Some water is diverted to irrigation for agriculture. Rivers and seas offer opportunity for travel and commerce. Through erosionrunoff shapes the environment creating river valleys and deltas which provide rich soil and level ground for the establishment of population centers. A flood occurs when an area of land, usually low-lying, is covered with water. It is when a river overflows its banks or flood comes from the sea. A drought is an extended period of months or years when a region notes a deficiency in its water supply.
This occurs when a region receives consistently below average precipitation. Some runoff water is trapped for periods of time, for example in lakes. At high altitude, during winter, and in the far north and south, snow collects in ice caps, snow packs and glaciers.
Water also infiltrates the ground and goes into aquifers. This groundwater later flows back to the surface in springsor more spectacularly in hot springs and geysers. Groundwater is also extracted artificially in wells. This water storage is important, since clean, fresh water is essential to human and other land-based life.
In many parts of the world, it is in short supply. Sea water contains about 3. The physical properties of sea water differ from fresh water in some important respects. The salinity of water in major seas varies from about 0.
Tides are the cyclic rising and falling of local sea levels caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and search thesis water bodies and produce oscillating currents known as tidal streams.
The changing tide produced at a given location is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of Earth rotation and the local bathymetry.
The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zoneis an important ecological product of ocean tides. From a biological standpoint, water has many distinct properties that are critical for the proliferation of life. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on water. Metabolism is the sum total of anabolism and catabolism. In anabolism, water is removed from molecules through energy requiring enzymatic chemical reactions in order to grow larger molecules e.
In catabolism, water is used to break bonds in order to generate smaller molecules e. Without water, these particular metabolic processes could not exist. Water is fundamental to photosynthesis and respiration. Hydrogen is combined with CO 2 absorbed from air or water to form glucose and release oxygen [ citation needed ]. Water is also central to acid-base neutrality and enzyme function. Water is considered to be neutral, with a pH the negative log of the hydrogen ion concentration of 7.
Acids have pH values less than 7 while bases have values greater than 7. Earth surface waters are filled with life. The earliest life forms appeared in water; nearly all fish live exclusively in water, and there are many types of marine mammals, such as dolphins and whales. Some kinds of animals, such as amphibiansspend portions of their lives in water and portions on land. Plants such as kelp and algae grow in the water and are the basis for some underwater ecosystems.
Plankton is generally the foundation of the ocean food chain. Aquatic vertebrates must obtain oxygen to survive, and they do so in various ways. Fish have gills instead of lungsalthough some species of fish, such as the lungfishhave both. Marine mammalssuch as dolphins, whales, ottersand seals need to surface periodically to breathe air. Some amphibians are able to absorb oxygen through their skin.
Invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters including breathing tubes see insect and mollusc siphons and gills Carcinus. However as invertebrate life evolved in an aquatic habitat most have little or no specialisation for respiration in water.
Civilization has historically flourished around rivers and major waterways; Mesopotamiathe so-called cradle of civilization, was situated between the major rivers Tigris and Euphrates ; the ancient society of the Egyptians depended entirely upon the Nile. Rome was also founded on the banks of the Italian river Tiber. Islands with safe water ports, like Singapore, have flourished for the same reason. In places such as North Africa and the Middle East, where water is more scarce, access to clean drinking water was and is a major factor in human development.
Water fit for human consumption is called drinking water or potable water. Water that is not potable may be made potable by filtration or distillationor by a range of other methods.
Water that is not fit for drinking but is not harmful for humans when used for swimming or bathing is called by various names other than potable or drinking water, and is sometimes called safe wateror "safe for bathing". Chlorine is a skin and mucous membrane irritant that is used to make water safe for bathing or drinking. Buy btec coursework use is highly technical and is usually monitored by government regulations typically 1 part per million ppm for drinking water, and 1—2 ppm of chlorine not yet reacted with impurities for bathing water.
Water for bathing may be maintained in satisfactory microbiological condition using chemical disinfectants such as chlorine or ozone or by the use of ultraviolet master thesis derivatives. In the US, non-potable forms of wastewater generated by humans may be referred to as greywaterwhich is treatable and thus easily able to be made potable again, and blackwaterwhich generally contains sewage and other forms of waste which require further treatment in order to be made reusable.
These terms may have different meanings in other countries and cultures. This natural resource is becoming scarcer in certain places, and its availability is a major social and economic concern.
Currently, about a billion people around the world routinely drink unhealthy water. Most countries accepted the goal of halving by the number of people worldwide who do not have access to safe water and sanitation during the G8 Evian summit. Poor water quality and bad sanitation are deadly; some five million deaths a year are caused by polluted drinking water.
