by Charalambos Gouvas - Edition 1998

The Water

 Water, common name applied to the liquid state of the hydrogen-oxygen compound H2O. The ancient philosophers regarded water as a basic element typifying all liquid substances. Scientists did not discard that view until the latter half of the 18th century. In 1781 the British chemist Henry Cavendish synthesized water by detonating a mixture of hydrogen and air. However, the results of his experiments were not clearly interpreted until two years later, when the French chemist Antoine Laurent Lavoisier proposed that water was not an element but a compound of oxygen and hydrogen. In a scientific paper presented in 1804, the French chemist Joseph Louis Gay-Lussac and the German naturalist Alexander von Humboldt demonstrated jointly that water consisted of two volumes of hydrogen to one of oxygen, as expressed by the present-day formula H2O.
Almost all the hydrogen in water has an atomic weight of 1. The American chemist Harold Clayton Urey discovered in 1932 the presence in water of a small amount (1 part in 6,000) of so-called heavy water, or deuterium oxide (D2O); deuterium is the hydrogen isotope with an atomic weight of 2. In 1951 the American chemist Aristid Grosse discovered that naturally occurring water contains also minute traces of tritium oxide (T2O); tritium is the hydrogen isotope with an atomic weight of 3.

Properties

Pure water is an odourless, tasteless liquid. It has a bluish tint, which may be detected only in layers of considerable depth. Under standard atmospheric pressure (760 mm of mercury, or 760 torr); the freezing point of water is 0° C (32° F) and its boiling point is 100° C (212° F). Water attains its maximum density at a temperature of 4° C (39° F) and expands upon freezing. Like most other liquids, water can exist in a supercooled state; that is, it may remain a liquid although its temperature is below its freezing point. Water can easily be cooled to about -25° C (-13° F) without freezing, either under laboratory conditions or in the atmosphere itself. Supercooled water will freeze if it is disturbed, if the temperature is lowered further, or if an ice crystal or other particle is added to it. Its physical properties are used as standards to define temperature scales and in the metric system for the original definition of the unit of mass, the gram.
Water is one of the best-known ionizing agents. Because most substances are somewhat soluble in water, it is frequently called the universal solvent. Water combines with certain salts to form hydrates. It reacts with metal oxides to form acids. It acts as a catalyst in many important chemical reactions.

Occurrence

Water is the only substance that occurs at ordinary temperatures in all three states of matter, that is, as a solid, a liquid, and a gas. As a solid, or ice, it is found as glaciers and ice caps, on water surfaces in winter, as snow, hail, and frost, and as clouds formed of ice crystals. It occurs in the liquid state as rain clouds formed of water droplets, and on vegetation as dew; in addition, it covers three-quarters of the surface of the earth in the form of swamps, lakes, rivers, and oceans. As gas, or water vapour, it occurs as fog, steam, and clouds. Atmospheric vapour is measured in terms of relative humidity, which is the ratio of the quantity of vapour actually present to the greatest amount possible at a given temperature.
Water occurs as moisture in the upper portion of the soil profile, in which it is held by capillary action to the particles of soil. In this state, it is called bound water and has different characteristics from free water. Under the influence of gravity, water accumulates in rock interstices beneath the surface of the earth as a vast groundwater reservoir supplying wells and springs and sustaining the flow of some streams during periods of drought.

Water in Life

Water is the major constitutent of living matter. From 50 to 90 per cent of the weight of living organisms is water. Protoplasm, the basic material of living cells, consists of a solution in water of fats, carbohydrates, proteins, salts, and similar chemicals. Water acts as a solvent, transporting, combining, and chemically breaking down these substances. Blood in animals and sap in plants consist largely of water and serve to transport food and remove waste material. Water also plays a key role in the metabolic breakdown of such essential molecules as proteins and carbohydrates. This process, called hydrolysis, goes on continually in living cells.

Natural Water Cycle

Hydrology is the science concerned with the distribution of water on the earth, its physical and chemical reactions with other naturally occurring substances, and its relation to life on earth; the continuous movement of water between the earth and the atmosphere is known as the hydrological cycle. Under several influences, of which heat is predominant, water is evaporated from both water and land surfaces and is transpired from living cells. This vapour circulates through the atmosphere and is precipitated in the form of rain or snow.

