1. The presence in or introduction into
the environment of a substance or
thing that has harmful or poisonous
2. Pollution of the water
in rivers and lakes
3. Water Pollution is harmful to the health of humans and animals. It may not
damage health immediately but can become harmful after long term exposure.
Different forms of pollutants affect the health of living beings differently.
They can be broadly classified under 4 categories:1) Biological agents: Virus, bacteria, protozoa, algae, fungus
2) Organic chemical agents: Oil, gasoline, pesticides
3) Inorganic Chemical agents: Salts, acids, nitrates, phosphates
4) Physical agents: Suspended solids and heat
4. Both organic and inorganic impurities are present in the soluble, insoluble and
colloidal forms in water. Impurities may be classified as the following1) Suspended impurities
(a) Bacteria and viruses, some of which cause various diseases
(b) Algae, protozoa and fungus cause odour, turbidity, colour and clogging
5. 2) Dissolved impurities
(i) Calcium causes alkalinity and hardness
(ii) Magnesium chloride causes hardness and is corrosive in nature.
(iii) Sodium causes alkalinity and has a brackish taste.
(i) Iron oxide causes bad taste, red water, discolouration of clothes and
(ii) Lead causes cumulative cumulative poisoning
(i) Oxygen corrodes metals/pipes
(ii) Carbon dioxide causes acidification and is corrosive
Sewage :sewage contains many chemicals ,
paper , plastic and other wastes people flush
Down their toilets. Untreated sewage and
fertilizers cause uncontrolled growth of algae
and plankton over large areas of oceans
which depletes oxygen from the water killing
life forms leading to what is known asdead
7. Industrial and chemical wastes :
Chemicals Discharged from the factories that
are washed down into drains and eventually
Into oceans causes tremendous harm to the
environment as the chemical compounds
Enter the food chain . Highly toxic chemicals
such as polyclorinated biphenils(PCB) which
were used to manifacture electronic circuit
board have now been widely
banned.however,their harmful effects on the
enviorment will take many years to fade
because PCBs last for a very long time in the
enviornment without breaking down.
8. SURFACE RUN
Surface run from agricultural fields carry with it a deadly
mixture of chemicals , pesticides and fertilizers .Most
pesticides are non- degradable and remain in water for a
long period of time and thus enter the food chain through
aquatic plants and animals . The fertilizers increase the
amount of nutrients in water bodies leading to
9. Offshore drilling- platform accidents and oil spills resulting from oill tanker
accidents have devastating effects on the environment.
Nuclear fallouts, chemical wastes and dumping of radioactive wastes.