What is POLLUTION ?

The word 'pollution' has been derived from latin word pollutionem which means to make dirty. Pollution can be defined as an undesirable change in the physical , chemical or biological characteristic of air , water and soil that may harmfully affect the life or create a potential health hazard of any living organism. Pollution is thus direct or undirect change in any component of biosphere , that is harmful to living components, particularly for human beings, affecting adversely their industrial progress and natural assets or general environment.....

Envionment pollution is the evil formed due to man made progresses. It is one of the most horrible ecological crisis to which we are subjected today. Our three basic amenities air, water and land which were pure , virgin and undisturbed , uncontaiminated and basically most hospitable are now become foul , contaminated , undesirable and therefore harmful for our health . This is all due to rapid urbanization and industrialization.

They are classified in basically three types which I will explain it to you in my next posts....... they are :

(1) Air pollution

(2) Water pollution

(3) Soil pollution

There are many pollutants which generally affect the environment ...... Pollutants are the subtances which cause the pollution...........they are divided into four categories :

(1) Primary pollutants - These pollutants remain in the same form as they released into environment , such as SO2 , NO2 etc....

(2) Secondary pollutants - They are been derived from primary pollutants by the chemical reactions between them , are called as secondary pollutants. For example PAN - peroxyacetyle nitrate.....

(3) Biodegradable pollutants - Pollutants which can be decomposed easily , in their natural environment by natural biological processes , such as carbonates, phosphates etc are Biodegradable pollutants......

(4) Non-Biodegradable pollutants - Pollutants which do not degrade or degrade very slowly in their natural environment are called non-biodegradable pollutants. They are mostly inorganic compounds like D.D.T and phenolic compounds.........

WHAT IS AIR POLLUTION ?.

Air pollution may be defined as the presence of one or more contaminants like , dust , gas mist , smoke , odour in the atmosphere which are injurious to human, plants or animals or which unreasonably obstruct the comfortable enjoyment of life and property..

Air pollution can also be defined as “presence of foreign substances in ambient atmosphere, resulting from the activity of man , in sufficient concentration , present for a sufficient time under the circumstances which interfere significantly with the comfort health , or welfare of persons or with the full use or enjoyment of property”.

The most important gaseous air pollutants are carbon monoxide , chlorine , halogenated solvents, hydrogen sulphide , hydrocarbons , nitrous oxide and sulphur dioxide. The low amount of these pollutants in air does not lead to any serious effects , due to nature’s self regulatory cycles. But when their concentration becomes so high that they cannot be tolerated by atmosphere’s regulatory cycles, the air is said to be polluted…….

SOME HARMFUL EFFECTS OF AIR POLLUTION

(1)Pollutants such as NOx , O3 , PAN , smog can cause eye irritation….

(2)SO2 , NOx , insecticide , pesticides tec can cause nose and throat irritation .

(3)SO2 can cause bleaching of leaves and necrosis.

(4)ozone can cause premature aging , suppressed growth, necrosis , bleaching and collapse of leaf.

(5)SO2 and NOx can dissolve in rainy water and get converted into H2SO4 and HNO3.Deposition of these acids corrodes the metal part of building roofs, railway tracks , bridges and other structures…..

(6)Acid deposition also deteriorates various building materials such as marble , limestone , mortar etc.

(7)Acid rain having pH value below 4.5 increases acidity of rivers , lakes and streams. This acidic water is highly lethal to fishes , bacteria and blue green algae..

(8)They can cause asthmatic attacks . Higher concentration of SO2,NO2 and photochemical smog can cause chronic pulmonary diseases..

(9)The air pollution can reduce the oxygen carrying capacity of the Haemoglobin.

(10)Radioactive isotopes can cause anaemia,leukaemia,cancer and other genetic effects…..

VARIOUS SOURCES OF AIR POLLUTION

Air is never found clean in nature........every thing goes right from the fire man to present... everybad thing done with environment by man has produced disastrous results...
There are two sources which cause the air pollution they are :

(1) NATURAL SOURCES : The natural sources of air pollution are volcanic eruptions , forest fires , natural organic and inorganic decay, marsh gases , deflation of sand, dust , cosmic rays and extra terrestrial bodies etc .....

