The water is a chemical Composé ubiquitaire on the Ground, essence for all the known organization S alive. The Human body is thus composed to 70% of water. Water is in general in its liquid state, and has with Room temperature single properties: it is in particular a very effective solvent - water is some time indicated under the name of “universal solvent”. For this reason, the water which one finds on Earth is only exceptionally a chemical compound pure . The Chemical formula of the Pure water, component principal of water, is. “Common” water can have properties different from that used in laboratory (known as “distilled”), so that the Chimiste S will prefer speech of aqueous Solution to define a nonpure water. However, much of components are practically, if not completely, insoluble in water.

Nearly 70% of the surface of the Earth is covered with water (salt water 97% and 3% of Fresh water in various tanks), primarily in the form of Océan S but water is also present in gas form (Steam), liquid and Glace. A stretch of water can be an ocean, a Mer, a Lac, a pond, a Fleuve, a Rivière, a Ruisseau, a channel…. The circulation of water within the various terrestrial compartments is described by the Cycle of water. As a compound essential with the life, water has a great importance in the history of the man (see Géopolitique water for more details).

Etymology and use of the word water

The term water drift probably of Latin aqua via the Languages of oil such as for example the words ewes . The term aqua was then taken again to form some words like aquarium . An aqueous mixture is a mixture whose solvent is water. The prefix Hydro drift him of the Greek.

By water, one often includes/understands colorless liquid made up with majority of water, and not simply the Pure water. According to his chemical composition which induces its origin or its use, one specifies:

Origin

See also: Origin of the water molecule

According to the current design,

  • the Hydrogène is produced very early in the history of the Univers, it is the first formed Atome (cf Big bang);
  • the Oxygène is the product a little later of thermonuclear reaction of Fusion within some star S;
  • These two atoms combine during a exothermic Réaction to form water;
  • When the Ground was formed, water was one of the Molécule S present in significant amount (as in the Météorite S and Comet S).

Water in the Universe

Water was found in interstellar clouds in our Galaxie, the Milky Way. It is thought that water also exists in abundance in other galaxies, because its components, the Hydrogène and the Oxygène, are among most abundant in the Univers.

The interstellar clouds possibly concentrate in solar nebulas and stellar systems such as ours. Initial water can then be found in the Comet S, the Planet S, the dwarf planets and their satellite S. In our solar system, water, in the form of ice, was found:

The liquid shape of water is only known on Earth, although signs indicate that it is (or was) present under the surface of the moon Encelade of Saturn and on the surface of Mars.

Water on Earth

See also: Origin of water on the Earth

The Cycle of water (known scientifically under the name of hydrological cycle ) refers to the continuous exchange of water between the Hydrosphère, the atmosphere, the water of the grounds, surface water, the Ground water, and the Plantes.

The approximate volume of the water of the ground (all water reserves of the world) is of 1.360.000.000 km 3. In this volume:

  • 1.320.000.000 km 3 (97.2%) is in the Océan S,

  • 25.000.000 km 3 (1.8%) is in the Glacier S and the icecaps,
  • 13.000.000 km 3 (0.9%) are subterranean water,
  • 250.000 km 3 (0.02%) in the form of fresh water in the lakes, the inland seas, and the rivers,
  • 13.000 km 3 (0.001%) in the form of atmospheric steam at a given time.

Liquid water is found in all kinds of stretch of water, such as the Océan S, the Mer S, the Lac S, and of river such as the Fleuve S, the Rivière S, the Torrent S, the channels or the pond S. the majority of water on Earth is sea water. Water is also present in the atmosphere in liquid phase and vapor. It also exists in the subterranean water (Aquifère S). The temperature of vaporization of water depends directly on the atmospheric pressure as the formulas show it:

  • presses (in. Hg) = 29.921* (1-6.8753*0.000001 * altitude, ft) ^5.2559

  • boiling not = 49.161 * ln (in. Hg) + 44.932

For example, at the top of the Everest, water boils to approximately 68 [[Degree Celsius °C]], to compare with the 100 °C with the Sea level. Reciprocally, the deep water of the ocean close to the geothermic currents (underwater volcanos for example) can reach temperatures of hundreds of degree and remain liquid.

