(3) Qualitative pollutant : The pollutant is a harmful substance, chemical or factor that does not occur in nature but is added by human beings, e.g., insecticide, herbicide.
(4) Quantitative pollutant : It is a normal component of nature that becomes pollutant when its concentration becomes higher than the normal, e.g., nitrogen oxides, carbon monoxide.
(5) Degradable pollutant : The pollutant degrades after some time either automatically (e.g., heat) or through the agency of microorganisms (= biodegradable, e.g., sewage, livestock wastes, market garbage). Biodegradable pollutants are easily disposed off or degraded through natural processes or waste treatment plants. They can be turned into a resource, e.g., compost, manure.
(6) Non-Degradable pollutant : It is a pollutant which does not breakdown or get converted to harmless state by natural processes of dissipation, dispersal, oxidation or biological decomposition, e.g., DDT, glass, plastic. It is also known as conservative or persistent pollutant.
Types of pollution
(1) Natural pollution : It is pollution caused by natural sources, e.g., volcanic eruptions, release of methane by paddy fields and cattle, release of carbon monoxide by plants and animals, emission of natural gas, ozone, nitrogen oxides, soil erosion, dust storms, cosmic rays, ultra-violet rays, etc.
(2) Anthropogenic or Man-made pollution : It is pollution caused by human activities like noise, automobiles, industries, smoking, pesticides etc. Anthropogenic pollution is often quite small in quantity as compared to natural pollution. Example, 0.05% of atmospheric pollution is man-made while 99.95% is natural pollution.
- On the basis of source of pollution, it can be :
(1) Air pollution : Air or atmospheric pollution is the addition of materials or chemicals into atmosphere in such concentration that they begin to exert adverse effect on human beings, other desirable species, human assets and resources. Total amount of air pollutants is estimated to be \[1\times {{10}^{12}}\] tonnes, out of which pollutants added by human activities are only \[5\times {{10}^{8}}\] tonnes or 0.05%.
(i) Air Pollutants : The common air pollutants are : Dust, Smoke, Carbon monoxide \[(CO),\] Ammonia \[(N{{H}_{3}}),\] Sulphur dioxide\[(S{{O}_{2}}),\] Hydrogen sulphide \[({{H}_{2}}S),\] Nitrogen dioxide \[(N{{O}_{2}}),\] Hydrogen cyanide, Hydrogen fluorides, Chlorines, Phosgenes, Arsines, Aldehydes, Ozone, Ionising and radiations. \[C{{O}_{2}}\] is not a normal air pollutant. There is 0.03% \[C{{O}_{2}}\] in the air its higher percentage is the cause of green house effect.
Types of air pollutants : It is of two types :
(a) Primary air pollutants : Air is polluted by poisonous gases and undesirable substances. They are released by burning fossil fuels. These substances are called primary air pollutants. The primary air pollutants are the following :
- Soot released from unburned fuel.
- Sulphur dioxide (SO2).
- Benzopyrene (hydrocarbon) released from cigarette smoke.
- Ammonia \[(N{{H}_{3}}).\]
- Oxides of nitrogen.
- Carbon monoxide (CO).
- Lead (Pb).
(b) Secondary air pollutants : Secondary air pollutants are poisonous substance formed from primary air pollutants. In bright sun light nitrogen, nitrogen oxides, hydrocarbons and \[{{O}_{2}}\] interact to produce more powerful photochemical oxidants like ozone \[({{O}_{3}}),\] peroxyacetyl nitrate (PAN), aldehydes, sulphuric acid,
more...