Download Inquiry into Life, Eleventh Edition

Honors Biology
Chapter 36
Environmental Concerns
John Regan
Wendy Vermillion
36-1
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36.1 Human use of resources
• Overview
– Resource- biotic or abiotic factor that helps meet basic needs
• Nonrenewable resource- can’t be replaced by nature, limited in supply
– Amount of land
– Fossil fuels, metals
– Can be recycled
• Renewable resource- can be replaced by nature, not limited, but
must not be wasted
– Water
– Solar energy
– Plants and animals for food
• Sustainable use - use resources at a rate that will not deplete them
– Pollution- alteration of the environment in an undesirable way
– Human impact is proportional to size of population
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Resources
• Fig. 36.1
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Human use of resources cont’d.
• Land
– Worldwide currently >32 persons per square kilometer
1. Beaches and human habitation
• Leads to erosion and loss of habitat for marine organisms
• Erosion
– 70% of world’s beaches are eroding
– Often result of human factors
» Global warming
» Sea wall construction, groin construction
» Filling in of wetlands
– US shorelines lose 40% more sediment than receive
• Coastal pollution
– Toxic substances travel downstream to sea
– oil
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Beach erosion
• Fig. 36.2
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Human use of resources cont’d.
• Land cont’d.
2. Semiarid lands and human habitation
40% of earth’s land is desert
• Desertification- conversion of semiarid land to desert
– Can result from overgrazing by livestock, farming, or removing
plants for fuel
3. Tropical rainforest and human habitation
• Deforestation- causes loss of soil nutrients and fertility
– Danger of desertification
• Loss of biodiversity- tropical rain forest has greatest biodiversity of
any biome
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Desertification
• Fig. 36.3
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Deforestation
• Fig. 36.4
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Human use of resources cont’d.
• Water
– Most water worldwide is used in agriculture and industry and not
for drinking
– Irrigation-intensive agriculture-40% of world’s food crops
– Dams
• 45,000 dams worldwide trap 14% of all precipitation runoff
• Disrupt flow of rivers- many barely reach sea
• Disadvantages to dams
– Evaporation and seepage into ground rock
– Increased concentration of salt from evaporation can make
downstream water unusable
– Silt buildup decreases reservoir size
– Habitat loss
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Freshwater resources
• Fig. 36.5
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Human use of resources cont’d.
• Water cont’d.
– Aquifers
• Hold approximately 1000 times as much water as falls on land as
precipitation each year
• People have begun tapping into aquifers as a source of water when
surface waters become depleted
– Environmental consequences
• Subsidence- settling of soil as it dries out from lack of groundwater
– Creates sinkholes
• Saltwater intrusion- as water table lowers sea water can back up
into streams and rivers
– Reduces supply of freshwater along the coasts
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Human use of resources cont’d.
• Water cont’d.
– Conservation of water
• Planting drought-resistant and salt-tolerant crops
• Drip irrigation
– Saves 50% over traditional methods
– Used on less than 1% of irrigated land
– Governments subsidize irrigation so farmers have little
incentive to use drip irrigation
• Using conservation methods and reusing water could help world’s
industries cut water demands by MORE THAN HALF!
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Human use of resources cont’d.
• Food
– 6 billion people on Earth and only enough food to provide 2,500
calories per person per day
– Food comes from 3 activities- growing crops, raising animals,
and fishing
– Biggest increase in food production has come from modern
farming methods- include some harmful practices
• Planting of few genetic varieties (monoculture)- means all could be
wiped out by same diseases, parasites, etc.
• Heavy use of fertilizers, herbicides, pesticides-runoff-water pollution
can kill off desirable species as well as cause pollution
• Generous irrigation- consumes water
• Excessive fuel consumption- transform fossil fuel energy into food
energy
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Human use of resources cont’d.
• Food cont’d.
– Soil loss and degradation
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Loss of topsoil
Single row crop planting
Eroded soil and chemicals end up in water
Salinization
– Green revolutions
• Tropical wheat and rice varieties that grow well in climates of LDCs
• Dramatic increases in yields- green revolution
• BUT- these crops are “high responders”- need irrigation, fertilizers,
pesticides
– Require same subsidies and create same ecological problems
as modern farming methods
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Conservation methods
• Fig. 36.6
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Human use of resources cont’d.
• Genetic engineering
– Can produce transgenic plants
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Herbicide and drought resistant
Less tillage, less water use, less soil loss
More nutrients
Some are opposed- possible damage to ecosystem?
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Human use of resources cont’d.
• Food cont’d.
– Domestic livestock
• MDCs
– Diet contains more than enough protein
– Livestock account for most of the energy expenditure in
agriculture
» 2/3 of cropland is used to grow feed
» Fossil fuel, fertilizer, water, herbicides, pesticides
» Pollution, energy, and water intensive
– 10 calories of energy in plant tissue 1 calorie of energy for
production of tissue in herbivore
» Can feed 10 times as many people on grain as meat
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Human use of resources cont’d.
• Food cont’d.
– Fisheries
• Increased efficiency of fishing has caused over-fishing of specific
species
• Impacts biodiversity as “undesirable” marine organisms are also
caught in fish nets
– These are disposed of
• World’s shrimp fishery has an annual catch of 1.8 million tons
caught and in the process 9.5 million tons of other animals caught in
the nets were destroyed
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Fisheries
• Fig. 36.7
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Human use of resources cont’d.