On striking the surface of the earth, the water follows two paths. In amounts determined by the intensity of the rain and the porosity, permeability, thickness, and previous moisture content of the soil, one part of the water, termed surface runoff, flows directly into rills and streams and thence into oceans or landlocked bodies of water; the remainder infiltrates into the soil. A part of the infiltrated water becomes soil moisture, which may be evaporated directly or may move upwards through the roots of vegetation to be transpired from leaves. The portion of the water that overcomes the forces of cohesion and adhesion in the soil profile percolates downwards, accumulating in the so-called zone of saturation to form the groundwater reservoir, the surface of which is known as the water table. Under natural conditions, the water table rises intermittently in response to replenishment, or recharge, and then declines as a result of continuous drainage into natural outlets such as springs.

Composition

Because of its capacity to dissolve numerous substances in large amounts, pure water rarely occurs in nature.

During condensation and precipitation, rain or snow absorbs from the atmosphere varying amounts of carbon dioxide and other gases, as well as traces of organic and inorganic material. In addition, precipitation carries radioactive fallout to the earth's surface.

In its movement on and through the earth's crust, water reacts with minerals in the soil and rocks. The principal dissolved constituents of surface and groundwater are sulphates, chlorides, and bicarbonates of sodium and potassium and the oxides of calcium and magnesium. Surface waters may also contain domestic sewage and industrial wastes. Groundwaters from shallow wells may contain large quantities of nitrogen compounds and chlorides derived from human and animal wastes. Waters from deep wells generally contain only minerals in solution. Almost all supplies of natural drinking water contain fluorides in varying amounts. The proper proportion of flourides in drinking water has been found to reduce tooth decay.
Sea water contains, in addition to concentrated amounts of sodium chloride, or salt, many other soluble compounds, as the impure waters of rivers and streams are constantly feeding the oceans. At the same time, pure water is continually lost by the process of evaporation, and as a result the proportion of the impurities that give the oceans their saline character is increased.

Water Purification

Suspended and dissolved impurities present in naturally occurring water make it unsuitable for many purposes. Objectionable organic and inorganic materials are removed by such methods as screening and sedimentation to eliminate suspended materials; treatment with such compounds as activated carbon to remove tastes and odours; filtration; and chlorination or irradiation to kill infective micro-organisms.

In aeration, or the saturation of water with air, water is brought into contact with air in such a manner as to produce maximum diffusion, usually by spraying water into the air in fountains. Aeration removes odours and taste caused by decomposing organic matter, and also industrial wastes such as phenols and volatile gases such as chlorine. It also converts dissolved iron and manganese compounds into insoluble hydrated oxides of the metals which may then be readily settled out. Hardness of natural waters is caused largely by calcium and magnesium salts and to a small extent by iron, aluminium, and other metals. Hardness resulting from the bicarbonates and carbonates of calcium and magnesium is called temporary hardness and can be removed by boiling, which also sterilizes the water. The residual hardness is known as noncarbonate, or permanent, hardness. The methods of softening noncarbonate hardness include the addition of sodium carbonate and lime and filtration through natural or artificial zeolites which absorb the hardness-producing metallic ions and release sodium ions to the water. Sequestering agents in detergents serve to render the substances that make water hard inactive. Iron, which causes an unpleasant taste in drinking water, may be removed by aeration and sedimentation or by passing the water through iron-removing zeolite filters, or the iron may be stabilized by addition of such salts as polyphosphates. For use in laboratory applications, water is either distilled or demineralized by passing it through ion-absorbing compounds.

Water Desalinization

To meet the ever-increasing demands for fresh water, especially in arid and semiarid areas, much research has gone into finding efficient methods of removing salt from sea water and brackish waters. Several processes are being developed to produce fresh water cheaply.

Three of the processes involve evaporation followed by condensation of the resultant steam and are known as multiple-effect evaporation, vapour-compression distillation, and flash evaporation. The last-named method, the most widely used, involves heating sea water and pumping it into lower-pressure tanks, where the water abruptly vapourizes (flashes) into steam. The steam then condenses and is drawn off as pure water.

