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Air Pollution

Air Pollution may be defined as the presence of impurities in excessive quantity and duration to cause adverse effects on plants,animals,human beings and materials.

Air Pollution from automobiles,industrial plants,coal burning power plants,incinerators,and furnaces have created serious environmental pollution problems


Sources of air pollution

The two main sources of air pollution are

a)Natural Sources

b)Man made or anthropogenic sources

Natural sources include dust,storms,volcanoes,lightening,sea salt,smoke,forest fires,etc.The man made sources are agricultural activities,industrial growth,domestic wastes,automobile exhausts,etc.


Types of Air Pollutants


Air Pollutants are generally grouped into the following two types.

a)Particulate Pollutants and
b)Gaseous Pollutants

a)Particulate Pollutants:In general the term 'Particulate'refers to all atmospheric substances that are not gases.They can be suspended droplets or solid particles or mixtures of the two.Particulates can be composed of materials ranging in size from 100 micrometers to 0.1 micrometers.

Dust,Smoke,Fumes,Fog,Mist,Aerosol are the classification of particulates.

2)Gaseous Pollutants:

These are toxic and poisonous gases such as carbon monoxide,chlorine,ammonia,hydrogen sulphates, sulphur dioxide,nitrogen oxides and carbon dioxide.

Effects of Air Pollution:

The effects of air pollution are listed below.

1.Effect of air pollution on human health:

aa)The effect of air pollutants on materials:

Effect on materials :: Responsible Air Pollutants

a)Discoloration and deterioration of limestone and building materials :: NO,CO₂,acids and aerosols

b)Reduction in tensile strength of textiles :: SO₂,acid and gases

c)Cracking and strength loss of rubber :: O₃,Oxidants

ab)Effects of air pollutants on vegetation:

Pollutant :: Effects on Vegetation

a)SO₂ :: Chlorosis

b)NO₂ :: Premature fall of leaves and suppressed growth of plants and seduced yield

c)Ozone :: Necrosis(Dead areas on leaves),leaf damages and reduced yield.

2.Effects on Animals:

Animals take up fluorides of air through plants.Their milk production falls and their teeth and bones are affected.They are also prone to lead poisoning and paralysis

3.Effects on Physical properties of Atmosphere

Some of the effects of air pollution on physical properties of atmosphere are

a)Impact of Air Pollution on Health

b)Carbon monoxide(CO)

c)Nitrogen Oxides

d)Hydrocarbons(HC)

e)Benzene(C₆H₆)

f)Lead(Pb

g)Suspended Particulate Matter(SPM)

h)Sulfur Dioxide(SO₂)

i)Ozone(o₃)

j)Cadmium

k)Mercury

l)Asbestos


Control measures of Air Pollution:

The two types of control measures of air pollution are
1.Dilution
2.Control at source.

1.Dilution:
Tall chimneys are used to dilute the air pollutants into the atmosphere.The tall chimneys may penetrate the inversion layer of the atmosphere and disperse the contaminants by reducing the ground level contamination.
However the method of dilution is a short term control measure and it is not suitable for long term control.Because the pollutants dispersed by the tall chimneys are carried and spread around the area of disposal,this may cause harmful effects to the surrounding area

2.Control at Source:
Control of contaminants at the source is better option than the method of dilution.This can be achieved by the following ways.
a. Proper use of the existing equipment.
b. Change in process.
c. Modification or Replacement of equipments.
d. Installation of controlling equipments.


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Water Pollution

Water Pollution is defined as any physical,chemical or biological change in quality of water that has a harmful effect on living organisms or makes the water unsuitable for needs.

Sources of Water Pollution

Water Pollution may be caused by many sources.But the two general categories of water pollution are:
1. Point sources and
2. Non-point sources.

1. Point sources:Point sources discharge pollutants at a specific place through pipelines,sewer lines,or ditches into water bodies.Identification,monitoring and control of point source discharge are easy.
Following are some of the point sources.
a. Factory outlets.
b. Power plants outlets.
c. Underground mines.
d. Oil wells
e. Sewage treatment plants.

2. Non-point sources:Non-point sources discharge pollutants from large and scattered area.These sources have no specific location.
Following are some of the non-point sources.

a. Urban streets.
b. Agricultural lands.
c. Runoff from feedlots,golf courses,lawns and gardens.
d. Sub-surface flow.
e. Soil erosion.

Effects of Water Pollution

1. Presence of the many infectious agents causes many diseases.

2. Change in color of water affects the usage of water and growth of plants and organisms in water.

3. The oxygen demanding wastes such as animal manure and plant residues deplete the dissolved oxygen content of water which is harmful to the aquatic lives.

