater salinity >21 ± 2 psu, or surface water salinity >15 ± 3 psu. Across sites, salinity was the dominant predictor of annual CH4 fluxes, while within sites, temperature, gross primary productivity (GPP), and tidal height controlled variability at diel and seasonal scales. At the diel scale, GPP preceded temperature in importance for predicting CH4 flux changes, while the opposite was observed at the seasonal scale. Water levels influenced the timing and pathway of diel CH4 fluxes, with pulsed releases of stored CH4 at low to rising tide. This study provides data and methods to improve tidal marsh CH4 emission estimates, support blue carbon assessments, and refine national and global GHG inventories.

Comments

This article was originally published in Global Change Biology, volume 30, issue 9, in 2024. https://doi.org/10.1111/gcb.17462

Copyright

Smithsonian Institution and The Author(s)

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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