2. INTRODUCTION
2
• Water pollution is a state of deviation from the pure condition, whereby its normal
properties and function are affected.
• Noticeable signs:-
Odors from rivers, streams, lakes and ocean beaches.
Oily and greasy materials floating on surface of water bodies.
Unchecked growth of aquatic weeds in water bodies.
Bad taste of drinking water.
Decrease of aquatic life etc.
• Water pollution is studied under 3 sub-heads, viz., inland fresh surface water
pollution, ground water pollution, and marine water pollution.
4. Sources of Water Pollution
5
4
The main sources of water pollution are natural, agricultural, mining,
municipal, industrial and accidental:
a)Natural pollution:-
•Aerial contaminants entering the water body due to rainfall or melting of ice.
•Decaying of plants, animals and organic matter.
•Leachates from animal excreta.
b)Agricultural pollution:-
•Soil and silt washings from land surfaces.
•Fertilizers, insecticides, pesticides and weed killers.
5. c) Mining pollution:-
•Tailings from ore washing
•Inert suspended solids
•Soluble toxic materials
•Acid drainage
d) Municipal pollution:-
•Sewage obtained from domestic premises, institutions, commercial and industrial
buildings.
e) Industrial pollution:-
•Effluents coming from various industries 5
5
6. Point sources
•Those sources which can be readily identified at a single
location.
•For instance- industrial, municipal sewage ,treatment plants,
combined sewer overflow, raw sewage discharges, etc.
•This type of discharge can be controlled.
Diffused sources
•Those sources whose location cannot be easily
identified.
•For instance- run off from agriculture lands, forestry,
mining, construction, etc.
•This cannot be easily controlled.
Sources of water pollution :-
7
7. Effects of Water Pollution
7
The adverse effects of water pollution can be studied under the following heads:-
i.Physical effects
ii.Oxidation effects
iii.Toxic chemical effects
iv.Chemical nutrient effects
v.Micro-organism effects
vi.Radionuclide effects
8. i. Physical Effects:-
•Due to suspended particle solids, cooling water from power stations and oily surface
films.
•Solids may be inert material wastes or insoluble finely divided organic solids.
1. Inert materials in water slowly accumulate on vegetation foliage and produce a
deposit on riverbed.
These may cause reduction in solar energy absorption thereby decreasing rate of
photosynthesis causing low oxygen conditions on the riverbed.
Suspended materials may also cause turbidity .
2. Finely divided organic solids will be biodegraded and will cause reduction of the
dissolved oxygen in water. 8
9. • Cooling water from power stations can cause a rise in water temperature and brings
about a thermal pollution.
• Variations in temperature will affect the metabolic rate of physiological processes.
• Increased temperature will cause decrease in freshwater fauna population and
increase in flora population.
• At higher temperatures blue green algae and sewage fungus will grow more which will
result in plant death.
• The oxygen saturation percentage will be reduced, and biodegradation will be
increased.
• Both these factors will cause oxygen deficiency in water.
9
10. • Waste oil, fats and grease can enter from several sources.
• These will form a thin film on the water surface which prevents the exchange of
oxygen with the atmosphere causing reduction of water oxygen saturation.
• Spillage from oil tankers in sea will cause marine pollution and shore contamination.
• Oil slicks are responsible for the death of many birds.
• Oil reduces the thermal insulation and resistance to cold, irritates digestive system and
produces toxic effects.
• A badly oiled shore can be largely denuded of animal life and sea weeds
are also affected.
10
11. ii. Oxidation Effects:-
There are two types of oxidation namely:
a) Oxidation by action of bacteria upon organic pollutants.
b) Chemical oxidation of other pollutants.
• Both type of oxidation involves the use of dissolved oxygen.
• It will cause increase in Biological Oxygen Demand (BOD) .
• Causes deficiency of oxygen in water.
• Bacterial Oxidation-
Sulphides
• Chemical oxidation-
Ferrous salts
Sulphate
Ferric salts
11
12. iii. Toxic chemical effects:-
•Some organic and inorganic chemical
substances are toxic to plant, animals and
humans.
•Chemical toxic substances can be broadly
classified as metals and salts, pesticides,
acids and alkalis etc.
•Pesticide pollutions produce harmful
effect over the body.
•Acids and alkalis may change the Ph value
of water .Changes in ph. value may affect
physiological processes and actions of
toxins.
12
13. iv. Chemical Nutrient Effects:-
•Chemical nutrients are required by plants and animals for maintaining their growth and
metabolism.
•Nitrates and phosphates occur in water in small quantities.
•The nutrient levels slowly rise as a result of bio-degradation of dead organic material.
