Download Human Population Effects On Environment

Human Po pulation Effects
On Environment
Andrew, Lauren &
Wendy.
Number one gimp
group =]
Number one idiot?
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The
population reached 6.1 billion in
2000.
The
United Nation projects that world
population for the year 2050 could
range from 7.9 billion to 10.9 billion,
depending on the actions we take today.
Human population growth is the number
one threat to the world's
environment.
Each
person requires energy, space and
resources to survive, which results in
environmental losses.
If
the human population were
maintained at sustainable levels, it would
be possible to balance these
environmental losses with renewable
resources and regeneration.
But
our population is rapidly
rising beyond the earth's ability
to regenerate and sustain us with
a reasonable quality of life.
We are exceeding the carrying
capacity of our planet.
Food Webs
• Green plants are the starting point in all
food chains.
• Animals depend either directly or
indirectly on plants for their energy as it
passes along food chains.
• Many food chains connect to form a
food web.
• These more complex relationships are
usually in a very finely balanced state,
in equilibrium with the environment.
Disruption of Food Webs
• If a factor affects one type of
organism in a food web, it is likely to
have a knock on effect which
disrupts the lives of several other
species in the food web.
Effects of Chemicals On
wildlife
Massive quantities of chemicals are used in
agriculture and forestry
Fertilisers: used to improve soil fertility
Pesticides: used to limit damage done to
crops by pests
Factors Relating to the
chemical…
Is the chemical specific in its action or is it
poisonous to a wide variety of organisms?
Is it biodegradable or is its molecular
structure so stable that it persists for a very
long time in the environment?
Is its concentration kept to a minimum or is
it used in excess?
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Nitrogen in
the air
nitrogen fixing plant
eg pea, clover
animal protein
plant made
protein
root nodules
(containing nitrogen
fixing bacteria)
denitrifying
bacteria
nitrates absorbed
dead plants & animals
urine & faeces
decomposition by bacteria & fungi
nitrates
bacteria
(nitrifying bacteria)
ammonia
nitrites
bacteria
Nitrogen Cylce
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The nitrogen cycle represents one of the most
important nutrient cycles found in terrestrial
ecosystems.
Nitrogen is used by living organisms to produce a
number of complex organic molecules like amino
acids, proteins, and nucleic acids.
The store of nitrogen found in the atmosphere,
where it exists as a gas (mainly N2), plays an
important role for life.
This nitrogen goes through four processes during
the nitrogen cycle: nitrogen fixation, decay,
nitrification and denitrification.

Plant and animal wastes decompose, adding nitrogen
to the soil.

Bacteria in the soil convert those forms of nitrogen
into forms plants can use.

Plants use the nitrogen in the soil to grow.

People and animals eat the plants; then animal and
plant residues return nitrogen to the soil again,
completing the cycle.

Another way nitrogen enters the cycle is as inorganic
nitrogen from the atmosphere and factories. The concern
with these forms is that the incremental amount of nitrates
they add to the nitrogen cycle may threaten groundwater.
･Rain storms contribute atmospheric nitrogen through rain drops that
reach the soil.
･Legumes, such as soybeans, alfalfa and clovers, are plants that can
convert atmospheric nitrogen into plant-usable nitrogen.
･Factories that produce nitrogen fertilizers add nitrogen to the soil
when farmers and gardeners "feed" their crops.
･Nitrogen in sewage sludge from municipal waste plants can be used
to fertilize farm fields.
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Eutrophication is the
enrichment of an aquatic
environment by nutrients
such as nitrate and
phosphate.
This is a natural process
which normally occurs at
a very slow rate.
Levels of eutrophivation
have significantly
increased in many
freshwater and marine
ecosystems in recent
years.
Eutrophication

