硫化海洋への移行は,およそ184億年前である
Simon W Poulton1, Philip W Fralick, Donald E Canfield
1Danish Center for Earth System Science, Institute of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. s.poulton@biology.sdu.dk
Nature
|September 10, 2004
まとめ
プロテロゾイク時代の海洋化学は,大気中の酸素が上昇したにもかかわらず,完全に酸素化されていなかった. 沈殿物は,酸素だけでなく,硫化物条件が,帯状鉄形成 (BIF) の堆積を終わらせ,生命の初期進化に影響を与えたことを明らかにしています.
科学分野:
- 地質化学 地質化学
- パレオセアノグラフィー
- 初期の地球の条件.
背景:
- プロテロゾイク・エオン (2550億54億年前) は,地球を無酸素から酸素の世界へと移行させた.
- 海洋化学の変化は,伝統的に大気中の酸素の上昇と海洋の酸素化に起因していた.
- この酸化が,鉄の酸化を引き起こし,約18億年前に結束帯状鉄形成 (BIF) の堆積を終わると考えられていた.
研究 の 目的:
- プロテロゾイク時代の帯状鉄形成 (BIF) 堆積の終結に関する競合する仮説を評価する.
- グローバルなBIF堆積の最終段階の海洋化学を調査する.
- プロテロゾイク時代の海洋環境における酸素と硫黄の役割を理解する.
主な方法:
- 堆積物における鉄-硫黄-炭素 (Fe-S-C) 体系学的分析.
- カナダの約18億年前のアニミキー群の堆積物の調査.
- 海洋化学と再酸化条件の再構築.
主要な成果:
- 主要の世界的なBIF堆積期間の後に継続した海洋無酸素が実証されています.
- 硫化基底水への移行がBIF堆積の終了の原因であることを示した.
- 硫化状態が0.80.58億年前まで続いた可能性があることを示した.
結論:
- 海洋の無酸素と硫黄の条件は,酸素のみではなく,BIFの堆積を終わらせるための鍵でした.
- これらの硫酸性条件は,原産物を潜在的に制限し,藻類の進化を阻害する可能性がある.
- プロテロゾイク時代の海洋が完全酸素化に至るまでの経路は複雑で長期的であった.
関連する概念動画
The Sulfur Cycle
Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the atmosphere as sulfur dioxide (SO2), sulfur is released by decaying organisms, weathered rocks, geothermal vents, volcanos, and burning fossil fuels. It is deposited into the ecosystem, cycled through the biotic community, and either released back into the atmosphere as gas or deposited in marine sediment for long-term storage and eventual...
The Colonization of Land
Changes in the environment of the early Earth drove the evolution of organisms. As prokaryotic organisms in the oceans began to photosynthesize, they produced oxygen. Eventually, oxygen saturated the oceans and entered the air, resulting in an increase in atmospheric oxygen concentration, known as the oxygen revolution approximately 2.3 billion years ago. Therefore, organisms that could use oxygen for cellular respiration had an advantage. More than 1.5 years ago, eukaryotic cells and...
What is Evolutionary History?
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.
The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
Origin of Photosynthesis
Photosynthesis represents a fundamental biological process that transformed Earth's atmosphere and paved the way for complex life. Emerging roughly 3.4–3.8 billion years ago, the earliest photosynthetic organisms harnessed light energy to produce organic compounds. These anoxygenic phototrophs used electron donors like hydrogen sulfide (H₂S) or ferrous iron (Fe²⁺), rather than water, and did not release molecular oxygen (O₂) as a byproduct. Various groups, including green sulfur and purple...
Microbes and the Sulfur Cycle
Sulfur is a vital element in Earth's biogeochemical systems. It transitions through various inorganic states, including sulfate (SO₄²⁻), elemental sulfur (S⁰), and sulfide (S²⁻). Abiotic and biological mechanisms across oxic and anoxic environments intricately mediate these transformations. Sulfate, the most oxidized form of sulfur, is predominantly stored in rocks, marine sediments, and oceanic waters, acting as a long-term reservoir in the global sulfur cycle.In oxic environments,...


