Humans Impact Environment
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Transcript of Humans Impact Environment
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Humans and The Environment
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HumanActivities
that have changed the biosphere include
may have once caused often relies on the methods of thehave resulted in
which increased
Food supply Pesticide use Monocultureuse
Hunting andgathering
AgricultureIndustrial
growthUrban
development
Extinctions oflarge animals
Greenrevolution
High standardof living
Increasedpollution
Section 6-1
Concept Map
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Leaving a Mark on the World
Have you ever seen very old photographs of
the town or city in which you now live? Has
your area changed? Perhaps there are morebuildings or roads than there were many
years ago. Maybe your town or city has more
trees and flowers now than it had years ago.
Humans, like all organisms, have an effect ontheir environment.
Section 6-1
Interest Grabber
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Earth is a kind of island
Limited resources
Nature must sustain the resources Human populations is growing
The planet is not
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Demands on
Air
Water
Land
Living things
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We must protect these resources
What human activities do you think have an
impact on the earths natural resources?
Hunting and gathering
Agriculture
Industry
Urban development
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Recent study concluded that human activity uses
as much energy as all of earths other
multicellular species combined
Humans are the most influential in changing the
environments of the planet
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Early man
Built dams
burned grasslands to encourage growth of certain
plants
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Agriculture
Early humans learned how plants grew, which
were edible, and which were good medicines
They began to plant those that were important
near their settlements
11,000 years ago, humans started farming
(Agriculture)
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Agriculture
Agriculture spread
With dependable food supply, people started
living in larger settlementstowns and cities
Domestication of Animals
Over time, people started keeping herds of
domesticated animals
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Agriculture
Milk, meat, hides, wool, companionship, perform
work
Overgrazing changed grasslands ecosystems
eroded soils, large demand on water
Human population grew at an increasing rate.
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Green Revolution
By 1950s food supply was straining
Green Revolutionto increase food supply,
governments and scientists introduced new
farming techniques to increase yields of crops
(rice, wheat, corn)
Relied on new, highly productive strains of crops
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Green Revolution
Monoculturelarge fields plowed, and planted
with a single crop year after year
Irrigation, fertilization, and pesticides were relied
on to sustain the crops
Animal and human power was replaced with
machine power
Within 20 years, Mexican farmers increasedproduction of wheat 10 times
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Green Revolution
Problems have been introduced by the green
revolution. Can you name a few?
Depletion of water supplies
Pollution of water by pesticides and fertilizers
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Industrial growth and Urban
Development
Wastes from manufacturing and energy
production have been poured into the air, water,
and soil
Tied to high standard of living that we all enjoy
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The question is: How do we control the harmful
effects of human activity on the environment?
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Tragedy of the Commons
Resource is something that can be used to take
care of a need
When an environmental resource is owned by
many people, or no one, but no one isresponsible for it, it is called a common
resource.
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Tragedy of the Commons
The Tragedy of the Commonsany resource
open to everyone will eventually be destroyed
because although everyone owns the resource,
no one is responsible for it. Air, Watershared by many countries, but no
one is responsible.
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Whalingif some countries attempt to protect
whales, but others continue to hunt whales to
extinction, what will eventually happen?
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2 types of resources Renewable and Nonrenewable
Renewable resources can be regenerated (but
not necessarily limitless)
Sunlight
Fresh water
A tree
Fish
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2 types of resources Renewable and Nonrenewable
Nonrenewablecannot be replenished by
natural resources
Fossil fuels
Coal
Oil
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1. Examine the list of natural resources shown below. Then,
classify each natural resource as either renewable or
nonrenewable.
a. Wood
b. Fossil fuels
c. Aluminum
d. Wool
e. Gold
2. Describe the impact that the loss of nonrenewable
resources would have on the environment.
Section 6-2
Interest Grabber continued
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Where Do NaturalResources Come From?
Natural resources are materials that are supplied
by nature. A renewable resource is one that isreplaceable. A nonrenewable resource is one that
cannot be replenished by natural processes.
Once a nonrenewable resource is used up, it is
gone forever.
Section 6-2
Interest Grabber
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Land Resources
Land is a resource
Provides space for living, raw materials for
building, and industry
Important for soils crops grow on
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Land Resources
Soil is a renewable resource that can be
damaged by human activities
Best fertile soil is a mixture of humus, sand, clay,
and rock particles
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Most of the humus is in the top layers called
Topsoil
Absorbs and retains moisture, but allows drainage
Lots of nutrients
Low in salts
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Different plants add and use different amounts ofnutrients
Plowing the land removes the roots that prevent
erosion Erosionthe wearing away of the surface soil by
water and wind
Combinations of farming, overgrazing, and
drought can cause productive areas to becomedeserts
Process is desertification
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Practices that can maintain the soil include
Contour plowing
Planting crops that maintain the soil while primary
crops are harvestedrye for example Leaving roots and stems of previous years crops
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Cover Crops
Legumes, grasses, and other
cover crops recycle soil nutrients,reduce fertilizer need, and
prevent weed growth.
Controlled Grazing
By managing graze periods and herd
densities, farmers can improve nutrientcycling, increase the effectiveness of
precipitation, and increase the carrying
capacity of pastures.
Biological Pest Control
The use of predators and parasites
to control destructive insectsminimizes pesticide use as well as
crop damage
Contour Plowing
Contour plowing reduces
soil erosion from land runoff.
