Water: A Gift of Environment

Arpit Kumar

Index

(i) Water(ii) Availability of Water(iii) Water Cycle(iv) Sea Water(v) Health & pollution (vi) Human uses: Agricultural purposes Drinking Purpose Other uses: Washing Transportation Chemical uses Heat exchange Fire extinction Recreation Water industry Industrial applications Food processing(vii) Important facts about water(viii) References

Water: A Gift of Environment(i) WATER :Wateris a transparent fluid which forms the world's streams, lakes, oceans and rain, and is the major constituent of the fluids of living things. As achemical compound, awater moleculecontains oneoxygenand twohydrogenatomsthat are connected bycovalent bonds. Water is aliquidatstandard ambient temperature and pressure, but it often co-exists onEarthwith itssolidstate,ice; andgaseousstate, steam(water vapor). It also exists assnow,fog,dewandcloud.(ii) AVAILABILITY OF WATER:Water covers 71% of the Earth's surface. It is vital for all known forms oflife. On Earth, 96.5% of the planet's water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in theairasvapor,clouds(formed of solid and liquid water particles suspended in air), andprecipitation. Only 2.5% of the Earth's water isfresh water, and 98.8% of that water is in ice andgroundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products. (iii) WATER CYCLE :Water on Earth moves continually through thewater cycleof evaporationand transpiration (evapo-transpiration),condensation, precipitation, andrunoff, usually reaching the sea. Evaporation and transpiration contribute to the precipitation over land. Water used in the production of a good or service is known asvirtual water.

(iv) SEA WATERSea watercontains about 3.5%salton average, plus smaller amounts of other substances. The physical properties of sea water differ from fresh water in some important respects. It freezes at a lower temperature (about 1.9C) and its density increases with decreasing temperature to the freezing point, instead of reaching maximum density at a temperature above freezing. The salinity of water in major seas varies from about 0.7% in theBaltic Seato 4.0% in theRed Sea.

(v) HEALTH & POLLUTIONWater fit for human consumption is called drinking water orpotable water. Water that is not potable may be made potable by filtration or distillation, or by a range ofother 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 calledsafe water, or "safe for bathing". Chlorine is a skin and mucous membrane irritant that is used to make water safe for bathing or drinking. Its use is highly technical and is usually monitored by government regulations (typically 1 part per million (ppm) for drinking water, and 12 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 aschlorineorozoneor by the use of ultravioletlight. Poorwater qualityand bad sanitation are deadly; some five million deaths a year are caused by polluted drinking water. The World Health Organizationestimates thatsafe watercould prevent 1.4 million child deaths fromdiarrheaeach year. Water, however, is not a finite resource, but rather re-circulated as potable water in precipitation in quantities many degrees of magnitude higher than human consumption. Therefore, it is the relatively small quantity of water in reserve in the earth (about 1% of our drinking water supply, which is replenished in aquifers around every 1 to 10 years), that is anon-renewable resource, and it is, rather, the distribution of potable and irrigation water which is scarce, rather than the actual amount of it that exists on the earth. Water-poor countries use importation of goods as the primary method of importing water (to leave enough for local human consumption), since the manufacturing process uses around 10 to 100 times products' masses in water.In the developing world, 90% of allwastewaterstill goes untreated into local rivers and streams. Some 50 countries, with roughly a third of the world's population, also suffer from medium or high water stress, and 17 of these extract more water annually than is recharged through their natural water cycles. The strain not only affects surface freshwater bodies like rivers and lakes, but it also degrades groundwater resources.(vi) HUMAN USES :

