Impact on Ecosystem 2015

CHAPTER 22

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; and

• understand the phenomenon of bioaccumulation.

22.1 How Do We Affect the Ecosystem?

CHAPTER 22.1i. Effect of Water pollution Due to Untreated Sewage

22.1

Pollution is the process whereby harmful substances are added to the environment.Substances that cause pollution are terms pollutants

Pollution

How Do We Affect the Ecosystem?

Water pollution is the contamination of water bodies.

It can be caused by:

(a) discharge of untreated sewage into water bodies,

(b)dumping of inorganic waste material into water

bodies.

(c) excessive use of fertilisers and insecticides

22.1

(a) Untreated sewage

• Sewage refers to waste materials from homes and industries.

• Untreated sewage may contain disease-causing bacteria and that can result in epidemics if discarded into water bodies. (e.g Chlolera)


• Untreated sewage also contains phosphates and nitrates that can lead to eutrophication.

3. The dead bodies of the algae and aquatic plants are decomposed by bacteria.

4. Bacteria grow and multiply rapidly, using up the oxygen in the water.

22.1

microQuestion


1. Excess phosphates, from fertilisers used in agricultural farms, are a common water pollutant that result in algae blooms. Algae blooms lead to the death of submerged aquatic plants. Which of the following factors causes the death of the submerged aquatic plants?

A) Too much bacteria

B)Too much carbon dioxide

C)Lack of sunlight

D)Lack of oxygen

( )

22.1

Inorganic waste includes poisonous metals (e.g. mercury, arsenic and cadmium) and some types of pesticides.

(b) Inorganic waste


• Poisonous metals that are dumped into rivers or lakes are extremely harmful to humans.

• A tragic example would be the case of mercury poisoning in 1971 in Minamata, Japan.

22.1

Mercury poisoning at Minamata Bay, Japan in 1971.


A plastic factory discharged waste water containing mercury into Minamata Bay.

Mercury was absorbed by the water weeds.

The water weeds were eaten by fish.

Fish caught contained high concentrations of mercury.

Villagers ate the contaminated fish and suffered from mercury poisoning.

http://www.youtube.com/watch?v=ihFkyPv1jtU

http://www.youtube.com/watch?v=ihFkyPv1jtU

22.1

(c) 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.

CHAPTER 22.2 Effect of Pollution Due to Insecticides

Effect of Pollution Due to Insecticides

Insecticides contain inorganic waste substances that are non-biodegradeable

Insecticides contain inorganic waste substances that are non-biodegradeable

22.2

DDT cannot beexcreted but instead stored in the fatty tissue of the organism. Furthermore, organism cannot breakdown the DDT.

DDT cannot beexcreted but instead stored in the fatty tissue of the organism. Furthermore, organism cannot breakdown the DDT.

Hence it got accumulated in the body of the consumers, increasing in concentration in the bodies of organisms

• Insecticide can enter the food chain by the aquatic plant absorbing it.

• • When the primary consumer feeds on the plant, the

insecticide is transferred from the plant into the body of the consumer.

• Since the DDT is insoluble and is stored in the fatty tissues of organisms, it will be accumulated in the organism and pass down to the next higher trophic level in the food chain.


Bioaccumulation

22.2

• The insecticide concentration increases and remains highest in the bodies of the final consumers.

22.2

Example: Agent Orange used in Vietnam War

http://www.youtube.com/watch?v=kkbnFfldsOcWatch this:

22.2

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.


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

The 1986 Chernobyl disaster triggered the release of substantial amounts of radioactivity into the atmosphere. It is one of the most significant unintentional releases of radioactivity into

the environment to date.

Fukushima Nuclear Plant Explosion

How does this affect the food chain?

http://www.whoi.edu/oceanus/feature/how-is-fukushimas-fallout-affecting-marine-life

22.2

microQuestion


2. In recent years, lakes in many parts of the world have become more acidic. What has caused this change?

A) Air pollution by sulfur dioxide

B) Deforestation

C) Increased use of insecticides

D) Increased use of nitrate fertilisers

( )

22.2

microQuestion


3. Which property of modern insecticides helps to keep environmental pollution at the lowest level?

A) They accumulate in the bodies of the prey.

