Pollution may be defined as "the introduction by man into the environment of substance or energy liable to cause hazards t human health, harm to living resources and ecological systems, damage to structure or amenity or interference with legitimate uses of the environment."
This definition is based on a more restricted and evolved by the group of experts on scientific aspects of marine pollution.
The important concepts in this definition are
- Pollution is caused by substances or energy.
- It has a source or sources and they are created by man. natural inputs of the same substances are excluded. Thus pollution is an increment added by man to bio geochemical cycles.
- Pollution acts in the environment as a result of these discharges, and follows a pathway leading to the exposure of structures or organisms.
Pollutants need not be material substances. Noise can be a pollutant and electromagnetic waves can be pollutants. However today man is the principal source of pollution because there is no way for nature to decompose many man-made materials and return their elements to the cycle of nature.
Thus pollution many be natural or artificial which originate due to the activities of man. It is better to classify pollution according to the environment such as air, water, soil, noise, radiation, thermal etc in which it occurs or according to the pollutants by which pollution is caused.
- Air pollution
- Water pollution
- Land or soil pollution
Air is never found clean in nature due to natural and anthropogenic reasons. Population explosion in the last few decades has led to enormous urban growth, extensive industrialization and the automobile revolution all of which are threatening the earths environment and making it unsuitable for future generations.
The release of poisonous gases like CO, N2
O and gases from industries and automobiles has disturbed the balance among the air components affecting both the living and a non-living components of earth.
Air pollution may be defined in the following ways.
- Any atmospheric condition in which certain substances are present in such concentrations that they can produce undesirable effects on man and his environment.
- Air pollution is the excessive concentration of foreign matter in the air which adversely affects the well being of individuals or causes damage to property.
Polluted water are those which have been made unfit for drinking supporting life or have been changed in other undesirable ways. Industrial wastes are the main source of water pollution.
Other includes home sewage, water run off from mines and farmlands and heated water discharge from the condensers of steam turbine electric power plants.
- Even slight change in temperature harms fish populations. Warmer water also encourage the growth of algae, which in turn use up oxygen needed by the fishes.
- The extent to which a body of water is pollutes often depends on how much water's oxygen is used up by the polluting wastes.
- Organic wastes from home sewage, food processing plants and paper mills use up enormous amount of oxygen as they decompose in the water.
- The dissolved oxygen (DO) becomes depleted. Without oxygen a waterway becomes lifeless and stagnant unable to cleanse itself.
- Poisoning wastes also threaten drinking water supplies and in ability of a waterway to support fish another aquatic life.
- Such water includes pesticides, chemicals and fertilizers used by food growers, which run off from the land into the stream and lake.
The basis of agriculture is soil. All crops for human food and animal feed depend upon it. Soil is the recipient of enormous quantities of man made waste products. In proximity of cities it is regarded as future recipient of sludge and other products from new waste treatment plants. Polluted water also causes soil pollution.
Soil pollution is usually a consequence of insanitary habits various agricultural practices and incorrect methods of disposal of solid and liquid wastes, but can also result from fallout from atmospheric pollution. It is closely related with the ultimate fate of those substances that are unlikely to undergo the natural recycling processes to which putrescible matter is subject to.In industrialized countries soil pollution is associated mainly with:
- The use of chemical such as fertilizers and growth regulating agents in agriculture.
- The dumping on land of large masses of waste materials from the mining of coal and minerals and the smelting of metals. Toxic or harmful substances can be leached out of such materials and enter the soil.
- The dumping on land of domestic refuse and solids resulting from the treatment of sewage and industrial wastes.
Noise is increasingly becoming a major pollutant.
This is the result of progress in technology. In modern communities, particularly in large cities noise pollution has effected most. Jet thunder overhead construction projects give off pounding and winning sounds, police, fire and ambulance sirens shrink periodically and traffic produces a constant roar.
Medical studies have shown that certain levels of sound produce nervous tension, psychological disorders hearing loss and psychological strains when exposed to constant noise during their jobs, workers steadily lose their hearing sharpness and can become deaf. Prolonged noise is torture and adversely effects emotional and intellectual sphere. Sleeplessness is common consequence. memory is also effected and concentration power is lowered. Sudden or intermittent noise is more harmful than the continuous noise.