water and pollution

8/6/2019 Water and Pollution

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Wateris a chemical substance that is composedof hydrogen and oxygen and is vital for all known

forms of life. In typical usage, waterrefers only to its liquid form

or state, but the substance also has a solid state, ice,and a gaseous state, water vapor or steam. Watercovers 71% of the Earth's surface.On Earth, it is foundmostly in oceans and other large water bodies, with1.6% of water below ground in aquifers and 0.001% inthe air as vapor, clouds (formed of solid and liquidwater particles suspended in air), and precipitation.

Oceans hold 97% of surface water, glaciers andpolar ice caps 2.4%, and other land surface watersuch as rivers, lakes andponds 0.6%. A very smallamount of the Earth's water is contained withinbiological bodies and manufactured products.Clean drinking water is essential to human and otherlifeforms. Access to safe drinking water has improvedsteadily and substantially over the last decades inalmost every part of the world.There is a clear

correlation between access to safe water and GDP percapita.[6] However, some observers have estimatedthat by 2025 more than half of the world population willbe facing water-based vulnerability.A recent report(November 2009) suggests that by 2030, in somedeveloping regions of the world, water demand willexceed supply by 50%.Water plays an important rolein the world economy, as it functions as a solvent for awide variety of chemical substances and facilitates

industrial cooling and transportation. Approximately70% of freshwater is consumed by agriculture.

Water in three states: liquid, solid

(ice), and (invisible)water vapor in

the air. Clouds are the accumulationsof the droplets, condensed from

vapor-saturated air.


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Water is the chemical substance with chemical formulaH2O: one molecule of water has

two hydrogen atoms covalently bonded to a single oxygen atom.Water appears in nature in allthree common states of matter and may take many different forms on Earth: water vapor andclouds in the sky; seawater and icebergs in the polar oceans; glaciers and rivers inthe mountains; and the liquid in aquifers in the ground. The major chemical and physicalproperties of water are:

Water is a tasteless, odorless liquid at standard temperature and pressure. The color ofwater and ice is, intrinsically, a very slight blue hue, although water appears colorless in smallquantities. Ice also appears colorless, and water vapor is essentially invisible as a gas.

Water is transparent, and thus aquatic plants can live within the water because sunlight canreach them. Only strong UV light is slightly absorbed.

Since the water molecule is not linear and the oxygen atom has a higher electronegativity thanhydrogen atoms, it carries a slight negative charge, whereas the hydrogen atoms are slightlypositive. As a result, water is a polar molecule with an electrical dipole moment.

A result of interplay of these properties, Capillary action refers to the tendency of water to moveup a narrow tube against the force of gravity. This property is relied upon by all vascular plants,such as trees.

Water is a good solvent and is often referred to as the universal solvent. Substances thatdissolve in water, e.g., salts, sugars, acids, alkalis, and some gases especiallyoxygen, carbon dioxide(carbonation) are known as hydrophilic(water-loving) substances, whilethose that do not mix well with water (e.g., fats and oils), are known as hydrophobic(water-fearing) substances.

Pure water has a low electrical conductivity, but this increases significantly with the dissolutionof a small amount of ionic material such as sodium chloride.


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Large bodies of water such as oceans

manifest water's inherent slightly blue color.Water in an indoor swimming pool appears blue against a

white background, right up to the waterline. The same

water inside a floating white bucket appears only veryslightly blue.

High concentrations of dissolved lime give the waterof Havasu Falls a turquoise color.

Red tide off the Californian coast.


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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 pack and glaciers. Water also infiltrates

the ground and goes into aquifers. This groundwater later flows back to the surface in springs, or 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.

Tides are the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of theMoon and the Sun acting on the oceans. Tides cause changes in the depth of the marineand estuarine water bodies and produce oscillating currents known as tidal streams. The changingtide produced at a given location is the result of the changing positions of the Moon and Sunrelative to the Earth coupled with the effects of Earth rotation and the local bathymetry. The strip ofseashore that is submerged at high tide and exposed at low tide, the intertidal zone, is animportant ecological product of ocean tides.

High tide (left)and low tide (right)Lake Chungar and Parinacota volcano

innorthern Chile


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Agriculture

Fordrinking

Hygiene : The ability of water to

make solutions and emulsions is used for washing. Chemical uses

Extinguishing fires

Waterindustry

Industrial applications

Food processing

Waterpurification facility

Irrigation offield crops


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Waterpollution is the contamination of water bodies(e.g. lakes, rivers, oceans, groundwater).

Water pollution affects plants and organisms living in these bodies of water and, inalmost all cases the effect is damaging either to individual species and populations,but also to the natural biological communities.

Water pollution occurs when pollutants are discharged directly or indirectly into waterbodies without adequate treatment to remove harmful compounds.

Water pollution is a major problem in the global context. It has been suggested that it

is the leading worldwide cause of deaths and diseases, and that it accounts for thedeaths of more than 14,000 people daily. Anestimated 700 million Indians haveno access to apropertoilet,and 1,000 Indian children die ofdiarrheal sicknessevery day.Some 90% ofChina's cities sufferfrom some degree ofwaterpollution, and nearly 500 millionpeople lackaccess to safe drinking water.Inaddition to the acute problems of water pollution in developingcountries, industrialized countries continue to struggle with pollution problems as well.In the most recent national report on water quality in the United States, 45 percent ofassessed stream miles, 47 percent of assessed lake acres, and 32 percent of

assessed bay and estuarine square miles were classified as polluted. Water is typically referred to as polluted when it is impaired

by anthropogenic contaminants and either does not support a human use, likeserving as drinking water, and/or undergoes a marked shift in its ability to support itsconstituent biotic communities, such as fish. Natural phenomena suchas volcanoes, algae blooms, storms, and earthquakes also cause major changes inwater quality and the ecological status of water.


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Millions depend onthepolluted Ganges river.

Raw sewage and industrial waste flows across

international borders New River passes from

Mexicali to Calexico, California.

Point sourcepollution - Shipyard - Rio de Janeiro.

DeerIsland WasteWaterTreatment Plant serving Boston,

Massachusetts and vicinit


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Point sourcepollutionPoint source

pollution refers to

contaminants that enter

a waterway through a

discrete conveyance,

such as a pipe or ditch.

Non-point sourcepollution

Non-point source (NPS)

pollution refers to

diffuse contamination

that does not originate

from a single discrete

source


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The specific contaminants leading to pollution in water include a widespectrum of chemicals, pathogens, and physical or sensory changes suchas elevated temperature and discoloration. While many of the chemicalsand substances that are regulated may be naturally occurring(calcium, sodium, iron, manganese, etc.) the concentration is often the keyin determining what is a natural component of water, and what is a

contaminant. Oxygen-depleting substances may be natural materials, such

as plant matter (e.g. leaves and grass) as well as man-made chemicals.Other natural and anthropogenic substances may cause turbidity(cloudiness) which blocks light and disrupts plant growth, and clogsthe gills of some fish species.

Many of the chemical substances are toxic. Pathogens can

produce waterborne diseases in either human or animal hosts. Alteration ofwater's physical chemistry includes acidity (change in pH), electricalconductivity, temperature, and eutrophication. Eutrophication is an increasein the concentration of chemical nutrients in an ecosystem to an extent thatincreases in the primary productivity of the ecosystem. Depending on thedegree of eutrophication, subsequent negative environmental effects suchas anoxia (oxygen depletion) and severe reductions in water quality mayoccur, affecting fish and other animal populations.

water and pollution

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