Articles | Volume 22, issue 18
https://doi.org/10.5194/bg-22-4851-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-22-4851-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Old carbon, new insights: thermal reactivity and bioavailability of saltmarsh soils
Department of Geography and Sustainable Development, University of St Andrews, St Andrews, KY16 9AL, United Kingdom
Mark H. Garnett
NEIF Radiocarbon Laboratory, Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, United Kingdom
William E. N. Austin
Department of Geography and Sustainable Development, University of St Andrews, St Andrews, KY16 9AL, United Kingdom
Scottish Association of Marine Science, Oban, PA37 1QA, United Kingdom
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William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
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Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
Tobias Roylands, Robert G. Hilton, Erin L. McClymont, Mark H. Garnett, Guillaume Soulet, Sébastien Klotz, Mathis Degler, Felipe Napoleoni, and Caroline Le Bouteiller
Earth Surf. Dynam., 12, 271–299, https://doi.org/10.5194/esurf-12-271-2024, https://doi.org/10.5194/esurf-12-271-2024, 2024
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Chemical weathering of sedimentary rocks can release carbon dioxide and consume oxygen. We present a new field-based method to measure the exchange of these gases in real time, which allows us to directly compare the amount of reactants and products. By studying two sites with different rock types, we show that the chemical composition is an important factor in driving the weathering reactions. Locally, the carbon dioxide release changes alongside temperature and precipitation.
Cited articles
Ascough, P., Bompard, N., Garnett, M. H., Gulliver, P., Murray, C., Newton, J.-A., and Taylor, C.: 14C measurement of samples for environmental science applications at the National Environmental Isotope Facility (NEIF) Radiocarbon Laboratory, SUERC, UK, Radiocarbon, 66, 1020–1031, https://doi.org/10.1017/RDC.2024.9, 2024.
Bao, R., McNichol, A. P., Hemingway, J. D., Gaylord, M. C. L., and Eglinton, T. I.: Influence of Different Acid Treatments on the Radiocarbon Content Spectrum of Sedimentary Organic Matter Determined by RPO/Accelerator Mass Spectrometry, Radiocarbon, 61, 395–413, https://doi.org/10.1017/RDC.2018.125, 2019a.
Bao, R., Zhao, M., McNichol, A., Wu, Y., Guo, X., Haghipour, N., and Eglinton, T. I.: On the Origin of Aged Sedimentary Organic Matter Along a River-Shelf-Deep Ocean Transect, J. Geophys. Res.-Biogeo., 124, 2582–2594, https://doi.org/10.1029/2019JG005107, 2019b.
Bianchi, T. S., Mayer, L. M., Amaral, J. H. F., Arndt, S., Galy, V., Kemp, D. B., Kuehl, S. A., Murray, N. J., and Regnier, P.: Anthropogenic impacts on mud and organic carbon cycling, Nat. Geosci., 17, 287–297, https://doi.org/10.1038/s41561-024-01405-5, 2024.
Boström, B., Comstedt, D., and Ekblad, A.: Isotope fractionation and 13C enrichment in soil profiles during the decomposition of soil organic matter, Oecologia, 153, 89–98, https://doi.org/10.1007/s00442-007-0700-8, 2007.
Brand, W. A., Coplen, T. B., Vogl, J., Rosner, M., and Prohaska, T.: Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report), Pure Appl. Chem., 86, 425–467, https://doi.org/10.1515/pac-2013-1023, 2014.
Bromberg, K. D. and Bertness, M. D.: Reconstructing New England salt marsh losses using historical maps, Estuaries, 28, 823–832, https://doi.org/10.1007/BF02696012, 2005.
Campbell, A. D., Fatoyinbo, L., Goldberg, L., and Lagomasino, D.: Global hotspots of salt marsh change and carbon emissions, Nature, 1–6, https://doi.org/10.1038/s41586-022-05355-z, 2022.
Chapman, S. K., Hayes, M. A., Kelly, B., and Langley, J. A.: Exploring the oxygen sensitivity of wetland soil carbon mineralization, Biol. Lett., 15, 20180407, https://doi.org/10.1098/rsbl.2018.0407, 2019.
Dean, J. F., Billett, M. F., Turner, T. E., Garnett, M. H., Andersen, R., McKenzie, R. M., Dinsmore, K. J., Baird, A. J., Chapman, P. J., and Holden, J.: Peatland pools are tightly coupled to the contemporary carbon cycle, Global Change Biology, 30, e16999, https://doi.org/10.1111/gcb.16999, 2023.
