Explanation Text

Why Seawater is Salty?

Most of our planet’s surface is covered in water – salt water. The oceans that support so much of Earth’s life are around 3.5% sodium chloride – 50 million billion tonnes of salt.

But where does it come from? While some of it comes from volcanic vents or rocks on the seabed, most of it is actually from the land around us. Every time it rains, tiny amounts of mineral salts are washed into rivers, which eventually flow into the sea.

The salt in rivers is less than 1/200th the amount usually found in seawater. It becomes more concentrated in the ocean, as the Sun’s heat causes water from the surface to evaporate, leaving the salt behind. Extra salt added every year from rivers is balanced by salt which returns to the sea floor.

But salinity isn’t the same everywhere. Towards the poles, water is not as salty because it’s diluted by melting ice, while the extra heat in the tropics makes water there saltier – and denser.

What is the text about?

• It explains how the seawater salty.

• The seawater becomes salty due to human intervention.

• The activities of volcanoes influence the salinity of seawater.

• The salinity of seawater comes from sodium chloride.

• It explains the reasons why the seawater becomes salty.

Why Seawater is Salty?

Most of our planet’s surface is covered in water – salt water. The oceans that support so much of Earth’s life are around 3.5% sodium chloride – 50 million billion tonnes of salt.

But where does it come from? While some of it comes from volcanic vents or rocks on the seabed, most of it is actually from the land around us. Every time it rains, tiny amounts of mineral salts are washed into rivers, which eventually flow into the sea.

The salt in rivers is less than 1/200th the amount usually found in seawater. It becomes more concentrated in the ocean, as the Sun’s heat causes water from the surface to evaporate, leaving the salt behind. Extra salt added every year from rivers is balanced by salt which returns to the sea floor.

But salinity isn’t the same everywhere. Towards the poles, water is not as salty because it’s diluted by melting ice, while the extra heat in the tropics makes water there saltier – and denser.

What step after mineral salts from rain flow into the sea?

• It will evaporate by the sun’s heat.

• It will be mixed by the rain water.

• It becomes more concentrated by the sun’s heat.

• Mineral salt settles on the seabed.

• Mineral salt separates form sea water.

Why Seawater is Salty?

Most of our planet’s surface is covered in water – salt water. The oceans that support so much of Earth’s life are around 3.5% sodium chloride – 50 million billion tonnes of salt.

But where does it come from? While some of it comes from volcanic vents or rocks on the seabed, most of it is actually from the land around us. Every time it rains, tiny amounts of mineral salts are washed into rivers, which eventually flow into the sea.

The salt in rivers is less than 1/200th the amount usually found in seawater. It becomes more concentrated in the ocean, as the Sun’s heat causes water from the surface to evaporate, leaving the salt behind. Extra salt added every year from rivers is balanced by salt which returns to the sea floor.

But salinity isn’t the same everywhere. Towards the poles, water is not as salty because it’s diluted by melting ice, while the extra heat in the tropics makes water there saltier – and denser.

Why does the water salinity at the poles less than at the tropics?

• The water is diluted by melting ice.

• At the poles has more sun’s heat.

• The rain happens more in the tropics.

• At the poles there is no land.

• There is no crust of the earth at the poles.

Why Seawater is Salty?

Most of our planet’s surface is covered in water – salt water. The oceans that support so much of Earth’s life are around 3.5% sodium chloride – 50 million billion tonnes of salt.

But where does it come from? While some of it comes from volcanic vents or rocks on the seabed, most of it is actually from the land around us. Every time it rains, tiny amounts of mineral salts are washed into rivers, which eventually flow into the sea.

The salt in rivers is less than 1/200th the amount usually found in seawater. It becomes more concentrated in the ocean, as the Sun’s heat causes water from the surface to evaporate, leaving the salt behind. Extra salt added every year from rivers is balanced by salt which returns to the sea floor.

But salinity isn’t the same everywhere. Towards the poles, water is not as salty because it’s diluted by melting ice, while the extra heat in the tropics makes water there saltier – and denser.

“It becomes more concentrated in the ocean, as the Sun’s heat...” (paragraph 3). The word “it” refers to...

• Seawater

• The ocean

• Sun’s heat

• The salt

• Sea surface

Why Seawater is Salty?

Most of our planet’s surface is covered in water – salt water. The oceans that support so much of Earth’s life are around 3.5% sodium chloride – 50 million billion tonnes of salt.

But where does it come from? While some of it comes from volcanic vents or rocks on the seabed, most of it is actually from the land around us. Every time it rains, tiny amounts of mineral salts are washed into rivers, which eventually flow into the sea.

The salt in rivers is less than 1/200th the amount usually found in seawater. It becomes more concentrated in the ocean, as the Sun’s heat causes water from the surface to evaporate, leaving the salt behind. Extra salt added every year from rivers is balanced by salt which returns to the sea floor.

But salinity isn’t the same everywhere. Towards the poles, water is not as salty because it’s diluted by melting ice, while the extra heat in the tropics makes water there saltier – and denser.

From the text above, we imply that ….

• The mineral salt comes from rain.

• The water salinity is different in everywhere.

• Salt water becomes more concentrated in the ocean due to rain.

• Water at the poles is more salty because of melting ice.

• The seawater becomes salty due to human intervention.