Security

Red Cross chief: cyber attacks increasing on hospitals

The president of the International Committee of the Red Cross warned Wednesday that the frequency of sophisticated cyber attacks against hospitals, electricity and water supplies, and other critical civilian infrastructure ...

Energy & Green Tech

Geothermal energy from shell limestone

In 2017 a huge storage facility in the pores of a sandstone layer at a depth of between 1015 and 1045 meters below Berlin's Grunewald forest that had been used to temporarily store natural gas, to cover the city's fluctuating ...

Engineering

Contextual engineering adds deeper perspective to local projects

When engineers develop drinking water systems, they often expect their technology and expertise to work in any context. But project success depends as much on the people and place as on technical design, says Ann-Perry Witmer, ...

Other

How dangerous are burning electric cars?

There' s a loud bang, and then it starts: A battery module of an electric car is on fire in the Hagerbach test tunnel. A video of the test impressively shows the energy stored in such batteries: Meter-long flames hiss through ...

Energy & Green Tech

Upcycling plastic waste toward sustainable energy storage

What if you could solve two of Earth's biggest problems in one stroke? UC Riverside engineers have developed a way to recycle plastic waste, such as soda or water bottles, into a nanomaterial useful for energy storage.

Energy & Green Tech

Harnessing the sun to purify concentrated waste streams

Reverse osmosis is one of the most common methods for purifying saline water, but the process produces limited results. About 20% to 50% of the water that enters the system remains as a concentrated waste stream.

page 1 from 19

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.

This text uses material from Wikipedia, licensed under CC BY-SA