Etcheverría, P., Huygens, D., Godoy, R., Borie, F., and Boeckx, P.: Arbuscular mycorrhizal fungi contribute to 13C and 15N enrichment of soil organic matter in forest soils, Soil Biol. Biochem., 41, 858–861, https://doi.org/10.1016/j.soilbio.2009.01.018, 2009.
Garnett, M. H., Pereira, R., Taylor, C., Murray, C., and Ascough, P. L.: A New Ramped Oxidation-14C Analysis Facility at the NEIF Radiocarbon Laboratory, East Kilbride, UK, Radiocarbon, 65, 1213–1229, https://doi.org/10.1017/RDC.2023.96, 2023.
Geraldi, N. R., Ortega, A., Serrano, O., Macreadie, P. I., Lovelock, C. E., Krause-Jensen, D., Kennedy, H., Lavery, P. S., Pace, M. L., Kaal, J., and Duarte, C. M.: Fingerprinting Blue Carbon: Rationale and Tools to Determine the Source of Organic Carbon in Marine Depositional Environments, Front. Marine Sci., 6, 263, https://doi.org/10.3389/fmars.2019.00263, 2019.
Goldstein, A., Turner, W. R., Spawn, S. A., Anderson-Teixeira, K. J., Cook-Patton, S., Fargione, J., Gibbs, H. K., Griscom, B., Hewson, J. H., Howard, J. F., Ledezma, J. C., Page, S., Koh, L. P., Rockström, J., Sanderman, J., and Hole, D. G.: Protecting irrecoverable carbon in Earth's ecosystems, Nat. Clim. Chang., 10, 287–295, https://doi.org/10.1038/s41558-020-0738-8, 2020.
Granse, D., Wanner, A., Stock, M., Jensen, K., and Mueller, P.: Plant-sediment interactions decouple inorganic from organic carbon stock development in salt marsh soils, Limnol. Oceanogr. Lett., 9, 469–477, https://doi.org/10.1002/lol2.10382, 2024.
Griscom, B. W., Adams, J., Ellis, P. W., Houghton, R. A., Lomax, G., Miteva, D. A., Schlesinger, W. H., Shoch, D., Siikamäki, J. V., Smith, P., Woodbury, P., Zganjar, C., Blackman, A., Campari, J., Conant, R. T., Delgado, C., Elias, P., Gopalakrishna, T., Hamsik, M. R., Herrero, M., Kiesecker, J., Landis, E., Laestadius, L., Leavitt, S. M., Minnemeyer, S., Polasky, S., Potapov, P., Putz, F. E., Sanderman, J., Silvius, M., Wollenberg, E., and Fargione, J.: Natural climate solutions, P. Natl. Acad. Sci. USA, 114, 11645–11650, https://doi.org/10.1073/pnas.1710465114, 2017.
Hajdas, I., Ascough, P., Garnett, M. H., Fallon, S. J., Pearson, C. L., Quarta, G., Spalding, K. L., Yamaguchi, H., and Yoneda, M.: Radiocarbon dating, Nat. Rev. Methods Primers, 1, 1–26, https://doi.org/10.1038/s43586-021-00058-7, 2021.
Hansom, J. D. and McGlashan, D. J.: Scotland's coast: Understanding past and present processes for sustainable management, Scottish Geographical Journal, 120, 99–116, 2004.
Hemingway, J. D.: rampedpyrox: Open-source tools for thermoanalytical data analysis, http://pypi.python.org/pypi/rampedpyrox (last access: 10 May 2025), 2016.
Hemingway, J. D., Galy, V. V., Gagnon, A. R., Grant, K. E., Rosengard, S. Z., Soulet, G., Zigah, P. K., and McNichol, A. P.: Assessing the Blank Carbon Contribution, Isotope Mass Balance, and Kinetic Isotope Fractionation of the Ramped Pyrolysis/Oxidation Instrument at NOSAMS, Radiocarbon, 59, 179–193, https://doi.org/10.1017/RDC.2017.3, 2017a.
Hemingway, J. D., Rothman, D. H., Rosengard, S. Z., and Galy, V. V.: Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation, Biogeosciences, 14, 5099–5114, https://doi.org/10.5194/bg-14-5099-2017, 2017b.
Hemingway, J. D., Rothman, D. H., Grant, K. E., Rosengard, S. Z., Eglinton, T. I., Derry, L. A., and Galy, V. V.: Mineral protection regulates long-term global preservation of natural organic carbon, Nature, 570, 228–231, https://doi.org/10.1038/s41586-019-1280-6, 2019.