Physical properties and chemical

See also: Molecule of water

For the majority of the substances, the solid form is more dense that the Phase liquid; thus the pure substance in its solid form will be immersed in a container filled by the pure substance in its liquid form. On the other hand an ordinary block of ice will float in a container filled with water because the ice is less dense than liquid water. It is a very important index property of water. With room temperature, the density of liquid water increases with the fall of the temperature, like the other substances. But to 4 [[Degree Celsius °C]], just above zero, water reaches its maximum density, and when water cools more up to 0 °C, liquid water, in the normal conditions of temperature and pressure, dilates to become less dense. Salinity and the pressure change this behavior. Also the sea water freezes only at temperatures much lower to form the Banquise. The water of the glaciers the Antarctic form of the Iceberg S whose salinity is lower and whose properties differ from that of the plates of the ice-barrier. If water when it freezes becomes less dense, it increases volume. One should not neglect the importance of the phenomenon because it plays a big role in the ecosystem on Earth. For example, if the water were denser when it freezes, the lakes and the oceans located in a polar environment should freeze (from top to bottom). This would occur because the ice would settle at the bottom of the lakes and the bed of the rivers, and the phenomenon necessary to the warming (see below) could not occur in summer, since the hot layer on the surface would be less dense than the frozen layer of the lower part. The fact that this does not occur is significant for the good performance of the natural systems.

Nevertheless, the unusual expansion, due to the hydrogen bond, of water at the time of the congelation which takes place under the usual conditions for the biological systems with 4 °C above the freezing point offers an important advantage for the fresh water life the winter. The cool water on the surface increases density and runs, thus defining currents of convection which cool the whole of the water mass, but when the temperature of water goes down to 4 °C, the water surface sees its density decreasing and it is formed a cold surfacing which finally is intended to freeze. Since the convection of water between 0 °C and 4 °C is blocked by these effects of density, any great stretch of water to the layer of the coldest water on the surface, far from the bottom. This gives an account of many phenomena little known.

some physical values

Specific heat: 4.186 X 10^3 K

Latent heat of vaporization: 22.5 X 10^5

density: 1000

Uses of water

In quantity, the human activity which consumes the most treated water is agriculture, with 70% consumption, comes then the fight against the fire and human consumption.

Water in Agriculture

Water in agriculture is useful has to irrigate everywhere in the world

Water in industry

Water is also used in many industrial processes and machines, such as the Turbine with vapor or the exchanging of heat: one can add to that his use as chemical Solvant. The water rejection used in industry and untreated, causes Pollution S. pollution includes the rejections of solutions (chemical pollution) and the cooling water rejections (thermal pollution). Industry needs pure water for multiple applications, and it uses a large variety of techniques of purification at the same time for the contribution and the rejection of water.

Fight against the fire

See also: Fire control

Water is composed of two gases, the Oxygène and the Hydrogène. Hydrogen is a fuel gas. Oxygen is a gas necessary to combustion. Why water, result of the combination of these two gases, burn doesn't and especially, why it extinguishes the Feu?

Brûler means to be linked with oxygen. It is because coal combines with oxygen in air which it burns and releases from heat. Water cannot burn, since it is already the result of a combustion: that of hydrogen with oxygen.

It extinguishes fire for two reasons, the first being that when an object is covered with water, the oxygen in air cannot arrive until him and activate its combustion; the second, and it is the principal one, is that water can absorb and retain a great quantity of heat when it vaporizes. So the temperature of the object which burns lowers below its ignition point (point burning).

Water in the food

Symbolic system, use and mythology

  • water, element vital for the man, is the natural Boisson par excellence.

  • water is one of the Four elements traditional mythical with the Feu, the Ground and the Air, and was seen by certain like the basic element of the universe. The characteristics of water in this system are the cold and moisture.

  • In the Western Symbolic system, water symbolizes the purification, the revival: for example, the Water bénite of the Baptism, the running water of a River.

  • It is also one of the five elements Chinese with the ground, the Feu, the Bois and the Métal, associated with North and the black color, and one of the Five elements Japanese.

  • In the theory of the body moods, water was associated with the Flegme, also called Pituite in ancient physiology.

Artistic water

Water fascine since always the artists. It was often used by the Watery International Show, which plays with the water and which became Master in art to grant the lights, the music and water moving. It is also an essential element for certain sports where it is the principal element as for the synchronized Natation where the swimmer plays with water to make him make harmonious movements. Water is also quite present on the scenes of theater, opera, of ballet, in the variety, the circuses, as well as the concerts which seeks to reproduce the sounds of water because they are more numerous than it is thought. Despite everything the challenges which water requires, much took up this challenge for the beauty of an element which also causes so many dreams but many nightmare for the world.

