ecology 2 ppt - manhasset secondary school€¦ · a pesticide alternative is the use of biological...
TRANSCRIPT
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Human Impact on the EnvironmentMajor Impacts:• Groundwater contamination and depletion• Elimination of habitats• Loss of Biodiversity: the variety of living things on Earth
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With the development of new technologies, humans often fail to consider the possible ecological effects.
• Water Pollution• Heat, litter, sewage, phosphates, and heavy metals
(e.g. mercury)
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• Water Eutrophication: Sewage and manure runoff increases nutrient levels in lakes leading to excessive growth of algae and other plants.
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• Air Pollution• Carbon monoxide, hydrocarbons, and other particulate
matter (from the burning of coal, oil, and gasoline).• Nitrogen and sulfur pollutants from the burning of coal
and petroleum can combine with water in the atmosphere to become Acid Rain (pH < 5.6)
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• Overhunting: Has lead to the extinction of many species. Endangers many species today.
• Exploitation of animals: Elephants and Walruses are hunted for their ivory.
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• Poor Land Usage: • Overcropping: Failure to allow soil to recover its
nutrients between plantings. • Overgrazing: Allowing too many animals to graze on
a small area, hurting the soil• Lack of Cover Crops: which protect soil from being
eroded away.
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• Toxins• Toxins used in industry have entered into our food chain
• Antibiotics and hormones in chicken and beef• Carcinogens and teratogens (causing birth defects) can accumulate in food chains.
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• Pesticides: chemicals that kill “pests”
• Pesticides save lives by increasing food production and killing pathogens.
• Exposure to pesticides can cause cancer in humans• Pesticides use can lead to the evolution of resistant pathogens through natural selection.
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A pesticide alternative is the use of Biological Controls:
• Crop Rotation: alternate the crops that are planted
• Introduce Pest Predators: can cause ecological problems if the predator becomes an invasive species
• Use Natural Plant Toxins
• Sterilize the Pests
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• Invasive Species• The transport of species from one area to another area can
have serious consequences• Invaded communities have not evolved defenses against the
invaders.• Invader population will grow unchecked, eat too much,
and outcompete native species.
Examples:• Zebra Musselshttps://www.youtube.com/watch?v=abImqGDzXBo
• “Killer” Honey Beeshttps://www.youtube.com/watch?v=d‐7kKqgPEGs
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• Global Warming: the increase in the average temperature on Earth.• The burning of fossil fuels has increased the atmospheric
concentration Carbon Dioxide.
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• Carbon Dioxide and Water Vapor are Greenhouse Gases• Greenhouse Gases in the atmosphere contribute to the
Greenhouse Effect: Infrared Radiation reflected from the Earth’s surface is trapped by greenhouse gases.
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• A global increase in temperature of 1 degree Celsius would cause the polar ice caps to melt, raising sea levels.
http://cegis.usgs.gov/video/30m/NewYorkSLR.swf
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• Depleting the Ozone Layer• Chlorofluorocarbons (CFCs) are chemicals used for
refrigeration and in aerosol cans.• They have eaten away at the protective ozone (O3) layer of
Earth’s atmosphere, allowing UV radiation to reach Earth.
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Positive Human Impacts:• Population Control• Conservation of Resources
• Environmental Law• Species Preservation• Pollution Control