This rise in nutrients is called ageing or eutrophication.
•Increased concentration of nitrates and phosphates in water produce the overall effects of an
increase in the rate of growth of plants and animals.
Unicellular green and blue green algae and blanket weed reduce light penetration and restrict
reoxygenation of water.
•It will cause adverse conditions for river and canal navigation, and for swimming, bathing and
fishing.
•Nitrates are taken into body by food and drink and excess will cause blood diseases
and gastric cancer.
13
15. v. Micro- organism Effects:-
•Wastes that are discharged into water
contain pathogenic organisms that are
capable of transmitting human diseases.
•Bacteria are responsible for cholera,
typhoid fever, bacillary dysentery,
gastroenteritis.
•Virus may cause poliomyelitis, infective
hepatitis, and echo and consackil fevers.
•Round worm beef and pork tape worms
may also cause diseases.
15
16. vi. Radio- Nuclide Effects:-
•Solid waste(nuclear) filed in containers is dumped into seabed.
•The corrosive action of sea water my cause leakage of radioactive waste in water
and it may pose health hazards.
•Radionuclides can enter the human body through dusts and aerosols and can also
be absorbed by plants and animals.
16
17. vii. Eutrophication of lakes:-
•The condition of excessive growth of plants in a water body is called ‘Eutrophication’.
•It is natural process of aging of water body.
•It is a result of very slow process of natural sedimentation of microscopic organisms
which takes geologic times to complete.
•The completion of the process results in the extinction of the water body.
•The process is propelled by increasing concentrations of nutrients necessary for
biological activity.
•Causes decreased D.O( dissolved oxygen), increased B.O.D, and emission of foul
gases.
17
18. Classification of Water Pollutant
18
• The various types of water pollutants can be broadly classified in to four categories.
1.Organic pollutant
2.Inorganic pollutant
3.Radioactive pollutant
4.Suspended solids and sediments
19. Organic Pollutant
19
The organic compounds may further be categorised as follows
• Natural organic pollutant
• Sewage and industrial effluents
• Synthetic organic contaminants
• Microbiological components
20. Natural Organic Pollutant
20
• Natural organic contaminants in water come from the breakdown of naturally
occurring organic materials like decay of leaves, plants ,dead animals etc.
• Many plants and micro-organisms release organic matter into a water body through
their metabolic processes.
• Various types of algae and vegetation flourishing in a lake or reservoir can
also be a source of objectionable organic compounds in water.
21. Sewage and Industrial Effluents
• Organic pollutants are also discharged as municipal sewage and industrial effluents (such as food
processing units,paper ills,etc .)
21
22. Synthetic Organic Components
22
• These are man made materials which may enter the water bodies along with
sewage and other wastes.
• Synthetic organic components includes both volatile organic chemicals and
synthetic organic chemicals.
• Most common organic pollutant in VOC are industrial solvents , such as
carbon tetrachloride(used as fire extinguisher and cleaning agent).
• Most common organic pollutant in SOC are pesticides and herbicides.
• Presently , the most controversial organic pollutant are polychlorinated biphenyls
and dioxin, which are very toxic and known to cause caner even at very low
concentration.
23. Micro-biological Pollutants
23
• Many different micro-organisms such protozoa ,viruses , bacteria are found in
polluted water.
• Most of these do not pose a health hazard to humans.
• The organisms that can cause sickness In human are called pathogenic organisms.
24. Inorganic Pollutant
24
• Apart from the organic matter discharged in the water body through sewage and
industrial wastes high concentration of heavy metals and other inorganic pollutants
contaminates the water.
• The accumulation of heavy metals may have adverse effect on aquatic flora and
fauna and may constitute a public health problem where contaminated organisms
ae used for food.
• Algal growth due to nitrogen and phosphorous compounds can be
observed . Metals in high concentration can be toxic to biota.
25. Radioactive Pollutant
25
• Mining and processing of ores.
• Use in research ,agriculture ,medical , and industrial activities such as I131
,P32 ,CO60 , Ca45 ,S35 , ETC.
• Radioactive discharge from nuclear power plants and nuclear reactors.
• Uses and testing of nuclear weapons.
• These isotopes are toxic to lifeforms ,they accumulate in the bones and can cause
serious disorders.
26. Suspended Solids And Sediments
26
• Comprises of silt ,sand , and minerals eroded from land.
• Appears in the water through surface runoff during rainy season and
through municipal sewers.
• This can lead to the siltation , reduces storage capacities of reservoirs.
• Deposition of solids in the quiescent stretches of the stream and ocean bottom
can affect normal aquatic life and affect the diversity of aquatic ecosystem.
