Tài liệu The Influence of Human Activity on the Environment ppt

The Influence of Human Activity on the Environment
Improvements in agriculture health and medicine have
produced a dramatic rise in the human population
This increase in population size leads to an increase in
pollution and higher demand for the world’s resources
Humans are using up the earth’s resources, including
fossil fuels.
Burning fossil fuels in cars and power stations produces
carbon dioxide, sulphur dioxide and other greenhouse
gases
• carbon dioxide traps heat in
the atmosphere and causes
the temperature of the
earth to rise.
• This leads to disruption of
the weather patterns eg
drought, floods
• Some weeds may thrive on
the extra carbon dioxide
while other plants are killed
Sulphur dioxide will dissolve in rain producing Acid Rain
• Acid rain damages trees and pollutes rivers and lakes.
Acid rain causes erosion of buildings
and statues particularly if they are made of limestone
Deforestation
• In may countries people
are chopping down
forests to provide
timber or space for
agriculture for the
growing population

This causes several problems
1. Burning the timber increases the level of carbon
dioxide in the air
2. Less trees means less carbon dioxide absorbed for
photosynthesis
3. Soil is eroded as it is exposed to the wind and rain
4. Less water is transpired into the atmosphere
5. Many animal and plant habitats are destroyed
causing extinction of species
Intensive Farming
• Farming has become more intensive to provide a
higher % yield from land
• Many people regard intensive farming of animals to be
cruel
• In order to produce more food from the land farmers
have to use more fertilisers and pesticides
Problems with Fertilisers
• Fertilisers enable farmers to grow more food as they
are replacing the nutrients removed from the soil by
plants
• However, if too much fertiliser is added and it then
rains, the fertiliser finds its way into rivers and lakes
• This causes the water plants to grow and as there is
competition for light, some will die
• Bacteria decay the dead
plants and in so doing
use up oxygen from the
water
• This means the fish

suffocate and die
• This process is called
Eutrophication
• Raw sewage pumped into
rivers has the same
effect
Pesticides
• Pesticides kill insects that will damage crops
• They also kill harmless insects or can get washed into
rivers and pollute the water
• They may even end up in the food chain
In the 1960s, DDT in the food chain threatened bird
populations.
Many birds of prey came close to extinction
What can we Do?
Organic Farming?
• This produces less food
and is more expensive
but it does not produce
the pollution problems
of intensive farming
Use farmyard manure as a fertiliser and set aside land
for growth of wild plants
Biological Control of Pests
• This means using natural
predators to eat pests
instead of pesticides
• It does not have
harmful effects

Develop alternative energy sources
• Conserve our rapidly
diminishing fossil fuel
reserves by using solar
power or wind power
Benefits of conserving endangered species
• Ecotourism
• Agricultural benefits
• Species indicators
• Maintaining diversity in
gene pool
•
WHAT ELSE?????????
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