Houston, A., Garnett, M. H., and Austin, W. E. N.: Blue carbon additionality: New insights from the radiocarbon content of saltmarsh soils and their respired CO2, Limnol. Oceanogr., 69, 548–561, https://doi.org/10.1002/lno.12508, 2024a.
Houston, A., Kennedy, H., and Austin, W. E. N.: Additionality in Blue Carbon Ecosystems: Recommendations for a Universally Applicable Accounting Methodology, Global Change Biol., 30, e17559, https://doi.org/10.1111/gcb.17559, 2024b.
Howard, J., Sutton-Grier, A. E., Smart, L. S., Lopes, C. C., Hamilton, J., Kleypas, J., Simpson, S., McGowan, J., Pessarrodona, A., Alleway, H. K., and Landis, E.: Blue carbon pathways for climate mitigation: Known, emerging and unlikely, Marine Policy, 156, 105788, https://doi.org/10.1016/j.marpol.2023.105788, 2023.
Komada, T., Bravo, A., Brinkmann, M.-T., Lu, K., Wong, L., and Shields, G.: “Slow” and “fast” in blue carbon: Differential turnover of allochthonous and autochthonous organic matter in minerogenic salt marsh sediments, Limnol. Oceanogr., 67, S133–S147, https://doi.org/10.1002/lno.12090, 2022.
Kwan, V., Friess, D. A., Sarira, T. V., and Zeng, Y.: Permanence risks limit blue carbon financing strategies to safeguard Southeast Asian mangroves, Commun. Earth Environ., 6, 1–8, https://doi.org/10.1038/s43247-025-02035-4, 2025.
Leng, M. J. and Lewis, J. P.: ratios and Carbon Isotope Composition of Organic Matter in Estuarine Environments, in: Applications of Paleoenvironmental Techniques in Estuarine Studies, edited by: Weckström, K., Saunders, K. M., Gell, P. A., and Skilbeck, C. G., Springer Netherlands, Dordrecht, 213–237, https://doi.org/10.1007/978-94-024-0990-1_9, 2017.
Lilly, A., Baggaley, N., and Donnelly, D.: Map of soil organic carbon in top soils of Scotland, https://map.environment.gov.scot/Soil_maps/?layer=7# (last access: 17 April 2025), 2012.
Luk, S. Y., Todd-Brown, K., Eagle, M., McNichol, A. P., Sanderman, J., Gosselin, K., and Spivak, A. C.: Soil Organic Carbon Development and Turnover in Natural and Disturbed Salt Marsh Environments, Geophys. Res. Lett., 48, e2020GL090287, https://doi.org/10.1029/2020GL090287, 2021.
Macreadie, P. I., Anton, A., Raven, J. A., Beaumont, N., Connolly, R. M., Friess, D. A., Kelleway, J. J., Kennedy, H., Kuwae, T., Lavery, P. S., Lovelock, C. E., Smale, D. A., Apostolaki, E. T., Atwood, T. B., Baldock, J., Bianchi, T. S., Chmura, G. L., Eyre, B. D., Fourqurean, J. W., Hall-Spencer, J. M., Huxham, M., Hendriks, I. E., Krause-Jensen, D., Laffoley, D., Luisetti, T., Marbà, N., Masque, P., McGlathery, K. J., Megonigal, J. P., Murdiyarso, D., Russell, B. D., Santos, R., Serrano, O., Silliman, B. R., Watanabe, K., and Duarte, C. M.: The future of Blue Carbon science, Nat. Commun., 10, 3998, https://doi.org/10.1038/s41467-019-11693-w, 2019.
Macreadie, P. I., Costa, M. D. P., Atwood, T. B., Friess, D. A., Kelleway, J. J., Kennedy, H., Lovelock, C. E., Serrano, O., and Duarte, C. M.: Blue carbon as a natural climate solution, Nat. Rev. Earth Environ., 2, 826–839, https://doi.org/10.1038/s43017-021-00224-1, 2021.
Middelburg, J. J., Nieuwenhuize, J., Lubberts, R. K., and van de Plassche, O.: Organic Carbon Isotope Systematics of Coastal Marshes, Estuar. Coast. Shelf Sci., 45, 681–687, https://doi.org/10.1006/ecss.1997.0247, 1997.