(a) Atmospheric Reactions - Natural chemical reactions in lower atmosphere leads to conversion of gases into solids and liquids by oxidation , reduction, combustion ..... In the upper atmosphere , photochemical reactions produces more complex compounds due to presence of ultraviolet solar radiations.....

(b) Dust and Aerosols : The salt particles from sea water , condensation nuclei , air borne particles from soil and vegetation , bacteria are major air pollutants.......

(c) Micro-organisms : Algae , fungi , bacteria are present as viable particles in the atmosphere....These micro-organism can be transported to distant places by wind , can affect plants ,animals and humans........

(d) Pollens : Pollens enter into atmosphere from weeds , grasses and trees and can be transported from one place to other by wind currents......

(e) Radioactive Minerals : Radioactive minerals present in earth's crust and cosmic rays from outer space are mainly responsible for the radioactivity of the atmosphere.....

(2) MAN MADE RESOURCES : The major pollution source are man made.... some of them are :

(a) Increase in population - Present world population is over 7 billion and expected to double after every 35 years.... Increase population not only needs fresh oxygen for breathing but it also erquire extra food and land which results in deforestation and also loss of wild species.......

(b) Deforestation : cutting of forest may cause increase in the level of CO2 , which can cause global warming......

(c) Combustion of fuels : The incomplete combustion of the fuels for meeting our daily requirement may cause air pollution......

(d) Emission from vehicles : The automobile exhausts are responsible for more than 75% of total air pollution..... They release a huge amount of poisonous gases such as carbon monoxide , hydrocarbons and nitrogen oxides.......

(e) Rapid industrialization : Industries are responsible for over 20% of air pollution ..... They emit harmful gases from their chimneys to atmosphere..... which cause the air pollution...

(f) Agricultural activities : Using of insecticide , pesticide , herbicides are main source to the air pollution.........

What are Primary air pollutants ?

HYDROCARBONS (HC's) - Hydrocarbons are organic compounds which contain only carbon and hydrogen . Most of the major chemicals in gasoline and other petroleum products are hydrocarbons....

Sources : Generally 85% of total hydrocarbon emission is from natural sources like geothermal areas , coal fields , natural gas from petroleum fields and trees.. Only 15% of the overall hydrocarbon emission is due to human activities from automobiles and industries (particularly oil refineries) ....

Effects : Hydrocarbons are not generally toxic , but inhalation of their vapour can cause irritation . Hydrocarbon along with the NOx produces photochemical smog. Hydrocarbons at concentration above 500 ppm have carcinogenic effects on lungs . Aldehydes , acrolein , peroxycyl and benzyle nitrates are strong eye , nose and throat irritants. Methane and benzpyrene emitted from gasoline exhaust , can cause narcotic effects in absence of oxygen...........

CARBON MONOXIDE

Carbon monoxide is one of the most series air pollutant. It is colourless , odourless , and tasteless and weighs about .965 times of air . Its composition in air is .00001% . It is a poisonous gas and considered as an asphyxiant (pulse stopper)

Sources : Natural sources of Carbon monoxide in atmosphere are volcanic eruptions , natural gas emissions , forest fires , oxidation of methane gas , etc... All these natural sources contribute less than 20% of the total Carbon monoxide production, while automobile exhaust alone contributes 80% of the total carbon monoxide emission. Other sources of Carbon monoxide are industries , and incomplete combustion of fuel.......

Effects : Carbon monoxide alone forms about 48% of all gaseous pollutants . It can seriously affect human aerobic metabolism due to its high affinity for haemoglobin . It reacts with the haemoglobin of blood and displaces oxygen and form carboxy-haemoglobin ,thus reducing the capablity of blood to carry oxygen . If percentage of carboxy-haemoglobin is below 1% it has no apparent effect , but if it reaches 2 to 5% it can affect central nervous system and cause impairment of visual perception and brightness discrimination. Over 5% can cause cardisc and pulmonary functional changes . 40-60 % can cause respiratory failure , coma and death after several hours , while above 65% it can cause rapid death........