On hilly areas, plowing is doneacross the hill rather than
straight up and down.
Crop Rotation
Different crops use and
replenish different nutrients.
By rotating crops, the lossof important plant nutrients
is decreased.
A B C
Yr. 1
Yr. 2
Yr. 3
Section 6-4
Sustainable Agriculture
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corn
corn
corn
alfalfa
alfalfa
alfalfa
oats
oats
alfalfa(plowed in)
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Forest Resources
Forests provide
Wood
Paper
Fuel
Remove CO2 and add O2
Food
Sore nutrients
Moderate climate
Limit soil erosion
Protect fresh water supplies
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Forest Resources
DeforestationLoss of forests
Soil erosiontopsoil and nutrients washed away
Grazing and plowing after deforestation can add
to problems
Sustainable use strategies
Harvesting mature trees selectively
Plant, manage, harvest, and replant tree farms
Geneticists breeding faster growing varieties
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Ocean Resources
Food
Fish catch has risen from 20 million tons/year to
over 90 million tons / year
As fish catches rose, fish stocks declined
Overfishing
Techniques to moderate include
Limits
Aquaculture
Temporary closing of areas to fishing
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World Fish Catch World Fish Catch per Person
TotalCatch
(milliontons
)
AmountofFishpe
rPerson
(kilograms
)
Year Year
Section 6-2
Growth of Fish Catch
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Air Resources
Air is a resourcewe breath it
Smogsmoke and fog
Auto and industrial exhaust include Nitrogen oxides andsulfur dioxides that are transformed into nitric and sulfuricacids
Cause acid rain
Pollutanta harmful material that can enter the biospherethrough land, air, or water
Acid rain can kill plants, and cause soil chemistry tochange
May release Hg, or other dissolved toxic elements
Figure 6 12 The Formation of
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Emissions to Atmosphere
Nitrogen oxides
Sulfur dioxide
Chemical Transformation
Nitric acid
Sulfuric acid
Precipitation
Acid rain, fog,
snow, and mist
Dry Fallout
Condensation
particulates, gases
Industry Transportation Ore smelting Power generation
Section 6-2
Figure 6-12 The Formation ofAcid Rain
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Water Resources
Water is a resource
Drinking, washing, watering crops, industry
71% of the earth is covered by water
97% of the water is sea water (salty)
2% more is frozen
1% of all water is liquid fresh water
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Pollution
Wastes discarded (on purpose or not) can
Seep into water supplies
Sewage
Contains nitrogen and phosphorus
Cause algal and bacterial growth
Spread disease
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Pollution
Wetlands such as swamps and estuaries can
help to protect water supplies
Purifies water as it passes through
Holds soil in place
What Is
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What Is
Biodiversity?
Biodiversity is the sum total of the variety of
organisms in the biosphere. Sometimes humanscan reduce biodiversity, which is considered a
natural resource.
Interest Grabber
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Biodiversity
1.5 million species identified so far
Food
medicinepainkillers, heart drugs, antibiotics
industrial products
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Insects
BacteriaFungi
Plants
Protists Other Animals
54.4%
4.2%
18%
3.4%0.3%
19.7%
Section 6-3
Species Diversity
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Biodiversity
Human activity can reduce biodiversity
May cause extinction
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Figure 6-16 Biological
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Fish-Eating BirdsMagnification of
DDT Concentration
10,000,000
100,000
10,000
1,000,000
1
1000
LargeFish
Small Fish
Zooplankton
Producers
Water
Section 6-3
Figure 6 16 BiologicalMagnification of DDT
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Biological magnification
Concentrates as herbivores eat plants sprayed
with DDT, then carnivores eat the herbivores
etc
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Introduced species
Organisms transferred from one area to another
that did not have them before
Zebra Mussel, Phragmites, Japanese shore crab
I t t G bb ti d
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1. Choose an animal other than a humanand describe at least two ways in which it
may change its environment.
2. What events might have led to the
changes that occurred in your town or city?
3. What positive effect have humans had
on their environment? What negative effect
have humans had on their environment?
Section 6-1
Interest Grabber continued
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1. List three ways in which other organisms have
proved to be a benefit to humans.
2. Compare biodiversity with other naturalresources, such as wood and fossil fuels. Do you
think biodiversity is a renewable or a
nonrenewable resource? Explain your answer.
3. What can be done to preserve the biodiversityof organisms?
Section 6-3
Interest Grabber continued
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I t t G bb
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How Much Should
It Cost?
You may have read that when something
becomes hard to obtain, its price usually
increases. Such is the case for materials like goldand diamonds, which are nonrenewable
resources. Using similar thinking, some
researchers believe that all the valuable services
provided by a healthy ecosystem should be
assigned a dollar value.
Interest Grabber
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I t t G bb ti d
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Rank the following items in order of their
importance to you. Then, next to each item, write
down how much you would be willing to pay for it. 1. Fresh, clean drinking water
2. Clean air to breathe
3. An endangered plant containing a substance
that can cure cancer
4. Gas for your family car
Section 6-4
Interest Grabber continued
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Solar energy
Production of oxygen
Storage and recycling ofnutrients
Regulation of climate
Purification of water and airStorage and distribution offresh water
Food production
Nursery habits for wildlife
Detoxification of human and
industrial wasteNatural pest and diseasecontrol
Management of soil erosionand runoff
Section 6-4 Figure 6-22 Ecosystem Services
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