Human Impact

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Human Impact
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Loss of Biodiversity

• Biodiversityvariety of life in an area
• Tropical regions contain two-thirds of all land
  species
• Number of mammals
• Canada163
• US367
• Mexico439
• Importancefood webs and ecosystem balance, 02
  for humans, diverse diets, clothing and building
  materials, medicines

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Endangered Species in GA

• Purple pitcherplantSarracenia purpurea
• Leatherback Sea TurtleDermochelys coriacea

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Endangered Species in GA

• Black right whaleEubalaena glacialis
• Red-cockaded woodpeckerPicoides borealis

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Loss of Biodiversity

• Possible causes
• Habitat loss
• Habitat fragmentation
• Habitat degradation (by pollution)

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Biomagnification

• Biomagnificationtoxins become more concentrated
  in successive trophic levels
• Example is DDT insecticide (Dichloro-diphenyl-tric
  hloroethane)
• Collects in fatty (adipose) tissues of animals

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History of DDT

• Developed and used during WWII-small tins given
  to soldiers to combat lice malaria
• Heavily used in US from 1940s to 1970s, even
  sprayed in public areas to kill mosquitoes
• Banned from US in 1972, but continues to be used
  in other countries

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Rachel Carson

• DDT a serious problemdecline in bird (top of
  food chain) populations (thin egg shells)
• Silent Spring written by Carson helped to bring
  about formation of EPA and banning of DDT
• Bird populations showed dramatic recovery
• Even today, traces of DDT have been found in
  every organism testedeven in human breast milk
  throughout world

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Land Resource Depletion

• What happening?
• Plowing removes the roots that hold the soil in
  place, increasing the rate of soil erosion.
• SOIL EROSION is the wearing away of surface
  soil by water and wind.
• Desertification the process of turning once
  productive areas into deserts from a combination
  of farming, overgrazing, and drought.

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Land Resources

• Why is it a problem?
• Soil is a renewable resource, however it can be
  permanently damaged if mismanaged
• What is being done?
• Contour plowing- fields plowed across the slope
  of the land
• Leaving stems and roots of the previous years
  crops in place to hold soil.

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Land Resource Depletion

• Deforestation loss of forest which leads to
  severe erosion

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Water Resources

• What is happening?
• Pollution such as OIL SPILLS threatens our water
  supply.
• Improperly discarded chemicals can enter streams
  and rivers.
• Domestic sewage entering our water ways can cause
  an increase in bacteria growth.

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Water Resources

• Why is this a problem?
• Fresh water is used daily for everything from
  drinking and washing to watering crops and making
  steel.
• Although water is a renewable resource, the total
  supply of fresh water is limited.
• What is being done?
• Conservation by drip irrigation and consumer
  awareness of conservation

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Water Resources (Oceans)

• Why is this a problem?
• People depend on the ocean as a major source of
  protein, both from finfish and from shellfish.
• With the amount of fish caught each year
  increasing the fish cannot reproduce fast enough
  to keep up

• What is happening?
• Overfishing - fish stocks in many fisheries are
  being harvested faster than they reproduce.

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Water Resources

• What is being done?
• Limiting the catch of fish
• Certain fishing grounds have been temporarily
  closed
• Aquaculture - farming of aquatic organisms

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Air Resources

• What is happening?
• Smog - a mixture of chemicals that occurs as a
  gray-brown haze in the atmosphere
• This is due primarily to automobile exhausts and
  industrial emissions.
• Pollutant - a harmful material that can enter the
  biosphere through air, land, or water
• The burning of fossil fuels can release
  pollutants that cause smog and other problems in
  the atmosphere.

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What is Acid Rain and What Causes It?

• "Acid rain" is a broad term used to describe
  several ways that acids fall out of the
  atmosphere. A more precise term is acid
  deposition, which has two parts wet and dry.
• Wet deposition refers to acidic rain, fog, and
  snow. As this acidic water flows over and through
  the ground, it affects a variety of plants and
  animals.
• Dry deposition refers to acidic gases and
  particles. About half of the acidity in the
  atmosphere falls back to earth through dry
  deposition. The wind blows these acidic particles
  and gases onto buildings, cars, homes, and trees.
  Dry deposited gases and particles can also be
  washed from trees and other surfaces by
  rainstorms.
• Prevailing winds blow the compounds that cause
  both wet and dry acid deposition across state and
  national borders, and sometimes over hundreds of
  miles.
• Scientists discovered, and have confirmed, that
  sulfur dioxide (SO2) and nitrogen oxides (NOx)
  are the primary causes of acid rain.
• In the US, About 2/3 of all SO2 and 1/4 of all
  NOx comes from electric power generation that
  relies on burning fossil fuels like coal.
• Acid rain occurs when these gases react in the
  atmosphere with water, oxygen, and other
  chemicals to form various acidic compounds.
  Sunlight increases the rate of most of these
  reactions. The result is a mild solution of
  sulfuric acid and nitric acid.

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Air Resource Depletion
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Air Resources

• Why is it a problem?
• This leads to toxins that enter the mouth, nose
  and lungs causing health problems over the long
  term.
• Gases released from the burning of fossil fuels
  combine with water vapor to form ACID RAIN
• Acid rain kills plants and changes the chemistry
  of soils
• What is being done?
• Technology to control emissions from factory
  smokestacks
• Strict automobile emission standards and clean
  air regulations

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Global Warming
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Global Warming

• Some warming is goodif not for the ozone, Earth
  would be -18C
• Estimated increase of 2C by end of 21st century
• Even 1.3C affects polar ice cap melting (sea
  level could rise 100 m, gradually going in 150 km
  or more)

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Global Warming
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Global Warming

• Why is this a problem?
• Polar ice caps will continue to melt and could
  rise enough to flood some low lying coastal
  areas.
• Storms and other weather disturbances could
  become more frequent and severe.
• Heat favors rodents, weeds, and insects that
  reproduce and spread quickly.

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Ozone Depletion

• Ozone layer (composed of 03 in lower
  stratosphere)
• Results from CFC (chloroflurocarbon) released
  from aerosol cans, coolants
• In stratosphere, 03 changes to 02, leaving Cl to
  combine with other compounds
• Over Antarcticacold winters promote decline

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Ozone Depletion
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Ozone Depletion
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Ozone Depletion

• Why is this a problem?
• The ozone layer absorbs a great deal of harmful
  UV rays before it reaches the earths surface.
• As the ozone layer is depleted, UV exposure can
  cause sunburns, cancer, eye damage and decreases
  an organisms resistance to disease.