UNIT 2: THE HYDROSPHERE

What do you remember? Look at the picture and answer the questions. •

Where can you find water on our planet?

•

How is sea water different to water river and lakes?

•

What is the water cycle? Can you describe it?

•

Do you know some easy ways to save water?

1. Where is the water on Earth? There is salt water and fresh water on Earth.

WATER 97 %

of the water on Earth is salt water. It is found in the oceans.

3%

of the water on Earth is fresh water. FRESH WATER

68,7% is ice and snow from glaciers or at the North and South Poles. 30,1 %

is groundwater: water below the Earth’s surface.

0,9 %

is in the atmosphere, in living things, etc.

0,3 %

is surface fresh water. SURFACE FRESH WATER

87 % is found in lakes 11 % is found in swamps 2 % is found in rivers: it is fit for human consumption

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1st.

Put the words in order and write correct sentences.

a) Earth both and salt fresh water you find can on. You…………………………………………………………………………………………………. b) Water covers of the but only is planet 68,7 % fresh water 3 %. Water………..………………………………………………………………………………………. c) In the atmosphere and in living things water 0,9 % of fresh is. 0,9 %………………………………………………………………………………………………. d) 2 % surface water is human fresh consumption for fit of. 2 % .…………………………………………………………………………………………………. e) Under groundwater Earth is fresh water located the surface of the. Groundwater……………………………………………………………………………………….

2. What are the properties of water? Water is a substance with unique properties. It plays an important part in the processes that occur on the Earth’s surface and is essential to living beings. Water is made up of molecules. Each molecule of water is made up of one atom of oxygen and two atoms of hydrogen.

At room temperature the molecules can move about freely: water flows. The main properties of water are: •

A powerful solvent. It dissolves many components of rocks. When water evaporate, it leaves deposits of mineral salts.

•

Absorbs heat. Water moderates the Earth’s climate by absorbing heat in summer and emitting heat in winter.

•

Cohesion and adhesion. Water is attracted to water: this is called cohesion. Water sticks to itself, it can travel through vessels in plants to transport food to the leaves. Water transports substances throughout the bodies of living things. Water molecules are also attracted to other materials: this is called adhesion. As a result, water wets surfaces such as soil and rocks. 2

Anomalous dilation. When water freezes, it dilates or increases in volume. As a result, the volume of ice is greater than the same mass of water in liquid form.

Did you Know that…? Water covers 75 % of the surface of our planet. This characteristic is unique in the solar system. There is water on other planets, but is never found in a liquid state nor in such huge quantities.

2nd. Complete the text about property of water. solvent

molecules

ice

oxygen

heat

adhesion

dilates

Water in solid form is called ________ . When water freezes it _____________ unlike other substances. It is made up of _______________ with one atom of hydrogen and two of ______________. Water molecules are attracted to other molecules. This is called ________________ . Water moderates the Earth’s climate by absorbing _________. It dissolves rock components because it is a powerful ___________. 3rd. Complete the sentences with compound nouns from the box. rock erosion

water courses

water molecules

sea water

river valleys

1. ________________ are attracted to each other and to other substances. 2. _______________ contains dissolved gases and salts. 3. One of the results of wave action is _________________. 4. Streams and torrents are _________________ fed by rain.

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5. ____________________ are also created by the action of water as it erodes rocky banks.

3. Where is fresh water found? Fresh water is found on the continents. It contains much less salt than sea water. It is found in different forms: lakes, rivers, torrents, underground rivers, pools and glaciers. Stream or torrents are water courses fed by rain. The flow of water varies a lot from season to season. Wetlands are areas of marshlands and swamps where the ground is inundated all year round. Glaciers are formed from the accumulation of snow on mountain tops. Rivers are permanent water courses. The River Nile is the longest river in the world. Groundwater is water located under the ground surface. Lakes are bodies of water of different sizes contained on a body of land. Example: Lake Victoria, Africa.

Stream

Wetlands

Glacier

River

Groundwater in a cave

Lake

4. What is the water cycle? The water cycle is the movement of water around, over, and through the Earth. It consists of the following processes: • • •

Evaporation. Liquid water changes to a gas (water vapour). Water passes from the hydrosphere to the atmosphere. Evapotranspiration o transpiration. Water evaporates into the atmosphere from the leaves and stems of plants. Condensation. Water vapour changes to liquid, forming clouds and dew. 4

• • •

Precipitation. Water in the clouds falls to the ground as rain, snow or hail. Surface runoff. Surface water moves across the land and forms rivers and streams. Infiltration o percolation. Surface water filters into the ground. This occurs more easily if the ground is porous.

