C6.3 - Interpreting And Interacting With The Earth's Systems

Question 1

What is the percentage of nitrogen, oxygen, argon and carbon dioxide in the Earth’s atmosphere?

Answer 1

Nitrogen - 78%

Oxygen - 21%

Argon - 0.9%

Carbon dioxide - 0.04%

There are also trace amounts of other gases.

Question 2

What is the theory in terms of how the Earth’s early atmosphere had came?

Answer 2

It is likely that Earth’s early atmosphere came from substances released by volcanoes.

However, no-one was around to record events as they happened, so it is difficult to be certain that this theory is correct.

Question 3

Describe how the Earth’s early atmosphere was formed?

Answer 3

The Earth of 4.54 billion years old and there was a great deal of volcanic activity during its early years.

Volcanoes release huge volumes of water vapour and carbon dioxide.

As the Earth cooled, the water vapour condensed to form oceans, leaving an atmosphere of mostly carbon dioxide.

It probably contained small amounts of other gases such as ammonia and methane, but little or no oxygen.

Question 4

How has the Earth’s atmosphere changed in terms of where the oxygen came from and where the carbon dioxide went?

Answer 4

Plants and algae make their own food by photosynthesis, absorbing carbon dioxide from the atmosphere and releasing oxygen.

At first, the oxygen reacted with metals in rocks to produce metal oxides.

Later, as most of the metals became oxidised, free oxygen began to accumulate in the atmosphere and eventually it has developed the oxygen-rich atmosphere that we have today.

Question 5

What are pollutants?

Answer 5

Pollutants are substances released into the environment that may harm living things.

Question 6

How is carbon monoxide, CO, produced and how does it cause problems?

Answer 6

Carbon monoxide, CO, is produced during the incomplete combustion of fuels that contain carbon.

It is a toxic gas, colourless, and has no taste or smell.

When breathed in, carbon monoxide attaches to the haemoglobin protein in red blood cells. This reduces the amount of oxygen that the bloodstream can carry.

It can lead to drowsiness, difficulty breathing, and even death.

Question 7

What are particulates and why are they dangerous?

Answer 7

Particulates are small particles that is produced by incomplete combustion.

The smallest particulates settle deep in the lungs when they are breathed in.

It can lead to diseases such as bronchitis and other other breathing problems, and increases the chance of heart disease.

Question 8

How is nitrogen monoxide and nitrogen dioxide form?

Answer 8

Nitrogen and oxygen react at high temperatures such as in vehicle engines to from nitrogen monoxide, NO.

The nitrogen oxide is then oxidised in air to form nitrogen dioxide.

These oxides of nitrogen are jointly called NO(small x).

Question 9

How is sulphur dioxide formed?

Answer 9

Fossil fuels naturally contain small amounts of sulphur compounds.

These impurities form sulphur dioxide when the fuel is burnt.

Sulphur dioxide can cause breathing difficulties.

Question 10

How is acid rain formed and why is it dangerous?

Answer 10

The nitrogen oxide, nitrogen dioxide and sulphur dioxide dissolves in the moisture in clouds, forming an acidic solution, which eventually falls as acid rain.

Acid rain erodes stonework, corrodes metal can kill trees, and living things in rivers and lakes.

Question 11

How can carbon monoxide and particulates pollution be decreased?

Answer 11

By using alternatives to fossil fuels.

Question 12

How can sulphur dioxide pollution be decreased?

Answer 12

Power stations can have scrubbers and flue gas desulphurisation plants.

Question 13

How can nitrogen oxide and nitrogen dioxide pollution be decreased?

Answer 13

By using catalytic converters in cars.

These turn nitrogen oxides into nitrogen which is not as harmful.

Question 14

What is the greenhouse effect?

Answer 14

The interaction of infrared radiation with greenhouse gas molecules in the atmosphere, reducing the transfer of energy to space.

Question 15

Describe the greenhouse efffect.

Answer 15

Energy transferred by radiation from the Sun reaches the Earth’s surface.

The radiation warms up the Earth’s surface.

Infrared radiation is emitted by the Earth’s surface. Some goes directly into space. Some is absorbed by greenhouse gas molecules in the atmosphere.

Greenhouse gas molecules emit infrared radiation in all directions, warming the Earth’s surface and atmosphere.

Question 16

How can an enhanced greenhouse effect be caused?

Answer 16

The release of additional greenhouse gases by human (anthropogenic) activities has the potential to cause an enhanced greenhouse effect.

Question 17

Why is an enhanced greenhouse effect dangerous?

Answer 17

An enhanced greenhouse effect, increases the temperature of the Earth’s atmosphere.

This global warming leads to the melting of ice caps and rising sea levels, and to climate change.

Climate change brings altered weather patterns, causing flooding, problems with farming and disease control.

Question 18

How can greenhouse gas emissions be reduced?

Answer 18

Reducing the consumption of fossil fuels, for example by using biofuels.

Using renewable energy resources such as wind and solar energy to generate electricity.

Stopping carbon dioxide escaping when fuels are used by using carbon capture.

Question 19

Where will tap water have originally have come from?

Answer 19

Water stored in lakes, reservoirs, or aquifers (layers of rock which stores water underneath).

Question 20

What microorganisms and many different substances does water contain originally before treated?

Answer 20

Insoluble materials such as leaves, and particles from rocks and soil.

Soluble substances, including salts, and pollutants such as pesticides and fertilisers.

Question 21

What is potable water?

Answer 21

Water that is safe for drinking.

Question 22

What are the stages in water treatment, from reservoir to potable water?

Answer 22

As the waters enters the water treatment works, it passes through a screen. This is made from bars of metal placed closed together. These catch large objects such as leaves and twigs.

The water then travels into a settlement tank, where the sand and soil settle out - through a coarse filter.

The water carries on moving into another tank (called the sedimentation tank) where aluminium sulphate and lime are added to it. Small particles of dirt clump together so that they sunk to the bottom of the water. The sludge that collects like this is dumped in a landfill site where is forms mud. The sludge may also be sent to tanks to be decomposed by anaerobic bacteria. However, methane, a greenhouse gas, is produced.

The water then carries on to another tank where it is passed through a special filter made of fine sand. This removes any remaining particles of mud or grit, so the water is clear.

The water then moves into another tank. Although the water now looks clean, it may still contain harmful bacteria. A small amount of chlorine is added to the water to kill bacteria.

The pH of the water is checked and corrected so that is it neutral. The water is then stored in large tanks and service reservoirs, ready to be pumped to homes, schools, offices, and factories.

Question 23

How is salt water treated?

Answer 23

The high concentration of dissolved salts is removed in a process called desalination.

Question 24

How is salt removed in small scale desalination?

Answer 24

Reverse osmosis using special ultrafilters is used to filter out the salts.

Pressure is applied on saline water. The water can pass through a partially permeable membrane and is filtered to become potable water.

Question 25

How is salt removed in large scale desalination?

Answer 25

Simple distillation.

Question 26

Where would desalination be worthwhile?

Answer 26

Desalination would not be worthwhile in countries like the UK, but it is worthwhile where fresh water supplies are limited, or where the cost of energy resources is low.