4. Growth of aquatic plants and fishes are affected by the presence of acids,alkalies and toxic substances.

5. Oil and other lubricants affect the self purification of the stream or water body.

6. Dumping of solid wastes resulting surfaces water as ground water pollution.

7. Run-off from farms,backyards,and golf courses contain pesticides such as DDT that in turn contaminate the water.

8. Over exploitation of ground results decline in water levels.Also it leads to sea water intrusion into the groundwater which deteriorates its quality.

Control of Water Pollution

1. Farmers can reduce the running of fertilizers from their agricultural lands to the nearby water bodies and leaching into aquifers.This can be obtained by using slow-release fertilizers and avoiding fertilizers in sloped ground.

2.Over fertilizers and improper application of pesticides can be avoided.

3.By using more biological control pests,pesticide usage may be minimized.

4.Soil erosion cab be minimized by reforesting critical and important water sheds.

5.Proper treatment must be given to all the effluents from the industries.

6.By preventing ground water contamination.

7.By reuse of treated waste water fro irrigation purposes.

8.By reducing poverty and birth rates.

Soil Pollution

Soil Pollution is defined as the introduction of substances,biological organisms, or energy into the soil,resulting in a change of the soil quality,which is likely to affect the normal use of the soil or endangering public health and the living environment.

Sources of Soil Pollution

1.urban wastes:Both domestic and commercial wastes are classified as urban wastes.All solid wastes of urban wastes are commonly termed as 'refuse' which contains garbage,and rubbish materials like papers,fibers,plastics,glasses,bottles,street sweepings,leaves,abandoned vehicles and other discarded products.

2.Industrial wastes:These are the major source of soil pollution.They consists of organic and inorganic compounds along with non-biodegradable materials.Most of the chemicals present in the liquid wastes are accumulated in the soil and causes soil pollution.

3.Agricultural practices:Plants on which we depend for food are under attack from insects,fungi,bacteria viruses,rodents and other animals, and must compete with weeds for nutrients.In modern agricultural practices,the types most commonly used are insecticides,fungicides an herbicides while other varieties include nematicides,miticides,rodenticide and molluscides.These causes accumulation of these chemicals in the soil.

4.Farm house wastes:Increase in population of cows,cattle,pigs and poultries in the farm house results pollution of soil

5.Biological agents:These are
a.Pathogenic organisms occurring in contaminated soil.
b.Pathogenic organisms excreted by man.
c.Pathogenic organisms excreted by animals.

Effects of Soil Pollution

1.Removal of the top soil of land causes low fertility for crop production.

2.Disposal of industrial effluents and domestic wastes on land causes accumulation of chemicals and loss of fertility.

3.Soil flora and fauna may be adversely affected.

4.The crop produced in a polluted land will be of inferior quality.

5.Deforestation is threatening not only the existence of many species and the livelihood of many indigenous people,but can also influence the climate.

6.Toxic chemicals leached from the land filling areas into the soil underneath causing an unusually large number of birth defects,cancers and respiratory,nervous and kidney diseases.

Control of Soil Pollution

The following measures may be adopted to control soil pollution:
a. Preserving the top soil which is the fertile soil.By planting of more trees soil erosion can be controlled.
b. Understanding the relationship between soil,water and plant and protect the mineral cycles of fixation.
c. Disposal of property treated industrial wastes,physically,chemically and biologically causes fewer hazards
d.Preventing the entry of leachates from the land fills into the soil layer can minimize the entry of chemicals.
e.Use of fertilizers and pesticides preferable in optimal dose.
f.More plough or mix can improve aeration,porosity and permeability of soil.

Marine Pollution

Marine Pollution is defined as "Introduction by man,directly or indirectly,of substances or energy into the marine environment resulting in such destructive effects as harm to living resources,hazard to human health,hindrance to marine activities including fishing,impairment of quality for use of sea-water,and reduction of amenities ."

Sources of Marine Pollution

1.Land based sources:
About 80% of marine pollution comes from land based activities.Land based sources of marine pollution are those types of pollution introduced into the marine environment from a variety of land sources.

2.Storm water:Storm water flow depends on rainfall,and the first flows following a dry spell often contain high levels of pollutions,such as heavy metals oil residues,nutrients,micro organisms,such as viruses,bacteria and protozoa from faecal material.

3.Pipelines:Disposal of fully or partially treated municipal and industrial wastes into rivers and/or bays,through pipe lines,also contributing to total land based marine pollution.Pipelines usually discharge below the low water mark.

4.Rivers:Rivers carry to the sea water containing contaminants such as nutrients and pesticides from agricultural runoff,faecal pollution resulting from poor sanitation,and industrial discharges.