B) They are biodegradable.

C) They are easily soluble in water.

D) They are easily taken up by the plant roots.

( )

22.2

microQuestion


4. Discuss how overuse of fertilizer on the agriculture land has a negative impact on aquatic biodiversity.

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CHAPTER 22.3 Conservation

Learning Outcomes

After this section, you should be able to:

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

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

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

22.3 Conservation

22.3

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

Conservation

22.3

Forest is a :

• Major source of oxygen

• Help to moderate the water

• Protection of soil

Management of Timber Production

Conservation

22.3

• Law is introduced to restrict the number of trees felled for timber. Tree below the stipulated measurement are not allowed to be cut.

• New seedling are planted to replace those trees that were cut down for timber (reforestation).

• Setting up of forest reserves that prohibit felling of tree for timber to maintain the ecosystem

Management of Timber Production

Conservation

Ways

22.3

• 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

Management of Fisheries

Conservation

22.3

• 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.

• Fishing ground are carefully manage to prevent over-fishing and indiscriminate fishing


Conservation

22.3

•Banning of drift nets which traps all form of marine life

•Impose law to use nets of certain mesh size so that young fish are not caught

•Regulating ship entering fishing group

•Limit period of fishing

•Ban harvesting of endangered species

•Building of hatcheries to artificially raise endangered fish


Conservation

Ways

CHAPTER 22.4 Main Reason for Conservation

http://www.babble.com/pets/10-extinct-animals-my-kids-will-never-see/

7 Main Reasons for Conservation1. Prevent extinction of plant & animal species.2. Maintain large gene pool.3. Ensure conservation of marine life because

they are a major source of food. 4. Preserves natural scenery & wildlife for people

to appreciate

5. Conservation is of scientific values6. Maintain biodiversity because many

plants are of great economic importance as sources of raw materials for drugs & food.

7. Maintain stable and balanced ecosystem.

7 Main Reasons for Conservation22.4

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

22.4

Reasons for conservation

Main reason of Conservation

5(a) Discuss the effects of deforestation on ecosystem.

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(b)Explain the importance of preventing any species from being extinct.

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Main Reasons for Conservation22.4

microQuestion

CHAPTER 22.5 Environment Biotechnology

Singapore new water reclaimation plant@Jurong: http://www.youtube.com/watch?v=7xoWmXO0GfM

Source:

http://www.pub.gov.sg/LongTermWaterPlans/gwtf.html

22.5

Wastewater treatment process

Environment Biotechnology

Wastewater is channelled into

water reclamation plants.

Heavy solids settle to the bottom of the tank and

are removed as sludge.

Wastewater enters the primary settling tank.

22.2 Conservation

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


22.5

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

The bacteria breaks down the organic pollutants into harmless substances.

Treated wastewater is discharged into the sea.

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



22.5

• 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:


1. Primary settling tank• Used water enters the primary settling tank. • Heavy solids settle to the bottom and removed as

sludge.• Sludge is treated in the anaerobic digesters and

dewatered and disposed of as a soil conditioner (fertilisers).

Environment Biotechnology22.5

2. Aeration tank•Air is mixed with bacteria.

•Oxygen present allow Aerobic Respiration to take place in the bacteria

•Bacteria secretes enzymes to digest organic pollutants into harmless soluble substances and carbon dioxide.

3. Final settling tank•Microorganisms are removed from the treated water. •

Environment Biotechnology22.5

22.5

microQuestion6. Untreated sewage is continuously discharged into a river at point X.Which graph shows the effects on the concentrations of oxygen and bacteria?


D

(apparently no answer )

22.5

microQuestion7.Which of the following shows the process of sewage treatment in the correct order?

A) Primary settling tank final settling tank aeration tank sea

B) Primary settling tank aeration tank final settling tank sea

C) Primary settling tank aeration tank sea final settling tank

D) Aeration tank primary settling tank final settling tank sea

( )


Education

Impact on Ecosystem 2015