We quantified whether pore-water exchange flushes out saltmarsh sediment carbon, driving carbon outwelling into the ocean and outgassing into the atmosphere. Radon-derived pore-water exchange released 1.8 times more sediment carbon in the wet than in dry season. Both crab burrow flushing and delayed seepage of surface water infiltrating sediments during the spring tide released sediment carbon to surface waters. The outwelling flux of dissolved inorganic carbon exceeded dissolved organic carbon. Carbon dioxide and methane emissions were 169 and 0.25 mmol m⁻² d⁻¹, respectively. Pore-water carbon fluxes exceeded carbon outwelling. This requires some carbon processing within the saltmarsh (e.g., degradation or outgassing to the atmosphere) before pore-water carbon is exported to the ocean. Overall, pore-water exchange and outwelling are key components of saltmarsh carbon budgets and should be considered when assessing their carbon sequestration potential and strategies to mitigate climate change.

中文翻译：

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孔隙水交换将潮间带盐沼沉积物中的蓝碳冲入大海

我们量化了孔隙水交换是否会冲走盐沼沉积物中的碳，从而驱使碳流入海洋并排放到大气中。氡衍生的孔隙水交换在湿季释放的沉积物碳是旱季的 1.8 倍。大潮期间蟹穴冲刷和地表水渗入沉积物的延迟渗流都将沉积物碳释放到地表水。溶解无机碳的流出通量超过溶解有机碳。二氧化碳和甲烷排放量分别为 169 和 0.25 mmol m ^-2  d ^-1， 分别。孔隙水碳通量超过了碳外流。这需要在将孔隙水碳输出到海洋之前，在盐沼中进行一些碳处理（例如，降解或排放到大气中）。总体而言，孔隙水交换和外流是盐沼碳预算的关键组成部分，在评估其碳封存潜力和减缓气候变化的战略时应予以考虑。