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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 oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. [ 1] The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O 2 ), as it ...
Cosmic rays ionize nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. Cosmic rays are also responsible for the continuous production of a number of unstable isotopes, such as carbon-14, in the Earth's atmosphere through the reaction: n + 14 N → p + 14 C.
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.
Ozone layer. The ozone layer visible from space at Earth's horizon as a blue band of afterglow within the bottom of the large bright blue band that is the stratosphere, with a silhouette of a cumulonimbus in the orange afterglow of the troposphere. The ozone layer or ozone shield is a region of Earth 's stratosphere that absorbs most of the Sun ...
A new study analyzing these modules reveals that these rocky lumps are capable of producing “dark oxygen” 4,000 meters below sea level where light cannot reach. While this discovery could ...
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, and after hydrogen and helium, it ...
Oxygen, O 2, meanwhile, was present in the atmosphere at just 0.001% of its present atmospheric level. [12] [13] The Sun shone at about 70% of its current brightness 4 billion years ago, but there is strong evidence that liquid water existed on Earth at the time. A warm Earth, in spite of a faint Sun, is known as the faint young Sun paradox. [14]