HYDROGEN SULPHIDE

Hydrogen sulphide is produced by the reduction of sulphur . It has rotten egg smell . It is not toxic in low concentration but higher concentration above 10 ppm may be toxic . Hydrogen sulphide is not stable and readily gets oxidised in air.....

Sources : Hydrogen sulphide is a biological waste produced from anaerobic bacterial decomposition of organic matter in the soil . It is also produced as a by-product of reduction of sulphur from mineral deposits......

Sources of Hydrogen sulphide include decaying vegetation and animal matter , volcanic eruptions , coal pits and sewers.......

Effects : The repeated exposures to even low concentration has irritating effects on the mucous membrane , eyes and respiration system . High concentration of hydrogen sulphide due to accidental leakage can cause death too.......

OXIDES OF NITROGEN

The oxides of nitrogen involved in air pollution denoted by NOx are N2O , NO , NO2 , N2O3 and N2O5 . Of these nitric oxide (NO) and Nitrogen dioxide (NO2) are the major pollutants. Nitric oxides is a colourless and odourless gas , while nitrogen dioxide is a reddish brown gas having a pungent suffocating odour . About 95% of nitrogen oxide is emitted as NO and the remaining 5% as NO2.......

Sources : Bacterial decomposition of organic matter releases NOx in the atmosphere , mainly in the form of NO.. Small concentration of NOx also produced in upper atmosphere by the action of cosmic rays . Human induced NOx produced by combustion of fuels , industrial processes using nitric acid , emissions from electric utilities , mining and electric arc welding.....

Effects : NOx are the second most abundant air pollutants next to SOx in many cities . Nitric oxide is relatively inert gas and moderately toxic . NO like carbon monoxide , can combine with haemoglobin to reduce oxygen carrying capacity of the blood . NO has no damaging effects on plants.......

NO2 has more harmful effects on human health , as compared to NO. Low concentration of NO2 about .7 to 2 ppm increase resistance of lung's airways to air movements , while 50-100 ppm concentration can cause inflammation of lung tissues , and concentration over 150 ppm can be very fatal. Secondary pollutants from NOx produced during photochemical reactions such as PAN and O3 are more likely to damaging plants.....

OXIDES OF SULPHUR

Oxides of sulphur , i.e. sulphur dioxide (SO2) and sulphur trioxide (SO3) are probably most serious air pollutants......

Sources : Natural sources of SO2 are volcanoes which provide 67% of the total SOx pollution , while man made sources , such as combustion of fuels in industries and transportation contributes 33% of SOx pollution.

SO2 is a colourless, non-inflammable and non-explosive gas with a suffocating pungent odour....

Effects : SO2 is highly irritating gas which can cause chronic respiratory diseases , particularly bronchitis and pulmonary emphysema. SO2 can cause cough pharyngitis , eye irritation and headache. SO2 is also associated with lung cancer, heart diseases and diabetes mellitus...

SO2 also affects plants and various materials. SO2 can cause bleaching of leaf pigment and leaf necrosis. SO2 attacks various materials such as marble , limestone , paper , textile , leather and building. It is also responsible for corrosion of zinc , copper and aluminium . It can also cause acid rain............



Some of the Disaster occured by Air Pollution are:

1.LONDON SMOG INCIDENT

The most severe air pollution ever occured was due to sulphurous smog caused in London in 1952 , and hence named as London Smog. On December 5th , 1952 , a high temperature air mass moved over Southern England. This mass created a temperature inversion and caused a white fog to settle over London . With the extensive use of coal-fired heating and power production system , levels of particulate and SO2 increased and the fog began to blacken, converting into smog . The high pressure area stalled and the pollutant build up worsened further , since there were no air currents to disperse the smog. Heavy smog conditions prevailed for five days at a stretch and took toll of 4000 lives. The smog so formed was intensely irritating to human respiratory system. As a result most of the people soon developed red eyes , burning throats and hagging coughs. The cause of death were bronchitis , pneumonia and allied respiratory troubles . Fog disappeared on December 9th , 1952. The episode was enough to pass the Clean Air Act , 1956 in England........