Freezing is an alternate method, based on the different freezing points of fresh and salt water. The ice crystals are separated from the brine, washed free of salt, and melted into fresh water. In another process, called reverse osmosis, pressure is used to force fresh water through a thin membrane that does not allow the minerals to pass. Reverse osmosis is still undergoing intensive development. Electrodialysis is being used to desalt brackish waters. When salt dissolves in water, it splits into positive and negative ions, which are then removed by electric current through anion and cation membranes, thus depleting the salt in the product water. One major problem in desalinization projects is the cost of producing fresh water. Using conventional fuels, plants with a capacity of 3.8 million litres (1 million gallons) per day or less produce water at a cost of $1 or more per 3,800 litres (1,000 gallons). Most experts expect more immediate results from efforts to purify mildly brackish water that contains between 1,000 and 4,500 parts per million of minerals, compared to 35,000 parts per million for ocean water. Because water is potable if it contains fewer than 500 parts per million of salt, the cost of desalting brackish water is correspondingly less than it is for desalting sea water.

Water Supply and Waterworks, provision of a supply of water for domestic, industrial, and irrigation needs, and the engineering installations necessary to treat and pump the water to the consumer. In the United Kingdom today, the average domestic daily water consumption rate per head is 150 litres (31.5 gal), and in the United States, 380 to 950 litres (100 to 250 gal) per person per day. Extensive water-treatment plants are essential for providing water safe for human consumption.

Sources of Water

The ultimate source of all natural drinkable water on the earth is rain, which is rarely used as a direct source except on islands in salt water, such as Bermuda, where the rain is collected and led into cisterns to serve as the only available water supply. When rain falls, it runs off into streams, in the case of heavy rains, or soaks into the ground, percolating through porous strata until it reaches an impervious stratum, upon which it collects, forming groundwater. Groundwater is the source of wells and of the springs that feed streams, rivers, and lakes. In its course, groundwater dissolves soluble mineral matter, and often the surface waters of rivers and lakes are polluted by the influx of sewage or industrial wastes. Groundwater provides 25 per cent of Britain's water; Scotland has many upland sources of unpolluted water. In modern water-supply systems, an entire watershed is usually made into a reservation to control pollution. The waters are impounded by a system of dams, and flow by gravity, or are pumped, to the local distribution system.

The quality of water from these sources varies greatly. Surface waters generally contain larger quantities of turbidity and bacteria than groundwaters, but groundwater contains higher concentrations of dissolved chemicals. Seawater contains high concentrations of dissolved chemicals and some microscopic organisms as well. Because water quality varies widely from source to source, the water companies and water authorities in Britain have to comply with certain standards for drinking water according to European Community regulations. High water quality standards have been adopted by all the American states and by the World Health Organization. In water being considered as a source for supply, these standards set the concentration levels of chemical compounds and bacteria that can be safely allowed in the treated water.

Treatment

Undesirable tastes and odours are removed from water by aeration. Bacteria are destroyed by the addition of a few parts per million of chlorine, and the taste of chlorine is then removed with sodium sulphite. Excessive hardness, which renders the water unsuitable for many industrial purposes, is reduced by the addition of slaked, or hydrated, lime or by an ion-exchange process using zeolite as a water softener. Suspended organic matter, which supports bacterial life, and suspended mineral matter are removed by the addition of a flocculating and precipitating agent, such as alum, before settling or filtration. Artificial fluoridation of public water is done in Britain and many parts of the United States as a measure for preventing tooth decay.

History

Early peoples had no need of engineering works to supply their water. Hunters and nomads camped near natural sources of fresh water, and populations were so sparse that pollution of the water supply was not a serious problem. After community life developed and agricultural villages became urban centres, the problem of supplying water became important for inhabitants of a city, as well as for irrigation of the farms surrounding the city. Irrigation works were known in prehistoric times, and before 2000 BC the rulers of Babylonia and Egypt constructed systems of dams and canals to impound the flood waters of the Euphrates and Nile rivers, controlling floods and providing irrigation water throughout the dry season. Such irrigation canals also supplied water for domestic purposes. The first people to consider the sanitation of their water supply were the ancient Romans, who constructed a vast system of aqueducts to bring the clean waters of the Apennine Mountains into the city and built settling basins and filters along these mains to ensure the clarity of the water. The construction of such extensive water-supply systems declined when the Roman Empire disintegrated, and for several centuries local springs and wells formed the main source of domestic and industrial water.

The invention of the force pump in England in the middle of the 16th century greatly extended the possibilities of development of water-supply systems. In London, the first pumping waterworks was completed in 1562; it pumped river water to a reservoir about 37 m (120 ft) above the level of the River Thames and from the reservoir the water was distributed by gravity, through lead pipes, to buildings in the vicinity.

