Related topics: hydrogen · protein · cells · bacteria · carbon dioxide

World's lakes losing oxygen rapidly as planet warms

Oxygen levels in the world's temperate freshwater lakes are declining rapidly—faster than in the oceans—a trend driven largely by climate change that threatens freshwater biodiversity and drinking water quality.

Small 'snowflakes' in the sea play a big role

In the deep waters that underlie the productive zones of the ocean, there is a constant rain of organic material called "marine snow." Marine snow does not only look like real snow but also behaves similarly: Large flakes ...

Recruiting bacteria to build catalysts atom by atom

Exploiting the unusual metal-reducing ability of the iron-breathing bacterium Geobacter sulfurreducens, KAUST researchers have demonstrated a cheap and reliable way to synthesize highly active single-atom catalysts. The innovation, ...

Water treatment: Removing hormones with sunlight

Organic pollutants such as pharmaceuticals, pesticides, and hormones, even at nanoscale concentrations, contaminate drinking water in a way that poses significant risks to humans, animals and the environment. In particular, ...

Nanoparticles: The complex rhythm of chemistry

Most commercial chemicals are produced using catalysts. Usually, these catalysts consist of tiny metal nanoparticles that are placed on an oxidic support. Similar to a cut diamond, whose surface consists of facets oriented ...

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Oxygen (pronounced /ˈɒksɨdʒɨn/, from the Greek roots ὀξύς (oxys) (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly reactive nonmetallic period 2 element that readily forms compounds (notably oxides) with almost all other elements. At standard temperature and pressure two atoms of the element bind to form dioxygen, a colorless, odorless, tasteless diatomic gas with the formula O2. Oxygen is the third most abundant element in the universe by mass after hydrogen and helium and the most abundant element by mass in the Earth's crust. Diatomic oxygen gas constitutes 20.9% of the volume of air.

All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all complex life. Oxygen is toxic to obligately anaerobic organisms, which were the dominant form of early life on Earth until O2 began to accumulate in the atmosphere 2.5 billion years ago. Another form (allotrope) of oxygen, ozone (O3), helps protect the biosphere from ultraviolet radiation with the high-altitude ozone layer, but is a pollutant near the surface where it is a by-product of smog. At even higher low earth orbit altitudes monatomic oxygen (O1) is a significant presence and a cause of erosion for spacecraft.

Oxygen was independently discovered by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774, but Priestley is often given priority because his publication came out in print first. The name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. Oxygen is produced industrially by fractional distillation of liquefied air, use of zeolites to remove carbon dioxide and nitrogen from air, electrolysis of water and other means. Uses of oxygen include the production of steel, plastics and textiles; rocket propellant; oxygen therapy; and life support in aircraft, submarines, spaceflight and diving.

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