Miller, L. C., Smeaton, C., Yang, H., and Austin, W. E. N.: Carbon accumulation and storage across contrasting saltmarshes of Scotland, Estuar. Coast. Shelf Sci., 282, 108223, https://doi.org/10.1016/j.ecss.2023.108223, 2023.
Morris, J. T., Edwards, J., Crooks, S., and Reyes, E.: Assessment of carbon sequestration potential in coastal wetlands, in: Recarbonization of the Biosphere: Ecosystems and the Global Carbon Cycle, edited by: Lal, R., Lorenz, K., Hüttl, R. F., Schneider, B. U., and Braun, J. V., Springer Netherlands, Dordrecht, 517–532, https://doi.org/10.1007/978-94-007-4159-1_24, 2012.
Noyce, G. L., Smith, A. J., Kirwan, M. L., Rich, R. L., and Megonigal, J. P.: Oxygen priming induced by elevated CO2 reduces carbon accumulation and methane emissions in coastal wetlands, Nat. Geosci., 16, 63–68, https://doi.org/10.1038/s41561-022-01070-6, 2023.
Peltre, C., Fernández, J. M., Craine, J. M., and Plante, A. F.: Relationships between Biological and Thermal Indices of Soil Organic Matter Stability Differ with Soil Organic Carbon Level, Soil Sci. Soc. Am. J., 77, 2020–2028, https://doi.org/10.2136/sssaj2013.02.0081, 2013.
Plante, A. F., Fernández, J. M., Haddix, M. L., Steinweg, J. M., and Conant, R. T.: Biological, chemical and thermal indices of soil organic matter stability in four grassland soils, Soil Biol. Biochem., 43, 1051–1058, https://doi.org/10.1016/j.soilbio.2011.01.024, 2011.
Plante, A. F., Beaupré, S. R., Roberts, M. L., and Baisden, T.: Distribution of Radiocarbon Ages in Soil Organic Matter by Thermal Fractionation, Radiocarbon, 55, 1077–1083, https://doi.org/10.1017/S0033822200058215, 2013.
Ramnarine, R., Wagner-Riddle, C., Dunfield, K. E., and Voroney, R. P.: Contributions of carbonates to soil CO2 emissions, Can. J. Soil. Sci., 92, 599–607, https://doi.org/10.4141/cjss2011-025, 2012.
R Core Team: R: A language and environment for statistical computing, R version 4.2.2 (2022-10-31 ucrt), Foundation for Statistical Computing, Vienna, Austria, https://www.R-project.org/ (last access: 17 April 2025), 2022.
Reed, D. J., Spencer, T., Murray, A. L., French, J. R., and Leonard, L.: Marsh surface sediment deposition and the role of tidal creeks: Implications for created and managed coastal marshes, J. Coast. Conserv., 5, 81–90, https://doi.org/10.1007/BF02802742, 1999.
Rosengard, S. Z., Mauro S. Moura, J., Spencer, R. G. M., Johnson, C., McNichol, A., Boehman, B., and Galy, V.: The Thermal Reactivity and Molecular Diversity of Particulate Organic Carbon in the Amazon River Mainstem, J. Geophys. Res.-Biogeo., 130, e2024JG008660, https://doi.org/10.1029/2024JG008660, 2025.
Rosenheim, B. E., Day, M. B., Domack, E., Schrum, H., Benthien, A., and Hayes, J. M.: Antarctic sediment chronology by programmed-temperature pyrolysis: Methodology and data treatment, Geochem. Geophys. Geosyst., 9, https://doi.org/10.1029/2007GC001816, 2008.
Saintilan, N., Rogers, K., Mazumder, D., and Woodroffe, C.: Allochthonous and autochthonous contributions to carbon accumulation and carbon store in southeastern Australian coastal wetlands, Estuar. Coast. Shelf Sci., 128, 84–92, https://doi.org/10.1016/j.ecss.2013.05.010, 2013.
Sanderman, J. and Grandy, A. S.: Ramped thermal analysis for isolating biologically meaningful soil organic matter fractions with distinct residence times, SOIL, 6, 131–144, https://doi.org/10.5194/soil-6-131-2020, 2020.
Sasmito, S. D., Taillardat, P., Adinugroho, W. C., Krisnawati, H., Novita, N., Fatoyinbo, L., Friess, D. A., Page, S. E., Lovelock, C. E., Murdiyarso, D., Taylor, D., and Lupascu, M.: Half of land use carbon emissions in Southeast Asia can be mitigated through peat swamp forest and mangrove conservation and restoration, Nat. Commun., 16, 740, https://doi.org/10.1038/s41467-025-55892-0, 2025.