Increased per-capita demand has coincided with water shortages in many countries. South-east England, for example, receives only 14 per cent of Britain's rainfall, has 30 per cent of its population, and experienced declining winter rainfall in the 1980s.
In recent years a great deal of interest has been shown in the conversion of seawater to fresh water to provide drinking water for very dry areas, such as the Middle East. Several different processes, including distillation, electrodialysis, reverse osmosis, and direct-freeze evaporation, have been developed for this purpose. Some of these processes have been used in large facilities in the United States. Although these processes are successful, the cost of treating seawater is much higher than that for treating fresh water.

Letter to Microsoft

FROM: Dr. Gkouvas Charalampos

(Orthopaedic Surgeon)
Preveza Hellas Kayak & Rafting Rowing Club
Address: 10 Speliadou str, Preveza 48100
GREECE / HELLAS

TO: Microsoft Corporation, International Customer Service, One Microsoft Way, Redmond WA 98052-6399 USA. (For the Director of Microsoft Encarta® Editing)
Copy to:: Μicrosoft Hellas SA, Polis Center, 64 Kifissias Avenue, 151 25 Maroussi, Athens GREECE

Preveza Hellas 02-08-1998
Dear Sir,

In the version of Microsoft Encarta® 1997, there are two small articles, about «Acheron River» and «Hades», very important for Mythology and Geography of my country, Greece. These are:

(1) Acheron, in Greek mythology, river in Hades. It was also the name of a river in southern Epirus, Greece, which flowed underground for part of its 58-km (36-mi) course to the Ionian Sea.

(2) Hades, in Greek mythology, god of the dead. He was the son of the Titans Cronus and Rhea and the brother of Zeus and Poseidon. When the three brothers divided up the universe after they had deposed their father, Cronus, Hades was awarded the underworld. There, with his queen, Persephone, whom he had abducted from the world above, he ruled the kingdom of the dead. Although he was a grim and pitiless god, unappeased by either prayer or sacrifice, he was not evil. In Roman mythology, he was known also as Pluto, lord of riches, because both crops and precious metals were believed to come from his kingdom below ground. The underworld itself was often called Hades. It was divided into two regions: Erebus, where the dead pass as soon as they die, and Tartarus, the deeper region, where the Titans had been imprisoned. It was a dim and unhappy place, inhabited by vague forms and shadows and guarded by Cerberus, the three-headed, dragon-tailed dog. Sinister rivers separated the underworld from the world above, and the aged boatman Charon ferried the souls of the dead across these waters. Somewhere in the darkness of the underworld Hades' palace was located. It was represented as a many-gated, dark and gloomy place, thronged with guests, and set in the midst of shadowy fields and an apparition-haunted landscape. In later legends the underworld is described as the place where the good are rewarded and the wicked punished.

Sir, I have to inform you, that Acheron river has never been flowed underground. It is all over the earth ground, but a part of the river (10Km) flows between a very short canyon, in some places of diameter of 1,5 m (!!!) (please see the poster pictures). These short parts of the Acheron River Canyon, the ancient Greeks called «The Hades Gates» («Οι Πύλες του Αδη») that means, the «doors of the underground world», because they were afraid to pass through them. For history, the first time that humans succeeded to pass all over this dificult canyon, was on 24-07-1994 (see the Athens newspaper «EΛΕΥΘΕΡΟΤΥΠΙΑ», of 10-08-1994, page 22, URL: http://www.enet.gr). It was a group of «The Alpine Club of Preveza» with leader Dr. Charalampos Gkouvas.

There are available for you, for next version of Encarta®, if you are interesting:

(a) An article about Acheron River, Hades Gates, and Nekromanteion (= Oracle, Nekromancy Palace), of 8 pages (writen by Charalampos Gkouvas, in Greek. The translation is easy but needs time. I send to you a diskette with the word file ACHERON.doc, to exam it.
(b) 300 color slides of all the length of the Acheron river, from snowy mountains to the sea (also by C.Gkouvas).

Please answer me about your interest, and about your financial regulations, about copyright© .

Sincerely yours

Dr.Charalampos Gkouvas
leader of Kayak and Rafting Rowing club
in Preveza Greece