Modulation of oxygen production in Archaean oceans by episodes of Fe(II) toxicity
Modulation of oxygen production in Archaean oceans by episodes of Fe(II) toxicity
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DOI：
10.1038/ngeo2327
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发表时间：
2015-02
影响因子：
18.3
通讯作者：
E. Swanner;Aleksandra M. Mloszewska;O. Cirpka;R. Schoenberg;K. Konhauser;A. Kappler
中科院分区：
文献类型：
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作者：
E. Swanner;Aleksandra M. Mloszewska;O. Cirpka;R. Schoenberg;K. Konhauser;A. Kappler
在24亿至23亿年前的大氧化事件之前的几亿年，氧气就积累在地球海洋和大气的表面沃茨中。在大氧化事件之前，与地幔柱事件相关的增强的海底火山作用时期向海水提供Fe（II）。这些时期通常与侏罗纪沉积记录中分子氧存在的标志消失相吻合。水体中Fe（II）的存在会导致某些生物体的氧化应激，这是由于Fe（II）和氧气之间的反应产生活性氧物质。在这里，我们测试的假设，富铁（II），缺氧的水上升到透光层在晚白垩世期间进行产氧光合细菌Fe（II）的毒性。在实验室实验中，我们发现，提供Fe（II）的缺氧生长介质住房的常见物种的嗜热蓝细菌的产氧光合作用的效率和它们的生长速率下降。我们认为，这是因为细胞内活性氧浓度增加。我们使用地球化学模型表明，在太古代晚期透光带条件下，Fe（II）的毒性可能会大大抑制水柱氧气的产生，从而减少氧气向大气的通量。因此，我们建议，大气氧化的时间是由海底，羽状火山活动的时间，与Fe（II）的毒性作为调节因素。
Oxygen accumulated in the surface waters of the Earth’s oceans and atmosphere several hundred million years before the Great Oxidation Event between 2.4 and 2.3 billion years ago. Before the Great Oxidation Event, periods of enhanced submarine volcanism associated with mantle plume events supplied Fe(II) to sea water. These periods generally coincide with the disappearance of indicators of the presence of molecular oxygen in Archaean sedimentary records. The presence of Fe(II) in the water column can lead to oxidative stress in some organisms as a result of reactions between Fe(II) and oxygen that produce reactive oxygen species. Here we test the hypothesis that the upwelling of Fe(II)-rich, anoxic water into the photic zone during the late Archaean subjected oxygenic phototrophic bacteria to Fe(II) toxicity. In laboratory experiments, we found that supplying Fe(II) to the anoxic growth medium housing a common species of planktonic cyanobacteria decreased both the efficiency of oxygenic photosynthesis and their growth rates. We suggest that this occurs because of increasing intracellular concentrations of reactive oxygen species. We use geochemical modelling to show that Fe(II) toxicity in conditions found in the late Archaean photic zone could have substantially inhibited water column oxygen production, thus decreasing fluxes of oxygen to the atmosphere. We therefore propose that the timing of atmospheric oxygenation was controlled by the timing of submarine, plume-type volcanism, with Fe(II) toxicity as the modulating factor.