Schmidt, M. W. I., Torn, M. S., Abiven, S., Dittmar, T., Guggenberger, G., Janssens, I. A., Kleber, M., Kögel-Knabner, I., Lehmann, J., Manning, D. A. C., Nannipieri, P., Rasse, D. P., Weiner, S., and Trumbore, S. E.: Persistence of soil organic matter as an ecosystem property, Nature, 478, 49–56, https://doi.org/10.1038/nature10386, 2011.
Smeaton, C., Garrett, E., Koot, M. B., Ladd, C. J. T., Miller, L. C., McMahon, L., Foster, B., Barlow, N. L. M., Blake, W., Gehrels, W. R., Skov, M. W., and Austin, W. E. N.: Organic carbon accumulation in British saltmarshes, Sci. Total Environ., 926, 172104, https://doi.org/10.1016/j.scitotenv.2024.172104, 2024.
Soldatova, E., Krasilnikov, S., and Kuzyakov, Y.: Soil organic matter turnover: Global implications from δ13C and δ15N signatures, Sci. Total Environ., 912, 169423, https://doi.org/10.1016/j.scitotenv.2023.169423, 2024.
Spivak, A. C., Sanderman, J., Bowen, J. L., Canuel, E. A., and Hopkinson, C. S.: Global-change controls on soil-carbon accumulation and loss in coastal vegetated ecosystems, Nat. Geosci., 12, 685–692, https://doi.org/10.1038/s41561-019-0435-2, 2019.
Spohn, M., Babka, B., and Giani, L.: Changes in soil organic matter quality during sea-influenced marsh soil development at the North Sea coast, CATENA, 107, 110–117, https://doi.org/10.1016/j.catena.2013.02.006, 2013.
Stoner, S. W., Schrumpf, M., Hoyt, A., Sierra, C. A., Doetterl, S., Galy, V., and Trumbore, S.: How well does ramped thermal oxidation quantify the age distribution of soil carbon? Assessing thermal stability of physically and chemically fractionated soil organic matter, Biogeosciences, 20, 3151–3163, https://doi.org/10.5194/bg-20-3151-2023, 2023.
Systat Software Inc: Sigmaplot v12.5, https://grafiti.com/ (last access: 17 April 2025), 2013.
Van Dam, B. R., Zeller, M. A., Lopes, C., Smyth, A. R., Böttcher, M. E., Osburn, C. L., Zimmerman, T., Pröfrock, D., Fourqurean, J. W., and Thomas, H.: Calcification-driven CO2 emissions exceed “Blue Carbon” sequestration in a carbonate seagrass meadow, Sci. Adv., 7, eabj1372, https://doi.org/10.1126/sciadv.abj1372, 2021.
Van de Broek, M., Vandendriessche, C., Poppelmonde, D., Merckx, R., Temmerman, S., and Govers, G.: Long-term organic carbon sequestration in tidal marsh sediments is dominated by old-aged allochthonous inputs in a macrotidal estuary, Global Change Biol., 24, 2498–2512, https://doi.org/10.1111/gcb.14089, 2018.
VERRA: VM0033 Methodology for Tidal Wetland and Seagrass Restoration, v2.1, https://verra.org/methodologies/vm0033- methodology-for-tidal-wetland-and-seagrass-restoration-v2-1/ (last access: 17 April 2025), 2023.
Werth, M. and Kuzyakov, Y.: 13C fractionation at the root–microorganisms–soil interface: A review and outlook for partitioning studies, Soil Biol. Biochem., 42, 1372–1384, https://doi.org/10.1016/j.soilbio.2010.04.009, 2010.
Williams, E. K. and Rosenheim, B. E.: What happens to soil organic carbon as coastal marsh ecosystems change in response to increasing salinity? An exploration using ramped pyrolysis, Geochem. Geophys. Geosyst., 16, 2322–2335, https://doi.org/10.1002/2015GC005839, 2015.
Short summary
Saltmarshes accumulate carbon through plant growth and older material deposited during tidal inundation. We found that more energy was required to decompose old carbon than younger carbon, and the youngest carbon was also the most susceptible to decomposition in a degradation scenario. Protecting saltmarshes can help prevent carbon losses and reduce CO2 emissions. Including this vulnerable stored carbon in climate policies and carbon credit systems could make them more accurate and effective.
Saltmarshes accumulate carbon through plant growth and older material deposited during tidal...
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