Transcript Research: Human impact on the environment

Human Impact on the Environment:
Current Crises for Human Survival:
Problems to be Solved Within the Next Generation
Practical observation of ONE example of human influence on the
environment in the local area (e.g. the impact of alien species on
biodiversity). Written report on the chosen example.
Look at the interrelatedness and interdependence of the human
impacts and the environment.
Research: Human impact on the environment
Food security
Deforestation
Loss of
Biodiversity
Discuss what
you
understand
these terms
to mean
Climate change
Desertification
The atmosphere and climate change
• carbon dioxide emissions;
• - concept of ‘carbon footprint’ and the need to
reduce the carbon footprint;
• - deforestation;
• - greenhouse effect and global warming:
– desertification, drought and floods;
• - methane emissions;
• - ozone depletion.
http://www.vanderbilt.edu/sustainvu/2009/03/so-what-isa-carbon-footprint-and-why-is-vanderbilt-calculating-one/
• Burning fossil fuels for electricity
• For transportation
South Africa is 13th in the world and 1st in Africa for CO2
emissions.
Carbon footprint: the amount
of carbon dioxide or other
carbon compounds emitted
into the atmosphere by the
activities of an individual,
company, country.
Brainstorm what
you can do to
reduce your carbon
footprint
Main greenhouse gases:
Carbon dioxide
Water vapour
Methane
Enhanced greenhouse effect (leads
to global warming)
http://www.epa.gov/climatechange/kids/basic
s/index.html
SOURCES:
o Anaerobic respiration in the intestines of herbivores
o Decomposition of organic waste
o Treatment of waste water (sewerage)
o Agricultural activities (e.g. rice paddies)
o Mining
o Making and using of fossil fuels and biofuels.
Forests take out CO2 from the air. But we are cutting
down forests for fuel, wood, paper, grazing space,
roads, mining and agriculture. This results in less CO2
being removed from the atmosphere
We have to stop cutting down trees!*
*This is getting really serious!*
•
Desertification
the
productive potential of arid and
semi-arid lands falls and topsoil is
lost or degraded.
– Desertification results mainly
from a combination of natural
climate changes causing
prolonged drought and
unsustainable human activities,
including overgrazing and
deforestation.
– Desertification may lead to the
formation of a desert or the
encroachment of an existing
desert onto formerly arable
land.
Overgrazing on marginal lands (top) can
extend desert zones (lower)
Effects of Climate Change
FLOODING
Effects of Climate Change
DROUGHT
Effects of Climate Change
http://www.epa.gov/climatechange/kids/
Research what
individuals, schools,
communities and
businesses can do to
reduce climate change
EFFECTS OF CLIMATE CHANGE
The ozone layer protects Earth from harmful UV radiation. However, it is getting
thinner due to CFC’s.
CFC’s are released by refrigerators and aerosol cans.
EFFECTS:
•Causes some trees to die → more greenhouse effect
•Increased skin cancer
•Can affect human immune systems.
HOW TO REDUCE CLIMATE
CHANGE PG 339
Most household cleaning
can be done with a half-andhalf mixture of vinegar and
water, or liquid soap
and baking soda.
If it has a
thermostat it
uses a large
amount of
electricity.
How can your
family/school
reduce its
electricity
consumption?
Water:Availability:
1.
2.
3.
4.
5.
6.
7.
8.
Construction of dams
- Destruction of wetlands
- Poor farming practices
- Droughts and floods
- Exotic plantations and depletion of water table
- Boreholes and effects on aquifers
- Wastage
- Cost of water
1. CONSTRUCTION OF DAMS
Functions of dams:
Stores water for human needs (residential,
industrial and agricultural).
Controls flood waters
Can be used to generate hydro-power
• NEGATIVES
• Affects flow downstream, impacting on
humans and the natural communities.
2. DESTRUCTION OF WETLANDS
What is a wetland?
• Wetlands are areas
where terrestrial and
aquatic ecosystems come
together.
• In a wetland, the water
table is at or near the
surface of the ground.
The land is either
temporarily or
permanently covered
with shallow water.
http://wetlands.sanbi.org/
• Wetlands are a source of water
• Wetlands purify water .
DESTRUCTION OF WETLANDS
Destroyed by:
• Draining the water
• Filling with soil
• Removing plants
(urbanisation)
3. POOR FARMING PRACTICES
• Water is needed for irrigation.
• Much water however is lost through poor
practices. E.g. Open ditch irrigation and
ploughing along the slope.
4. DROUGHTS AND FLOODS
Due to climate change, some areas will become
drier and others wetter.
Floods and Droughts
5. Exotic plantations and the
depletion of the water table.
• Exotic plantations can be beneficial financially.
• Exotic plants have deeper roots and use more
water than indigenous plants and thus
deplete the water table
Exotic plantations
6. Boreholes and effects on
aquifers
• Aquifer – permeable rock,
saturated with water.
• Boreholes remove water
from aquifers and only
precipitation and rivers can
“recharge” these systems
7. Wastage
• Poor practices
• Leaks
8. Cost
• 6 kilolitres given free per
household.
ACT 3.6.9 pg 354 (exclude no2 )
Water: Quality
• - Water for domestic use, industry, agriculture
and mining: pollution, diseases,
eutrophication and algal bloom.
• - The effect of mining on quality of water
• - Thermal pollution The need for water
purification and recycling
• - Alien plants, e.g., Eichornia
Uses of water
DOMESTIC: washing, cooking, cleaning,
gardening, etc)
INDUSTRIAL USES: parts of ingredients, to cool
down machinery.
AGRICULTURAL: Drinking water for livestock and
watering (irrigation)
After being used water is polluted.
WATER POLLUTION
Domestic pollutants: detergents and pathogenic
bacteria from sewage.
Industrial pollutants: heavy metals, paints
solvents, oil, heat
Agricultural pollutants: pesticides, herbicides
and fertilisers.
EUTROPHICATION
• Excess fertilisers → water system → nutrients
(N and P) → rapid growth of algae (algal
blooms) →Block sunlight → plants die →
decomposition → oxygen is used up →
animals die.
EFFECT OF MINING
• Releases acidic water with a high temperature
(thermal pollution) which contains heavy
metals (poisonous).
THERMAL POLLUTION
• Increased temperature of water.
• Some benefit, but others negatively affected,
because warm water has less O2. Warm waters
more likely to get algal blooms.
EFFECT OF ALIEN PLANTS
• Some alien species grow out of control
(invasive). No natural predators/parasites →
outcompete indigenous species.
Water hyacinth (Eichhornia
crassipes)can form a continuous
layer blocking light. The impact is
similar to that of algal blooms.
They also prevent recreational
activities.
It cost millions of rands to clear
them from the water.