The World Health Organization estimates that safe water could prevent 1. Water, however, is not a finite resource meaning the availability of water is limitedbut rather re-circulated as potable water in precipitation  in quantities many orders of magnitude higher than human consumption.
The most important use of water in agriculture is for irrigationwhich is a key component to produce enough food. Fifty years ago, the common perception was that water was an infinite resource. At the time, there were fewer than half the current number of people on the planet. People were not as wealthy as today, consumed fewer calories and ate less meat, so less water was needed to produce their food. They required a third of the volume of water we presently take from rivers.
Today, the competition for the fixed amount of water resources is much more intense, giving rise to the concept of peak water. An assessment of water management in agriculture was conducted in by the International Water Management Institute in Sri Lanka to see if the world had sufficient water to provide food for its growing population.
A further 1. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently. Water scarcity is also caused by production of cotton: While cotton accounts for 2. Significant environmental damage has been caused, such as disappearance of the Aral Sea.
On 7 Aprilthe gram was defined in France to be equal to "the absolute weight of a volume of pure water equal to a cube of one hundredth of a meter, and at the temperature of melting ice". Work was therefore commissioned to determine doctoral degree with no dissertation the mass of one liter of water.
The Kelvin temperature scale of the SI system is based on the triple point of water, defined as exactly Natural water consists mainly of the isotopes hydrogen-1 and oxygen, but there is also a small quantity of heavier isotopes such as hydrogen-2 deuterium. The amount of deuterium oxides or heavy water is very small, but it still affects the properties of water. Water from rivers and lakes tends to contain less deuterium than seawater. Most of persuasive organ donor speech is ingested through foods or beverages other than drinking straight water.
It is not clear how much water intake is needed by healthy people, though most specialists agree that approximately 2 liters 6 to 7 glasses of water daily is the minimum to maintain proper hydration. For those who have healthy kidneys, it is rather difficult to drink too much water, but especially in warm humid weather and while exercising it is dangerous to drink too little.
People can drink far more water than necessary while exercising, however, putting them homework is helpful articles risk of water intoxication hyperhydrationwhich can be fatal. Most of this quantity is contained in prepared foods. Specifically, pregnant and breastfeeding women need additional fluids to stay hydrated. The Institute of Medicine US recommends that, on average, men consume 3 liters 0. Water is excreted from the body in multiple forms; through urine and fecesthrough sweatingand by exhalation of water vapor in the breath.
With physical exertion and heat exposure, water loss will increase and daily fluid needs may increase as well. Humans require water with few impurities. Some solutes are acceptable and even desirable for taste enhancement and to provide needed electrolytes.
The single largest by volume freshwater resource suitable for drinking is Lake Baikal in Siberia. The propensity of water to form solutions and emulsions is useful in various washing processes. Washing is also an important component of several aspects of personal body hygiene. Most of personal water use is due to showeringdoing the laundry and dishwashingreaching hundreds of liters per day in developed countries.
The use of water for transportation of materials through rivers and canals as well as the international shipping lanes is an important part of the world economy. Water is widely used in chemical reactions as a solvent or reactant and less commonly as a solute or catalyst. In inorganic reactions, water is a common solvent, dissolving many ionic compounds, essays on video games well as other polar compounds such as ammonia and compounds closely related to water.
In organic reactions, it is not usually used as a reaction solvent, because it does not dissolve the reactants well and is amphoteric acidic and basic and nucleophilic. Nevertheless, these properties are sometimes desirable. Also, acceleration of Diels-Alder reactions by water has been observed. Supercritical water has recently been a topic of research. Oxygen-saturated supercritical water combusts organic pollutants efficiently.
Water vapor is used for some processes in the chemical industry. An example is the production of acrylic acid from acrolein, propylene and propane. Water and steam are a common fluid used for heat exchangedue to its availability and high heat capacityboth for cooling and heating.
Cool water may even be naturally available from a lake or the sea. A disadvantage is that metals commonly found in industries such as steel and copper are oxidized faster by untreated water and steam. In almost all thermal power stationswater is used as the working fluid used in a closed loop between boiler, steam turbine and condenserand the coolant used to exchange the waste heat to a water body or carry it away by evaporation in a cooling tower.
In the United States, cooling power plants is the largest use of water. In the nuclear power industry, water can also be used as a neutron moderator. In most nuclear reactorswater is both a coolant and a moderator.
