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Oxygen began building up in the atmosphere at approximately 1.85 Ga. At current rates of primary production, today's concentration of oxygen could be produced by photosynthetic organisms in 2,000 years. [ 4] In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 ...
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans ), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes ), all retained by Earth's gravity.
The Miller–Urey experiment was a synthesis of small organic molecules in a mixture of simple gases in a thermal gradient created by heating (right) and cooling (left) the mixture at the same time, with electrical discharges. The Miller–Urey experiment[ 1] (or Miller experiment[ 2]) was an experiment in chemical synthesis carried out in 1952 ...
Banded iron formation largely disappears from the geological record at 1.85 Ga, after peaking at about 2.5 Ga. [19] Banded iron formation can form only when abundant dissolved ferrous iron is transported into depositional basins, and an oxygenated ocean blocks such transport by oxidizing the iron to form insoluble ferric iron compounds. [20]
The atmosphere of Earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases. [2] Most organisms use oxygen for respiration ; lightning and bacteria perform nitrogen fixation which produces ammonia that is used to make nucleotides and amino acids ; plants , algae , and cyanobacteria use carbon ...
For oxygen partial pressures above 2.4 bar, the quantity of oxygen dissolved in the arterial blood exceeds the amount that the body can use, and the hemoglobin is saturated with oxygen in both the veins and the arteries. If more oxygen is added, the partial pressure of oxygen in the venous blood rises. [103]
The iron cycle (Fe) is the biogeochemical cycle of iron through the atmosphere, hydrosphere, biosphere and lithosphere. While Fe is highly abundant in the Earth's crust, [10] it is less common in oxygenated surface waters. Iron is a key micronutrient in primary productivity, [11] and a limiting nutrient in the Southern ocean, eastern equatorial ...
The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the rocky planets in the Solar System in having oceans of liquid water on its surface. [ 2] Liquid water, which is necessary for all known forms of life, continues to exist on the surface of ...