Salinity influence on methane emissions from tidal marshes

Hanna J. Poffenbarger, Brian A. Needelman, J. Patrick Megonigal

Research output: Contribution to journalArticlepeer-review

442 Scopus citations


The relationship between methane emissions and salinity is not well understood in tidal marshes, leading to uncertainty about the net effect of marsh conservation and restoration on greenhouse gas balance.We used published and unpublished field data to investigate the relationships between tidal marsh methane emissions, salinity, and porewater concentrations of methane and sulfate, then used these relationships to consider the balance between methane emissions and soil carbon sequestration. Polyhaline tidal marshes (salinity >18) had significantly lower methane emissions (mean ± sd=1±2 gm-2 yr-1) than other marshes, and can be expected to decrease radiative forcing when created or restored. There was no significant difference in methane emissions from fresh (salinity=0-0.5) and mesohaline (5-18) marshes (42±76 and 16±11 gm-2 yr-1, respectively), while oligohaline (0.5-5) marshes had the highest and most variable methane emissions (150±221 gm-2 yr-1). Annual methane emissions were modeled using a linear fit of salinity against log-transformed methane flux ( logCH4 = 0:056 salinity 1:38; r 2 = 0. 5 2 ; p < 0.0001). Managers interested in using marshes as greenhouse gas sinks can assume negligible methane emissions in polyhaline systems, but need to estimate or monitor methane emissions in lower-salinity marshes.

Original languageEnglish
Pages (from-to)831-842
Number of pages12
Issue number5
StatePublished - Oct 2011

Bibliographical note

Funding Information:
We thank Andrew Baldwin, Raymond Crew, Emily Hutchins, Miriam Meyers, Nicholas Mudd, Jim Duls, Caitlin Megonigal and U.S. Fish and Wildlife Service staff at the Blackwater Natural Wildlife Refuge. This work was supported by funding from the Maryland Department of Natural Resources Power Plant Research Program.


  • Carbon sequestration
  • Methane flux
  • Porewater
  • Sulfate reduction

ASJC Scopus subject areas

  • Environmental Chemistry
  • Ecology
  • Environmental Science (all)


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