www.duke.edu/~eac23/NonHTMLDocs/EcologyWaterAir.ppt
Human Activities and the Earth’s
Valuable Water and Air Resources
Objectives:
Ozone Depletion
Global Warming and Global Climate Change
Acid Rain
Biological Magnification
Human Impacts on Water, Air, Fisheries
What we can do
Ozone Depletion
•Ozone layer (20-50km up) protects
the Earth from UV radiation
•Gases (CFCs) used in aerosols break
down ozone causing the “holes” over the
Arctic and Antarctica
•Montreal Protocol stopped production
of CFC’s on January 1, 1996
•Holes are not growing but will not recover until
. . . . . . . 2065!
Excess UV radiation:
•Skin cancer
•Cataracts
•Immune System Problems
•Other unknown effects on plant/animal life
Global Warming
• Caused by gases (mostly CO2) that trap heat
•Burning of fossil fuels, cutting/burning of forests
releases CO2 faster than Carbon cycle can
remove it
•Temperatures have risen 0.6oC. since industrial
age
•Since 1980, average temp risen 0.3OC.
Global Warming
Global Climate Change
 Melting of permafrost, increasing release of
greenhouse gases
Melting of poles
Rising sea level
Flooding, Drought
Loss of habitat, species extinction
Loss of coral reef ecosystems (fisheries, tourist
revenue, natural storm barriers)
 All the above have economic impacts
Acid Rain
Burning of fossil fuels release nitrogen and sulfur
gases
Combined with H2O vapor = nitric and sulfuric acids
Fall as acid rain
Plants damaged
Soil chemistry altered, potentially hazardous
compounds released and flow into water system
BIOMAGNIFICATION
(mercury)
Eastern U.S:
average pH of 3.6,
with some values
as low as pH 2.6
Los Angeles:
pH of fog has
been measured
at 2.0
Biomagnification
Pesticides and heavy
metals work their way
into rivers or lakes and
move up the food chain
becoming more
concentrated at each level
“Silent Spring” by Rachel
Carson
FOR EXAMPLE:
If in one day a small fish eats 1,000 plankton and a larger fish
eats 1,000 small fish, the human who catches the larger fish
is ingesting all the toxins that were in a 1,000,000 plankton!
(1,000 x 1,000 = 1,000,000)
Add that up over a lifetime and you’re in trouble!
Clean Water
•
Renewable but not unlimited!
 same water is recycled (the water cycle!)
BUT if contaminated during that cycle, may not be
reusable
Two issues: Pollution and loss of water filtration!
Some water pollutant sources:
 Sewage
 Runoff: agricultural fertilizers, factory farms
 Factory outfall
Some Effects of Water Pollution
•Contaminated drinking water
• Contaminated food animals (biological magnification
of toxins from the environment over their life spans)
•Unbalanced river and lake ecosystems that can no
longer support full biological diversity
• Deforestation from acid rain
•Loss of natural beauty
For water use to be sustainable we need to protect the natural
systems of the water cycle.
Preserve wetland areas = water filtration
Think before you pave it = less filtration
Think before you cut it = less transpiration
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Fisheries
Overfishing - harvesting fish
faster than they reproduce
An example of “tragedy of the
commons”
•Everyone uses the resource but no one
maintains it
• If properly managed, can be a renewable
resource
Air
Air Quality Issues (caused by burning of
fossil fuels):
•Smog
•Particulates - microscopic particles of ash and dust
•Acid Rain
Their Effects:
Human health
Deforestation
Things we can do
Don’t litter
Turn off lights, all electronic equipment
Recycle - don’t fill up our landfills
Conservative or little use of fertilizers
Walk or bike when possible
Drive more fuel efficient vehicles
Support wetlands preservation
Develop sustainable energy sources: Wind, solar, fuel cells
Think before you pave it
Use sustainable building practices - green space and gravel,
porous paving
Design pedestrian friendly cities