Sessions Alex L, Doughty David M, Welander Paula V, Summons Roger E, Newman Dianne K
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
Curr Biol. 2009 Jul 28;19(14):R567-74. doi: 10.1016/j.cub.2009.05.054.
The rise of atmospheric O(2) was a milestone in the history of life. Although O(2) itself is not a climate-active gas, its appearance would have removed a methane greenhouse present on the early Earth and potentially led to dramatic cooling. Moreover, by fundamentally altering the biogeochemical cycles of C, N, S and Fe, its rise first in the atmosphere and later in the oceans would also have had important indirect effects on Earth's climate. Here, we summarize major lines of evidence from the geological literature that pertain to when and how O(2) first appeared in significant amounts in the atmosphere. On the early Earth, atmospheric O(2) would initially have been very low, probably <10(-5) of the present atmospheric level. Around 2.45 billion years ago, atmospheric O(2) rose suddenly in what is now termed the Great Oxidation Event. While the rise of oxygen has been the subject of considerable attention by Earth scientists, several important aspects of this problem remain unresolved. Our goal in this review is to provide a short summary of the current state of the field, and make the case that future progress towards solving the riddle of oxygen will benefit greatly from the involvement of molecular biologists.
大气中氧气的增加是生命史上的一个里程碑。尽管氧气本身并非一种影响气候的气体，但其出现会消除早期地球上存在的甲烷温室效应，并可能导致急剧降温。此外，通过从根本上改变碳、氮、硫和铁的生物地球化学循环，其首先在大气中、随后在海洋中的增加也会对地球气候产生重要的间接影响。在此，我们总结了地质文献中有关氧气首次大量出现在大气中的时间和方式的主要证据线索。在早期地球上，大气中的氧气最初会非常低，可能低于当前大气水平的10^(-5)。大约在24.5亿年前，大气中的氧气在现在被称为大氧化事件的过程中突然增加。虽然氧气的增加一直是地球科学家相当关注的主题，但这个问题的几个重要方面仍未得到解决。我们在这篇综述中的目标是对该领域的当前状况进行简要总结，并说明未来在解开氧气之谜方面取得的进展将极大地受益于分子生物学家的参与。