This provides something of a passive safety measure, as removing the water from the reactor also slows the nuclear reaction down. However other methods are favored for stopping a reaction and it is preferred to keep the nuclear core covered with water so as to ensure adequate cooling.
Water has develop research proposal phd high heat of vaporization and is relatively inert, which makes it a good fire extinguishing fluid. The evaporation of water carries heat away from the fire. It is dangerous to use water on fires involving oils and organic solvents, because many organic materials float on water and the water tends to spread the burning liquid.
Use of water in fire fighting should also take into account the hazards of a steam explosionwhich may occur when water is used on very hot fires in confined spaces, and of a hydrogen explosion, when substances which react with water, such as certain metals or hot carbon such as coal, charcoalor coke graphite, decompose the water, producing water gas. A steam explosion occurred when the extreme overheating of the core caused water to flash into steam.
A hydrogen explosion may have occurred as a result of reaction between steam and hot zirconium. Humans use water for many recreational purposes, as well as for exercising and for sports. Some of these include swimming, waterskiingboatingsurfing and diving. In addition, some sports, like ice hockey and ice skatingare played on ice. Lakesides, beaches and water parks are popular places for people to go to relax and enjoy recreation.
Many find the sound and appearance of flowing water to be calming, and fountains and other water features are popular decorations. Some keep fish and other life in aquariums or ponds for show, fun, and companionship. Humans also use water for snow sports i. The water industry provides drinking water and wastewater services including sewage treatment to households and industry.
Water supply facilities include water wellscisterns for rainwater harvestingwater supply networksand water purification facilities, water tankswater towerswater pipes including old aqueducts.
Atmospheric water generators are in development. Drinking water is often collected at springsextracted from artificial borings wells in the ground, or pumped from lakes and rivers.
Building more wells in adequate places is thus a possible way to produce more water, assuming the aquifers can supply an adequate flow. Other water sources include rainwater collection.
Water may require purification for human consumption. This may involve removal of undissolved substances, dissolved substances and harmful microbes. Popular methods are filtering with sand which only removes undissolved material, while chlorination and boiling kill harmful microbes. Distillation does all three functions. More advanced techniques exist, such as reverse osmosis.
Desalination of abundant seawater is a more expensive solution used in coastal arid climates. The distribution of drinking water is done through municipal water systemstanker delivery or as bottled water. Governments in many countries have programs to distribute water to the needy at no charge.
Reducing usage by using drinking potable water only for human consumption is another option. In some cities such as Hong Kong, sea water is extensively used for flushing toilets citywide in order to conserve fresh water resources. Polluting water may be the biggest single misuse of water; to the extent that a pollutant limits other uses of the water, it becomes a waste of the resource, regardless of benefits to the polluter. Like other types of pollution, this does not enter standard accounting of market costs, being conceived as externalities for which the market cannot account.
Pharmaceuticals consumed by humans often end up in the waterways and can have detrimental effects on aquatic life if they bioaccumulate and if they are not biodegradable. Municipal and industrial wastewater are typically treated admission to college wastewater treatment plants. Mitigation of polluted surface runoff is addressed through a variety of prevention and treatment techniques.
See Surface runoff Mitigation and treatment. Many industrial processes rely on reactions using chemicals dissolved in water, suspension of solids in water slurries or using water to dissolve and extract substances, or to wash products or process equipment.
Processes such as miningchemical pulpingpulp bleachingpaper manufacturingtextile production, dyeing, printing, and cooling of power plants use large amounts of water, requiring a dedicated water source, and often cause significant water pollution.
Water is used in power generation. Hydroelectricity is electricity obtained from hydropower. Hydroelectric power comes from water driving a water turbine connected to a generator. Hydroelectricity is a low-cost, non-polluting, renewable energy source.
The energy is supplied by the motion of water. Typically a dam is constructed on a river, creating an artificial lake behind it. Water flowing out of the lake is forced through turbines that turn generators. Pressurized water is used in water blasting and water jet cutters. Also, very high pressure water guns are used for precise cutting. It works very well, is relatively safe, and is not harmful to the environment.
It is also used in the cooling of machinery to prevent overheating, or prevent saw blades from overheating. Water is also used in many industrial processes and machines, such as the steam turbine and heat exchangerin addition to its use as a chemical solvent.
Discharge of untreated water from industrial uses is pollution. Pollution includes discharged solutes chemical pollution and discharged coolant water thermal pollution.
