The disequilibrium combination of abundant methane and carbon dioxide has been proposed as a promising exoplanet biosignature that is readily detectable with upcoming telescopes such as the James Webb Space Telescope. However, few studies have explored the possibility of nonbiological CH 4 and CO 2 and related contextual clues. Here we investigate whether magmatic volcanic outgassing on terrestrial planets can produce atmospheric CH 4 and CO 2 with a thermodynamic model. Our model suggests that volcanoes are unlikely to produce CH 4 fluxes comparable to biological fluxes. Improbable cases where volcanoes produce biological amounts of CH 4 also produce ample carbon monoxide. We show, using a photochemical model, that high abiotic CH 4 abundances produced by volcanoes would be accompanied by high CO abundances, which could be a detectable false-positive diagnostic. Overall, when considering known mechanisms for ...

中文翻译：

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来自火山作用的地球大气中的大量甲烷是不可能的，并加强了甲烷作为生物签名的理由

大量甲烷和二氧化碳的不平衡组合已被提出作为一种有前途的系外行星生物特征，可以用即将出现的诸如詹姆斯·韦伯太空望远镜这样的望远镜来探测。但是，很少有研究探索非生物CH 4和CO 2以及相关上下文线索的可能性。在这里，我们用热力学模型研究了地球行星上的岩浆火山脱气是否能产生大气中的CH 4和CO 2。我们的模型表明，火山不太可能产生与生物通量相当的CH 4通量。火山产生生物量的CH 4的可能性极小，也会产生大量的一氧化碳。我们使用光化学模型显示，火山产生的高非生物CH 4丰度将伴随着高CO丰度，这可能是可检测的假阳性诊断。总的来说，在考虑已知的机制时...