Radiocarbon (∆¹⁴C) measurements suggest the deep ocean stores marine dissolved organic carbon (DOC) on millennial timescales. The mechanisms that mediate this residence time remain unconstrained. Solid-phase extraction (SPE) has emerged as a widely used technique to isolate DOC for subsequent analyses. We present SPE-DOC concentrations and ∆¹⁴C values for three GO-SHIP Repeat Hydrography transects, spanning the Pacific, Southern and Indian Oceans. Comparisons of SPE-DOC with total DOC ∆¹⁴C values are used with an isotopic mass-balance to estimate the size of the refractory DOC (RDOC) reservoir and changes in RDOC relative abundance in the global ocean. Estimated RDOC abundance is similar across the deep Pacific and Indian Oceans (average = 93 ± 5%, 35 ± 6 μM), whereas RDOC in the surface ocean varies as a function of total DOC concentration. Our results fill in spatial SPE-DOC ∆¹⁴C sampling gaps for the global ocean, and our mass-balance RDOC estimates are consistent with previous observations.

中文翻译：

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对固相可萃取溶解有机碳的全球循环的新放射性碳约束

放射性碳 (∆ ¹⁴ C) 测量表明，深海在千年时间尺度上储存了海洋溶解有机碳 (DOC)。调节此停留时间的机制仍然不受限制。固相萃取 (SPE) 已成为一种广泛使用的技术，用于分离 DOC 以进行后续分析。我们展示了跨越太平洋、南洋和印度洋的三个 GO-SHIP 重复水文横断面的SPE-DOC 浓度和 Δ ¹⁴ C 值。与总DOCΔSPE-DOC的比较¹⁴C 值与同位素质量平衡一起使用，以估计难熔 DOC (RDOC) 储层的大小以及全球海洋中 RDOC 相对丰度的变化。估计的 RDOC 丰度在深太平洋和印度洋中相似（平均值 = 93 ± 5%，35 ± 6 μM），而表层海洋中的 RDOC 作为总 DOC 浓度的函数而变化。我们的结果填补了全球海洋的空间 SPE-DOC ∆ ¹⁴ C 采样空白，我们的质量平衡 RDOC 估计值与之前的观察结果一致。