Industry requires pure water for many applications and utilizes a variety of purification techniques both in water supply and discharge. Boilingsteamingand simmering are popular cooking methods that often require immersing food in water or its gaseous state, steam. Water also plays many critical roles within the field of food science. It is important for a food scientist to understand the roles that water plays within food processing to ensure the success of their products.
Solutes such as salts and sugars found in water affect the physical properties of water. The boiling and freezing points of water are affected by solutes, as well as air pressurewhich is in turn affected by altitude. Water boils at lower temperatures with the lower air pressure that occurs at higher elevations.
One mole of sucrose sugar per kilogram of water raises the boiling point of water by 0. Solutes in water also affect water activity that affects many chemical reactions and the growth of microbes in food.
Water hardness is also a critical factor in food processing and may be altered or treated by using a chemical ion exchange system. It can dramatically affect the quality of a product, as well as playing a role in sanitation. Water hardness is classified based on concentration of calcium carbonate the water contains. The formation of stars is accompanied by a strong outward wind of gas and dust. When this outflow of material eventually impacts the surrounding gas, the shock waves that are created compress and heat the gas.
The water observed is quickly produced in this warm dense gas. According to the researchers, the "discovery shows that water has been prevalent in the universe for nearly its entire existence". Water has been detected in interstellar clouds within our galaxythe Milky Way. Based on models of the formation and evolution of the Solar System and that of other star systems, most other planetary systems are likely to have similar ingredients.
Water and other volatiles probably comprise much of the internal structures of Uranus and Neptune and the water in the deeper layers may be in the form of ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and deeper still as superionic water in which the oxygen crystallises but the hydrogen ions float about freely within the oxygen lattice.
The existence of liquid water, and to a lesser extent its gaseous and solid forms, on Earth are vital to the existence of life on Earth as we know it. Water vapor and carbon dioxide in the atmosphere provide a temperature buffer greenhouse effect which helps maintain a relatively steady surface temperature.
If Earth were smaller, a thinner atmosphere would allow temperature extremes, thus preventing the accumulation of water equations homework help in polar ice caps as on Mars. This proposal is known as the Gaia hypothesis. If a planet is sufficiently massive, the water on it may be solid even at high temperatures, because of the high pressure caused by gravity, as it was observed on exoplanets Gliese b  and GJ b. Water politics is politics affected by water and water resources.
For this reason, water is a strategic resource in the globe and an important element in many political conflicts. It causes health impacts and damage to biodiversity. Access to safe drinking water has improved over the homework helpster grade 2 decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.
This trend is projected to continue. This goal is projected to be reached. A United Nations report stated that "there is enough water for everyone", but that access to it is hampered by mismanagement and corruption.
The authors of the Comprehensive Assessment of Water Management in Agriculture cited poor governance as one reason for some forms of water scarcity. Water governance is the set of formal and informal processes through which decisions related to water management are made. Good water governance is primarily about knowing what processes work best in a particular physical and socioeconomic context.
The Mekong river is one example; a review by the International Water Management Institute of policies in six countries that rely on the Mekong river for water found that thorough and transparent cost-benefit analyses and environmental impact assessments were rarely undertaken.
More than 2. Inthe UK charity WaterAid reported that a child dies every 15 seconds from easily preventable water-related diseases; often this means a doll house essay of sewage disposal; see toilet.
The International Water Management Institute undertakes projects with the aim of using effective water management to reduce poverty. Water is considered a purifier in most religions. Faiths that incorporate ritual washing ablution include ChristianityHinduismIslamJudaismthe Rastafari movementShintoTaoismand Wicca. Immersion or aspersion or affusion of a person in water is a central sacrament of Christianity where it is called baptism ; it is also a part of the practice of other religions, including Islam GhuslJudaism mikvah and Sikhism Amrit Sanskar.
In addition, a ritual bath in pure water is performed for the dead in many religions including Islam and Judaism. In Islam, the five daily prayers can be done in most cases after completing washing certain parts of the body using clean water wuduunless water is unavailable see Tayammum.
In Shinto, water is used in almost all rituals to cleanse a person or an area e. In Christianity, holy water is water that has been sanctified by a priest for the purpose of baptismthe blessing of persons, places, and objects, or as a means of repelling evil.
The Ancient Greek philosopher Empedocles held that water is one of the four classical elements along with fire, earth and airand was regarded as the ylemor basic substance of the universe. Buy books onlinewho was portrayed by Aristotle as an astronomer and an engineer, theorized that the earth, which is denser than water, emerged from the water.