Water in the beliefs

Water a long time covered several aspects in the beliefs and the religions of the people. Thus, of mythology gréco-Roman to the current religions, water is always present under various aspects: destroying, purifying, source of life, healer and protective.

  • destroying water:

Water revêt this aspect in particular when one speaks about end of the world or genesis. But that is not limited to the religions monotheists. Thus, in the epopee of Gilgamesh, a storm which lasted six days and seven nights were at the origin of the floods and the destruction of humanity. The Aztèques have them also this representation of water since the world of the Water Sun placed under the sign of the wife of Tlaloc is destroyed by a flood which will shave even to the mountains. “And the Eternal known as: I will exterminate face of the earth the man whom I created, since the man to the cattle, with the reptiles, and the birds of the sky; because I repens to have done them. ”, it is by that the end of the world in the genesis Judeo-Christian is indicated, and to add: “Water grew bigger more and more, and all the high mountains which are under the whole sky were covered. ” (the Genesis, (VI, 7)/(VII, 19)). The myth of the aboriginals of Australia east, as for him, attached to the idea of punishment and not of destruction, since a giant frog would have absorbed all water and drains the ground but would have very recraché while laughing with the distorsions of an eel.

  • purifying water:

This aspect gives to water a character almost crowned in certain beliefs. Indeed, in addition to the external purification that water confers, there is also this faculty to erase the difficulties and the sins of the believers to his contact, and to wash the believer of any stain. The examples are many energy of the purification in the Gange in the hindouism (where many ritual are carried out at the edge of water such as the funeral), or ablutions with water in Islam until the baptism in the Christianity or the initiation of the priests shintoïstes.

  • water healer and protective:

In addition to the purifying aspect, water was packed during the centuries and of the beliefs of a faculty of cure. Several signs of worship and worship dating from the Neolithic era were found close to sources of water in Europe. A long time, of the water bénite amulets were fixed on the entry houses to protect its occupants from the Evil. It is considered that the contact with certain water can go until curing certain diseases. The example nearest is that of the pilgrimage with Lourdes in France where each year of the thousands of people go to bathe in its hot source. Among the cases of cure by the water of Doors, 67 were recognized by the Catholic church. From the point of view of science, the curative properties were shown since, today, hydrotherapy is current in the care of certain diseases.

  • water source of life:

Although sciences showed that water was essential to the life, mythology had well before bench the relationship between water and the birth. Thus, several gods and goddesses Roman and Greek come from water: thus Ocean, a Titan, the river which surrounds the world and his wife Téthys, a titanide, both resulting from water gave rise to the gods rivers and to more than three miles Océanides, their daughters. Others more famous have their life related to water such Venus (“that which leaves the sea”), Amphitrite (goddess of the sea), Poséidon or Nérée (marine divinity).

Water like reference in the metric system

Mass reference

At the origin, a Décimètre cubic of water defined a mass of a Kilogram (kg). Water had been selected because it is simple to find and distill. In our current system of measurement - the international system of units (IF) - this definition of the Masse is not valid any more since 1889, date on which the first General conference of the weights and measures defines the kilogram as the mass of a prototype of iridic Platine preserved at Sevres. Today to 4 °C, the Density is of 0.99995 kg DM -3. This correspondence thus remains an excellent approximation for all the needs for the everyday life.

Reference of temperature

The system centigrade (not to be confused with the Degree Celsius, below) fixes degree 0 on the Température of the melting Glace and defines as degree 100 the temperature of the water in boiling under Atmospheric pressure normal. The scale is then divided into 100°. Thus the temperature of the human body is on average of 37°.

The system Fahrenheit fixes the point of solidification of the water at 32 °F and its point of boiling to 212 °F.

The Kelvin is an absolute measurement of thermodynamic temperature which is equal to 1/273,16 times the temperature of the triple point of the water .

The system Celsius is defined arbitrarily by a translation of 273.15 K compared to the Kelvin, to approach closest to the centigrade degree.

