Lecture # 2

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Contents of the lecture

Water

Earth’s water supply & distribution

Hydrologic cycle

Water pollution

Sources of water pollution

Types of water pollution

Types of water pollutants

Acid rain

Water borne diseases

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Water is essential to life on earth.

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Three forms of Water.

Solids: When water becomes very cold

and freezes it will change from a liquid to

a solid. It has a definite form and shape.

Liquids: When water takes the shape

of its container it is in a liquid form.

Gases: When water is seen in a vapor

form and has no definite size or shape it

is in a gas form.

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The earth's water supply

97.2% of the Earth's water supply is salt water.

Only 2.8% is fresh water!

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World Water Supply

97.200% salt water in the oceans

02.014% ice caps and glaciers

00.600% groundwater

00.009% surface water

00.005% soil moisture

00.001% atmospheric moisture

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Distribution of water

Ocean Water: The vast majority of water on the planet is the salt water in the oceans and seas.

Fresh Water: This is the fresh water in rivers, streams, lakes, ponds and similar bodies of water.

Groundwater: The majority of the planet's liquid freshwater is stored in underground aquifers. Water that enters an aquifer remains there for an average of 1,400 years!

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Water : A precious Natural Resource

We use water for drinking, irrigation, industrial purposes and energy production. Water use

agriculture and energy production - 80%

industry and public use - 20%

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Hydrologic cycle - water cycle

It describes the continuous

movement of water on,

above or below the

surface of the earth

Powered by energy from

the sun

Hydrologic cycle purifies

water

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Pollution of water

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Water Pollution

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Where do Water pollutants come from?

Point Sources – A single definable source of the pollution, e.g. a factory, a sewage plant, etc. Point-source pollution is

usually monitored and regulated.

Non-point sources – No single source, but a wide range of sources, e.g. runoff from urban areas, or farmland. Non-point sources are much more difficult to monitor and control.

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Pollution of Water

1. Surface water pollution

2. Groundwater pollution

3. Microbiological pollution

4. Oxygen depletion pollution

5. Nutrients pollution

6. Suspended matter pollution

7. Chemical pollution

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1. Surface water pollution

It is the visible form of pollution

and can be seen on waters in

lakes, streams, rivers. E.g.plastic

bottles, shopping bags and trash

from human consumption

Pollution of Water

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Pollution of Water

2. Groundwater pollution

Effects drinking water and aquifers

below the soil caused by highly

toxic chemicals and pesticides

from farming

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Pollution of Water

3. Microbiological pollution

Natural form of water pollution

caused by microorganisms. E.g.

bacteria and viruses cause serious

diseases.

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Pollution of Water

4. Oxygen depletion pollution

Some microorganisms in water use

up the available oxygen, called as

oxygen depletion which results in

lower oxygen.

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Pollution of Water

5. Nutrients pollution

Found in waste water and

fertilizers. They can cause

excess vegetation in water such

as algae and weeds which use

up oxygen in water hurting

marine life.

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Pollution of Water

6. Suspended matter pollution

It occurs when pollutants enter the

water and do not mix with water

molecules. These suspended

matter forms fine silt in water.

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Pollution of Water

7. Chemical pollution

There is a lot of chemical run off

from factories into the water bodies

which includes metals, solvents,

pesticides from industries. They

add poison to wildlife in water.

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Non-persistent (degradable) water pollutants

These compounds can be broken down by chemical reactions or by natural bacteria into simple substances such as carbon dioxide and nitrogen.

If the pollution load is high, this process can lead to low oxygen levels.

E.g. Domestic sewage, fertilizers and

some industrial wastes

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Persistent Water pollutants

This is the most rapidly growing type of

pollution

This includes substances that degrade very

slowly or cannot be broken down at all;

They may remain in the aquatic environment

for years or longer periods of time.

some pesticides, petroleum products,

radioactive materials and metals.

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Acid rain Acid rain is formed when moisture in the

clouds mixes with sulfur or nitrogen oxides in the air.

Acid rain includes rain or snow with a pH level that falls below 5.6 (normal rainwater).

The sulfur and nitrogen get into the air by the burning of fossil fuels such as coal and gasoline. The average pH of acid rain is 4.3.

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Consequence of Acid Rain

Water borne diseases

Diseases caused by the ingestion of

water contaminated with pathogenic

bacteria, viruses, or parasites include:

cholera

typhoid

Dysentery

Other diarrheal diseases

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Remedial measures

Locate the point sources of pollution.

Work against acid rain.

Educate your community.

Ensure sustainable sewage treatment.

Watch out for toxins.

Be careful what you throw away.

Think globally, act locally.

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Thank you 43