Agriculture :The most important use of water inagricultureis forirrigation, which is a key component to produce enough food. Irrigation takes up to 90% of water withdrawn in some developing countries(in India Freshwater withdrawal for agriculture is 90% of761 cu km/yr = 685 cu km/yr)and significant proportions in more economically developed countries (United States, 30% of freshwater usage is for irrigation). Fifty years ago, the common perception was that water was an infinite resource. At this 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 ofpeak water. This is because there are now nearly seven billion people on the planet, their consumption of water-thirsty meat and vegetables is rising, and there is increasing competition for water fromindustry,urbanizationand bio fuel crops. In future, even more water will be needed to produce food because the Earth's population is forecast to rise to 9 billion by 2050. For drinkingThehuman bodycontains from 55% to 78% water, depending on body size.To function properly, the body requires between one and seven liters of water perdayto avoiddehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors.Safe drinking wateris essential to humans and other life forms even though it provides nocaloriesororganicnutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequatesanitation.There is a clear correlation between access to safe water and gross domestic product per capita.However, some observers have estimated that by 2025 more than half of theworld populationwill be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.Water plays an important role in theworld economy, as it functions as asolventfor a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70% of the fresh water used by humans goes toagriculture.

Hazard symbolfor non-potable waterAn original recommendation for water intake in 1945 by the Food and Nutrition Board of theUnited States National Research Council read: "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods."The latest dietary reference intake report by theUnited States National Research Councilin general recommended (including food sources): 3.7 liters for men and 2.7 liters of water total for women. Normally, about 20% of water intake comes from food, while the rest comes from drinking water and beverages (caffeinatedincluded). Water is excreted from the body in multiple forms; throughurineandfeces, throughsweating, and 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. Common impurities include metal salts and oxides, including copper, iron, calcium and lead, and/or harmfulbacteria, such asVibrio. Somesolutesare acceptable and even desirable for taste enhancement and to provide needed electrolytes. The single largest (by volume) freshwater resource suitable for drinking isLake Baikalin Siberia.

Other uses: WashingThe propensity of water to formsolutionsandemulsionsis useful in variouswashingprocesses. Many industrial processes rely on reactions using chemicals dissolved in water, suspension of solids in waterslurriesor using water to dissolve and extract substances. Washing is also an important component of several aspects of personalbody hygiene. TransportationThe 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. Chemical usesWater is widely used in chemical reactions as asolventorreactantand less commonly as asoluteorcatalyst. In inorganic reactions, water is a common solvent, dissolving many ionic compounds. In organic reactions, it is not usually used as a reaction solvent, because it does not dissolve the reactants well and isamphoteric(acidicandbasic) and nucleophilic. Nevertheless, these properties are sometimes desirable. Also, acceleration ofDiels-Alder reactionsby water has been observed.Supercritical waterhas recently been a topic of research. Oxygen-saturated supercritical water combusts organic pollutants efficiently. Heat exchangeWater and steam are a common fluid used forheat exchange, due to its availability and highheat capacity, both for cooling and heating. Cool water may even be naturally available from a lake or the sea. It's especially effective to transport heat throughvaporizationandcondensationof water because of its largelatent heat of vaporization. A disadvantage is that metals commonly found in industries such assteelandcopperareoxidizedfaster by untreated water and steam. In almost allthermal power stations, water is used as the working fluid (used in a closed loop between boiler, steam turbine and condenser), and the coolant (used to exchange the waste heat to a water body or carry it away byevaporationin acooling tower). In theUnited States, cooling power plants is the largest use of water. In thenuclear powerindustry, water can also be used as aneutron moderator. In mostnuclear reactors, water is both a coolant and a moderator. This provides something of a passive safety measure, as removing the water from the reactor alsoslows 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. Fire extinctionWater has a high heat of vaporization and is relatively inert, which makes it a goodfire extinguishingfluid. 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 asteam explosion, which 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 ascoal,charcoal, orcokegraphite, decompose the water, producingwater gas. RecreationHumans use water for many recreational purposes, as well as for exercising and for sports. Some of these includeswimming,water skiing, boating,surfinganddiving. In addition, some sports, likeice hockeyandice skating, are played on ice. Lakesides, beaches andwater parksare 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 inaquariumsorpondsfor show, fun, and companionship. Humans also use water for snow sports i.e.skiing,sledding,snowmobilingorsnowboarding, which require the water to be frozen. Water industryThewater industryprovides drinking water andwastewaterservices (includingsewage treatment) tohouseholdsandindustry.Water supplyfacilities includewater wells,cisternsforrainwater harvesting,water supply networks, andwater purificationfacilities,water tanks,water towers,water pipesincluding oldaqueducts.Atmospheric water generatorsare in development.Drinking water is often collected atsprings, extracted from artificialborings(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 harmfulmicrobes. Popular methods arefilteringwith sand which only removes undissolved material, whilechlorination andboilingkill harmful microbes.Distillationdoes all three functions. More advanced techniques exist, such asreverse osmosis.Desalinationof abundantseawateris a more expensive solution used in coastalaridclimates.The distribution of drinking water is done throughmunicipal water systems, tanker delivery or asbottled 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 asHong Kong, sea water is extensively used for flushing toilets citywide in order toconserve 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 asexternalitiesfor which the market cannot account. Thus other people pay the price of water pollution, while the private firms' profits are not redistributed to the local population, victims of this pollution.Pharmaceuticalsconsumed by humans often end up in the waterways and can have detrimental effects onaquaticlife if theybio-accumulateand if they are notbiodegradable.Wastewater facilities arestorm sewersandwastewater treatment plants. Another way to remove pollution fromsurface runoffwater is bioswale. Industrial applicationsWater is used inpower generation.Hydroelectricityis electricity obtained fromhydropower. 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 adamis constructed on a river, creating an artificial lake behind it. Water flowing out of the lake is forced through turbines that turn generators.

