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DR. S. N. SINGHKRISHI VIGYAN KENDRA

INSTITUTE OF AGRICULTURAL SCIENCES

BANARAS HINDU UNIVERSITY

BARKACHHA, MIRZAPUR

Water resources: Pollution and control.

Oceans (71%)

Land(29%)

Most of theEarthiscoveredby water“...water, water, every where,not any drop to drink!”

Global OverviewWhile 67% of Earth’s surface is covered by

water, only less than 2.7% of global water is freshwater. Most of the freshwater (2.05%) are locked in ice caps and glaciers. Only less than 0.7% is available for human use.

In use

Potentialfarming

Unusable

Potentialgrazing

Cultivated11%

Grazed10%

14%Forests, semi-arid6% Arid

Ice, snow, deserts,mountains (51%)

8%Tropicalforests

Oceans (71%)

Land(29%)

andbarely a fifth of itis available forfarming related activities.

But the supply of land too is limited...

How much water in the hydrosphere?Conventional estimate assumesa total groundwater storage of about 1,700 quadrillion gallons. This gives the estimate of hydrosphere’s total water content as 3.5x1020 gallons.

Oceans (97%)

Ice (1.2%)

Underground water (0.5%)Surface water (0.02%)

Atmosphericmoisture (0.001%)

Competing water uses (I)

Competing water uses (II)Industrialized / developed countries tend to

use more water in their industrial production.Other countries tend to use more water for

agricultural uses.

Problems related to Water crisisInadequate access to safe drinking water by

over 1.1 billion peopleGroundwater overdrafting leading to

diminished agricultural yieldsOveruse and pollution of water resources

harming biodiversityRegional conflicts over scarce water

resources sometimes resulting in warfare.

Threats to fresh water resources Climate change causes change in frequencies

of droughts and floods.Depletion of aquifers caused by over-

consumption as a result of population growth.Pollution and contamination by sewage,

agricultural and industrial runoff.

Water pollutionWater pollution occurs when harmful substances are

released into the water in large quantities which cause damage to people, wildlife, or habitat or indirectly into water bodies without proper treatment to remove harmful compounds.

Effects of water pollution 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 the deaths of more than 14,000 people daily.

An estimated 700 million Indians have no access to a proper toilet,

and 1,000 Indian children die of diarrhea sickness every day.

Some 90% of China's cities suffer from some degree of water pollution, and nearly 500 million people lack access to safe drinking water.

Ground Water PollutionInteractions between groundwater and

surface water are complex. Consequently, groundwater pollution is not as easily classified as surface water pollution.

Chemical & other contaminants

Inorganic water pollutants include:-Acidity caused by industrial discharges

(especially sulphur dioxide from power plants)

Ammonia from food processing wasteChemical waste as industrial by-

productsFertilizers containing nutrients--nitrates

and phosphates--which are found in storm water run off from agriculture, as well as commercial and residential use

Heavy metals from motor vehicles (via urban storm water runoff) and acid mine drainage

Silt (sediment) in runoff from construction sites, logging, slash and burn practices or land clearing sites

Macroscopic pollution—large visible items polluting the water—may be termed "floatables" in an urban storm water context, or marine debris when found on the open seas, and can include such items as:

Trash: (e.g. paper, plastic, or food waste) discarded by people on the ground, and that are washed by rainfall into storm drains and eventually discharged into surface waters

Nurdles: small ubiquitous waterborne plastic pellets

Shipwrecks: large derelict ships.

Pathogens are another type of pollution that prove very harmful.  They can cause many illnesses that range from typhoid and dysentery to minor respiratory and skin diseases.  Pathogens include such organisms as bacteria, viruses, and protozoan.  These pollutants enter waterways through untreated sewage, storm drains, septic tanks, runoff from farms, and particularly boats that dump sewage. 

Additional forms of water pollution     Three last forms of water pollution exist in the forms of petroleum, radioactive substances, and heat.  Petroleum often pollutes waterbodies in the form of oil, resulting from oil spills.

Thermal PollutionThermal pollution is the rise or fall in the temperature of a natural body of water caused by human influence.

A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers

Elevated water temperatures decreases oxygen levels (which can kill fish) and affects ecosystem composition

Thermal pollution can also be caused by the release of very cold water from the base of reservoirs into warmer rivers.

Water-borne Diseases

Diseases caused by ingestion of water contaminated by human

or animal excrement, which contain pathogenic

microorganisms

Include cholera, typhoid, amoebic and bacillary dysentery and other diarrheal

diseases

In addition, water-borne disease can be caused by the

pollution of water with chemicals that have an adverse

effect on health

ArsenicFlourideNitrates from fertilizersCarcinogenic pesticides (DDT)Lead (from pipes)Heavy Metals

Water-related Diseases

Water-related diseases are caused by insect vectors, especially mosquitoes, that breed

or feed near contaminated water.

They are not typically associated with lack of access to clean drinking water or sanitation services

Include dengue, filariasis, malaria, onchocerciasis, trypanosomiasis

and yellow fever

IT’S TIME TO GIVE WATER A SERIOUS THOUGHT?

What are the possible solutions of water pollution?Industrial effort : Industry is responsible for a

large amount of pollutants including ones that pollute water.

Legislation has been passed forcing industry to make efforts to clean up their waste. Through reducing the waste that they produce, it has been possible to reduce the amount of pollutants that enter the water cycle .

Municipal treatment plants are designed to control conventional pollutants: BOD and suspended solidsWell-designed and operated systems (i.e., secondary treatment or better) can remove 90 percent or more of these pollutants. Some plants have additional sub-systems to treat nutrients and pathogens. Most municipal plants are not designed to treat toxic pollutants found in industrial wastewater

Fig. 20-13, p. 545

SOLUTIONS

Groundwater PollutionPrevention Cleanup

Find substitutes for toxic chemicals

Pump to surface, clean, and return to aquifer (very expensive)Keep toxic

chemicals out of the environmentInstall monitoring wells near landfills and underground tanks

Inject microorganisms to clean up contamination (less expensive but still costly)

Require leak detectors on underground tanksBan hazardous waste disposal in landfills and injection wellsStore harmful liquids in aboveground tanks with leak detection and collection systems

Pump nanoparticles of inorganic compounds to remove pollutants (still being developed)

Fig. 20-17, p. 551

SOLUTIONS Coastal Water

PollutionPrevention CleanupReduce input of toxic pollutants

Improve oil-spill cleanup capabilities

Separate sewage and storm lines

Use nanoparticles on sewage and oil spills to dissolve the oil or sewage (still under development)

Ban dumping of wastes and sewage by ships in coastal watersBan ocean dumping of sludge and hazardous dredged material

Require secondary treatment of coastal sewageRegulate coastal

development, oil drilling, and oil shipping Use wetlands, solar-

aquatic, or other methods to treat sewage

Require double hulls for oil tankers

What Can You Do? Water Pollution, Ways to Help Reduce Water Pollution