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This is because;
Intensive crop growing uses ever
increasing quantities of fertilisers
containing nitrate and phosphate,
much of which have been washed
into rivers/lochs by rain.
Intensive livestock farming
produces vast amounts of animal
sewage, some of which finds its
way into waterways adding
phosphate and nitrate.
Effluent from sewage treatment
works containing nitrate and
phosphate is discharged into rivers
and canals.
Some forms of detergent are rich
in phosphate which is not removed
by sewage treatment and ends up
in rivers and canals.
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When sunshine and warm temperatures
coincide with an artificially high level of
eutrophication, the affected environment is
suddenly able to support the enormous
number of algae. These tiny plants reproduce
prolifically, forming an algal bloom.
A river or canal with slow moving water is
more prone to an algal bloom since the
excess nutrients are not as well diluted as in
fast flowing water.
Sewage
 Raw sewage contains many different organic
chemicals such as protein and urea which are
rich in nitrogen.
 In developed countries, several species of
bacteria are used during the treatment of
sewage.
 These convert protein to ammonium
compounds which are then oxidised to nitrites
and nitrates by nitrifying bacteria.
 This is basically an intensification of the
natural processes that take place during the
nitrogen cycle.
Overloaded sewage works
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 If a sewage treatment works
becomes overloaded, raw or
inadequately treated sewage may
be discharged into a river,.
 The presence of large amounts of
sewage and millions of bacteria
cause the water to become cloudy
(turbid).
 In such conditions of poor
illumination, photosynthesis is
reduced and the number of algae
decreases.
Problems of sewage disposal
 As the human population increases so too
does the volume of sewage that needs to be
disposed of.
 This is a particularly serious problem in
densely populated countries.
 In recent years, much of Britain’s sewage is
deposited in the North Sea. However, even
this vast volume of water is being badly
polluted.
 As a result, Britain has agreed to find an
alternative; our only one being land fill sites!
Contamination of Drinking
Water
 Nitrate is very soluble in water and does not bind to
soil particles.
 When the fertiliser is excessively or ill-timed in use,
much can wash away and eventually reach water
supplies intended for human consumption.
 According to medical experts; its harmless to
humans. You can have as much as 100ppm in
drinking water and pose no threat to health.
 However, when nitrate is reduced to nitrite by
enzyme action in the gut of babies, the nitrite
combines with haemoglobin and hinders the oxygen
carrying capacity of the babies blood.
WHO guidelines…
 They recommend a 50ppm limit of nitrate in drinking
water
 Most of the UK meet this.
 In some parts of the world, levels are found to be
well above 100ppm.
 This excessive level has been linked with gastric
ulcers in adults and abnormalities in fetal
development.
Global warming:
Greenhouse Effect
 ‘Greenhouse’ gases are;
-Carbon dioxide
- Methane
-Chloroflurocarbons
(CFC’s)
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 They are referred to as ‘Greenhouse’ gases
because they trap infra-red radiation coming
from the Earth’s surface and reflect it back to
Earth, keeping the planet warm.
 This greenhouse effect, appropriately named
because the gases play a role similar to the
panes of glass in a greenhouse, causes
GLOBAL WARMING, which is essential for
life on Earth.
 Without it, the world would be too cold to
support life.
Excessive Global Warming
 As the concentrations of CO2, CH4 and
CFC’s build up in the atmosphere and form
an even denser layer, a corresponding
increase in the greenhouse effect is
expected to occur.
•This would result in
global warming well
in excess of the
present desirable
levels.
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The Future…
 Greenhouse Gases
 Increased or constant levels of these gases
will result in a significant increase in the
greenhouse effect and a major contribution
to further global warming
 Temperature
 Experts predict an increase in global temperature of 4-5
degC by 2050.
 (NB: a change of a few degrees can make an enormous
difference to climatic conditions worldwide)
 Rise In Sea Levels
 If a rise in global temperature does occur, this could cause
partial melting of the polar ice caps, releasing extra water
into the worlds oceans
 The inevitable result would be a substantial rise in sea
level, estimated at 1.5metres in the next 50 years
 PROBLEMS: flooding, low lying coastal regions would
become submerged
Excessive Global Warming…
 Is likely to lead to a decrease in forests, an
increase in desertification and a worsening
of conditions for the rural poor of the world
scraping a loving in marginal farming
regions.
There are many potential impacts of global warming than hypothetically affect the
environment and human life according to the theory of global warming. The main
thing is the average temperature increased gradually.From here, there are a number
of different effects such as rising sea levels, changes in agricultural ecosystems, the
spread of tropical diseases, the increasing intensity of natural phenomena. Some of
this phenomenon will produce today, but it is difficult to determine a direct relationship
to global warming.
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The Consequences of Global Warming
 Earths climate is very difficult to predict, because there are many
factors to consider: rain, sunshine, wind, temperature ﾉ So you can not
specify what the effects would cause global warming. But it turns out,
can be very severe climate change. The first consequence, it is
possible, is the improvement of drought: in some places less rainfall.
On the other, the rain will increase, causing flooding.Warmer
atmosphere can cause the ice near the poles are melting. The amount
of water would raise the sea level.
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Increased by only 60 cm would inundate
fertile soil in Bangladesh, India, among them
hundreds of thousands of people depend on
for food. tropical storms may occur more
frequently.The first step to stop the
phenomenon In the ﾕ70s, many people
begin to realize changes that the earth is
suffering. By studying them, they could
observe how the environment is fragile, and
how many people depend on it. Gradually we
all realized that it was not possible to
continue to pollute the water, earth and air
pollution will not go away by itself.
 Wildlife
 Global warming by a few degC would bring about dramatic
changes to many natural ecosystems
 Many plant and animal species, especially those living in
the wild would be unable to adopt to this pace of change
 Especially at risk would be those plants and animals highly
specialised to suit life in one specific ecosystem
 It is certain then that many forms of wildlife will become
extinct.
 Changes In Climate
 A rise in temperature of a few degrees would cause a
global shift in climate and rainfall patterns
 Agriculture
 If equatorial regions were to become even hotter and drier,
there would b a shift of thermal limits of agriculture towards
the poles
 “breadbasket” regions such as the American mid-west
would suffer a reduction in salt water and be unable to
produce the vast quantities of crops with which they supply
the world at present.
 This would effect food supply’s on a global scale.
Possible Courses of Action
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Emission of CO2 could be cut by promoting more efficient use of energy and
reducing our reliance on the combustion of fossil fuels by developing
alternative sources of energy
Destruction of tropical forest could be reduced by offering financial incentives
to the developing countries that possess the forests, in exchange for
guaranteed conservation.
Well designed land fill dumps, which allow methane to be collected and put to
use instead of escaping to the atmosphere.
Exerting strict control over the use of CFC’s and phasing them out completely
as soon as harmless substitutes are found.
 International co-operation.
Carbon Cycle
• Carbon dioxide makes up only a very small part
of the worlds atmosphere.
• Prior to the industrial revolution this tended to
remain fairly constant due to the activities of the
carbon cycle.
• The volume of CO2 released by the processes of
respiration and combustion was absorbed by
green plants during photosynthesis.
• It is thought that any slight imbalances that
occurred were corrected by the absorbing or
releasing it as required, therefore maintaining an
equilibrium
Video-carbon cycle
Scotland 2050
From
Scotland on Sunday, 27 May
1990
By Rob Edwards