The Influence of Human Activity on the Environment

Page
2

This causes the water plants to grow and as there is competition for light, some will die

Slide 12

Bacteria decay the dead plants and in so doing use up oxygen from the water

This means the fish suffocate and die

This process is called Eutrophication

Raw sewage pumped into rivers has the same effect

Slide 13

Pesticides

Pesticides kill insects that will damage crops

They also kill harmless insects or can get washed into rivers and pollute the water

They may even end up in the food chain

Slide 14

In the 1960s, DDT in the food chain threatened bird populations. Many birds of prey came close to extinction

Slide 15

Slide 16

What can we Do?

Slide 17

Organic Farming?

This produces less food and is more expensive but it does not produce the pollution problems of intensive farming

Slide 18

Use farmyard manure as a fertiliser and set aside land for growth of wild plants

Slide 19

Biological Control of Pests

This means using natural predators to eat pests instead of pesticides

It does not have harmful effects

Slide 20

Develop alternative energy sources

Conserve our rapidly diminishing fossil fuel reserves by using solar power or wind power

Slide 21

Benefits of conserving endangered species

Ecotourism

Agricultural benefits

Species indicators

Maintaining diversity in gene pool