Antiquity and evolutionary status of bacterial sulfate reduction: Sulfur isotope evidence
Antiquity and evolutionary status of bacterial sulfate reduction: Sulfur isotope evidence
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细菌硫酸盐还原的古代和进化状态：硫同位素证据
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发表时间：
1979
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通讯作者：
M. Schidlowski
中科院分区：
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作者：
M. Schidlowski
根据前寒武纪沉积硫同位素记录，可以得出以下结论：（1）早白垩世不存在细菌硫酸盐还原的δ3 4型。特别是在Isua条带状铁建造（3.7×109 yr）中观察到的δ3 - 4展度非常窄，与假定的地幔起源的同生岩石产生的相应展度完全一致。最初的同位素模式的微小差异，特别是硫酸盐的同位素模式的微小差异，可能是由光合硫细菌，而不是硫酸盐还原剂。(2)异化硫酸盐还原的同位素证据首先在西伯利亚阿尔丹地盾的上白垩统（1.30 ×109年）和加拿大的Alpicoten和Woman River带状铁建造（2.75×109年）中观察到。这将硫酸盐呼吸器出现的可能时间缩短到2.8-3.1×109年。(3)各种证据表明，光合作用比硫酸盐呼吸作用更古老，第一个硫酸盐还原剂利用的SO 42-很可能来自光合硫细菌对还原态硫化合物的氧化。硫酸盐呼吸必须，反过来，早氧呼吸的O2呼吸多细胞真核生物出现晚在前寒武纪。(4)在古海洋中，大部分的硫酸盐可能是由光合硫细菌产生的，因此SO 42-在古海洋中的积累一定先于自由氧的稳定水平的积累。因此，在古陆沉积物中出现硫酸盐碳酸盐岩并不一定是古大陆氧化风化的证据，因此也不一定是大气氧气库存在的证据。
The presently available sedimentary sulfur isotope record for the Precambrian seems to allow the following conclusions: (1) In the Early Archaean, sedimentary δ3 4 patterns attributable to bacteriogenic sulfate reduction are generally absent. In particular, the δ3 4 spread observed in the Isua banded iron formation (3.7×109 yr) is extremely narrow and coincides completely with the respective spreads yielded by contemporaneous rocks of assumed mantle derivation. Incipient minor differentiation of the isotope patterns notably of Archaean sulfates may be accounted for by photosynthetic sulfur bacteria rather than by sulfate reducers. (2) Isotopic evidence of dissimilatory sulfate reduction is first observed in the upper Archaean of the Aldan Shield, Siberia (∼3.0×109 yr) and in the Michipicoten and Woman River banded iron formations of Canada (2.75×109 yr). This narrows down the possible time of appearance of sulfate respirers to the interval 2.8–3.1×109 yr. (3) Various lines of evidence indicate that photosynthesis is older than sulfate respiration, the SO42− utilized by the first sulfate reducers deriving most probably from oxidation of reduced sulfur compounds by photosynthetic sulfur bacteria. Sulfate respiration must, in turn, have antedated oxygen respiration as O2-respiring multicellular eucaryotes appear late in the Precambrian. (4) With the bulk of sulfate in the Archaean oceans probably produced by photosynthetic sulfur bacteria, the accumulation of SO42−in the ancient seas must have preceded the buildup of appreciable steady state levels of free oxygen. Hence, the occurrence of sulfate evaporites in Archaean sediments does not necessarily provide testimony of oxidation weathering on the ancient continents and, consequently, of the existence of an atmospheric oxygen reservoir.