Pollutants

INTRODUCTION OF POLLUTANTS

1. INTRODUCTION The environment is composed of air, water and land, technically called as atmosphere, hydrosphere and lithosphere which together constitute the biosphere. In the biosphere human beings, plants, animals, birds, fishes, insects and microorganisms (algae, bacteria and virus) exist. Atmosphere provides oxygen, while the hydrosphere and lithosphere provides food, water and shelter. There is a balance between the living organisms and the environment.

2. Disturbance in any components of environments is likely to have a harmful effect on the ecosystem. Whenever a change, physical or chemical occurs in the atmosphere, hydrosphere or lithosphere, all living beings are affected This change is termed as pollution and the agents that cause these changes are called as Pollutants. This change either in the physical, chemical or biological characteristics of physical environment is undesirable and harms human life, other living organisms and cultural assets.

3. In general pollution is defined as an undesirable and excessive addition of substances to water, air and land which adversely alters the natural quality of the environment. The Quality of life is based on clean environment which generally is aggregated into air quality, water quality, noise levels etc.

4. “Pollution can be defined as an undesirable change in the physical, chemical or biological characteristics of our air, water and land that may or will harmfully affect the life or creates a potential health hazard and threaten the survival or activities of humans or other living organisms.” Pollution is thus direct or indirect change in any environmental components that is adversely affecting the industrial progress, cultural or natural assets or general environment.

5. POLLUTANTS Any substances presents in the environment in harmful concentration ,which adversely alters the environment by damaging the growth rate of species and by interfering with the food chains, is toxic and affects the health, comfort and property is called as pollutants. The substance which spoils or pollutes the environment is called pollutants.

6. It includes dust from house and garbage from home, effluents from industries, emission of smoke from automobiles. It also includes smoke generating from industries and automobiles, domestic and commercial sewage, radioactive substances from nuclear plants and discarded household articles (tins, bottles, broken crockery etc.)

7. Classification of Pollutants Depending upon their existence in nature A. Quantitative Pollutants B. Qualitative Pollutants

8. A. Quantitative Pollutants Substances that occurs in the environment, who acquire the status of a pollutant when their concentration gets increased due to the various activities of man. Carbon Dioxide, if present in the atmosphere in concentration greater than normal due to automobiles and industries, causes measurable effects on humans, animals, plants or property is classified as a quantitative pollutant.

9. B. Qualitative Pollutants These are those substances which do not normally occur in nature but are added by man. e.g. insecticides.

10. Depending upon the form in which they persist after being released into the environment A. Primary Pollutants B. Secondary Pollutants

11. A. Primary Pollutants These are those which are emitted directly from the source and persist in the form in which they are added to the environment. Examples are ash, smoke, fumes, dust, nitric oxide, sulphur dioxide, hydrocarbons etc.

12. B. Secondary Pollutants These are those pollutants which are formed by the primary pollutants by chemical interaction with some constituent available in the atmosphere. Examples are sulphur trioxide, nitrogen dioxide, aldehydes , ozone etc.

13. As per ecosystem point of view, i.e. according to their natural disposal A. Bio-degradable pollutant B. Non-degradable pollutants

14. Bio-degradable pollutants These are the pollutants that are quickly degraded by natural means. These are the pollutants which can be decomposed, removed or consumed or reduced to acceptable levels either by natural or artificial process. It includes pollutants such as human sewage and animal and crop waste. Heat or thermal pollution, and domestic sewage are considered in this category as these can be rapidly decomposed by natural processes or by engineered systems such as municipal treatment, plants etc.

15. B. Non-degradable pollutants These are the substances that either do not degrade or degrade very slowly in the natural environment. These include radioactive materials, heavy metals, plastics, mercury salts, long chain phenolic chemicals, DDT etc.

16. On the basis of nature, pollutants are of following three types : Physical Pollutants : Heat , Noise, Radioactive substances etc. Chemical Pollutants : Oxides of carbon, oxides of sulphur , oxides Of nitrogen, halogen gas etc. Biological Pollutants : Microorganisms such as bacteria, virus and fungi etc.

17. On the basis of their source of origin Point source pollutants Those sources which can be originated from a single location are called as point source. When the emission or origin source is point. i.e. the area are very less as compare to the environment. It includes emission from stack, industries, municipal sewage treatment plants, combined sewer outflow, raw water sewage discharge etc. These types of discharge can be controlled by giving necessary treatment.

18. B Line source pollutants These are such type of sources whose location can not be easily identified. When the emission is in the form of line or curve e.g. transportation of material by conveyor belts, road rollers and run–off from agricultural land, mining, construction etc. It can not be easily controlled. Water pollution caused by diffused source like agricultural can be controlled by changing crop pattern and advance farm management practices.

19. C. Area source pollutants When the emission or origin source is an area i.e. the area is large e.g. crushing, grinding and blasting in mines etc.

20. SOURCES OF POLLUTION: There are mainly two sources a) Natural sources, b) Man made or anthropogenic sources.

21. Natural sources of Pollution

22. Volcanic eruptions release gases and volcanic ash

23. Forest fires produce smoke and trace gases

24. Other sources are Dust storms increase the wind blown dust into the environment, Bacteria , spores, cysts and pollens are all natural pollutants. Decay of organic matter in marshy places releases marsh gas which is a light colorless inflammable hydrocarbon.

25. b) Man made or anthropogenic sources.

26. Invention of automobiles

27. Over population

28. Deforestation : Destruction of natural habitant

29. Nuclear explosions

30. Over – exploitation of natural sources

31. Construction of buildings, roads and dams

32. Explosives used in wars

33. Use of fertilizers and pesticides

34. Mining and quarrying

35. TYPES OF ENVIRONMENTAL POLLUTION: Main types of pollution are 1) Water Pollution 2) Air Pollution 3) Marine Pollution 4) Noise Pollution 5) Thermal Pollution 6) Land Pollution