NEET Biology Notes Environmental Issues Pollution
Pollution
Rapidly growing population along with a move toward urbanisation and industrialisation, has caused a Serious damage and placed significant pressure on India’s infrastructure and its natural resources.
We can see many environmental issues around us which cause undesirable changes in the physical, chemical or biological characteristics of air, land and water that will harmfully affect the human life. These undesirable changes in physical, chemical and biological characteristics of air, water and soil are called pollution. In order to control environmental pollution, the Government of India has passed the Environment (protection) Act, 1986 to protect and improve the quality of environment.
Pollutant
A pollutant is a substance or energy introduced into the environment that has undesired or adverse effects on the useful resources. Hence, pollutant is a chemical, geochemical substance or a biological product that deteriorates our natural environment.
Types of Pollutants
Pollutants can be divided into following types :
- Non-degradable pollutants such as aluminium cans, mercury salts, DDT, etc., either do not degrade or degrade extremely slowly in the natural environment.
- Biodegradable pollutants are rapidly decomposed by the natural process or through some artificial systems that enhance nature’s great capacity to decompose and recycle.
‘Non-degradable are more harmful to environment than biodegradable pollutant’.
Types of Pollution
The pollution can be classified into the following categories.
- Air Pollution
It is the release of any foreign materials or gases, which are harmful to man, animals, vegetation or buildings into atmosphere.
Effects of Air Pollution
- There are major pollutants, which can cause major effect on air as
Carbon Monoxide (CO)
It is harmful to man because it competes with Oz for haemoglobin. Carbon monoxide has 200 times greater affinity for haemoglobin than oxygen. CO makes the most stable combination with haemoglobin of RBCs and form
carboxyhaemoglobin. - Sulphur Dioxide (SO 2)
Sulphur dioxide causes membrane damage, plasmolysis, chlorophyll destruction, metabolic inhibition, growth and yield reduction. - Acid Rain
It is the result of S02 and NO 2 pollution in atmosphere. Taj Mahal of Agra is affacted by S02 and other air pollutants (which causes acid rain) released by oil refinery of Mathura.
Lichens These are bioindicators for air pollution especially S02 pollution. Due to S02 pollution, lichens start disappearing from the habitat. - Smog
It is a mixture of smoke and fog, which arises from factories, oil refineries, chemical plants, etc. In bright sunlight, nitrogen oxides, hydrocarbons and oxygen interact chemically to form secondary pollutants like ozone and Peroxy Acetyl Nitrate (PAN), which leads to formation of photochemical smog.
Control of Air Pollution
The air pollutants must be separated/filtered out before releasing the harmless gases into the atmosphere.
There are various steps which have been taken to check it as follows :
- Important Acts Regarding Control of Air Pollution
Air (Prevention and control of pollution) Act, 1981 amended in 1987 to include noise. According to Central Pollution Control Board (CPCB). Particulate size 2.5 micrometer or less in diameter can be inhaled deep into the lungs and can cause breathing and respiratory symptoms and even premature deaths. - Electrostatic Precipitator (ESP)
It is the most commonly used method for the removal of particulate matter. About 99% of particulate matter are removed from the exhaust of thermal power plant. - Scrubber
A scrubber can remove gases like sulphur dioxide from the industrial exhaust. The exhaust is passed through water or lime which reacts with sulphur dioxide to form a precipitate. - Control of Vehicular Pollution
(a) Switching over public transport from diesel to compressed Natural gas from 2002.
(b) Euro-II norms should be applied. Bharat State II (equivalent to Euro II norms) will be applicable to all automobiles in all cities from 1 April, 2005. Euro-IV norms should be applied in 11 cities by 1 April, 2010. The rest of the country have to meet. Euro IV norms by April, 2010.Catalytic Converters
Vehicles fitted with catalytic converter should use unleaded petrol as leaded petrol inactivate the catalyst present in it as platinum, palladium and rhodium.