CHAPTER 19 Our Impact on the Ecosystem. 19.1How Do We Affect the Ecosystem? 19.2Conservation Chapter...

CHAPTER 19Our Impact on the Ecosystem

19.1 How Do We Affect the Ecosystem?

19.2 Conservation

Chapter 19

Our Impact on the Ecosystem

Learning Outcomes

After this section, you should be able to:

• evaluate the effects of deforestation and uncontrolled fishing practices;

• evaluate the effects of water pollution by sewage, fertilisers and inorganic waste;

• outline the roles of microbes in sewage disposal as an example of environmental biotechnology; and

• understand the phenomenon of bioaccumulation.



Human beings use natural resources every day.

The use of natural resources must be controlled and regulated because their depletion will result in environmental damage that is largely irreversible.

19.1

Natural resources

Renewable- can be replaced via natural cycles as long as they are not overused

Examples: Air, water, soil, and wildlife

Non-renewable

- cannot be replaced once they are used

Examples: Fossil fuel and minerals

How Do We Affect the Ecosystem?


Human activities can damage the environment

19.1

• Deforestation refers to the clearing of forests.

• Forests are cleared to make land available for agricultural and/or urban development.

• Forests are usually cleared at a rate faster than they can be replaced.

Deforestation


19.1

Activity

URL


1) what deforestation is,

2) why deforestation occurs, and

3) the effects of deforestation.

Deforestation results in many environmental problems. Watch the video on deforestation. While watching the video, list down:

http://www.youtube.com/watch?v=6hcSbwqJHfc&feature=related

19.1

Forests prevent soil erosion by:

• providing a leafy canopy that protects the topsoil from the direct impact of rain, and

• retaining water in the forest through the absorption of water by plant roots.

Effects of deforestation

rain


In a deforested areas, topsoil would be easily washed away during heavy rain causing soil erosion.

1) Soil erosion

19.1

2) Flooding

Rise in water level increases the chances of flooding

rain

soil erosion Soil gets washed into river



19.1

• Without the leafy canopy, sunlight falls directly onto the ground and causes water to evaporate from the ground.

• This creates a desert-like condition that is not suitable for plants to grow.


3) Desertification


19.1

4) Climate changes

• Reduced plant life results in less carbon dioxide being removed from the atmosphere via photosynthesis.

• Carbon dioxide is a greenhouse gas. It traps heat within the Earth’s atmosphere and results in warmer climates.



19.1

• Fish is an important food source for humans.

• As the human population increases, the demand for fish increases.

• Uncontrolled and unregulated fishing can result in reduced aquatic biodiversity.

Uncontrolled fishing practices


19.1

• destroy coral reefs and organisms that live on the sea bed

Fishing techniques that are detrimental to the aquatic environment involve the use of:


1) Dredges:

2) Drift nets and trawlers:

• catch marine life indiscriminately

drift net

dredge

dredger

trawler


19.1

• kills corals and other reef organisms.

URL


3) Cyanide fishing:

Effects of uncontrolled fishing practices

• Destruction of marine habitat

• Decrease and extinction of certain fish populations


http://www.youtube.com/watch?v=fNDwSrRgtyA&feature=related

19.1

Pollution is the process by which harmful substances are added to the environment.

Pollution


discharge of untreated

sewage into water bodies

excessive use of fertilisers

and insecticides

Water pollution (The contamination of

water bodies)

dumping of inorganic waste

material into water bodies

is caused by

19.1

Sewage

Sewage refers to waste materials from homes and industries.

Untreated sewage may contain disease-causing bacteria and if discharged into water bodies could cause:


• an epidemic (outbreak of a disease that affects a large population of humans in a given period) such as Cholera

• eutrophication as they contain phosphates and nitrates

19.1

Chemical fertilisers


• Chemical fertilisers that contain nitrates and phosphates are used to increase crop yield.

• Excessive use of these fertilisers can lead to a phenomena called eutrophication.

Excess fertilisers are washed into a water body.

Nutrients in fertilisers increase the growth of algae and water plants in the water body.

Submerged plants die due to lack of sunlight.

Bacteria grow rapidly and use up dissolved oxygen as they decompose the dead plants.

Other organisms die due to lack of oxygen.

19.1

Sewage treatment via environmental biotechnology

• Used water (i.e. sewage) has to be treated before being removed

• The usage of microorganisms in sewage treatment helps to speed up the water treatment process.

Environmental biotechnology refers to the use of biological sciences to provide environmentally friendly solutions in reducing pollution.

Example:

URL


http://www.youtube.com/watch?v=Ldz29NqwK78

19.1

Sewage treatment process

Sewage is channelled into

water reclamation plants.

Heavy solids settle to the bottom the tank and are

removed as sludge.

Sewage enters the primary settling tank.


19.1

Partially treated sewage is transferred to the aeration tank and mixed with bacteria.

The bacteria breaks down the organic pollutants into harmless substances.

Treated sewage is discharged into the sea.

Liquid is sent to final settling tank where the bacteria are removed.



19.1

Sludge is treated in anaerobic digesters before being dewatered and disposed into a soil container.

Sludge removed from primary settling tanks

Sludge removed from final settling tanks



19.1

Insecticides

• Some insecticides, such as DDT, (dichlorodiphenyltrichloroethane) are inorganic compounds that are non-biodegradable.

• DDT cannot be excreted and it is stored in fatty tissues of organisms that consume it.

• Therefore, DDT can be passed along food chains, leading to bioaccumulation.


19.1

Bioaccumulation:

Chemicals that are not excreted, accumulate in bodies of organisms that consume them.

1

1

1

1

1

515

45


15

15

5

5

The chemicals are then passed along the food chain and become concentrated in the bodies of the final consumers.

Chapter 19



19.2 Conservation

Learning Outcomes

After this section, you should be able to:

• discuss reasons for conservation of species with reference to the maintenance of biodiversity;

• discuss the conservation of species with reference to management of timber production and fisheries.

19.2 Conservation

19.2

Conservation

• Human activities have depleted natural resources, polluted the environment and destroyed wildlife habitats.

• This threatens the biodiversity on Earth.

Conservation: The protection and preservation of natural resources in the environment.

Biodiversity: The range of species that is present in a particular ecosystem.

Conservation

Maintenance of a large gene

pool

Prevents extinction of animal and

plant species

Preservation of natural scenery

and wildlife

Scientific value

Studies on wildlife give us insight on

human beings

Maintenance of biodiversity

Maintenance of a balanced

ecosystem

Economic importance

Rainforests are a source of raw materials for

industries

Food source

Marine life are a major source of

human food

19.2

Reasons for conservation

Conservation

19.2

Forests can be managed to prevent the adverse effects of deforestation via:

• Creation of laws to regulate the logging industry

• Reforestation: The planting of new trees or seedlings to replace trees that have been destroyed

• Designation of lands as forest reserves

• Research to improve quality of forests and making them more productive

Conservation

Conservation of forests

Conservation measures

19.2

Fishing grounds can be managed to prevent over-fishing and indiscriminate catches via:

• Banning the use of drift nets, trawlers and dredges

• Using nets with a certain mesh size

• Limiting the number of ships allowed in fishing grounds at any one time

• Raising endangered species of fish in hatcheries for release into the sea

Conservation

Conservation of fishing grounds

Conservation measures

Chapter 19


CHAPTER 19 Our Impact on the Ecosystem. 19.1How Do We Affect the Ecosystem? 19.2Conservation Chapter...

Documents

Transcript of CHAPTER 19 Our Impact on the Ecosystem. 19.1How Do We Affect the Ecosystem? 19.2Conservation Chapter...