4th. Write these words associated with the processes of the water cycle in the correct columns. rain

clouds

hail

groundwater

from the leaves and stems of plants

water vapour

from the hydrosphere to the atmosphere

rivers and streams

porous ground

snow

dew

The water cycle Evaporation

Evapotranspiration Condensation

Precipitation

Surface run off

Infiltration

rain

5th. Read the descriptions and identify the stages of the water cycle. Then put them in order. a)

_____________: The leaves and stems of plants release water into the atmosphere.

b)

_____________: A lot of water also filters into the ground, especially in places where the ground is porous. 5

c)

_____________: Water passes from the hydrosphere to the atmosphere as it changes to a gas.

d)

_____________: Clouds and dew are formed when water vapour changes to liquid.

e)

_____________: Water on the surface of the Earth moves across the land and into rivers and streams.

5. What is water used for? Water is the most abundant substance in living things. Every day your body loses 1,5 to 2 litres of water through sweat, urine and respiration. You replace it by drinking water. Water is used in different ways, depending on the country. The main uses are: • • •

Agriculture. To water crops. Industry. Water is used in many industrial processes. Domestic use. Drinking water is used for human consumption, cleaning, etc.

Did you Know that…? A person can live about a month without food, but can live only about 1 week without water.

How can you save water? Water is a scarce resource. You can reduce domestic water consumption if you…: • • • •

Take a shower, not a bath. Turn off taps when brushing teeth or soaping your body. Load dishwashers and washing machines completely before use. Install water-saving devices in the lavatory cistern.

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6. What pollutes water? Water becomes polluted for many reasons. For example, as a result of: • • • •

Waste water from industries and farmland. Sewage water from towns and cities. Oil slicks caused by the accidental spillage of crude oil at sea. Agricultural fertilizers and pesticides which filter into the soil and pollute rivers and groundwater.

Some causes and prevention of water pollutions Causes Rubbish thrown in the countryside, on beaches, in rivers, etc. Toxic waste from domestic use makes it difficult and expensive to purify water Chemical pollution.

6th.

Prevention Pick up rubbish and place in rubbish bins. Do not throw paints, oils or solvents down the drain or toilet. Recycle batteries. They release toxic chemicals into the soil, then into rivers.

Read the text and answer the questions.

A precious resource Water is a finite resource which cannot be created or synthesized. Your body lose 1,5 to 2 litres of water through sweat, urine and respiration. You need to drink at least an equivalent amount of fluids to replace it for the correct maintenance of the body’s systems. If there are six thousand million people on Earth, twelve million cubic metres of fresh water are needed every day just to provide enough drinking water for everyone!. So, we should all try to reduce water consumption by adopting simple everyday habits. For example, take showers instead of baths, turn off the tap when brushing your teeth, fill dishwashers and washing machines before using them. You can install water-saving devices in the shower head and lavatory cistern. If water in your town was suddenly rationed, you would be amazed at how many things you can do with a small amounts of it! 7

1. Why do we need to drink water? ____________________________________________________________________ ____________________________________________________________________ 2. How much water is needed on Earth each day? ____________________________________________________________________ ____________________________________________________________________ 3. Write three ways of saving domestic water. ____________________________________________________________________ ____________________________________________________________________

7th. About 15 litres of water a minute flow through an open tap. a) A person cleans his teeth three times a day and takes a shower once a day. Calculate how much water he saves if he turns off the tap for two minutes.

b) And if he takes five minutes less in the shower.

8th. Match the questions and answers.

2. Where do glaciers originate? 3. What are wetlands? 4. How much of the water on Earth is fresh water?

a) Water located under the surface of the ground. b) Areas of marshlands and swamps. c) Mineral salt deposits.

5. What happens when water freezes?

d) It dilates.

6. What does water leave when it evaporates?

e) On mountain tops.

7. What is groundwater?

f) 3 %.

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8. Where is most surface fresh water located?

g) In lakes.

9th. Work in pairs. Take turns to read and classify the sentences. Write the numbers in the boxes. Fresh water

Salt water

Properties of water

Uses of water

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1. It is a powerful solvent which can dissolve many components of rock. 2. It is used in many industrial processes. 3. About 0,9 % of it is found in the atmosphere and in living things. 4. It is used for human and animal consumption. 5. It contains dissolved salt. 6. Groundwater accounts for 30,9 % of it. 7. It is poisonous if you drink too much, and can kill you within days. 8. It can also exist as a solid and a gas. 9. Only 0,3 % of it is found on the surface of the Earth. 10. At room temperature, it flows because its molecules move freely.

10th. Find the words in this table.

river cloud runoff condensation sea energy snow evaporation stream hail sun ice crystal water cycle lake water droplet ocean precipitation water vapor wind rain

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11th. Answer the questions in pairs. 1. List different forms in which you can find water. _______________________________________________________________________ _______________________________________________________________________ 2. List four ways of saving water. _______________________________________________________________________ _______________________________________________________________________

Visual Dictionary

Evaporation

Ground water

Infiltration

Evaporation

Transpiration

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