Air Pollution: Gaseous Pollutants
* Pollution is the harmful effect on the environment that can prove fatal to all living organisms.
* Pollutant can be solid, liquid or gaseous, and originate from human actions and natural sources.
* Air pollution takes place in two different layers of the earth’s atmosphere- the troposphere and the stratosphere.
* The major pollutants of the troposphere are harmful gaseous oxides and oxidants, and particulate pollutants such as dust, mist and smoke.
* An increase in the level of the oxides of sulphur and nitrogen makes the pH value of rain water drop below 5.6, causing acid rain.
* An increase in the level of the carbon dioxides leads to an increase in the average global temperature, and this is known as global warming.
Air Pollution: Particulate Pollutants
* Particulate pollutants are tiny solid or liquid particles in the air that cause pollution.
* Smoke is either solid or a mixture of solid and liquid airborne particles.
* Dust is fine solid particles of over one micron in diameter.
* Mist is liquid particles produced by liquid spraying or vapour condensation.
* Photochemical smog consists of ozone, nitrogen dioxide, acrolein, and formaldehyde and peroxyacetyl nitrate.
* Taking control over the production of nitrogen dioxide, hydrocarbons, ozone and peroxyacyl nitrate will help to prevent photochemical. Smog.
Water Pollution
* Sources of water pollution can be divided into two types- point sources and non- point sources.
* Point sources are the easily identifiable sources of pollution, such as municipal and industrial discharge pipes.
* Non- point sources are not easily identifiable such as agricultural runoff form farm, acid rain and storm water drainage from streets and parking lots, etc.
* Pathogens are the micro- organisms that cause diseases and are the most harmful of the causes of water pollution.
* Organic wastes are the biodegradable wastes caused by organic matter such as leaves and grass.
* Chemicals pollutants include heavy metals, fertilisers, pesticides and radioactive substances.
* The process of rapid plant growth in water and the depletion of oxygen, causing death to animals that result in a disfunctioning ecosystem, is called eutrophication.
Domestic Sewage and Industrial Effluents
* Pollutants entering water bodies are broadly classified as domestic sewage and industrial effluents.
* Domestic sewage is the waste water that drains from houses in a town or city.
* Domestic sewage contains about 99.9 percent water and 0.1 percent impurities such as suspended soils, colloidal and dissolved materials.
* Algal blooms, pathogens, thermal waste water and excessive nutrients polluted water.
* Industrial effluents such as toxic metals, detergent, alcohol and acids polluted water bodies.
* Toxic, non- biodegradable substances get incorporated into the food chain, causing biomagnifications of the toxicant.
* Biomagnification is an increase in the concentration of a toxicant at successive trophic levels.
Harmful Effects of Waste Generation
* Waste from open dumps often ends up in drains, where it causes blackages.
* Drain blockages cause flooding and serve as breeding grounds for diseasecausing vectors.
* Yellow fever, typhoid, encephalitis and skin diseases are known to be caused by insanitary waste disposal.
* Polluted ground water causes cholera and gastroenteritis.
* The content of garbage can harm the environment as well as living beings.
* Excess mercury, lead, cardmium, zinc and copper harm the health due to their toxicity.
* The Minamata disease is caused by severe mercury poisoning.
