The word pollution, having its origin in the Laitn word pollutionem (mean to defile or made dirty), is the act of polluting the environment. Environmental pollution is defined as the unfavourable alteration of our founding wholly as a by-product of man’s activities, through direct or indirect effects of changes in the physical, chemical and biological characteristics of the land, air or water that harmfully affect human life or any desirable living things. Human population explosion, rapid industrialisation, deforestation, unplanned urbanisation, scientific and technological advancement, etc are the major caused of environmental pollution.
Classification of Pollution
Pollution may be classified in different ways as follows:
1. According to the Source: It may be classified as natural and artificial or manmade pollution.
(i) Natural pollution: Originates from natural processes or sources such as hydrocarbons in atmosphere, radiation pollution coming from the sun or radioactive materials found in nature, oxides of carbon, sulphur etc coming out from volcanic activity.
(ii) Artificial or Man-made pollution: It originates due to the activities of man such as lead aerosols in atmosphere coming from automobile exhaust, chlorinated hydrocarbons (DDT, etc) from excessive use of pesticides, etc.
2. According to type of Pollutants: Pollution may be classified according to the nature of pollutant, Pollutant is defined as anything, living or non-living or any physical agent.(e.g., heat, sound, etc.) that in its excess makes any part of the environment undesirable. In general, the term pollutant is applied to non-living man-made substances or nuisances, and it refers to their being excess in a particular area. As per the Indian Environment (Protection) Act 1986, a pollutant is any solid, liquid or gaseous substance present in such concentration as may be or tend to be injurious to environment.
3. According to Environment Segment: Pollution may be classified according to the segment of environment (air, water, soil) in which it occurs, as follows:
(i) Air pollution or Atmosphere pollution
(ii) Water pollution or Hydrosphere pollution
(iii) Soil pollution or Land pollution
Air pollution, according to WHO, is the presence of materials in the air that are harmful to man and his environment. Air pollutants are mainly of two types: (i) gaseous pollutant like hydrocarbons, carbonmonoxide, carbondioxide, oxides of sulphur and nitrogen, hydrogen sulphide, azone etc; (ii) particulate pollutants like smoke, dust, mist, fume, spray etc.
(i) Industrial pollutants like CO2, sulphurdioxide, carbonmonoxide, hydrogen sulphide, nitrous oxide, ozone, chlorine, arsenic etc.
(ii) Domestic pollutants from fossil fuels burnt by humans.
(iii) Automobile exhaust or vehicular emission.
(iv) Industrial accidents like leakage of chlorine gas from in Delhi, leakage of methyl isocyanate from the Union Carbide Plant at Bhopal etc.
(v) Suspended particulate matter (SPM) like fine dust particles and soot emitted by industrial units.
According to WHO and UNEP, the six major pollutants in 20 mega cities of the world are sulphur dioxide (SO2), chiefly from power generation and industrial emissions; suspended particulate matter (SPM) from domestic fire, power generation and industries; lead (Pb) largely from petro-engine exhaust; carbonmonoxide (CO) also from motor vehicle; and nitrogen dioxide (NO2), and ozone (O3), due to heavy traffic and high levels of sunshine.
(i) Carbonmonoxide having affinity with haemoglobin, when enters blood replaces oxygen from oxyhaemoglobin and thus increases concentration of CO 2 in blood causing headache, eye irritation, breathing problem and death.
(ii) Ozone, which also causes smog, is toxic to plant growth and harms human and animal heath.
(iii) Carbondioxide released by burning of fossil fuel causes global warming.
(iv) SPM like asbestos dust causes lung diseases, lead causes nervous disorder and brain damage. Smog causes reduced visibility, eye irritation and plant damage.
(i) Problem should be identified at regional and local levels and treated accordingly.
(ii) Strict enforcement of pollution control laws.
(iii) Urban planners must locate residential, commercial and industrial zones suitably.
(iv) Introduction of clean technologies.
Water, an essential component for our survival and the most important ecological factor present everywhere, has also been extensively polluted over the years.
(i) Domestic sewage
(ii) Industrial waste
(iii) Chemical inputs of agriculture
(iv) Elevated temperatures
Fresh water pollution is mainly due to:
(i) excess of nutrients from sewage and soil erosion causing algae blooms;
(ii) pathogens from sewage which spread disease;
(iii) heavy metals and organic compounds that bioaccumulate in aquatic organisms.
(i) Increased water treatment costs
(ii) Spread of epidemics like cholera, jaundice, dysentery, typhoid, gastroenteritis, etc.
(iii) Metals like mercury, copper, zinc, lead etc and their oxides from industrial waste cause; nervous disorder
(iv) Release of dyes, etc into water sources and their use by humans and animals affect biological processes.
(i) Input control or pollutants should be prevented from being generated in the first place.
(ii) Output control—it attempts to control the pollutant and/or its effect after it has been produced.
(iii) Developing of proper sewage system can reduce incoming point source of pollution.
(iv) Extensive afforestation can help in minimising non-point sources of pollution.
(v) Strict enforcement of pollution control laws.
(vi) Discharge of drinking water after primary and secondary treatment of water using chlorinator unit.
Thirty major enactments related to protection of environment are now being administered by the central and state governments. Prominent among these are : Wildlife (Protection) Act, 1972: the Forest (Conservation)Act, 1980; the Water (Prevention and Control of Pollution ) Act, 1974; the Air (Prevention) Act, 1981; the Water (Prevention and Control Pollution) Cess Act,1977; the Environment (Protection) Act, 1986; the Public Liability, Insurance Act, 1991; the Motor Vehicle Act, 1938 as amended in 1988. These are implemented through several organisations like Central and state pollution control boards, chief inspectors of factories, etc.