Thales, a monistbelieved further that all things are made from water. Plato believed the shape of water is an icosahedron which accounts for why it is able to flow easily compared to the cube-shaped earth. In the theory of the four bodily humorswater was associated with phlegmas being cold and moist. The classical element of water was also one of the five elements in traditional Chinese philosophyalong with earthfirewoodand metal.
Water is also taken as a role model in some parts of traditional and popular Asian philosophy. The excellence of water appears in its benefiting all things, and in its occupying, without striving to the contrarythe low place which all men dislike.
Hence its way is near to that of the Tao" and "There is nothing in the world more soft and weak than water, and yet for attacking things that are firm and strong there is nothing that can take precedence of it—for there is nothing so effectual for which it can be changed. The false story consisted of safety concerns about the substance.
From Wikipedia, the free encyclopedia. This article is about general aspects of water. For a detailed discussion of its physical and chemical properties, see Properties of water. For other uses, see Water disambiguation. Main article: Properties of water. See also: Water data page and Water model. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. Find sources: Chemical bonding of H2O. Main articles: Hydrology and Water distribution on Earth.
Water cycle. Water resources. The Bay of Fundy at high tide and low tide. At low tide, many rocks are exposed and the boat in the picture is grounded.
Seawater and Tides. Further information: HydrobiologyMarine lifeand Aquatic plant. Water supply. Play media. Drinking water. Ship transport. Water sport recreation. Water distribution on Earth. Water lawWater rightand Water crisis. Water and religion. Dihydrogen monoxide hoax. Water portal Sustainable development portal. Outline of water. Central Intelligence Agency. Archived from the original on 1 February Retrieved 20 December Water in Crisis: Oxford University Press.
Archived from the original on 8 April European Journal of Clinical Nutrition. Online Etymology Dictionary. Archived from the original on 2 August Retrieved 20 May Chemistry of the Elements 2nd ed. Archived from the original on 9 July Retrieved 27 June Campbell Biology 10 ed. Water—an enduring mystery". Archived from the original on 17 November Retrieved 15 November CS1 maint: Multiple names: Del; Mallamace, F. International Journal of Nanotechnology. Eugene 18 December Scientific Reports.
Rolls"Emotion Explained". Oxford University Press, Medical. Llinas, W. Precht"Frog Neurobiology: A Handbook". Water Science and Technology. Archived from the original on 2 October The body utilizes water in to facilitate several functions such as: It also facilitates digestion of food and absorption of nutrients through their dissolving in water, transports nutrients, chemicals and heat throughout the body.
Water is our primary source of food. It does so by facilitating the growth of plants thus, the formation of food. Plants make their food by the process of photosynthesis. Here, starch is formed using water derived from the soil by air combining graduate nursing admission essay sunlight.
After this, the plant germinates in the presence of water and begins to grow and water supplies nutrients and materials to these plants. Water also facilitates the swelling, production of energy and loss of heat of a plant throughout its cycle, until it matures and is harvested as food.
Additionally, water provides food through its numerous sources by being a home to fishes and aquatic life that are considered food. Water facilitates the continuance of life through reproduction. Water facilitates this movement, and once fertilization occurs, the woman becomes pregnant.
The developing offspring requires many nutrients to enable it to develop well, and it receives them through water referred to as amniotic fluid. During delivery, the first substance to come out is water to facilitate delivery, and once how to write college admissions essay, they are nourished using milk that is rich in water.
Water also enables transportation. Throughout the world, water acts as a useful connector of different continents and destinations. In instances, where land and air transports are not effective, water methods such as boats, ferries, and ships transport among others container ships, oil, and people. Water also facilitates the transportation of nutrients and fertile soils from the highlands to lowland areas where it is used for farming. Additionally, water transports nutrients and waste in plants from different cells and carries electric charges that promote comprehensible reasoning in humans.
Water calms down the temperature. When the earth is at optimum temperatures, the presence of water in various water bodies facilitates the cooling of the surrounding.
It does so by releasing some of its water through evaporation, consequently, cooling the temperatures. On the other hand, when the temperatures fall, water freezes and creates heat that warms the air. Moreover, water alleviates the heat produced by volcanoes or burning vegetation by creating moisture that goes to the sky and forms clouds that then condenses and drop down as rain.
Water is the most important substance in our evolution and our daily lives.
Without water, life as we know it would not have been possible. Each water molecule consists of one oxygen atom and two hydrogen atoms. The oxygen atom also called the "apex of the water molecule" bears a slight electronegative charge while hydrogen possesses a more positive one Kirk Because of the opposite charges attract, the water molecules are drawn together.
There are several types of water molecule such as liquid water, ice and water vapor.