Environmental of Class 11
Environmental pollution may be described as the contamination of the environment with harmful wastes arising mainly from human activities. These activities release certain materials which produce pollution in the atmosphere, water & soil. The environmental pollution can be caused by
Chemical agents (gases, pesticides, particulates)
Physical agents (heat, noise, radiation) or
Biological agents (micro – organisms)
Pollution produces adverse effect on living as well as on non living materials. The effect of pollution are increasing at an alarming rate & if the same are not checked & controlled, they will pose a serious threat to human existence & habitat common terms to understand Prob. of pollution are
Any substance or species produced either by a natural source or by human activity, which produces adverse effect on the environment is called pollutant. Some common examples of pollutants are carbon monoxide, oxides of sulphur (SO2, SO3), oxides of nitrogen, pollens, dust particles etc.
A substance which does not occurs in nature but is introduced by human activity into the atmosphere affecting its composition is called contaminant.
The contaminant is classified as pollutant when it has some harmful effect.
The site from which the pollution or contaminants originate is called source.
The material or medium which consumes or interacts with a long lived pollutant is called sink. For example a marble wall acts as a sink for atmospheric sulphuric acid because of the reaction
Similarly, the oceans act as sink for atmospheric CO2 & other water soluble gases.
Any thing that is affected by the pollutants is called receptor. For example human being are the receptor of photochemical smog which cause irritation in the eyes & also breathing Prob.s.
Threshold limit value (TLV)
This indicates the permissible limit of a pollutant in atmosphere to which a healthy worker is exposed during hours a day or 40 hours a weak for life time without any adverse effects. TLV are determined by experimentation on animals, by use of medical knowledge, epidemiology surverys & environmental studies.
Flow sheet of Environmental pollution process
Earth is surrounded by thick envelope of gases called atmosphere. Atmosphere is divided into different layers depending upon the distance from the sea level. The nearest rexampleion which extends to the height of about 10 km from sea level is called troposphere. It contains about 80% of total mass of air & almost all the water vapours.
The rexampleion above the troposphere between 50 km is called stratosphere. Atomspheric pollution is generally studied under two heads.
(a) Tropospheric pollution
(b) Stratospheric pollution
Tropospheric pollution or Air pollution
Air is one of the important coustituent of the environment that is prone to pollution. Pollution of air refers to that part of atmosphere which is nearest to the earth’s surface extending to a height of about 80 km. This part is known as homosphere because it consist of homogenous mixture of various constituent. It constitutes about 99.9% of total atmosphere.
Air pollution may be defined as any atmosphere condition in which the presence of certain concentration produce harmful effects on man and his environment. These substances include:
(i) Gases such as oxides of sulphur, CO, oxide of N2 and hydrocarbons
(ii) Particulate matter such as dust, smoke, fumes etc.
(iii) Radioactive material & many others.