Using DNA in the water tell us how many fish are there

River water, lake water, and seawater contain DNA belonging to organisms such as animals and plants. Ecologists have begun to actively analyze such DNA molecules, called environmental DNA, to assess the distribution of macro-organisms. ...

How life on Earth could help us find life on Mars

In our continuing search for other life in the universe, one place has always looked promising—Mars. It is a rocky planet like Earth, orbiting the same star, and at a distance where water could have been present on the ...

Scientists dissociate water apart efficiently with new catalysts

University of Oregon chemists have made substantial gains in enhancing the catalytic water dissociation reaction in electrochemical reactors, called bipolar membrane electrolyzers, to more efficiently rip apart water molecules ...

Cause of abnormal groundwater rise after large earthquake

Increases in groundwater levels and volumes after large earthquakes have been observed around the world, but the details of this process have remained unclear due to a lack of groundwater data directly before and after an ...

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Water

Water is a ubiquitous chemical substance, composed of hydrogen and oxygen, that is essential for the survival of many known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.

Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.

Clean, fresh drinking water is essential to human and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.

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