Environmental Pollution

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The meaning of the words pollution and pollute as given in Oxford dictionary are as under :

Pollute : Contaminate (or make air, water etc. impure) with harmful or poisonous substances.
Pollution : The presence in or introduction into the environment of a substance which has harmful or poisonous effect.

Thus it is clear that pollution cannot be defined in exact words, however the word can be analyzed in order to form a concept of environment. Pollution is the unwanted change in the air, water, soil, biological creatures etc. which degrades the basic composition of these resources. It can have adverse impact on the biotic components, specially man, by bringing about direct or indirect changes in one or more abiotic components of the environment. Some pollutants like bad-odour, noise etc. can have psychological consequences. At times they become risky and hazardous for human heath.

Pollution can be categorized into two types

Those which result in harmful changes, in the physical and chemical components of the environment, for man.
Those in which some new substances are incorporated in the environment by the modern industrial and technological activities of man. As compared to the first category of pollutants these new substances are negligible.

Increase in population is a direct attack on natural resources. Modern man believes that earth is made for man. He is authorized for the exploitation of resources. Our Father of Nation had said that “Earth provides enough to satisfy every man’s needs but not every man’s greed.” Thus the prime reason for the exploitation of nature and the danger of pollution is the greed and ignorance of man.

If evaluated judiciously, it will be obvious that the fast growing population, unplanned destruction of forests, urbanization, industrialization, the blind-pace of development etc are the actual reasons of the ever growing pollution.

In Bharat, the awareness about nature has been there since Vedic times. Environmental conservation had been an integral part of life- practices in the entire Vedic and Post-vedic era.

Upanishads presents policies to conserve resources for our future generations. Samrat Ashok’s inscriptions perhaps is the first record of wild life conservation. They reveal that Ashok had made hospitals and reserved areas for protection wild life and birds. The moghul attacks on our country were quite unfortunate, in the sense that it destroyed our social system to an extent that our ancestor’s knowledge of times immemorial was concealed.

The so called development related to the technological revolution and blind-pace for technological development has set the concern for nature at backfoot. Neglect of long term benefits for humanity and the desire to obtain instant benefits have generated conditions which are having harmful effects on plants, animals and human-life.

Air pollution

The air that forms the atmosphere is actually a mixture of various gases. It includes oxygen the life-giving, indispensable gas for respiration and other metabolic processes of living beings.

Environmental Pollution-Air pollution

Other components include Argon, Krypton, Helium, Ozone, Carbon-mono-oxide, water vapour, Ammonia, Methane etc.

Causes of Air Pollution

Air pollution may be caused naturally or may have anthropogenic (caused by man) origin. Following are the natural causes of air pollution :

Volcanic eruption : In this gaseous pollutants such as Sulphur-di-oxide (SO2), Hydrogen sulphide (H2S), Carbon-mono-oxide (CO) etc. are evolved.
Forest fires.
Marsh gases (like methane – CH4).
Products of natural decomposition of various organic and inorganic substances.
Suspended particulate matter.
Extra-terrestrial substances.
Cosmic-dust.
Allergens and irritants like pollens, spores etc.

Following are the examples of pollutants of anthropogenic origin :

Industrial effluents (discharge)
Vehicular effluents
Domestic effluents
Substances produced by burning of fossils
Explosives and other chemicals used in wars etc.
Various substances used in agriculture and agricultural practices.

Effect of Air Pollution

These pollutants have adverse effects on human health. Given below are a few pollutants and their effects.

Sulphur-di-oxide : Chest congestion, headache, vomiting etc. Disorders caused by it may become fatal.
Oxides of nitrogen : They cease the activity of cilia. This is the reason why carbon and dust particles may reach the lungs causing various respiratory disorders.
Hydrogen sulphide : Causes irritation in throat and eyes and nausea.
Carbon-mono-oxide : It reduces the oxygen carrying capacity of blood and causes fatigue.
Hydrogen cyanide : If affects the nerve cells and results in dry throat, vague vision, headache etc.
Ammonia : It causes swelling in upper respiratory tract.

Control of Air Pollution

Judicious and limited use of resources can control air pollution. A few strategies of controlling it, include :

Adsorption : It is a physical process that depends upon the surface properties of some substances. In it the flow of liquid and gas is coupled with a solid, so that the solid holds a thin film of the liquid or gas on the outside surface – thus entrapping it. Activated charcoal, silica gel. Resin etc. are used as adsorbents. In this process the adsorbents may be reused hence it is an economic (thrift) process.
Absorption : This also is a physical process. In it the gases are allowed to dissolve in fluids. Water is the best solvent or medium for absorption.
Condensation : The gaseous vapours are controlled by condensation. It is the best method for removing the hydrocarbons having very low vapour pressure at ambient temperature, (i.e. air temperature of the surroundings). Air pollution can be satisfactorily controlled by using water or air cooled condensers.
By chemical reactions : Pollutants can be removed from the air by various chemical reactions.

