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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)
How Do We Affect the Ecosystem?
• 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
How Do We Affect the Ecosystem?
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
How Do We Affect the Ecosystem?
• 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.
How Do We Affect the Ecosystem?
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
22.1
(c) Chemical fertilisers
How Do We Affect the Ecosystem?
• 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.
Effect of Pollution Due to Insecticides
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.
Effect of Pollution Due to Insecticides
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
How Do We Affect the Ecosystem?
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
How Do We Affect the Ecosystem?
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
How Do We Affect the Ecosystem?
4. Discuss how overuse of fertilizer on the agriculture land has a negative impact on aquatic biodiversity.
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….[4]
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
Management of Fisheries
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
Management of Fisheries
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.
………………………………………………………………………………
………………………………………………………………………………
………………………………………………………………………………
………………………………………………………………………… [3]
(b)Explain the importance of preventing any species from being extinct.
………………………………………………………………………………
………………………………………………………………………………
………………………………………………………………………………
………………………………………………………………………………
………………………………………………………………………… [3]
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
Wastewater treatment process
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.
Wastewater treatment process
Environment Biotechnology
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:
Environment Biotechnology
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?
Environment Biotechnology
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
( )
Environment Biotechnology