Groundwater releases CO <sub>2</sub> to diverse global coastal ecosystems
Coastal ecosystems play a major role in marine carbon budgets, but substantial uncertainties remain in the sources and fluxes of coastal carbon dioxide (CO<sub>2</sub>). Here, we assess when, where, and how submarine groundwater discharge (SGD) releases CO<sub>2</sub> to shallow coastal ecosystems. Time-series observations of dissolved CO<sub>2</sub> and radon (<sup>222</sup>Rn, a natural groundwater tracer) across 40 coastal systems from 14 countries revealed large SGD-derived CO<sub>2</sub> fluxes. The mean groundwater partial pressure of CO<sub>2</sub> was 35 times higher than surface seawater. The mean SGD-derived CO<sub>2</sub> flux was 148 ± 226 millimoles per square meter per day (mmol m<sup>-2</sup> day<sup>-1</sup>), resulting in a mean water-air CO<sub>2</sub> flux of 80 ± 133 mmol m<sup>-2</sup> day<sup>-1</sup>. Tidal rather than diel cycles drove CO<sub>2</sub> enrichment in most ecosystems. Tidally driven SGD was the primary CO<sub>2</sub> source in mangroves, salt marshes, tidal flats, estuaries, and canals. Overall, we expand current knowledge of marine carbon cycles by demonstrating SGD as an important source of CO<sub>2</sub> that requires inclusion in coastal carbon budgets.
Authors
- Rogger E. Correa (ORCID: https://orcid.org/0000-0002-4585-2544)
- Yvonne Y. Y. Yau (ORCID: https://orcid.org/0000-0002-4692-751X)
- Stefano Bonaglia (ORCID: https://orcid.org/0000-0003-4366-0677)
- Xiaogang Chen (ORCID: https://orcid.org/0000-0003-4329-0530)
- Jackie R. Webb (ORCID: https://orcid.org/0000-0003-1274-363X)
- Claudia Majtényi‐Hill (ORCID: https://orcid.org/0000-0003-2283-843X)
- Mahmood Sadat‐Noori (ORCID: https://orcid.org/0000-0002-6253-5874)
- Luke C. Jeffrey (ORCID: https://orcid.org/0000-0001-6536-6757)
- Mitchell Call (ORCID: https://orcid.org/0000-0002-6070-5905)
- M. Bayani Cardenas (ORCID: https://orcid.org/0000-0001-6270-3105)
- Alex Cabral (ORCID: https://orcid.org/0000-0002-3873-3432)
- Linnea Henriksson (ORCID: https://orcid.org/0009-0008-5186-0293)
- Isaac R. Santos (ORCID: https://orcid.org/0000-0003-0524-842X)
- Douglas R. Tait (ORCID: https://orcid.org/0000-0001-7690-7651)
- Damien T. Maher (ORCID: https://orcid.org/0000-0003-1899-005X)
- Tristan McKenzie (ORCID: https://orcid.org/0000-0003-4656-439X)
- Kay L. Davis (ORCID: https://orcid.org/0000-0002-7223-4303)
- Aprajita S. Tomer (ORCID: https://orcid.org/0009-0000-2311-0454)
- Shibin Zhao (ORCID: https://orcid.org/0000-0001-5143-8481)
Institutions
- Australian Institute of Marine Science (AU)
- University of Southern Queensland (AU)
- Westlake University (CN)
- Qingdao National Laboratory for Marine Science and Technology (CN)
- NSW Forestry Corporation (AU)
- Corporación para Investigaciones Biológicas (CO)
- Ocean University of China (CN)
- Southern Cross University (AU)
- James Cook University (AU)
- The University of Texas at Austin (US)
- University of Gothenburg (SE)
Publication Details
- Journal
- Science Advances
- Published
- 2025-01-10
- DOI
- https://doi.org/10.1126/sciadv.adr3240
- Citations
- 18
- Primary Topic
- Methane Hydrates and Related Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 15.48
Funders
- Svenska Forskningsrådet Formas
- Knut och Alice Wallenbergs Stiftelse
- Vetenskapsrådet
- Göteborgs Universitet
- HORIZON EUROPE Framework Programme
- HORIZON EUROPE Marie Sklodowska-Curie Actions