Friday, April 24, 2009

ADDITIONAL TASK FOR 7 GRADE

HUMAN IMPACT ON THE ECOSYSTEM

No one can deny that we, human beings, are capable of changing our evironment to suit our needs. Some of the actions taken to change the environment. However, many human activities such as thse that pollute the air, water and land, and the over-exploitation of natural resources have adverse consequences on our ecosystem
Some of these activities do not have immediate effects on the environment, but they may have long-term and irreversible consequences later. These activities not only harm our physical environment, they also harm other organisms living in the environment, including ourselves. Eventually, man himself may become endangered because of his own activities.

1. Effects on the Atmosphere
Air polution is a global problem because air pollutants can flow freely. For example, a burning forest, which occurs in one place, can give rise to haze at another place thousands of kilometres away.

Some of the problems caused by air pollution are acid rain, thinning of the ozone layer and global warming.

Gaseous pollutants from industries and vehicles, when released into the air, result in the formation of acid rain. Acid rain corrodes stonework and metalwork of buildings, destroys trees in the forest and kills plants ad animals on land and in water.

Chlorofluorocarbon or CFCs from aerosol cans, refrigerators, air-conditioners amd foam packaging materials, as well as other substances such as carbon tetrachloride, halons and trichloroetane, destroy the ozone layer. The ozone layer prevents most of the sun’s ultraviolet radiation from reaching the surface of the earth. Thinning of the ozone layer and the eventual formation of holes in the layer result in overexposure to ultraviolet radiation. This can cause skin cancer and eye diseases such as cataracts in human. It can also harm plants and animals living on land or in the sea.

Carbondioxide, oxides of nitrogen, methane and CFCs released into the atmosphere trap the heat from the sun and prevent it from escaping into space. The levels of these gases in the atmosphere have been rising due to human activities such as the burning of forests and fossil fuels. This results in the warming up the earth’s climate, a phenomenon called global warming.

2. Effects on rivers and oceans
The world’s rivers and oceans are gradually becoming more and more polluted as a result of human activities. This affects the ecosystem greatly as life cannot exist in polluted waters.

Man pollutes the rivers and oceans in a variety of ways.
Bacteria and other harmful waste substances in untreated sewage may harm human health and cause diseases such as cholera.

The pesticides and fertilisersare washed off into rivers and oceans by the rain. Fish and othe aquatic life may be killed by the pesticides.

Fertilisers encourage the growth of algae on the river surface, hence preventing sunlight from reaching other aquatic plants.

The harmful chemicals contaminate the water and kill fish in the rivers and oceans. People who eat these contaminated fish can get cancer and other diseases.

Fish are killed when they swallow the oil. Marine animals or seabirds may drown or freeze to death because the oil causes their fur or feathers to stick together.

3. Effects on land
Harmful chemicals and waste are released into the soil by individuals and industries. Most of the land pollutants come from the rubbish that we throw every day.

People used to burn their rubbish in the open and caused air pollution. Nowadays, people dispose or their rubbish by burying it in dumping grounds called sanitary landfills or burning it in incineration plants. Harmful substances can also be released into the air from the burning of rubbish.

4. Over-exploitaton
Over-exploitation of a resources means using the resource until it runs out or is so badly damaged that it can no longer be used again.

Over hunting
Over hunting of animals is an example of over-exploitation of wildlife and has resulted in many animals becoming extinct or endangered.

Overuse of energy

Excessive Deforestation
A forest has a big web of life with thousands of food links. Deforestation removes the habitats of forest plants and animlas and will eventually lead to their extinction. This may result in the loss of potential cures for illnesses as some of the plants have medicinal value.

The potential to produce better quality crops from crossbreeding will also be lost if wild plants are threatened with extinction. This is because wild plants often have qualities that cultivated species lack.


SAVING THE EARTH
The environmental problems that we are facing now are mainly created by human activities. Some environmental problems can be solved immediately and easily by individuals while others require the combined efforts of many different parties over long periods of time.
What can we do to take care of our environment?

Every individual should try to….
· Throw all litter and solid waste that cannot be recycled into litterbins, not into drains or into the ground
· Pour liquid waste into sewers and not into open drains, rivers of the sea
· Stop using products that contain harmful substances such as CFCs which can damage our environment
· Use environmental-friendly products
· Use products made from biodegradable materials such as paper or biodegradable plastics
· Use product made from recycled materials such as recycled paper
· Use less disposables
· Save energy by using energy efficient machines
· Save water
· Campaigns tree-planting
· Walk or cycle for short trips
· Use public transport for longer trips
· Consume less
· Minimize wastage.

Project for Students:
Please make a poster to campaign what can we do to take care of our environment! Do in group of 4 or 6 and you can choose your groupmates by yourself.
Make your poster on ‘mahjong’ paper and you can use crayon or another pens to make it colorful. Submit your poster on 5th May, 2009.

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