The evolution of the atmosphere in the Archaean and early Proterozoic  

作　　者：NISBET Euan FOWLER C Mary R 

机构地区：[1]Deptartment of Earth Sciences,Royal Holloway,University of London

出　　处：《Chinese Science Bulletin》2011年第1期4-13,共10页

摘　　要：Key steps in atmospheric evolution occurred in the Archaean.The Hadean atmosphere was created by the inorganic processes of volatile accretion from space and degassing from the interior,and then modified by chemical and photochemical processes.The air was probably initially anoxic,though there may have been a supply of oxidation power as a consequence of hydrodynamic escape to space of hydrogen from water.Early subduction may have removed CO2 and the Hadean planet may have been icy.In the Archaean,as anoxygenic and then oxygenic photosynthesis evolved,biological activity remade the atmosphere.Sedimentological evidence implies there were liquid oceans despite the faint young Sun.These oceans may have been sustained by the greenhouse warming effect of biologically-made methane.Oxygenesis in the late Archaean would have released free O2 into the water.This would have created oxic surface waters,challenging the methane greenhouse.After the Great Oxidation Event around 2.3 to 2.4 billion years ago,the atmosphere itself became oxic,perhaps triggering a glacial crisis by cutting methane-caused greenhouse warming.By the early Proterozoic,all the key biochemical processes that maintain the modern atmosphere were probably present in the microbial community.Key steps in atmospheric evolution occurred in the Archaean. The Hadean atmosphere was created by the inorganic processes of volatile accretion from space and degassing from the interior, and then modified by chemical and photochemical processes. The air was probably initially anoxic, though there may have been a supply of oxidation power as a consequence of hydrodynamic escape to space of hydrogen from water. Early subduction may have removed CO2 and the Hadean planet may have been icy. In the Archaean, as anoxygenic and then oxygenic photosynthesis evolved, biological activity remade the atmosphere. Sedimentological evidence implies there were liquid oceans despite the faint young Sun. These oceans may have been sustained by the greenhouse warming effect of biologically-made methane. Oxygenesis in the late Archaean would have released free 02 into the water. This would have created oxic surface waters, challenging the methane greenhouse. After the Great Oxidation Event around 2.3 to 2.4 billion years ago, the atmosphere itself became oxic, perhaps triggering a glacial crisis by cutting methane-caused greenhouse warming. By the early Proterozoic, all the key biochemical processes that maintain the modem atmosphere were probably present in the microbial community.

关 键 词：晚太古代 大气演化 早元古代 二氧化碳 温室效应 光化学过程 微生物群落 调制解调器 

分 类 号：P532[天文地球—古生物学与地层学]