Tomer, Aprajita S., McKenzie, Tristan, Majtényi-Hill, Claudia, Cabral, Alex, Yau, Yvonne Y.Y., Call, Mitchell, Chen, Xiaogang, Correa, Rogger E., Davis, Kay, Jeffrey, Luke, Sadat-Noori, Mahmood, Tait, Douglas, Webb, Jackie, Maher, Damien T., Henriksson, Linnea, Bonaglia, Stefano, Zhao, Shibin, Cardenas, M. Bayani, and Santos, Isaac R. (2025) Groundwater releases CO2 to diverse global coastal ecosystems. Science Advances, 11 (2). eadr3240.

Preview

PDF (Published Version) - Published Version Available under License Creative Commons Attribution. Download (2MB) | Preview

3

Abstract

Coastal ecosystems play a major role in marine carbon budgets, but substantial uncertainties remain in the sources and fluxes of coastal carbon dioxide (CO<inf>2</inf>). Here, we assess when, where, and how submarine groundwater discharge (SGD) releases CO<inf>2</inf> to shallow coastal ecosystems. Time-series observations of dissolved CO<inf>2</inf> and radon (²²²Rn, a natural groundwater tracer) across 40 coastal systems from 14 countries revealed large SGD-derived CO<inf>2</inf> fluxes. The mean groundwater partial pressure of CO<inf>2</inf> was 35 times higher than surface seawater. The mean SGD-derived CO<inf>2</inf> flux was 148 ± 226 millimoles per square meter per day (mmol m⁻² day⁻¹), resulting in a mean water-air CO<inf>2</inf> flux of 80 ± 133 mmol m⁻² day⁻¹. Tidal rather than diel cycles drove CO<inf>2</inf> enrichment in most ecosystems. Tidally driven SGD was the primary CO<inf>2</inf> 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<inf>2</inf> that requires inclusion in coastal carbon budgets.

Actions (Repository Staff Only)

Item Control Page