Online Course for Central Armed Police Forces (CAPF) Exam
Environment & Ecology
Pollution can be defined as, “the act or process of polluting
or the state of being polluted, especially the contamination of soil, water or
the atmosphere by the discharge of harmful substances”. Accidental release of
these substances in the environment lead to mass death. History witnesses these
disasters today known in the form of episodes such as “London Smog” in 1912 and
“Meuse River valley episode” in 1930. In 1948, the honour went to “Donora”,
Pennsylvania when 40% of its population fell sick due to pollution from zinc
smelter, steel mill and’ sulfuric acid plant. In 1952, London Smog struck again
killing 4000 elderly and sick people. Soon simultaneous occurrences of severe
air pollution in eastern United States, Western Europe and Japan turned into a
world-wide episode. The fatal gas MIC (Methyl iso cyanate) killed over 2500
people in Bhopal in 1984.
Dear Candidate, This Material is from CAPF (Assistant Commandant) Study Kit.
Pollution is the effect of undesirable changes in our
surroundings that have harmful effects on plants, animals and human beings.
This occurs when only short-term economic gains are made at the cost of
long-term ecological benefits for humanity.
Pollutants include solid, liquid or gaseous substances
present in greater than natural abundance, produced due to human activity, which
have a detrimental effect on our environment.
An average human requires about 12 kg of air each day, which
is nearly 12-15 times greater than the amount of food we eat. So, even a small
concentration of pollutants in the air becomes more significant in comparison to
similar levels present in food.
From an ecological perspective, pollutants can be
classified as follows
Non-degradable pollutants: These cannot be degraded by
natural processes. Once they are released into the environment they are
difficult to eradicate and continue to accumulate; e.g., toxic elements like
lead or mercury, and nuclear wastes.
Slowly-degradable or persistent pollutants: These are
pollutants that remain in the environment for many years in an unchanged
condition and take decades or longer to degrade; e.g., DDT (pesticides) and most
Degradable or non-persistent pollutants: These can be rapidly broken down by
natural processes; e.g., domestic sewage, discarded vegetables, etc.