大気中の酸素の上昇を年代付けする
A Bekker1, H D Holland, P-L Wang
1Department of Earth and Planetary Sciences, 20 Oxford Street, Harvard University, Cambridge, Massachusetts 02138, USA. abekker@fas.harvard.edu
Nature
|January 9, 2004
まとめ
大気中の酸素の上昇は,232億年前に発生し,ピライトと鉄の形成における硫黄の同位体によって証明されました. この発見は,初期の地球についての私たちの理解を洗練します.
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
- 初期の地球の地質学
背景:
- 以前の地質学的および地化学的データによると,大気中の酸素が低かったのは24億5500万年前より前であり,22億2200万年前には有意なレベルに達していた.
- 大酸化イベントのタイミングは,初期の地球の大気進化を理解する上で重要な問題です.
研究 の 目的:
- 大気中の酸素の上昇のタイミングに関する新しい証拠を提示する.
- 南アフリカにあるRooihoogteとTimeball Hillの堆積環境を調査する.
主な方法:
- 硫黄の同位体組成のための有機に富んだシェールにおけるシンゲネティックピライトの分析.
- 研究された地質単位内の鉄の形成物,例えば sideritic 石塊や hematitic pisolites/oölites の調査.
- 硫黄の同位体データを解釈して,質量独立分化 (MIF) の証拠と,大気中の酸素濃度に対するその影響.
主要な成果:
- 硫黄イソトープの幅広く,質量独立分化がないシンゲネティックピライトは,232億年前のシェールで発見された.
- これは,シェール堆積の過程で,大気中の酸素 (10−5倍以上の現在の大気レベル) が有意に存在していることを示している.
- シデリト型鉄形成の小石と厚い鉄岩層の存在は,これらの形成の堆積の間に大気中の酸素の有意な上昇をさらにサポートしています.
結論:
- 大気中の酸素の上昇は232億年前に発生し,以前に推定された時間枠に先行しました.
- この発見は,この酸化イベントが,古プロテロゾーイク期の氷河イベントと一致した可能性があることを示唆しています.
- この研究は,大酸化イベントのタイムラインと,初期の地球における主要な気候変化との潜在的なリンクを精査しています.
関連する概念動画
Gas Exchange and Transport
73.6K
Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them.
73.6K
Physical Principles Governing Gas Exchange
4.0K
Gas behavior plays a vital role in understanding bodily processes such as external and internal respiration. External respiration involves the diffusion of oxygen into the blood and carbon dioxide out of it in the lungs. In contrast, internal respiration happens in body tissues, where these gases move in opposite directions.
Gas Laws Governing Respiration
The behavior of gases is guided by Dalton's Law of partial pressures and Henry's Law.
Dalton's Law asserts that the total...
Gas Laws Governing Respiration
The behavior of gases is guided by Dalton's Law of partial pressures and Henry's Law.
Dalton's Law asserts that the total...
4.0K
Oxygen Transport in the Blood
7.9K
Hemoglobin (Hb) is a crucial molecule in the human body, consisting of four polypeptide chains, each bound to an iron-containing heme group. This unique structure enables hemoglobin to bind to oxygen, with each molecule capable of combining with four molecules of oxygen, leading to rapid and reversible oxygen loading. When fully loaded with oxygen, it is called oxyhemoglobin, while hemoglobin that has released oxygen is called reduced hemoglobin or deoxyhemoglobin. As hemoglobin binds oxygen,...
7.9K
Chemical Factors Affecting Respiration Centers
2.7K
Chemical factors such as changing CO2, O2, and H+ levels in arterial blood play a critical role in influencing respiration depth and rates. These variations are detected by chemoreceptors—specialized sensors located in two primary body areas. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla, while peripheral chemoreceptors are located in the aortic arch and carotid arteries.
CO2 has a potent influence on respiration and is strictly regulated....
CO2 has a potent influence on respiration and is strictly regulated....
2.7K
Gas Solubility
133
Gas solubility in liquids forms liquid-gas solutions, such as soft drinks, where carbon dioxide is dissolved in water, and the ocean, where the solubility of oxygen and carbon dioxide supports marine life. The ability of oceans to dissolve gases impacts weather conditions in the troposphere.However, gas-liquid interactions vary. For instance, hydrogen chloride gas is highly soluble in water, while oxygen's solubility is much lower. Because these solutions are non-ideal, Raoult’s law,...
133
Oxygen Delivering System II: Venturi Mask and Transtracheal Oxygen
3.7K
Oxygen therapy is a pivotal aspect of medical care, particularly for patients with respiratory ailments. Two prominent oxygen-delivering systems include the Venturi mask and the transtracheal oxygen catheter.
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
3.7K


