Ramped pyrolysis oxidation (RPO) thermogram data of DOC from water samples collected during R/V Western Flyer Benthic-Pelagic Coupling expedition to Station M in the eastern Pacific Ocean in April 2018

The >5000-year radiocarbon age (14C-age) of much of the 630±30 Pg C oceanic dissolved organic carbon (DOC) reservoir remains an enigma in the marine carbon cycle. The fact that DOC is significantly older than dissolved inorganic carbon (DIC) at every depth in the ocean forms the basis of our current framing of the marine DOC cycle where some component persists over multiple cycles of ocean mixing. As a result, 14C-depleted, aged DOC is hypothesized to be present as a uniform reservoir with a constant 14C signature and concentration throughout the water column. However, a key requirement of this model would be direct observations of DOC with similar 14C signatures in the surface and deep ocean. To address this data gap, we applied a thermal fractionation method to investigate DOC in water samples collected from a range of water column depths during the R/V Western Flyer cruise to Station M off the coast of central California in April 2018. This dataset presents thermogram data and evolved CO2 from ramped pyrolysis oxidation (RPO) procedures.

全球海洋溶解有机碳（dissolved organic carbon, DOC）库总储量为630±30 Pg C，其中大部分组分的放射性碳年龄（radiocarbon age, 14C-age）已超5000年，这一问题仍是海洋碳循环研究领域的未解之谜。海洋各深度层的DOC均显著老于溶解无机碳（dissolved inorganic carbon, DIC），这一事实构成了当前海洋DOC循环研究框架的核心依据：部分DOC组分可在多次海洋混合循环中持续留存。据此，学界提出假说：贫化14C的老化DOC以均匀储库的形式存在，在整个水柱中保持恒定的14C同位素特征与浓度。然而，该模型的核心验证条件是需直接观测到表层与深海大洋中具有相似14C特征的DOC。为填补这一数据空白，我们于2018年4月参与「Western Flyer」号科考船前往加州中部沿岸M站位的航次，采集了不同深度层的海水样品，并采用热分级方法（thermal fractionation method）对其中的DOC开展研究。本数据集包含升温热解氧化（ramped pyrolysis oxidation, RPO）流程得到的热谱数据与逸出的CO₂数据。