Geological sources of methane (CH₄), such as hydrocarbon seeps, are significant yet poorly constrained sources of CH₄ to seawater and the overlying atmosphere_. We investigate the radiocarbon content (¹⁴C) and concentrations of dissolved CH₄ in surface waters from the Coal Oil Point seep field to test the hypothesis that geological sources can dominate the regional background signal of CH₄. We find that surface waters with elevated CH₄ concentration were populated with seep‐CH₄ and that lower concentrations of CH₄ were well explained by mixing with the regional background of nongeological CH₄. Substantial differences in concentration and ¹⁴C‐CH₄ were observed over distances <5 km, demonstrating that surface currents mix background‐CH₄ into the seep field. These results indicate that even a prolific seep region like the Santa Barbara Basin exerts limited influence on the regional background of CH₄ in the surface layer but is a significant driver of patchiness in oceanic CH₄ biogeochemistry.

中文翻译：

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海洋甲烷中的放射性碳揭示了渗漏对地表水的斑片效应

甲烷（CH ₄）的地质来源，例如碳氢化合物渗漏，是重要的甲烷，但对海水和上覆大气的CH ₄来源的限制却很有限_。我们调查了来自煤油点渗漏场的地表水中的放射性碳含量（¹⁴ C）和溶解的CH ₄浓度，以检验假说地质源可支配CH ₄的区域背景信号。我们发现与升高CH该表面水域₄浓度填充有渗漏-CH ₄和CH的较低浓度₄是井通过与nongeological CH的区域背景解释混合₄。在小于5 km的距离上观察到浓度和¹⁴ C-CH _4的显着差异，表明表面电流将背景-CH ₄混合到渗流场中。这些结果表明，即使像圣塔芭芭拉盆地这样的多产的渗漏区域，对表层CH ₄的区域背景的影响也有限，但却是海洋CH ₄生物地球化学中斑片状的重要驱动力。