低硫酸塩の海洋とプロテロゾーイク生物圏の長期にわたる酸素化
Linda C Kah1, Timothy W Lyons, Tracy D Frank
1Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA. lckah@utk.edu
Nature
|October 16, 2004
まとめ
海の硫酸塩レベルは,初期の地球から10億年以上も低かった.
科学分野:
- 地質化学 地質化学
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- バイオジオケミストリー バイオジオケミストリー
背景:
- 地球の初期の生物圏の酸素化は,おそらく海洋硫酸塩を増加させた.
- プロテロゾイク期の硫酸塩濃度の再構築は,初期の地球を理解する上で極めて重要です.
- プロテロゾーイク時代の硫酸塩濃度に関するデータは限られている.
研究 の 目的:
- プロテロゾーイク時代の海洋硫酸塩濃度を再構築するために.
- 低レベルの海洋硫酸塩の持続期間を調査する.
- 生物圏の進化を地化学的変化と結びつける.
主な方法:
- 海洋炭酸塩関連硫酸塩における硫黄の同位体組成の分析.
- 硫黄の同位体変化の速度依存モデルを適用する.
- 地質学的時間スケールにおける海洋硫酸塩濃度の変化を追跡する.
主要な成果:
- 海洋硫酸塩の濃度は,初期酸化後の1 Gyr以上で1.5~4.5 mM (5~15%の現代値) であった.
- 硫黄の同位体における重層学的な変化が観察されました.
- 低濃度の海洋硫酸塩は長期にわたって持続した.
結論:
- 地球の生物圏の長期にわたる酸素化は,持続的に低い海洋硫酸塩レベルによって支えられています.
- この発見は,生物圏の進化を鉱物堆積,元素循環,微量金属の利用可能性と結びつけるものである.
- プロテロゾイク硫酸塩の動態を理解することは,初期の地球の環境史の解釈の鍵です.
関連する概念動画
Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
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...
Microbial Mats
Microbial communities forming biofilms and mats represent complex, spatially structured ecosystems where metabolic processes are stratified according to light, oxygen, and nutrient gradients. Biofilms are initial colonization stages, only a few millimeters thick, while mature microbial mats can reach centimeter-scale thickness and display intricate vertical organization. Their structural and functional heterogeneity allows microorganisms to occupy distinct ecological niches within a few...
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,...
Marine Microbial Ecology
Marine microbial ecosystems are shaped by distinct physicochemical limits, including high salinity, low nutrient availability, and fluctuating oxygen levels. These conditions favor smaller microbial cell sizes, which maximize their surface-to-volume ratio for efficient nutrient uptake.Microbial activity and community composition are closely linked to biogeochemical cycles, particularly in dynamic environments like estuaries, where halotolerant microbes thrive in response to variable salinity...
Deep Sea Microbial Ecology
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches extending beyond...


