In recent years, methane (CH4) has received increasing scientific attention because it is the most abundant non-CO2 atmospheric greenhouse gas (GHG) and controls numerous chemical reactions in the troposphere and stratosphere. However, there is much that is unknown about CH4 sources and sinks and their evolution over time. Here we show that near-surface cavities in the uppermost vadose zone are now actively removing atmospheric CH4. Through seasonal geochemical tracing of air in the atmosphere, soil and underground at diverse geographic and climatic locations in Spain, our results show that complete consumption of CH4 is favoured in the subsurface atmosphere under near vapour-saturation conditions and without significant intervention of methanotrophic bacteria. Overall, our results indicate that subterranean atmospheres may be acting as sinks for atmospheric CH4 on a daily scale. However, this terrestrial sink has not yet been considered in CH4 budget balances.

中文翻译：

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地下大气可能是每天的甲烷汇。

近年来，由于甲烷（CH4）是最丰富的非CO2大气温室气体（GHG），并且控制对流层和平流层中的许多化学反应，因此受到越来越多的科学关注。但是，关于CH4的源和汇及其随时间的演变，还有很多未知的地方。在这里，我们表明最上方的渗流带中的近地表腔现在正在积极清除大气中的CH4。通过对西班牙不同地理和气候位置的大气，土壤和地下空气进行季节性地球化学示踪，我们的结果表明，在接近蒸汽饱和的条件下，并且没有显着的甲烷营养细菌的干扰下，地下气体中CH4的完全消耗受到青睐。全面的，我们的结果表明，地下大气每天可能是大气中CH4的汇。但是，尚未在CH4预算余额中考虑此地面沉没。