Effects of Marine Pollution

1. Organic matter:Decomposition of organic matter present in the untreated or partially treated waste causes depletion of dissolved oxygen content of the marine water.This can cause the death of marine plants and animals,and may lead to changes in biodiversity.

2.Eutrophication:Disposal of effluent with more nitrogen and phosphorus causes 'eutrophication',which may cause algal blooms.These blooms can discolour the water,clog fish gills, or even be toxic.

3.Pathogenic micro-organisms:These cause gastric and ear-nose-throat infections,hepatitis,and even cholera and typhoid.

4.Toxic chemicals:Substances causing toxic effects that damage the physiological processes and functions of reproduction,feeding and respiration.

5.Pesticides:Pesticides such as DDT(Dichlorodiphenyltrichloroehane),and other persistent chemicals accumulate in the fatty tissu of animals.These chemicals can cause reproductive failure in marine mammals and birds

6.Human health:Many pollutants such as dioxins,furans,polychlorinated biphenyls(PCB's),and some heavy metals are accumulating in the marine organisms.When humans are consuming sea foods from the polluted areas they are exposes to those pollutants

7.Radioactive wastes:Any leakage of failure of radioactive waste containers,which are used to dispose low level radioactive wastes in deep sea causes more effects that could be devastating.

Preventions/control of Marine Pollution

Following are some of the preventive measures of marine pollution:

1.Careful handling of oil and petroleum products.
2.Ban ocean dumping of sludge and hazardous dredged materials.
3. Dispose fully treated municipal and industrial wastes.
4. Regulate coastal development.
5. Hygienic and aesthetic maintenance of recreational beaches.
6. Controlled use of pesticides and chemicals in agricultural activities in delta portions.
7. Separate sewage and storm water lines.
8.Ban on dumping of radioactive wastes.

Noise Pollution

Noise pollution can be defined as any unwanted or offensive sounds that unreasonably intrude into and disturb our daily lives

Measurement of Sound

The decibel(abbreviated dB) is the logarithmic scale used to measure the intensity of a sound.The zero dB is hearing threshold.On the decibel scale,0 dB is the smallest audible sound which is nearly about total silence.A sound 10 times more powerful than near total silence is 10 dB. and that 100 dB times more powerful is 20dB.

some common sounds with decibel rating

0 dB ------------>Near total silence
13 dB ----------->Human heart beat
15 dB------------> A whisper
40 dB------------> Typing
60 dB------------> Normal conversation
66 dB------------> Barking of dog
70 dB------------> Truck noise
90 dB ----------->A lawnmower
110 dB------------> A car horn
120 dB-------------> A jet engine
140 dB--------------> A fire cracker or gunshot

Causes of Noise Pollution

Noise pollution can be caused by:

1. Road traffic noise:Road traffic noise has become a major urban environmental problem because:
a.Historically land use planning has not been well integrated with transport,planning,allowing residential developments and major transport corridors to occur in close proximity without appropriate buffer zones or treatment to buildings.

b. There has been an increasing community dependence on road transportation,and an unwillingness to implement or accept partial solutions involving greater use of public transport.

c. Traffic on many existing roads through built up areas has increased well beyond expectations prevailing during planning or construction of the roadways.

2.Air traffic noise:
The extent of aircraft noise impact depends on the types of aircraft flown,the number of flights and flight paths.
The increase in number of flights,an important factor in overall noise levels,has led to an increase in general noise levels associated with air traffic.

3.Rail traffic noise:
Rail noise can be considerable,but generally affects a far smaller group of the pollution than road or aircraft noise as it is generally confined to residents living along rail lines in urban areas.

4.Domestic noise:
Domestic noise is any noise from residential areas such as a house,apartment,and flat.The noise from barking dogs and road traffic have the greatest impact on residential communities.

5.Construction noise:
Construction noise is defined as 'the noise created by the equipment at the construction sites for the fabrication,erection,modification,demolition,or removal of any structure or facility,including all related activities such as clearing of land,site preparation,excavation,cleanup, and landscaping.

Effects of Noise Pollution

1.Annoyance:A noise is said to be annoying if an exposed individual or a group of individuals would reduce the noise.avoid,or leave the noisy area if possible.Noise can cause annoyance and frustration as a result of interference,interruption and distraction.

2.Communication Interference:Noise pollution can have a considerable effects on communication.Noise can mask speech.Even when speech is accurately understood,background noise may result in greater pains for the talker as well as the listener.Many factors contribute to the effect of noise on communication interference.Some of them are:
a. Frequency of noise.
b. Speech content.
c. Speech intensity.
d. Closeness of the people.
e. Age of the people.
f. Location of the speech.

