The response of Arctic Ocean biogeochemistry to subsurface flow driven by permafrost thaw is poorly understood. We present dissolved chloride and water isotopic data from the Chukchi Sea Shelf sediments that reveal the presence of a meteoric subsurface flow enriched in cations with a radiogenic Sr fingerprint. This subsurface fluid is also enriched in dissolved inorganic carbon and methane that bear isotopic compositions indicative of a carbon reservoir modified by reactions in a closed system. Such fluid characteristics are in stark contrast with those from other sites in the Chukchi Sea where the pore water composition shows no sign of meteoric input, but reflect typical biogeochemical reactions associated with early diagenetic sequences in marine sediment. The most likely source of the observed subsurface flow at the Chukchi Sea Shelf is from the degradation of permafrost that had extended to the shelf region during the Last Glacial Maximum. Our data suggest that the permafrost-driven subsurface flow most likely took place during the 2–3°C warming in the Early Holocene Thermal Maximum. This time scale is supported by numerical simulation of pore water profiles, which indicate that a minimum of several thousand years must have passed since the cessation of the subsurface methane-bearing fluid flow.

中文翻译：

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在早期全新世热最大值 (EHTM) 期间向楚科奇海排放的流星地下流体脉冲

北冰洋生物地球化学对永久冻土融化驱动的地下流动的响应知之甚少。我们提供了来自楚科奇海陆架沉积物的溶解氯化物和水同位素数据，这些数据揭示了存在富含具有放射成因 Sr 指纹的阳离子的流星地下流。这种地下流体还富含溶解的无机碳和甲烷，这些无机碳和甲烷具有同位素组成，表明在封闭系统中的反应改变了碳储层。这种流体特征与楚科奇海其他地点的流体特征形成鲜明对比，那里的孔隙水成分没有显示出大气输入的迹象，但反映了与海洋沉积物中早期成岩序列相关的典型生物地球化学反应。在楚科奇海陆架观测到的地下流的最可能来源是在末次盛冰期扩展到陆架区域的永久冻土退化。我们的数据表明，永久冻土驱动的地下流动最有可能发生在早期全新世热最大值的 2-3°C 变暖期间。这个时间尺度得到了孔隙水剖面的数值模拟的支持，这表明自地下含甲烷流体流动停止以来，至少已经过去了几千年。