JKBOSE/CBSE Class 12th E-Science Notes | Air & Noise Pollution | Download Here | jkboseclassnotes.blogspot.com 


JKBOSE/CBSE Class 12th E-Science Notes | Air & Noise Pollution | Download Here | jkboseclassnotes.blogspot.com

Unit: Air & Noise Pollution

Environmental Pollution
Developmental activities such as construction, transportation and manufacturing not only deplete the natural resources but also produce large amount of wastes that leads to pollution of air, water, soil, and oceans; global warming and acid rains. Untreated or improperly treated waste is a major cause of pollution of rivers and environmental degradation causing ill health and loss of crop productivity. In this lesson you will study about the major causes of pollution, their effects on our environment and the various measures that can be taken to control such pollutions. 

OBJECTIVES 
After completing this lesson, you will be able to: 
• define the terms pollution and pollutants; 
• list various kinds of pollution; 
• describe types of pollution, sources, harmful effects on human health and control of air pollution, indoor air pollution, noise pollution; 
• describe water pollution, its causes and control; 
• describe thermal pollution; 
• describe soil pollution, its causes and control; 
• describe radiation pollution, sources and hazards.  

POLLUTION  AND POLLUTANTS 
Human activities directly or indirectly affect the environment adversely. A stone crusher adds a lot of suspended particulate matter and noise into the atmosphere. Automobiles emit from their tail pipes oxides of nitrogen, sulphur dioxide, carbon dioxide, carbon monoxide and a complex mixture of unburnt hydrocarbons and black soot which pollute the atmosphere. Domestic sewage and run off from agricultural fields, laden with pesticides and fertilizers, pollute water bodies. Effluents from tanneries contain many harmful chemicals and emit foul smell. These are only a few examples which show how human activities pollute the environment. Pollution may be defined as addition of undesirable material into the environment as a result of human activities. The agents which cause environmental pollution are called pollutants. A pollutants may be defined as a physical, chemical or biological substance unintentionally released into the environment which is directly or indirectly harmful to humans and other living organisms. 

TYPES OF POLLUTION 
Pollution may be of the following types: 
• Air pollution 
• Noise pollution 
• Water pollution 
• Soil pollution 
• Thermal pollution 
• Radiation pollution 

AIR POLLUTION 
Air pollution is a result of industrial and certain domestic activity. An ever increasing use of fossil fuels in power plants, industries, transportation, mining, construction of buildings, stone quarries had led to air pollution. Air pollution may be defined as the presence of any solid, liquid or gaseous substance including noise and radioactive radiation in the atmosphere in such concentration that may be directly and indirectly injurious to humans or other living organisms, plants, property or interferes with the normal environmental processes. 
Air pollutants are of two types 
(1) suspended particulate matter, and 
(2) gaseous pollutants like carbon dioxide (CO2), NOx etc.

Particulate pollutants 
Particulate matter suspended in air are dust and soot released from the industrial chimneys. Their size ranges from 0.001 to 500 µm in diameter. Particles less than 10µm float and move freely with the air current. Particles which are more than 10µm in diameter settle down. Particles less than 0.02 µm form persisent aerosols. Major source of SPM (suspended particulate matter) are vehicles, power plants, construction activities, oil refinery, railway yard, market place, industries, etc. 

• Fly ash 
Fly ash is ejected mostly by thermal power plants as by products of coal burning operations. Fly ash pollutes air and water and may cause heavy metal pollution in water bodies. Fly ash affects vegetation as a result of its direct deposition on leaf surfaces or indirectly through its deposition on soil. Fly ash is now being used for making bricks and as a land fill material. 

•  Lead and other metals particles 
Tetraethyl lead (TEL) is used as an anti-knock agent in petrol for smooth and easy running of vehicles. The lead particles coming out from the exhaust pipes of vehicles is mixed with air. If inhaled it produces injurious effects on kidney and liver and interferes with development of red blood cells. Lead mixed with water and food can create cumulative poisoning. It has long term effects on children as it lowers intelligence. Oxides of iron, aluminum, manganese, magnesium, zinc and other metals have adverse effect due to deposition of dust on plants during mining operations and metallurgical processes. They create physiological, biochemical and developmental disorders in plants and also contribute towards reproductive failure in plants.
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