Water Pollution

Water is the most valuable resource of the planet earth, on which the life of all organisms depend. It is the main component of all living beings. In some organisms it forms upto 90% of the body weight. History reveals that all the great civilizations prospered on the banks of various rivers. Non-judicious use and wastage of water converted these civilizations into graveyards. Water provides natural beauty to landscapes and generates aesthetic beauty in them. It is the basis of entertainment and water sports. It is an important component for human health. Its pollution gives rise to many epidemics and water-borne diseases.

Causes of water pollution

As in case of air pollution, even water- pollution has two reasons

(1) Natural and
(2) Anthropogenic.

In the natural process of water pollution fusion of natural substances like salts, chemicals, minerals and products of the decomposition of the water soluble plant and animal products are involved. All of them are washed off to water bodies like ponds, lakes, puddles, rives etc. by the rain water and ultimately they may reach the oceans or ground water. The oceanic water is saline because accumulation of various salts which are brought down to it, over centuries, by the ever flowing rivers.

The present day problem of water-pollution is the result of the modern industrial activities. Dirty domestic water, sewage water, sewage, urban wastes, industrial effluents, agricultural wash-out, oil-grease, decomposition products of the solid waste etc. when immersed in natural water bodies result in water pollution. The water soluble pollutants from air and land ultimately reach water bodies thus polluting them. The soluble effluents then may reach down to the ground water sources.

Various substances which pollute water by dissolving in it include : (1) Acids (2) Base (3) Coal (4) Dyes (5) Fats, Soap and waxes (6) Gaseous adjunct (dissolved gases) (7) Fertilizers (8) Insecticides (9) Weedicides (10) Farm products (11) Poisonous metals like mercury and its compounds (12) Synthetic detergents (13) Oil (14) Proteins and carbohydrates (15) Dissolved solids (16) Other organic pollutants (1) Poly chlorinated biphenyls (PCBs) (b) Phenol and phenolic compounds (c) Polynuclear aromatic hydrocarbons (d) Aldehydes (17) Radioactive substances (18) Thermal pollutants which include heated industrial waste water or water from the cooling towers of the nuclear power plants (19) Colours (20) Biological pollutants – Virus, Algae, Fungi etc. (21) Odour and (22) Turbidity etc.

All the fourteen big rivers of Bharat, including Ganga, Yamuna, Godavari, Gomti, Kosi, Kauvery, Ravi, Son, Chinaab, Jhelum, Narmada, Mahi, Tapti and Krishna are the victims of intense water pollution.

Effects of water pollution

If the pollutants accumulating in the oceanic waters cross the threshold, then the planktons which release nearly 60% of the photosynthesis oxygen of earth, will land into a condition of mismanagement and disaster. It will be very difficult even to estimate the harm caused by decrease in dissolved oxygen level to levels less than the biological oxygen demand.

Control of water pollution

Integrated water and waste management programs are required to get rid of the menace of water pollution. This approach comprises : (1) Water treatment (2) Waste water treatment, (3) Waste water recycling (4) Product recovery. The following techniques of waste water treatment can be made use of :

(1) Oxidation and stabilization ponds – The effluent water is stablized in these ponds which gets oxidised in sufficient sun-light and hot-climate.
(2) Treatment of sewage effluent water and reuse it for agricultural purpose.
(3) Remove the pollutants :
- (a) separation of salts by reverse osmosis
- (b) removal of metals by electrolysis, ion dispersion resins etc.
- (c) Controlled culture of water hyacinth (though it is very harmful for the existence of water bodies)
- (d) Root zone treatment technique.

There is a need to have a water management policy, on a local level, with the aim of making available water for human consumption. Following measures may be taken for ensuring water availability :

Take proper measures to control pollution of puddles, rivers, rivulets, lakes etc.
Conservation of natural vegetation.
Improvement in the catchment area of rivers, rivulets, lakes, ponds etc.
Proper sewage treatment before immersing it in water bodies.
Construction of water reservoirs.
Development of underground water reservoirs on large scale.
Rain water harvesting.
Recharging the ground water and aquifers.

Soil pollution

Soil is the part of lithosphere which interacts with atmosphere, hydrosphere and biosphere. Thus it fulfils the fundamental requirements of terrestrial living beings. Soil provides the essential elements to planets which then produce organic substances from which the basic needs of human – food, cloth and shelter – are fulfilled.

In soil, different types of particles are present in different combinations and proportions. It has inter-particulate spaces that are filled with air and water. If the soil is not well aerated, the spaces between soil particles get water logged and prevents the growth of the root system. This happens in soil which lack proper drainage and the soil becomes water logged.

Causes of Soil Pollution

Soil pollution has resulted from the modern life style, and the human activities related to industries and agriculture. A few important sources of soil pollution includes :

Industrial wastes/effluent : The solid and liquid effluent from industries are spread on the soil without any type of pre-treatment. The fly-ash which spreads for miles harm the soil to a great extent. The minerals, chemicals, toxins etc. of the effluents pollute the soil and make it barren.
Urban effluents : Paper, glass, metallic boxes, plastic, fibres, food-waste, rubber, dyes, paint etc. are the solid urban wastes which pollute the soil to a large extent. The liquid urban wastes include the organic and inorganic chemicals, oil, grease, toxic substance etc. which spread on the soil and pollutes it. These effluents have pathogens which cause various diseases.
Agricultural activities : In-judicious, unforeseen use of chemical fertilizers in excess and excessive irrigation makes the soil water logged and devoids the soil of the essential nutrients. This makes the soil barren.