Environment Protection Act, 1986
Environment Protection Act 1986, is a landmark legislation as it provides for the protection of environment and aims at plugging the loopholes in the other related areas. The Act gives the government all embracing power to coordinate and control the activities of state government; to lay down standards, safeguards and constitute an authority or authorities to exercise powers. It empowers people to complain to courts about its violations after a notice of 60 days to the authorities. The Act provides stringent penalties for violations. Jurisdiction of civil courts is barred.
To provide legal and institutional basis for implementing the Act the government has: (i) issued rules and notified standards; (ii) set up environmental laboratories; (iii) strengthened state departments of environment and pollution control board; (iv) delegated powers; and (v) set up Environmental Protection council in states. Environment Monitoring Committee oversees adherence to environmental safeguards at the clearance stage.
Causes and Formation Acid rain
The basic agent of the acid rain is sulphur-dioxide which is transmitted into atmosphere through thermal power plants, metallurgical processing of copper and nickel and many other fuel burning methods.
Acid rain is caused by 65% sulphuric acid, 30% nitric acid and 5% hydrochloric acid. Now Ozone is also recognised as a major factor in the formation of acid rain.
Acid Rain in India
India is a country with a large coal reserve. Production of coal in 1989-90 was about 214 million tonnes and increased to about 310 million tonnes in 2001. Annual SO2 emissions tripled from the early 1960s to reach 3.2 million tonnes in 1979 and was around 13.198 million tonnes in 2000. Indian coal has low sulphur content (less then 1%) but the projected increase in coal consumption in the next 10 years, so2 emissions would increase by some 7 million tonnes. NO2 emissions are also likely to rise with the growth in road traffic and the operations of fertilizers plants, refineries plants, refineries and petrochemical and other industries. The other source of acidic rain pollution in India is the melting of metals, for example melting of copper, lead and zinc.
There are several reports of rain with ph lower than 5 in industrial centres. Among Indian cities, the possibility of acid rain has increased in Mumbai, Delhi, Kanpur, Bangalore, Ahmedabad, Kolkata and Hyderabad. Acid rain has once been recorded in Mumbai. In Mumbai and Trombay the ph value of rain water is recorded at 4.45 and 4.85 respectively. In Kolkata it is 5.80, in Chennai 8.85 and in Delhi 6.21.
The increased emphasis on thermal power generation, including plans for several Super Thermal Power Station, is bound to result in increase in Sulphur and Nitrogen oxide levels in the atmosphere and consequently dry or wet deposition of these acidic substances. The use of high rise stacks may help reduce pollution locally but would transport these substances to long distances, which would aid transformation into acid and would affect a larger region.
The main harmful affects of acid rain are :
(1) Due to affects of acid rain, the internal balance in forests, rivers, fields and lakes are being disturbed and react against the ecosystem.
(2) There is heavy decrease in the productivity of crop, forests and quatic life. Acid rai kills nutrient algae fungi and many useful bacteria which are so essential for the fertility of the soil and thus, adversely affect the fertility of land and decrease the productivity.
(3) Due to increasing acidification, the resistance power of the lives in terrestrial and aquatic system is decreasing. Acidity kill fish, bacteria and algae and the aquatic ecosystem collapses in the sterility leaving a crystal-clear but ultimately a dead lake. Due to heavy acid rains thousands of fishes collapse in one day.
According to the World Wildlife Fund (W.W.F.) the effect of acid rain on both forests and fresh water lakes was not simply to eliminate one or two species. It could inhibit fundamental nutrient cycling and cause major losses to vital nutrients, interfere with primary productions, disrupt the main biological process and relationship of the ecosystem.
Micro-organisms are gradually : becoming inactive due to acid rain
1. Nitrogen Fixation by Lichen, Lobario Orenga (epiphyte) is markedly decreased by treatment with simulated acid rain containing H2 SO4.
2. Azotobacter’s efficiency likewise is also reduced under acid precipitation.
3. Root mycorrhiza relationship and Rhizosphere organisms and soil respiration due to soil acidity are also reduced.
4. Pathogenic Phyllosphere organisms are also affected.
5. Decrease in nitrogen fixation (symbiotic) nitrification and ammonification in terrestrial ecosystem.
6. Release of aluminium and heavy metal ions which are toxic to plant growth.
Dry deposition has several direct effects on the environment. It attacks building materials, principally sand stone, lime-stone, marble, steel and nickel, which is called, stone cancer. When deposited in gaseous form it causes direct damage to plants and trees. Visible injury leads to gradual yellowing.
The only way to stop the acid rain is to emit less SO2 & NO2 in the atmosphere. An international treaty, signed by 25 countries in November 1988 in Bulgaria, puts emphasis on ways to lessen the quantity of emission of oxides of nitrogen. A similar treaty was also signed in 1985 in which the participant countries laid stress on ways to bring a reduction of 30% in extraction of sulphur during the year 1992-93.
The questions arise about what should be done to the lakes and other water reservoirs which have already become acidic. Such lakes elsewhere are being treated with lime. Lime, too, has its adverse effects on the aquatic lives, yet the effects are less dangerous compared with the effect of acidity of the lakes.