Methane fluxes in tidal marshes of the conterminous United States

Methane (CH<sub>4</sub>) 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 CH<sub>4</sub> emissions, yet the magnitude and factors controlling CH<sub>4</sub> fluxes in tidal wetlands remain uncertain. We synthesized CH<sub>4</sub> 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 CH<sub>4</sub> 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 CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>, with a median of 3.9 g CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>, and only 25% of sites exceeding 18 g CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>. 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 CH<sub>4</sub> flux and porewater biogeochemistry revealed that the 90th percentile of fluxes fell below 5 ± 3 nmol m<sup>-2</sup> s<sup>-1</sup> 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 CH<sub>4</sub> 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 CH<sub>4</sub> flux changes, while the opposite was observed at the seasonal scale. Water levels influenced the timing and pathway of diel CH<sub>4</sub> fluxes, with pulsed releases of stored CH<sub>4</sub> at low to rising tide. This study provides data and methods to improve tidal marsh CH<sub>4</sub> emission estimates, support blue carbon assessments, and refine national and global GHG inventories.

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Journal
Global Change Biology
Published
2024-09-01
DOI
https://doi.org/10.1111/gcb.17462
Citations
23
Primary Topic
Coastal wetland ecosystem dynamics
Type
article
Field-Weighted Citation Impact
10.55

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article

Methane fluxes in tidal marshes of the conterminous United States

PETER R. MUELLER, Rebecca Sanders‐DeMott, Ken W. Krauss, James R. Holmquist et al.
23 citations
Global Change Biology
Coastal wetland ecosystem dynamics
10.55
article

Methane fluxes in tidal marshes of the conterminous United States

PETER R. MUELLER, Rebecca Sanders‐DeMott, Ken W. Krauss, James R. Holmquist, Thomas J. Mozdzer, Margaret Capooci, Nathaniel B. Weston, J. L. Wolfe, Robert R. Lane, Inke Forbrich, Ariane Arias‐Ortiz, Cheryl A. Kelley, Sara Knox, Lisamarie Windham‐Myers, Serena Moseman‐Valtierra, Genevieve L. Noyce, Joshua S. Caplan, Helena S. Kleiner, Ellen Stuart‐Haëntjens, Gina N. Groseclose, Benjamin J. Wilson, Heida L. Diefenderfer, Julie Shahan, Rodrigo Vargas, Charles A. Schutte, Sarah K. Mack, Amr E. Keshta, Patricia Y. Oikawa, Scott C. Neubauer, Gavin McNicol, Kenneth M. Czapla, Scott D. Bridgham, Brian A. Needelman, R. Kyle Derby, Karina V. R. Schäfer, Jason K. Keller, J. Patrick Megonigal, Dennis Baldocchi
article en
23 citations

Abstract

Methane (CH<sub>4</sub>) 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 CH<sub>4</sub> emissions, yet the magnitude and factors controlling CH<sub>4</sub> fluxes in tidal wetlands remain uncertain. We synthesized CH<sub>4</sub> 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 CH<sub>4</sub> 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 CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>, with a median of 3.9 g CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>, and only 25% of sites exceeding 18 g CH<sub>4</sub> m<sup>-2</sup> year<sup>-1</sup>. 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 CH<sub>4</sub> flux and porewater biogeochemistry revealed that the 90th percentile of fluxes fell below 5 ± 3 nmol m<sup>-2</sup> s<sup>-1</sup> 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 CH<sub>4</sub> 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 CH<sub>4</sub> flux changes, while the opposite was observed at the seasonal scale. Water levels influenced the timing and pathway of diel CH<sub>4</sub> fluxes, with pulsed releases of stored CH<sub>4</sub> at low to rising tide. This study provides data and methods to improve tidal marsh CH<sub>4</sub> emission estimates, support blue carbon assessments, and refine national and global GHG inventories.

Global Change BiologyVol. 30(9)
Rutgers, The State University of New Jersey (US), Bryn Mawr College (US), University of California, Riverside (US), Claremont McKenna College (US), Louisiana State University (US), Universitat Autònoma de Barcelona (ES), United States Geological Survey (US), Marine Biological Laboratory (US), University of British Columbia (CA), Pacific Northwest National Laboratory (US), University of Rhode Island (US), University of Oregon (US), California State University, East Bay (US), Virginia Commonwealth University (US), Chapman University (US), Florida International University (US), Tanta University (EG), University of Münster (DE), Temple University Ambler (US), University of Illinois Chicago (US), Maryland Department of Natural Resources (US), Louisiana Department of Natural Resources (US), U.S. Geological Survey, Wetland and Aquatic Research Center, Woods Hole Coastal and Marine Science Center, Rowan University (US), McGill University (CA), Smithsonian Environmental Research Center (US), University of Maryland, College Park (US), Woods Hole Oceanographic Institution (US), University of Missouri (US), Villanova University (US), University of Delaware (US), University of Toledo (US), University of California, Berkeley (US), Stanford University (US)
National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, University Corporation for Atmospheric Research, Nuclear Safety and Security Commission, Agencia Estatal de Investigación
Clean water and sanitation
Openalex Percentile: Top 1%
Coastal wetland ecosystem dynamics
10.55
DOIOpen Access PDFOpenAlex
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