BIOGEOCHEMICAL ASPECTS OF ATMOSPHERIC METHANE
BIOGEOCHEMICAL ASPECTS OF ATMOSPHERIC METHANE
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DOI：
10.1029/gb002i004p00299
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发表时间：
1988-12-01
影响因子：
5.2
通讯作者：
Oremland, R.
中科院分区：
文献类型：
--
作者：
Cicerone, R.;Oremland, R.
甲烷是地球大气中最丰富的有机化学物质，正如各种独立测量结果所示，其浓度随着时间的推移而增加。光化学反应氧化大气中的甲烷；通过这些反应，甲烷对对流层和平流层的化学性质以及包括臭氧、羟基自由基和一氧化碳在内的许多物质产生强烈影响。此外，通过其红外吸收光谱，甲烷是气候系统中重要的温室气体。我们描述并列举了关键角色和反应。然后我们重点关注两种甲烷生产方式：微生物甲烷生产和产热甲烷生产。描述了微生物产甲烷作用，并确定了关键生物体和底物及其特性和栖息地。微生物甲烷氧化限制了某些产甲烷区域的甲烷释放。本文描述了需氧和厌氧氧化以及通过实验测量甲烷产生和氧化速率的方法。回顾了甲烷来源的指标，包括 C 和 H 同位素。我们确定并评估了大气甲烷预算、其来源、汇和停留时间的几个限制。根据这些约束以及有关源和汇的其他数据，我们构建了源和汇、身份和大小的列表。准稳态（文中定义）年源（或汇）总量约为 310(+/- 60) x 10(12) mol (500(+/- 95) x 10(12) g)，但源和汇大小以及多种类型的数据仍存在许多不确定性，可能导致未来更强的约束和修订估计。确定足够的无放射性碳甲烷来源尤其困难。
Methane is the most abundant organic chemical in Earth's atmosphere, and its concentration is increasing with time, as a variety of independent measurements have shown. Photochemical reactions oxidize methane in the atmosphere; through these reactions, methane exerts strong influence over the chemistry of the troposphere and the stratosphere and many species including ozone, hydroxyl radicals, and carbon monoxide. Also, through its infrared absorption spectrum, methane is an important greenhouse gas in the climate system. We describe and enumerate key roles and reactions. Then we focus on two kinds of methane production: microbial and thermogenic. Microbial methanogenesis is described, and key organisms and substrates are identified along with their properties and habitats. Microbial methane oxidation limits the release of methane from certain methanogenic areas. Both aerobic and anaerobic oxidation are described here along with methods to measure rates of methane production and oxidation experimentally. Indicators of the origin of methane, including C and H isotopes, are reviewed. We identify and evaluate several constraints on the budget of atmospheric methane, its sources, sinks and residence time. From these constraints and other data on sources and sinks we construct a list of sources and sinks, identities, and sizes. The quasi-steady state (defined in the text) annual source (or sink) totals about 310(+/- 60) x 10(12) mol (500(+/- 95) x 10(12) g), but there are many remaining uncertainties in source and sink sizes and several types of data that could lead to stronger constraints and revised esti-mates in the future. It is particularly difficult to identify enough sources of radiocarbon-free methane.