Three Gorges Damis thelargest hydro-electric power station.Pressurized water is used inwater blastingandwater 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 thesteam turbineandheat exchanger, in addition to its use as a chemicalsolvent. Discharge of untreated water from industrial uses ispollution. 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. Food processingBoiling,steaming, andsimmeringare popularcookingmethods that often require immersing food in water or its gaseous state, steam. Water is also used fordishwashing. Water also plays many critical roles within the field offood 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.Solutessuch 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 asair pressure, which is in turn is affected byaltitude. Water boils at lower temperatures with the lower air pressure that occurs at higher elevations. Onemoleof sucrose (sugar) per kilogram of water raises the boiling point of water by 0.51C (32.918F), and one mole of salt per kg raises the boiling point by 1.02C (33.836F); similarly, increasing the number of dissolved particles lowers water's freezing point. Solutes in water also affect water activity that affects many chemical reactions and the growth of microbes in food. Water activity can be described as a ratio of the vapor pressure of water in a solution to the vapor pressure of pure water.Solutes in water lower water activitythis is important to know because most bacterial growth ceases at low levels of water activity. Not only does microbial growth affect the safety of food, but also the preservation and shelf life of 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 the amounts of removable calcium carbonate salt the water contains per gallon. Water hardness is measured in grains: 0.064 g calcium carbonate is equivalent to one grain of hardness. Water is classified as soft if it contains 1 to 4 grains, medium if it contains 5 to 10 grains and hard if it contains 11 to 20 grains. The hardness of water also affects its pH balance, which plays a critical role in food processing. For example, hard water prevents successful production of clear beverages. Water hardness also affects sanitation; with increasing hardness, there is a loss of effectiveness for its use as a sanitizer. According to a report published by the Water Footprint organization in 2010, a single kilogram of beef requires 15 thousand litres of water; however, the authors also make clear that this is a global average and circumstantial factors determine the amount of water used in beef production.