2.CHERNOBYL DISASTER

The worst nuclear accident in the history occurred at Chernobyl , power plant in Soviet Ukraine , USSR on April 25th , 1986 at 1:23 A.M. Poor design of the reactor combined with operator's negligence caused the havoc. The operator ignored the warnings coming from various sensors and even disconnected the emergency core cooling system. As a result of which neutrons went out of control and an enormous amount of steam built up in pipes. The ensuing explosion sent the graphite slabs of the reactor core through the roof , setting it a fire and spewing radioactive materials.........
Twenty percent of the plant's radioactive iodine escaped along with 15% of radioactive caesium, hazardous plutonium and several other radioactive isotopes. A column of fluorescent blue light emerged from reactor and spread over a large area in Scandinavian countries 200km away from Russian regions . A devastating fire set up in the reactor which causes few casualties and severe damage to the nuclear plant.
USSR government claimed only two death and few injuries due to the accident . However data collected by a U.S. spy satellite , death toll of was about 2000 peoples. Soil , water and vegetation over 60 sq.km area around the Chernobyl severely damaged and will remain radioactive for several decades.
Chernobyl incident was proceeded by a series of minor accidents and safety lapses which were not taken as warning of the disaster that was lurking not far away...........

3.BHOPAL GAS DISASTER

The worst tragic accident of air pollution took place on December 3rd , 1984 in Bhopal , Madhya Pradesh , India . It took over 10000 human lives , over 2000 heads of cattle , sheep , goats , hundreds of poultry birds, temporary destruction of the surroundin vegetation and rendering thousands of people sick and disabled perhaps for their lifetime......
The disaster struck Bhopal on December 3rd , 1984 at mid-night when city was virtually asleep . A pesticide manufacturing company known as Union Carbide released a potent toxicant methyl isocyanate into the atmosphere due to alleged functional failure of vent scrubber outlet. The pressure of MIC storage tank goes beyond 55 psi , which causes the safety valve to open and gas starts shooting out. Venturi scrubber was turned on to neutralise the escaping gas , but it was out of order. Safety valve remained open for about 2 hours and released 30 tonnes of MIC in liquid and vapour form.......
Around 2:30 A.M. there were 4000 people in Hamidia hospital suffering from eye irritation and respiratory problems due to unknown reasonstill thattime. Next morning thousands lay dead on the roads and in homes. The death drama continued for days. Within a week 10,000 people died ,1000 became blind while more than lakh continue to suffer from various diorders. The chief causes of death and casualties were violent coughing , eye infections , suffocation , cardiac failure and pulmonary disorders....
The chemical company was prosecuted for the negligence shown in its functioning and was held responsible for tradegy. After a complicated, lengthy and costly legal battle , the supreme court ordered company to pay 470 million U.S. dollars to the Indian Government on behalf of all the victims in full and final settlement of all past ,present and future claims arising from the disaster.....

WHAT IS WATER POLLUTION ?

Water pollution may be defined as , “alteration in physical , chemical and biological characteristics of water which may cause harmful effects on human , animals , plants or aquatic biota.”

Natural water is never pure in chemical sense. It contains various impurities such as dissolved gases (H2S , CO2 , NH3), dissolved minerals (Ca, Mg , Na salts), suspended matter such as (clay,silt,sand) and even microbes . These natural impurities are in very low amounts and normally do not pollute water and it is potable. But when addition of these undesirable foreign substances increase from natural or anthropogenic sources , the water is said to be polluted . These impurities may make the water toxic , reduce its oxygen level , makes it aesthetically unsuitable and cause epidemic diseases. Thus , water pollution may also be defined as : “addition of excess of undesirable substances to water that makes it unsuitable for use to man , animal and aquatic life. ”

There are two sources of water pollution, which are divided into two categories:

(1) Point Sources: Those sources which can be readily identified at a single location are known as point sources. They include industries effluents, municipal sewage, sever overflow , raw sewage discharges. Water pollution by these sources can be minimized by collecting them at a central location, treated up to acceptable limits and reused.