3. Danger to people:Noise can cover warning signals,causing accidents to occur and noise can hide shouts for help if a person is in danger.

4. Headache:Noise can cause increased number of headaches.

5. Heart disease:Noise causes stress and the body reacts with increased adrenaline,changes in heart rate,and a rise in blood pressure.

6.Mental depression:Continuous exposure to high noise level can result increased mental depression rates.

7. Sleep disruption:It is common knowledge that noise can disturb sleep.Several factors that cause sleep disturbances are:
a. Types of noise. d. Intensity of noise.
b. Repetition of noise. e. Health condition of the people.
c. Duration of noise f. Stage of sleep.

Control of Noise Pollution
Noise pollution can be effectively controlled by taking the following measures:
1. By providing ear protection aids to the people aids to the people working in noisy places.Ear-plugs.ear-muffs,noise helmets,headphones etc.may be used as ear protection aids in reducing the occupational exposure.

2. Designing,fabrication and using quieter machines to replace the noisy machines.

3. Providing proper lubrication to the machines.

4. Providing proper maintenance to the machines.

5. Providing sound proof chambers to the noisy machines.

6. Industrial zones,aerodromes and highways would be located outside the city limits.

7. Plants are efficient absorbers of noise,especially noise of high frequency.Planting of green trees on both sides of streets,hospitals,educational institutions etc.,can reduce the noise level effectively.

8. Minimum use of loud speakers.

9. Banning loud horns in automobiles.

10. Framing noise pollution act.

11. Creating public awareness about noise pollution and its effects through newspapers,radio and televisions.

Thermal Pollution

Thermal Pollution may be defined as 'the excessive raising or lowering of water temperature above or below normal seasonal ranges in streams,lakes, or estuaries or oceans as the result of discharge of hot or cold effluents into such water'.

Sources of Thermal Pollution

Thermal pollution may be caused by four major sources.They are:

a. Water as a cooling agent,
b. Soil erosion,
c. Deforestation of shorelines, and
d. Run-off from hot paved surfaces.

a.Water as a cooling agent:It is the major source of thermal pollution of water in most part of the world.The use of water as a cooling agent in power plants and factories and industrial facilities causes thermal pollution.

b. Soil erosion:Soil erosion makes the water muddy,which in turn increases the absorption of light, thus increasing the water temperature.

c. Deforestation of shorelines:This contributes to the problem of thermal pollution in two ways.First the plant roots hold soil particles together.Hence the deforestation results erosion of soil particles.Secondly, vegetation provides shade to the water surface.Deforestation increases the amount of light hitting the water surface,thereby raising the water temperature.

d. Run-off on hot surface:Storm water runoff on warmed urban surfaces,such as streets,sidewalks and parking lots causes raising of the temperature water that flows on the surface

Effects of Thermal Pollution

Thermal Pollution increased the temperature of water considerably.This increase in temperature causes the following effects.

1.Change in water properties:Temperature affects physical,biological and chemical parameters in a water body

2.Disturbed Ecosystem:Most aquatic organisms have adapted to survive within a range of water temperatures.Some organisms like trout and stonefly nymphs prefer cooler water,while others such as carp and dragonfly nymphs thrive under warmer conditions.As the temperature of river or lake increases,cool water species will be replaced by warm organisms.Few organisms can survive in temperatures of extreme heat or cold.

3.Reduced dissolved oxgen:The addition of heat reduces the water's ability to hold dissolved gases,including the oxygen required for aquatic life.If the water temperature in greater than 95 degree fahernheit.,the dissolved oxygen content may be too low to support some species.

4.Increased bacterial growth:Warmer water allows bacterial populations to increase and thrive and algae blooms may occur.

5.Photosynthesis:The rate of photosynthesis by algae and larger aquatic plants is also affected by thermal pollution.

6.Thermal shock:When a power plant first opens or shut down for repair,fish and other organisms adapted to a particular temperature range can be killed by the abrupt change in water temperature.This is called as thermal shock.

7.Increase in toxicity:The rising temperature increases toxicity of the chemicals present in water causes massive morality of fishes.

Control of Thermal Pollution

Following are some of the preventive measures of thermal pollution.

a)Temperature of water can be reduced by taking the water to wet or dry cooling towers which are being used to pre cool that water before discharge tranfers the heat from the water to the atmosphere.

b)Discharging the heated water into shallow ponds or canal,allowing it to cool,and reusing it as cooling water.

c)The thermal discharge from an industry can also be used in heating homes,building or other such structures.This is achieved by circulating the hot water through pipes in the structures.

d)Water with temperature can be successfully used in aquaculture.

e)The heated water can also be used in agriculture,especially for frost protection during the cold seasons.