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, Santos Isaac R
Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden.
National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, P.O. Box 4321, Coffs Harbor, NSW 2450, Australia.
Sci Adv. 2025 Jan 10;11(2):eadr3240. doi: 10.1126/sciadv.adr3240.
Coastal ecosystems play a major role in marine carbon budgets, but substantial uncertainties remain in the sources and fluxes of coastal carbon dioxide (CO). Here, we assess when, where, and how submarine groundwater discharge (SGD) releases CO to shallow coastal ecosystems. Time-series observations of dissolved CO and radon (Rn, a natural groundwater tracer) across 40 coastal systems from 14 countries revealed large SGD-derived CO fluxes. The mean groundwater partial pressure of CO was 35 times higher than surface seawater. The mean SGD-derived CO flux was 148 ± 226 millimoles per square meter per day (mmol m day), resulting in a mean water-air CO flux of 80 ± 133 mmol m day. Tidal rather than diel cycles drove CO enrichment in most ecosystems. Tidally driven SGD was the primary CO 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 that requires inclusion in coastal carbon budgets.
沿海生态系统在海洋碳收支中发挥着重要作用，但沿海二氧化碳（CO）的来源和通量仍存在很大的不确定性。在此，我们评估了海底地下水排放（SGD）在何时、何地以及如何向浅海沿海生态系统释放CO。对来自14个国家的40个沿海系统的溶解CO和氡（Rn，一种天然地下水示踪剂）进行的时间序列观测揭示了源自SGD的大量CO通量。CO的平均地下水分压比表层海水高35倍。源自SGD的平均CO通量为每天每平方米148±226毫摩尔（mmol m² day⁻¹），导致平均水-气CO通量为80±133 mmol m² day⁻¹。在大多数生态系统中，潮汐而非昼夜循环驱动了CO的富集。潮汐驱动的SGD是红树林、盐沼、潮滩、河口和运河中CO的主要来源。总体而言，我们通过证明SGD是CO的重要来源，需要纳入沿海碳收支，从而扩展了当前对海洋碳循环的认识。
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