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Published (Version of record)CC BY-NC V4.0, Open Access
Published (Version of record)CC BY-NC V4.0, Open
Journal article
Methane emissions in seagrass meadows as a small offset to carbon sequestration
Journal of geophysical research. Biogeosciences, Vol.128(6), e2022JG007295
06/2023
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Source: InCites
Abstract
Seagrass meadows are effective carbon sinks due to high primary production and sequestration in sediments. However, methane (CH4) emissions can partially counteract their carbon sink capacity. Here, we measured diffusive sediment-water and sea-air CO2 and CH4 fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High resolution timeseries observations revealed large spatial and temporal variability in CH4 concentrations (2 to 36 nM). Lower sea-air CH4 emissions were observed in an area with dense seagrass meadows compared to patchy seagrass. A 6 − 40% decrease of CH4 concentration in the surface water around noon indicates that photosynthesis likely limits CH4 fluxes. Sediments were the major CH4 source as implied from radon (a natural porewater tracer) observations and evidence for methanogenesis in deeper sediments. CH4 sediment-water fluxes (0.1 ± 0.1 − 0.4 ± 0.1 µmol m-2 d-1) were higher than average sea-air CH4 emissions (0.12 ± 0.10 µmol m-2 d-1), suggesting that dilution and CH4 oxidation in the water column could reduce net CH4 fluxes into the atmosphere. Overall, relatively low sea-air CH4 fluxes likely represent the net emissions from subtidal seagrass habitat not influenced by allochthonous CH4 sources. The local CH4 emissions in P. oceanica can offset less than 1% of the carbon burial in sediments (142 ± 69 g CO2eq m-2 yr-1). Combining our results with earlier observations in other seagrass meadows worldwide reveals that global CH4 emissions only offset a small fraction (<2%) of carbon sequestration in sediments from seagrass meadows.
Details
- Title
- Methane emissions in seagrass meadows as a small offset to carbon sequestration
- Creators
- Yvonne Y.Y. Yau - University of GothenburgGloria Reithmaier - University of GothenburgClaudia Majtenyi-Hill - University of GothenburgOscar Serrano - Edith Cowan UniversityNerea Piñeiro-Juncal - Centre d'Estudis Avançats de BlanesMartin Dahl - Centre d'Estudis Avançats de BlanesMiguel Angel Mateo - Centre d'Estudis Avançats de BlanesStefano Bonaglia - University of GothenburgIsaac R. Santos - University of Gothenburg
- Publication Details
- Journal of geophysical research. Biogeosciences, Vol.128(6), e2022JG007295
- Publisher
- Wiley-Blackwell Publishing, Inc.
- Grant note
- Vetenskapsrådet. Grant Number: 2020-00457 Ministerio de Ciencia e Innovación. Grant Number: PIE HOLOCENO 20213AT014 Ministerio de Universidades MCIN/AEI/10.13039/501100011033. Grant Number: RYC2019-027073-I modality Margarita Salas. Grant Numbers: UIDB/50017/2020, UIDP/50017/2020, LA/P/0094/2020
- Identifiers
- 991013116172302368
- Copyright
- © 2023 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, (https://creativecommons.org/licenses/by-nc/4.0/).
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article