Why are the Oceans Salty?

As water flows in rivers, it picks up small amounts of mineral salts from the rocks and soil of the river beds. This very-slightly salty water flows into the oceans and seas. The water in the oceans only leaves by evaporating (and the freezing of polar ice), but the salt remains dissolved in the ocean – it does not evaporate. So the remaining water gets saltier and saltier as time passes.

The salinity (salt content) of ocean water varies. The oceans and seas contain roughly 5 x tons of salts. One cubic foot of average sea water contains 2.2 pounds of salt.

The oceans are about 3.5% salt (by weight). Salinity is generally reported in terms of parts per thousand (abbreviated ‰), the number of pounds of salt per 1,000 pounds of water; the average ocean salinity is 35 ‰.

The saltiest water is in the Red Sea and in the Persian Gulf, which have a salinity of about 40 ‰ (due to very high evaporation rates and low fresh water influx). The least salty seas are in the polar regions, where both melting polar ice and a lot of rain dilute the salinity.

1. w atercourse

2. vanish

3. melted

4. salt content

5. approximately

6. entry

7. weaken

(Based on http://www.enchantedlearning.com/subjects/ocean/Salty.shtml)

Task 5. Read the text and complete the sentences after it choosing the best answer:

Why is the ocean blue?

Sunlight is made up of all the colours of the rainbow: red, orange, yellow, green, blue, and violet. Some of the sunlight is reflected off the surface of the water, reflecting the colour of the sky. Some of the sunlight penetrates the water and is scattered by ripples and particles in the water (this tinges the appearance of the ocean with the colour of the particles). In deep water, much of the sunlight is scattered by the oxygen in the water, and this scatters more of the blue light.

Water absorbs more of the red light in sunlight; the water also enhances the scattering of blue light. Sir Chandrasekhar Venkata Raman (an Indian physicist) won the Nobel Prize in 1930 for his work on light.

Some oddly-coloured seas are the Red Sea and the Black Sea. The first often looks red due to red algae that live in this sea. The latter looks almost black because it has a high concentration of hydrogen sulphide (which appears to be black).

1. The word ‘penetrates’ in line 3 means

1. to go into or through something;

2. to float on the surface;

3. to drift with a current.

2. If something is scattered, it means it is

1. gathered together;

2. thrown and dropped in different directions;

3. rolled or moved in one direction.

3. Small waves on the sea or ocean surface are called

1. ripples;

2. rainbow;

3. skittles.

4. The verb ‘to tinge’ in line 4 means

1. to evaporate liquid;

2. to scatter the particles around;

3. to add a small amount of colour to something.

5. ‘To absorb’ in line 7 means

1. to release particles into the air;

2. to take in a liquid, gas or other substance from the surface or space around;

3. to connect the substances.

6. When something increases or the good quality, value or status are improved, we use the verb

1. to chance;

2. to absorb;

3. to enhance.

7. The word algae in line 11 means

1. very simple plants, such as seaweed, that have no real leaves, stems or roots, and that grow in or near water;

2. the organisms inhabiting the surface layer of a sea or lake, consisting of small drifting plants and animals;

3. mineral salts from the rocks and soil of the river beds.

8. If we denote the second or second mentioned of two, we use the word

1. the letter;

2. the former;

3. the latter.

(Based on http://www.enchantedlearning.com/subjects/ocean/Blue.shtml)

Task 6. Read the texts and answer the following questions choosing the best variant: