tenth lecture human effects on ecological balance example 1 hawks are natural enemies for mice, rats...
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Tenth lecture
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Human effects on ecological balance
• Example 1
• Hawks are natural enemies for mice, rats & rabbits.
• If they were eliminated; mice, rats & rabbits would increase in number and ruin the crops.
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• Example 2
Pumas, wolves &coyotes prey on deer.• One year, a drive killed these enemies.• Deer multiplied in numbers.• They didn’t have enough food.• Many of them died from starvation.• The others chewed the bark of the trees;
the trees died; the small mammals and birds lost shelter and food.
Human effects on ecological balanceHuman effects on ecological balance
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Human effects on ecological balance
• Example 3
• Mongoose was introduced to Jamaica to control rats.
• Mongoose also killed birds, snakes & lizards.
• The cane beetles multiplied & do much damage as rats.
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Human effects on ecological balance
• Example 4• In 1862, a few pairs of rabbits were
introduced to Australia. • Within a few decades; there were millions
of rabbits.• They destroyed grassland and crops.• In 1950; A deadly virus, myxomatosis, was
introduced to control rabbits.
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Human effects on ecological balance
• Example 5
• In 1916, Japanese beetle, spread rapidly in New Jersey and soon were responsible for loss of millions of dollars’ worth of fruit, crops, lawns and flowers.
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Air pollution
• Is the contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health
• Air pollution only occurs outdoors
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Sources of Outside Air Pollution
• Combustion of gasoline and other hydrocarbon fuels in
cars, trucks, and airplanes• Burning of fossil fuels (oil, coal,
and dinosaur bones)• Insecticides• Herbicides• Everyday radioactive fallouts• Dust from fertilizers• Mining operations• Livestock feedlots
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Sources of Indoor pollution
• Efficient insulation• Bacteria• Molds and mildews• Viruses• animal dander and cat saliva• plants• house dust• Mites• Cockroaches• pollen
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Effects on the environment
• Acid rain• Ozone depletion• Global warming• In human population- respiratory problems,
allergies, strengthens lugs, and a risk for cancer
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What’s in smog?
• particulates (especially lead)
• nitrous oxides
• potassium
• Carbon monoxide
• Other toxic chemicals
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Acid rain
• contains high levels of sulfuric or nitric acids
• contaminate drinking water
and vegetation
• damage aquatic life
• erode buildings
• Alters the chemical equilibrium of some soils
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CO2
Reflected Light
Re-radiated Heat
CO2
HEAT!
HEAT!Trapped Heat
Cloud, Dust
Greenhouse effect 13