Reference of density

See also: Density

Stock management and policy of water

The multiplicity of its uses makes water a fundamental resource of the human activities. Its management is the permanent monitoring object and affects the relations between the States. See the article devoteds to on these subjects:

In France, the management of the water resources is very complex. According to the departments, the actors of water are different and their missions on the territory can vary. The agencies of water are public corporations. Their principal role is to perceive royalties and to redistribute them in order to finance actions of communities, industrialists, farmers or others making it possible to fight against pollution and to better manage the water resources. The distribution of drinking water is a Public service managed on the level of each commune or EPCI, either directly in Régie, or by delegation at a privately held company (Affermage, concession). The new Law on the Water and the Aquatic environments (LEMA) of 2007 amends in-depth the preceding law and makes it possible to translate in the French legislation the Parent directive of Water (DCE) European.

The management of water covers many activities:

  • the agricultural production (Irrigation and drainage);
  • production of Drinking water;
  • the cleansing (or purification);
  • production of energy and the Transport;
  • the management of the natural environments and forest (wetlands and aquatic environments).

In France, the production of drinking water and the cleansing are two major activities.

Purification of water, production of drinking water

See also: Drinking water in France

(for France)

Drinking water or relatively pure is necessary for many industrial applications and human consumption. The human ones have need for water without too many salts and other impurities, like toxic products or of Bactérie S Pathogène S.

Purification, cleansing

See also: Purification of water

Purification, or cleansing, is the activity which consists in purifying waste water resulting from the industrial activity, the domestic uses, or others, before their rejection in the Nature. This process is increasingly necessary, in order to avoid the Pollution and the Nuisance S on the Environnement.

Problems of water in mountain

The mountains cover a very significant part of surfaces of the ground. In Europe, they cover 35,5% of the total territory (90% in Switzerland and Norway) and more than 95 million Europeans live there in 2006. They are true Tower water and play a key role in the stock management aquafères because they concentrate a big part of precipitations and all the large rivers and their principal affluents take their source there.

Water in mountain is an ecological richness there but also economic créatice of development: hydroelectricity, bottled of mineral water, sports and leisures out of waters running. In Europe, 37 large hydro-electric power stations are established in mountain (on 50, that is to say 74%) to which are added 59 other large power stations on 312 (18,9%).

The mountains present typical locations, because they are first of all zones of risks:

  • With the slope and the relief, combined with an often close-cropped and fragile vegetation because of a harder climate, they are zones of intense erosions and fast concentration of water which forms the risings and the floods which can be devastating for the low parts of the basins and the plains. The phenomenon is accentuated by the overgrazing and deforestation, the proofing of the ground by constructions, the spaces parkings and the roads, in particular in the zones of strong urban and tourist development.
  • Contrary, the abandonment of the most difficult sectors by the populations which practice traditional economic activities like the pastoralism, has as consequences the stop of maintenance and the destruction of the collective works, the zones of terraces and the systems of drainage.

But water in mountain, is especially a source of richness and development. A better valorization of this potential by town and country planning, can be the source of new richnesses for the economy of the mountainous areas, but within the framework of a sparing and responsible behavior. In the future, with climate warming, the extreme situations of events like the drynesses, the floods and accelerated erosion, are likely to multiply and be, with pollution and the wasting, from here only one generation one of the independent factors, limiting economic development and social in the majority of the countries of the world.

According to the brought together experts with Megève in March 2007 within the framework of the “international Year of the mountain” with the participation of FAO, UNESCO, the Total Toilets Partnership and the Global area network of the organizations of basin, in order to draw a diagnosis and to formulate the proposals presented to the World forum of the water of Kyoto (March 2003): The " solidarity upstream-aval" remain too weak: it is to better help the mountains within the framework of integrated policies of basins, so that they ensure the management and the equipment necessary of the high basins slopes. (…) It is imperative indeed to lead in mountain of the reinforced particular actions of installation and management for better protecting themselves from the floods and erosion, fighting against pollution and to optimize the water resources available to divide them between the users, as well upstream as in the plains downstream.

References

  • Hans Silvester, Bernard Fischesser and Marie-France Dupuis-Touches, ''' water between sky and ground ''' - Editions of Martinière - Paris (2000) -

See too

Related articles

External bonds

  • Management of water by Ekopédia
  • “fresh water: an invaluable resource”, Sagascience file of CNRS
  • territories of water, file set of themes of the review Sustainable development and territories

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