Air Pollution: Gaseous Pollutants
* Pollution is the harmful effect on the environment that can prove fatal to all living organisms.
* Pollutants 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 carbon dioxide 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 air that cause pollution.
* Smoke is either solid or 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, formaldehyde and peroxyacetyl nitrate.
* Taking control over the production of nitrogen dioxide, hydrocarbons, ozone and peroxyacetyl nitrate will help to prevent photochemical smog.
Air Pollution: Stratospheric Pollution
* The sun’s rays contain ultra violet or UV radiations, which are harmful for animals and plants.
* Ozone acts as an umbrella to the earth’s planet, absorbing most of the ultra violet radiations.
* Chlorofluorocarbon compounds are non-reactive, non-inflammable and non-toxic organic compounds, and are responsible for ozone depletion.
* Chlorofluorocarbon compounds are used in refrigerators, air conditioners and electronic goods.
* Chlorine radicals are regenerated constantly in a chain reaction and cause ozone depletion.
* Stratospheric clouds are responsible for the ozone hole over Antarctica.
* UV radiation causes aging of skin, sunburn, skin cancer and cataract.
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 from farms, 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.
* Chemical 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 results in a disfunctioning ecosystem, is called eutrophication.
Soil Pollution
* Pesticides are substances intended for preventing, destroying or controlling any pest.
* Higher level toxins are carried from the lower species to the higher species through food chain.
* Herbicides decompose in a few months, and hence, are less persistent than organic toxins.
* Chemicals contaminate the soil, causing plant metabolism alteration, with a reduction in crop yield.
* If the same or similar kind of pesticide is used continuously a number of times, the pests grow resistant to them.
Industrial Waste and its Management
* Solid industrial waste can be categorised as biodegradable and non-biodegradable.
* Biodegradable waste consists of plant and animal waste that can be degraded by micro organisms.
* Non-biodegradable waste consists of material that cannot be degraded and remains as such in the environment.
* A simple three-way method of waste management is denoted by three R’s: which stand for Reduce, Reuse and Recycle.
* Human beings should avoid direct contact with waste by using protective device such as gloves or water proof boots and gas masks.
Green Chemistry
* The branch of chemistry that deals with the research and discovery of alternative production methods to reduce pollution is known as green chemistry.
* Green chemistry emphasises the prevention of harmful chemical impact through a chemical process that involves decreasing the amounts of harmful chemical to achieve zero discharge of pollutants and emissions.
* The use of green chemistry in our day-to-day life can be seen in the dry cleaning of clothes, bleaching of paper and chemical synthesis.
* In 2005, Yves Chauvin, Robert H. Grubbs and Richard R. won the Noble Prize for research related to green chemistry.
