High methane concentrations in tidal salt marsh soils: Where does the methane go?
| Author(s) | Capooci, Margaret | |
| Author(s) | Seyfferth, Angelia L. | |
| Author(s) | Tobias, Craig | |
| Author(s) | Wozniak, Andrew S. | |
| Author(s) | Hedgpeth, Alexandra | |
| Author(s) | Bowen, Malique | |
| Author(s) | Biddle, Jennifer F. | |
| Author(s) | McFarlane, Karis J. | |
| Author(s) | Vargas, Rodrigo | |
| Date Accessioned | 2024-02-12T21:26:31Z | |
| Date Available | 2024-02-12T21:26:31Z | |
| Publication Date | 2023-11-30 | |
| Description | This article was originally published in Global Change Biology. The version of record is available at: https://doi.org/10.1111/gcb.17050. © 2023 The Authors. Global Change Biology published by John Wiley & Sons Ltd. This research was featured in UDaily on February 19, 2024, available at: https://www.udel.edu/udaily/2024/february/methane-tidal-salt-marshes-soils-rodrigo-vargas/ | |
| Abstract | Tidal salt marshes produce and emit CH4. Therefore, it is critical to understand the biogeochemical controls that regulate CH4 spatial and temporal dynamics in wetlands. The prevailing paradigm assumes that acetoclastic methanogenesis is the dominant pathway for CH4 production, and higher salinity concentrations inhibit CH4 production in salt marshes. Recent evidence shows that CH4 is produced within salt marshes via methylotrophic methanogenesis, a process not inhibited by sulfate reduction. To further explore this conundrum, we performed measurements of soil–atmosphere CH4 and CO2 fluxes coupled with depth profiles of soil CH4 and CO2 pore water gas concentrations, stable and radioisotopes, pore water chemistry, and microbial community composition to assess CH4 production and fate within a temperate tidal salt marsh. We found unexpectedly high CH4 concentrations up to 145,000 μmol mol−1 positively correlated with S2− (salinity range: 6.6–14.5 ppt). Despite large CH4 production within the soil, soil–atmosphere CH4 fluxes were low but with higher emissions and extreme variability during plant senescence (84.3 ± 684.4 nmol m−2 s−1). CH4 and CO2 within the soil pore water were produced from young carbon, with most Δ14C-CH4 and Δ14C-CO2 values at or above modern. We found evidence that CH4 within soils was produced by methylotrophic and hydrogenotrophic methanogenesis. Several pathways exist after CH4 is produced, including diffusion into the atmosphere, CH4 oxidation, and lateral export to adjacent tidal creeks; the latter being the most likely dominant flux. Our findings demonstrate that CH4 production and fluxes are biogeochemically heterogeneous, with multiple processes and pathways that can co-occur and vary in importance over the year. This study highlights the potential for high CH4 production, the need to understand the underlying biogeochemical controls, and the challenges of evaluating CH4 budgets and blue carbon in salt marshes. | |
| Sponsor | This research was supported by the National Science Foundation (NSF-1652594) and the US Department of Energy (#DE-SC0023099 and #DE-SC0022185). Margaret Capooci acknowledges support from an NSF Graduate Research Fellowship (NSF-1247394) and the Department of Energy's Office of Science Graduate Student Research Program (DE-SC0014664). A portion of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We thank the onsite support from Kari St. Laurent and the Delaware National Estuarine Research Reserve, as well as from Victor and Evelyn Capooci for field assistance during the first campaign and Sean Fettrow for assistance with soil coring. The authors acknowledge that the land on which they conducted this study is the traditional homeland of the Lenni-Lenape tribal nation (Delaware nation). Any opinions, findings. and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. | |
| Citation | Capooci, M., Seyfferth, A. L., Tobias, C., Wozniak, A. S., Hedgpeth, A., Bowen, M., Biddle, J. F., McFarlane, K. J., & Vargas, R. (2023). High methane concentrations in tidal salt marsh soils: Where does the methane go? Global Change Biology, 30, e17050. https://doi.org/10.1111/gcb.17050 | |
| ISSN | 1365-2486 | |
| URL | https://udspace.udel.edu/handle/19716/33975 | |
| Language | en_US | |
| Publisher | Global Change Biology | |
| dc.rights | Attribution 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | |
| Keywords | blue carbon | |
| Keywords | carbon cycling | |
| Keywords | fluxes | |
| Keywords | methane | |
| Keywords | radiocarbon | |
| Keywords | salt marsh | |
| Title | High methane concentrations in tidal salt marsh soils: Where does the methane go? | |
| Type | Article |
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