(vii) SOME INTERESTING & USEFUL FACTS ABOUT WATER1. At birth, water accounts for approximately 80 percent of an infants body weight.2. A healthy person can drink about three gallons (48 cups) of water per day.3. Drinking too much water too quickly can lead to water intoxication. Water intoxication occurs when water dilutes the sodium level in the bloodstream and causes an imbalance of water in the brain.4. Water intoxication is most likely to occur during periods of intense athletic performance.5. While the daily recommended amount of water is eight cups per day, not all of this water must be consumed in the liquid form. Nearly every food or drink item provides some water to the body.6. Soft drinks, coffee, and tea, while made up almost entirely of water, also contain caffeine. Caffeine can act as a mild diuretic, preventing water from traveling to necessary locations in the body.7. Water dissolves more substances than any other liquid. Wherever it travels, water carries chemicals, minerals, and nutrients with it.8. Much more fresh water is stored under the ground in aquifers than on the earths surface.9. 68.7% of the fresh water on Earth is trapped in glaciers.10. The earth is a closed system, similar to a terrarium, meaning that it rarely loses or gains extra matter. The same water that existed on the earth millions of years ago is still present today.11. The total amount of water on the earth is about 326 million cubic miles of water.12. Of all the water on the earth, humans can use only about three tenths of a percent of this water. Such usable water is found in groundwater aquifers, rivers, and freshwater lakes.13. By the time a person feels thirsty, his or her body has lost over 1 percent of its total water amount.14. The weight a person loses directly after intense physical activity is weight from water, not fat.15. Water can dissolve more substances than any other liquid including sulfuric acid.16. The freezing point of water lowers as the amount of salt dissolved in at increases. With average levels of salt, seawater freezes at -2 C (28.4 F).17. About 6,800 gallons of water is required to grow a days food for a family of four.18. To create one pint of beer it takes 20 gallons of water.19. 780 million people lack access to an improved water source.20. In just one day, 200 million work hours are consumed by women collecting water for their families.21. Unsafe water kills 200 children every hour.22. 70% of the human brain is water.23. 80% of all illness in the developing world is water related.24. 40 billion hours are spent collecting water in Africa alone.25. A person can live about a month without food, but only about a week without water.26. Water expands by 9% when it freezes.27. There is about the same amount of water on Earth now as there was millions of years ago.28. Children in the first 6 months of life consume seven times as much water per pound as the average American adult.29. 85% of the world population lives in the driest half of the planet.30. Agriculture accounts for ~70% of global freshwater withdrawals (up to 90% in some fast-growing economies).31. 300 tons of water are required to manufacture 1 ton of steel.32. If the entire worlds water were fit into a 4 liter jug, the fresh water available for us would equal only about one tablespoon.33. Over 90% of the worlds supply of fresh water is located in Antarctica.34. A swimming pool naturally loses about 1,000 gallons (3,785 liters) a month to evaporation.35. 40% of freshwater withdrawals in the United States are used for agriculture.36. 65% of freshwater withdrawals in China are used for agriculture.37. Freshwater withdrawals for agriculture exceed 90% in many countries: Cambodia 94%, Pakistan 94%, Vietnam 95%, Madagascar 97%, Iran 92%, Ecuador 92%.38. An acre of corn will give off 4,000 gallons of water per day in evaporation.39. In Washington state alone, glaciers provide 1.8 trillion liters (470 billion gallons) of water each summer.40. It takes seven and a half years for the average American residence to use the same amount of water that flows over the Niagara Falls in one second (750,000 gallons).41. Household leaks can waste more than 1 trillion gallons annually nationwide. Thats equal to the annual household water use of more than 11 million homes.42. 1 pound of beef requires 1,799 gallons of water.43. 1 gallon of wine requires 1,008 gallons of water.44. A 0.3 pound burger requires 660 gallons of water.45. 1 slice of bread requires 11 gallons of water.46. 1 apple requires 18 gallons of water.47. 1 pound of chocolate requires 3,170 gallons of water.48. 500 sheets of paper requires 1,321 gallons of water.

(viii) REFERENCES http://en.wikipedia.org/wiki/Waterhttp://www.indexmundi.com/india/freshwater_withdrawal_(domestic_industrial_agricultural).htmlhttp://hppcb.gov.in/eiasorang/spec.pdfhttp://en.wikipedia.org/wiki/Drinking_waterhttp://www.allaboutwater.org/water-facts.htmlhttp://www.seametrics.com/blog/water-facts/http://www.factslides.com/s-Water

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