The concentration of soluble salts increases in the soil due to excessive use of chemical fertilizers every year. Such soils are known as the saline soil. If the sodium content of such soils increases they become alkaline and are known as the alkaline or sodic soil. Both the types of soils – alkaline and saline – are known as ‘usar’ in Bharat. They are the most unsuitable soil for agriculture.

In modern-agricultural practices, various chemicals like- pesticides (like DDT), fungicides bactericides and herbicides are used on large scale to protect plants from pathogens, diseases, weeds etc. These chemicals do not decompose, in general and remain in the soil. Plants, at times, absorb them and they reach the higher trophic levels by means of the food chain. In this process, there is biomagnification of these substances and they become toxic for human consumption.

Noise pollution

The sound energy, which flows in unit area of the medium in unit time, is measured in watt/meter square. The sound pressure can also be 2measured in Newton/meter square (N/m). The loudness of sound is expressed in terms of a unit ‘sone’. 1 Sone = 40 dB sound amplitude. 1 dB (decible) = 0.002 microbar sound pressure 2 –16 (dynes/cm) – approx. 10 watt energy. The range of human hearing may vary from 0 to more than 120 dB. Generally a sound of 80 dB is considered to be critical level to damage the ears. Therefore this and higher amplitude sounds are considered to be pollutant.

WHO (World Health Organization) has fixed 45dB as the safe noise level for any city. A sound level of more than 90dB for more than 10 milliseconds leads to aural reflex action and contracts the tympanic membrane. Sound of more than 140dB changes the direction of movement of ear ossicle, because of which the intensity of sound received by internal ear decreases. This protective reflex action can protect us from the danger of loud noise only for some time. On the basis of these facts 65dB has been accepted to be the limit to tolerance, in hospital areas, according to international standards.

Noise pollution affects human health, ease and efficiency. It may contract blood vessels and may increase the secretion of a hormone – adrenalin which generates blood pressure. This results in strained muscles which may lead to psychological tension, nervous disorder and madness. high level of noise pollution may lead to mental fatigue, high cholesterol level, heart attack and may damage brain, kidney, liver etc. and may cause long-lasting damage to the ciliated cells on the inner lining layers which may lead to deafness.

Thermal Pollution

The temperature of a natural water body increases if hot effluents are added to it, causing thermal pollution. This reduces the water quality and harms aquatic and terrestrial organisms. The sources of thermal pollution include :

Coolants of nuclear power plants : The temperature of the effluent coolants of these power plants is on an average 10ºC higher than the water entering the system. This affects the aquatic life adversely.
Effluents of the thermal power plants: These power plants use coal for generating electricity. For the purpose, water from nearest water body is made use of and then the effluent having a temperature of at least 15ºC more is again sent to the water body. This warm effluent reduces the amount of dissolved oxygen which results in the death of fishes and other aquatic living beings.
Effluents from the hydro electric power plants : This is perhaps the only process of power generation in which there is negative thermal loading of a water system.
Industrial effluents : The cloth, paper, sugar etc. industries produce heated effluents which have a temperature that is approximately 8 to 10ºC high. The effect caused by the temperature of these effluents depends on the original temperature and size of the water body.
Domestic sewage: The domestic sewage is immersed in water bodies without pre-treatment. Normally, the temperature of the domestic waste is higher and hence may increase the water temperature. This leads to reduction of the number of aquatic organisms. This may also lead to anaerobic conditions because of which fishes may die. Some of the physical and chemical changes and the adverse effect of thermal pollution on the biology of living beings and biological communities, includes :

- (a) Physical conditions :
  - Increase in temperature
  - Increase in vapour pressure
  - Increase in the silting-rate of suspended particles etc.
  - Decrease in density
  - Decrease in viscosity

- (b) Chemical conditions :
  - Increase in chemical oxygen demand (COD)
  - Increase in biological oxygen demand (BOD)
  - Increase in toxicity

- (c) Biological effects :
  - Changes in physiological activities
  - Change in Metabolic rates
  - Change in biochemical parameters
  - Interference in reproduction
  - Variation in the rate of reproduction
  - Increase in direct mortality of aquatic organisms.

- (d) Effect on Biological communities:
  - The distribution patterns of living organisms change.
  - Unwanted changes in algal population.
  - Formation of water blooms by cyanobacteria.
  - Attack of destructive organisms.

In order to reduce thermal pollution the plant design should be altered to reduce the temperature of the effluents. The effluents produced may be cooled off to normal temperature before immersing them in water bodies. For the purpose special cooling tanks or towers can be constructed.

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