4.4.1 The Effects of Pollution

Question 1

Human population growth globally has been increasing exponentially for the last, how long?

Answer 1

for the last 150 years

Question 2

There are many reasons for this exponential growth, including:

Answer 2

1. Improved technology leading to an abundance of food = rapid increase in birth rate

Question 3

Rapid growth in the human population and an increase in the standard of living means, what?

Answer 3

our negative effect on the environment is also increasing

Question 4

As increasingly more resources are used to sustain the growing human population, what happens?

Answer 4

more waste is produced and more pollution is created

Question 5

Unless waste and chemical materials are properly handled, what will happen?

Answer 5

pollution will continue to be created

Question 6

What is the Source/Cause of Toxic Chemicals (Pesticides and Herbicides)

Answer 6

Source/Cause:

Sprayed on crops to prevent damage by insects and growth of weeds. Runoff occurs from agricultural land if these tocic chemicals are applied in too high a concentration causing them to enter water courses

Question 7

How do Toxic Chemicals affect Biodiversity

Answer 7

1. These chemicals cannot be broken down by organisms.

• This is called bioaccumulation.

• This is called biomagnification

Question 8

What is the Source/Cause of Untreated Sewage

Answer 8

Lack of sewage treatment plants in inhabitated areas (due to poor infrastructure or lack of money) meaning sewage runs or is pumped into watercourses

Question 9

What is a watercourse

Answer 9

watercourse is the channel that a flowing body of water follows ie, river, lake, stream.

Question 10

How does Untreated Sewage affect biodiversity

Answer 10

Sewage provides a good source of food for bacteria which increase rapidly, depleting the oxygen dissolved in the water (as they respire Aerobically)

This lack of oxygen eventually results in the death of aquatic organisms such as fish and aquatic invertebrates. This is known as Eutrophication

Question 11

What is Eutrophication?

Answer 11

Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients

Question 12

What is the Source/Cause of Fertilisers

Answer 12

Runoff occurs from agricultural land if fertilisers are applied in too high a concentration, causing fertilisers to enter watercourses

Question 13

Define agricultural

Answer 13

used for farming or relating to farming

Question 14

How do Fertilisers cause biodiversity

Answer 14

Fertilser causes increased growth of algae and water plants. The resulting ‘algae bloom’ blocks sunlight so water plants on the bottom start to die, as does the algae when competition for nutrients becomes too intense. Dead plants and algae are a good soruce of food for bacteria. As described above, this eventually leads to eutrophication and the death of many aquatic organisms.

Question 15

What is the source of Toxic Chemicals (Land Pollution)

Answer 15

When sprayed onto crops, these toxic chemicals also get into the soil.

Question 16

How do Toxic Chemicals (Land Pollution) affect biodiversity

Answer 16

These chemicals cannot be broken down by organisms. They can be absorbed by plants or taken in by other organisms living in the soil and can build up tissues of these organisms over time. This is called bioaccumulation, At each stage of the food chain, increasing levels of the chemicals build up in organisms, which can eventually build up to dangerously toxic levels in top predators, leading to death or failure to breed. This is called biomagnification.

Question 17

What is the source/cause of Discarded Rubbish

Answer 17

Household waste that cannot be recycled is bured in landfill sites.

Question 18

How does Discaded Rubbish affect Biodiversity

Answer 18

Landfill site take up a lot of room and their creation often results in the destruction of natural habitats. Toxic chemicals can spread from the waste into soil. Much rubbish, such as that made from plastic, is non-biodegradable and remains in the enviroment for hundreds of years.

Question 19

What is a landfill site?

Answer 19

A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials

Question 20

What is the source/cause of Sulphur Dioxide and Nitrogen Oxides

Answer 20

Combustion of fossil fuels that contain sulphur impurities creates sulphur dioxide. Nitrogen oxides are also fuel combustion. These gases react with oxygen and dissolve in rainwater to produce dilute sulphuric acid and nitric acid, which leads to acid rain.

Question 21

How does Sulphur Dioxide and Nitrogen Oxides affect biodiversity

Answer 21

Acid rain can damage the leaves, buds, flowers and roots of trees and other plants. It can make rivers and lakes to acidic, resulting in the death of certain aquatic organisms. It can also cause the leaching of minerals that are toxic to fish, such as aluminium, into lakes.

Question 22

Exam Tip

Answer 22

Water pollution from sewage and water pollution from fertiliser runoff have the same end result (increase in decomposing bacteria leading to a decrease in dissolved oxygen and death of aquatic organisms) but they do not arrive at this point in the same way.

You need to learn both and be aware of the differences between them. A common misconception is that sewage pollution also causes growth of water plants and algal blooms – this is very rarely the case, only runoff of fertiliser does this.