(2) Diffused Sources: Sources of generalized discharge of waste water whose location cannot be easily identified are termed as diffused sources. They include run-offs from agricultural lands, forestry , mining , construction , etc. These sources cannot be easily controlled.

ORGANIC WATER POLLUTANTS

Pollutants are the elements which are responsible for the cause of the various pollutions.
Most of the substances of which living things composed of is the organic compounds. Some of the elements such as fats , proteins , carbohydrate , petroleum , rubber are organic compounds. Their presence in the water is undesirable as they impart taste, odour and colour to water , some of these compounds may be toxic and carcinogenic too....

The mostly found organic pollutants in water are fats , proteins , carbohydrate etc . Organic pollutants enter into the water system through domestic sewage , industrial waste from paper mills , waste from slaughter house , meat packing plants , food processing plants , run off from crop lands and decomposition products of organic compounds.......

Organic pollutants may be suspended or dissolved in water. Suspended organic matter is due to presence of certain industrial wastes or vegetables or animals , vegetables are in the form of algae , decayed leaves , fungi etc . , they impart acidity , green or brown colour and taste to water .Dead animals and insects are responsible for growth of bacteria in water . This water contains , large quantity of albuminous ammonia , small quantity of free ammonia and chloride and certain types of bacteria and viruses.

Water containing dissolved organic matter is due to certain industrial wastes and decay of vegetables and animals . This water contains large quantities of albuminous ammonia, free ammonia and chloride . This water may also contain pathogenic or disease creating bacteria......

It is divided into sub categories as :-

(1) Natural Organic Pollutants :-

They came in water generally from breakdown of naturally occurring organic compounds , such as decay of leaves , plants , dead animals etc . Various types of aquatic plants , micro-organisms releasing organic compounds into a water body through their metabolic processes also comes in this category.

(2) Sewage and Industrial Effluents :-

Municipal sewage and effluents from industries such as food processing units , paper mills , tanneries , slaughter houses etc , contains a large number of organic pollutants. Sewage and waste from other sources also contain a large number of synthetic organic compounds such as tetrachloride , tetrachloroethylene , pesticide , herbicide and chemicals used in industrial processes such as ethyl benzene , styrene and toluene. Most of this are toxic to human beings and animals.....

(3) Microbiological Pollutants :-

Polluted water contains a number of micro-organisms such as bacteria , virus , protozoa , algae . Most of these are not harmful but some can cause sickness to humans they are called pathogens . Human feces are main source of these pathogens.

(4) Oils :-

Oil is a naturally occurring mixture of thousands of different hydrocarbons . They are produced by leakage in oil pipelines , spills during transportation of oil , sewage containing oily contents. Oil pollution reduces light transmission through surface water and hence obstructs photosynthesis by marine plant and reduce D.O. level (dissolved oxygen) of water bodies....

INORGANIC WATER POLLUTANTS

Inorganic water pollutants consists inorganic salts , metal compounds , mineral acids , metallic complexes , finely divided metals , organometallic compounds and poly phosphatic detergents.

Inorganic pollutants may be categorised in the following categories -

(1) Acids and Alkalies - Industries manufacturing hydrochloric , nitric , sulphuric and phosphoric acids , sulphur dioxide , oxides of nitrogen , chlorine , ammonia and bases of sodium , potassium or calcium , discharge a huge amount of acids and alkalies in water system . These alkalies and acids destroy the bacteria and other micro organisms in water , thus effect its self purification capability.

(2) Toxic Inorganic Compounds - These are derived from industrial wastes of industries producing fertilizers , coke ovens , gas liquors , alkalies etc . They include salts containing anions of carbonate , acetate , nitrate , nitrite , fluoride , chloride , sulphate , phosphate and sulphides of copper , cadmium , zinc , manganese , lead , tin , iron and arsenic etc . Toxic compounds also include free chlorine , H2S , NH3 and free metals such as Ni, Cu , Co, Hg ,As ,Ag U etc......

(3) Dissolved Inorganic Substances - Dissolved materials and gases includes carbonates , bicarbonates , sulphates and chlorides of Ca , Mg and Na , iron oxide , Mn , CO2 , h2 , O2 etc