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Pollution and Pollutants

  • Environmental Pollution

Environmental pollution is the effect of undesirable changes taking place in our surrounding which affect the living organisms. The substance, which causes pollution, is known as pollutant. Every substance is present in environment naturally in a fixed amount. Whenever concentration of any substance exceeds its natural abundance, it becomes a pollutant for the environment. Pollutants can be solid, liquid or gaseous substances present in greater concentration than it’s natural abundance and are produced due to natural or human activities. Every pollutant has a threshold limit value (TLV) which is the permissible limit of a pollutant in atmosphere to which a person is exposed during hours a day or 40 hours a week for life time without any adverse effects. TLV are determined by experimentation on animals, by use of medical knowledge, epidemiology surveys & environmental studies.  

Today environmental pollution is one of the most serious problems in front of us. In last few years, we have achieved lots of success in field of science and technology which resulted in industrialization and modernization. For this, natural resources were used excessively and we forgot to think about the harm which we were causing to our environment. By end of the 20th century, the level of pollution in environment was very high. Now, it’s time to take steps in order to repair the damage which we have already done to our environment and also to prevent further damage. This makes it very important to have s systematic study of the environment and application of science and technology to overcome this problem.

  • Pollutants

?Pollutant is any substance already present in environment or a new substance whose concentration increases to undesirable proportions causing danger to living organisms or other materials.Pollutants are the substances which cause pollution. Pollutants can be physical or chemical. They can be waste matter that contaminates the water or air or soil. Pollutants cause pollution when they are in greater amount than the natural abundance. Pollutants alter the physical and chemical composition of air, water and soil that are not feasible for organism and plants. A pollutant may change growth rate of plant or animal species, or interfere with human amenities, comfort and health. Pollutants not only harm the living organisms but also to the property. For example acid rain causes harm to marble buildings. Some  common pollutants are..

(i) Gases like CO2, SO2 ,NO2 etc.

(ii) Solid substances like lead, mercury, 

(iii) Natural substances like pollen grains

(vi) Sewage and radioactive substances

  • Types of Pollutants

?1. Primary Pollutant : Those pollutants which enter the environment after their formation and remain as such i.e. do not undergo any chemical change are called primary pollutants.

For Example: NO, NO2 ,SO2 & CO2

2. Secondary Pollutants: These are the harmful materials which are formed by chemical reactions between primary pollutants in the atmosphere. Some examples are sulphur trioxide, nitrogen dioxide, ozone, aldehyde, ketones, various sulphate & nitrate salts

3. Particulate Matter: These are the small sized solid particles and liquid droplets. Their size ranges from 2\times 10-10 m to 5\times 10-4 m.  Examples are  ash, smoke, dust, fumes etc. We will discuss this in more details under the topic air pollution.

4.  Bio- Degradable Pollutants:  The materials (such as cow dungs) which are easily decomposed by the microorganisms into inorganic material are called bio-degradable materials. Similarly the pollutants, which are of organic nature (such as paper) can be decomposed by microorganisms are called bio-degradable pollutants. They are thus less harmful as they do not remain in environment for long time. But if they are present in excess in environment and do not undergo decomposition or degradation completely may cause problems. 

5. Non Bio- degradable Pollutants : The pollutants such as HG, Al & DDT) which do not undergo degradation or degrade very slowly are called non-bio degradable pollutants. These are harmful even when present in very small amount. They react with the other compound present in the environment to produce even more toxic compounds.

Biodegradable Pollutants

Non-biodegradable Pollutants

Biodegradable pollutants are those which can be broken down by microorganisms into inorganic substances which are taken up by soil and are not harmful to the environment.

Non-biodegradable pollutants cannot be decomposed by micro-organisms and are harmful to the environment.

Biodegradable Pollutants are made up of organic material.

Non-biodegradable pollutants  may or may not be or organic nature

For example: Papers, Dry leaves, Waste food  etc.

Example: Plastic, heavy metals, .DDT etc.

  • Types of Pollution

?Pollution is classified on following two bases

Part of the environment polluted:

  1. Air Pollution

  2. Water Pollution

  3. Soli Pollution (or Land Pollution)

Nature of pollutants:

  1. Oil Pollution

  2. Slit Pollution

  3. Noise Pollution

  4. Smog Pollution

  5. Plastic Pollution

  6. Effluent Pollution

  7. Thermal Pollution

  8. Chemical Pollution

  9. Acid- Rain Pollution

  10. Radioactive Pollution

  11. Metal Toxicity Pollution

  12. Soap and Detergent Pollution

You can also refer to  JEE Organic Chemistry SyllabusEnvironmental Chemistry Notes & Reference books of Organic Chemistry

To read more, Buy study materials of Environmental Chemistry comprising study notes, revision notes, video lectures, previous year solved questions etc. Also browse for more study materials on Chemistry here.

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