HUMAN INFLUENCES ON ECOSYSTEM

How has the use of modern technology resulted in increased food production?

1. Development and use of chemical fertilizers.2. Development and use of pesticides.3. Development and use of herbicides.4. Use of modern machinery such as tractors.5. Development of biological control methods for pest control.6.Artificial selection to produce new variety of plants with a good yield and new breeds of animals to increase meat and milk production.7. Use of yeast and bacteria in the large scale production of bread, beer, wine, yoghurt and cheese.8. Use of medicines like antibiotics.9. Artificial insemination techniques in intensive animal rearing.10. Use of plant hormones in plant growing and food production.

11. Use of genetic engineering.12. Development of systems to water plants in greenhouses automatically and to grow plants in nutrient solutions (a process called hydroponics)13. Use of satellites to monitor crop development and observe crop diseases.14. Development of intensive farming and automated feeding mechanisms.

Problems associated with increase in population

• 1. Deforestation• Undesirable effects of deforestation are as follows:• A. Reduction of habitat of animals leading to their

extinction.• B. Loss of plant species important for genetic

engineering.• C. removal of trees resulting in soil erosion and

leaching.• D. Lack of trees leading to flooding and mudslides.

E. Leaching of nutrients into lakes and rivers leading to EUTROPHICATION.F.Less carbon dioxide absorbed from atmosphere increasing greenhouse effect.G. Less oxygen produced resulting in oxygen depletion in the atmosphere.H. Less transpiration leading to reduced rainfall.

2. Overuse of fertilisers

• Problems associated are as follows• A. Leaching• B. Death of plants• C. Eutrophication

POLLUTION

• 1. WATER POLLUTION• CAUSED BY A Chemical waste like heavy metals (mercury,

nickel ) and Oil• EFFECT OF MERCURY ON HUMANS• Damages central nervous system• EFFECT OF OIL• Poisons bird

• B. Caused by SEWAGE• EFFECT• Results in• EUTROPHICATION as sewage contains high

levels of nutrients such as phosphates, organic matter and bacteria.

. Leads to diseases like cholera and typhoid.

2. AIR POLLUTION Caused by 1. SUPHUR DIOXIDE when coal and oil are burned.This gas dissolves in the water vapour in clouds forming sulphuric acid.When it rains the rain becomes acid2. Caused by oxides of nitrogen in the exhaust fumes when combustion of petrol takes place in the car engines. This also contributes to acid rain.

PROBLEMS CAUSED BY ACID RAIN

1. Damage to plant leaves killing trees.2. Acidification of lakes killing fish.3. Increased risk of asthma and bronchitis.4. Corrosion of stonework on buildings.5. Washes away important minerals from the soil

like calcium and magnesium.6. Washes away Aluminium from soil to rivers which stops functioning of gills in fish.

REDUCING POLLUTION FROM ACID RAIN

• 1. Installing scrubbers which removes all sulphur dioxide from waste gases at power stations.

• 2. Using calalytic converters on car exhaust which convert nitrogen oxides into nitrogen.

• 3. Changing power stations from burning fossil fuels to gas or nuclear power or using renewable energy sources like wind.

The Greenhouse Effect

• Earth has a natural greenhouse effect

• This is important to prevent large fluctuations in temperature

• Without a greenhouse effect on Earth, we would not have life as we know it.

• 3. GREENHOUSE GASES like• A. Carbon dioxide produced by burning of fossil fuels• B. Methane produced by incomplete decomposition

of organic matter due to activity of bacteria under anaerobic conditions.

• Other sources of methane production are • Flooded paddy fields,• Marshes,• Biogas plants.

HOW INCREASE IN GREENHOUSE GASES ARE THOUGHT TO CAUSE GLOBAL WARMING

Greenhouse Effect

Light from the sun has short wavelengths and can pass through most of the atmosphere.

This sunlight warms the Earth which in turn emits long wave radiation.

This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, CFCs, water vapour, and sulphur dioxide

POLLUTION DUE TO PESTICIDES

• Example DDT: • It is non- biodegradable therefore causes

bioaccumulation• Example Insecticides:• They are nonspecific which kills useful insects

like Bees . Thus food webs can be affected.

POLLUTION DUE TO HERBICIDES

• Used to kill weeds but may also kill rare plant species near the field being sprayed.

• POLLUTION DUE TO NUCLEAR FALLOUTS

• Nuclear fall out from nuclear power stations or nuclear explosions can lead to cancer or birth defects

POLLUTION BY NON- BIODEGRADABLE PLASTICS

• EFFECTS• Remain in environment taking up valuable space

or causing visual pollution.• Discarded plastic bottles can trap animals.• Nylon fishing lines and nets can trap birds and

mammals like seals and dolphins.DISPOSAL OF PLASTIC IS A PROBLEMWhen buried remain in the soil for years.When burnt releases toxic gases.

CONSERVATION OF NATURAL RESOURCES

• 1. FOSSIL FUEL CONSERVATION• Increase the use of renewable energy like

wind, solar power and hydroelectric power.• Improve the efficiency of energy use ( better

insulation, smaller car engines, more public transport)

2. CONSERVATION OF SPECIES:Loss of species due to• habitat destruction• Introduction of other species• International trade• Pollution

EFFECT OF LOSS OF SPECIES1. Loss of species means loss of genes which is important for genetic engineering2. Presence of rare species can be an important source of money through tourism.3. The species may play an important role in a food chain.

3. CONSERVATION OF HABITATS• Habitat can be conserved by:• A. Using laws to protect the habitat.• B. Using warden to protect the habitat.• C. Reducing or controlling public access to the

habitat.• D. Controlling factors like water drainage and

grazing that may otherwise contribute to destruction of the habitat.

4. CONSERVATION OF TREES

• This can be done by recycling paper, which will reduce cutting down of trees.

• RECYCLING PAPER in RECYCLING PLANTS• A. Used paper is collected.• B. Print on the paper removed by using chemicals.• C. Paper mixed with water to make a slurry or pulp.• D. Pulp being re- rolled into sheets• E. Dried and used to make newspaper, hand towel

and toilet paper.

5. CONSERVATION OF WATER

• One way of conserving water is to reuse or recycle it.

• Recycling involves SEWAGE TREATMENT• STEPS INVOLVED IN SEWAGE TREATMENT:• A. Large objects such as sticks screened out of

raw sewage.• B. Suspended Grit allowed to settle out by

gravity settling tank.

• C. Organic matter allowed to settle out in Sludge settling tank.

• D. Digested in a sludge digester• E. Now can be used as a fertilizer or to produce

methane gas to be used as fuel.• F. Remaining liquid sprinkled on top of an aeration

tank containing stones and microorganisms on stones to digest any remaining organic matter.

• G. Water passing out may now be chlorinated to kill any bacteria, so that it is safe for drinking.