New, electricity-free desalination method shows promise

Researchers from The Australian National University have proposed a new method for desalinating water that avoids many of the unwanted side effects of traditional desalinating techniques and that reduces the energy required ...


Bionic robot arms as flexible and gentle as an elephant's trunk

Artificial muscles and nerves made from the shape memory alloy nickel-titanium are making robot arms as supple and agile as their animal counterparts. But these artificial limbs also weigh less, will work tirelessly and can ...

Energy & Green Tech

A step toward producing solar fuels out of thin air

A device that can harvest water from the air and provide hydrogen fuel—entirely powered by solar energy—has been a dream for researchers for decades. Now, EPFL chemical engineer Kevin Sivula and his team have made a significant ...

Energy & Green Tech

'Bio-batteries' enable us to store solar and wind energy

Up until now it has been a challenge to store the energy we generate when the sun is shining and the wind is blowing. But researchers at a laboratory in Trondheim in Norway have succeeded in doing just this—and entirely ...


Nano-engineered sealer leads to more durable concrete

A nanomaterials-engineered penetrating sealer developed by Washington State University researchers is able to better protect concrete from moisture and salt—the two most damaging factors in crumbling concrete infrastructure ...


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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