• Energy
– Nonrenewable sources
• 6% of world’s energy comes from nuclear power
– People are concerned of possible danger of meltdown
– Disposal of radioactive waste is a problem
• 75% from fossil fuels
– Oil burns cleaner that coal
– All fossil fuels emit pollution into the air when burned
– US uses > ½ fossil fuels
– Fossil fuels and global climate change
– Greenhouse gases- carbon dioxide, methane are examples
» Do not allow infrared heat to escape back to space
» Global warming effect
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Human use of resources cont’d.
• Energy cont’d.
– Renewable energy sources
• 2 types commonly used
– Hydropower - 10% electricity in US
» Small dams as opposed to large dams
– Geothermal power
» From radioactive decay of elements in ground
• Other types may be used more in the future
– Wind-generated – electricity
» Migratory birds
– Solar power
» Passive- south facing windows
» Photovoltaic (solar) cell- electricity
» Advantages- less dependent on foreign oil
- cleaner
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Hydropower
• Fig. 36.8
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Other renewable energy sources
• Fig. 36.9
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Human use of resources cont’d.
• Minerals
– Nonrenewable raw materials
– Fossil fuels, metals, nonmetals
– Being depleted at a rapid rate
– Strip mining
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Leaves land devoid of vegetation and top soil
Toxic wastes washed into streams and rivers
Law now requires reclamation of land
Heavy metals- dangerous to human health
– Lead, arsenic, cadmium, tin, chromium, zinc, copper
– Found in batteries, paints, etc.-careful disposal is critical!
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Modern mining capabilities
• Fig. 36.10
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Human use of resources cont’d.
• Synthetic organic compounds
– Used in making plastics, pesticides, herbicides, cosmetics
Halogenated hydrocarbons- halogens (chlorine, bromine,
fluorine) have replaced hydrogen in chemical structure
• CFCs- chlorofluorocarbons
– Involved in thinning of the ozone shield
– Increases the amount of solar radiation Earth’s surface
receives
– Legislation passed to prevent production of any more CFCs
– Many pesticides
• DDT
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Human use of resources cont’d.
• Wastes
– Early 1970’s- legislation passed to prevent venting wastes into
the air
• As a result, most wastes are buried in landfills
• Top most commonly found contaminants
– Lead, arsenic, cadmium, chromium, trichloroethylene, toluene,
benzene, polychlorinated biphenyls (PCBs), chloroform
– Endocrine-disrupting contaminants
• Interfere with normal hormone function
• Occur at levels 1000 times greater that the concentration in blood
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Human use of resources cont’d.
• Wastes cont’d.
– Sewage
• Raw sewage depletes oxygen levels in lakes and rivers
– Decreases diversity of organisms
– Feces can contain human pathogens- cholera, typhoid fever,
dysentery
• Treatment plants use bacteria to break down raw sewage
– Broken down to inorganic nutrients- nitrates, phosphates
– Released into surface waters
» Can cause eutrophication
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Human use of resources cont’d.
• Wastes cont’d.
– Industrial wastes
• Biological magnification
– Decomposers cannot break them down
– Accumulate in their tissues
– Amplified as you move up the food chain
• Humans are final consumers
– Human milk in some areas contains DDT, PCBs
– Mercury in fish
– Pollution control measures are the best way to address the
problem.
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36.2 Impact on biodiversity
Biodiversity- variety of life on earth, # species
Causes:
1. Habitat loss
– Most frequent cause of extinction
– Has occurred all over biosphere, but concern is focused on
tropical rain forests and coral reefs
• Areas of high biodiversity
• Rainforests reduced from 14% of landmass to 6%
• 60% of coral reefs have been destroyed
– May be completely gone in 40 years!
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Loss of biodiversity
• Fig. 36.11
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Impact on biodiversity cont’d.
2. Alien species
– Nonnative members of an ecosystem
– Introduced by
• Colonization
– Dandelion from England
• Horticulture and agriculture
– Kudzu vine from Japan
• Accidental transport
– Zebra mussels, Dutch elm disease, Asian longhorn beetle,
Asian carp
– Exotics on islands
• Particularly susceptible to environmental disruption by alien species
• Native species are specially adapted to each other and cannot
compete
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Alien species
• Fig. 36.12
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Impact on biodiversity cont’d.
• Pollution
– Acid deposition
• Weakens trees and makes them susceptible to disease, insects
• Kills organisms in lakes
– Eutrophication
• Over-enrichment of lakes by inorganic nutrients
• Agricultural runoff, wastes
• Algae blooms, decomposers break them down
– Oxygen depleted and fish die
– Global warming
• From greenhouse gases
• Destruction of wetlands as seas rise, shift in temperature so that
species cannot survive, die off of coral reefs
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Global warming and coral reefs
• Fig. 36.13
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Impact on biodiversity cont’d.
• Pollution cont’d.
– Ozone depletion
• Release of CFCs causes ozone shield to break down
– Impairment of crop and tree growth, death of plankton
– Organic chemicals
• Many are endocrine-disrupting contaminants
• Affect the endocrine system and reproductive potential
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Impact on biodiversity cont’d.
• Overexploitation
– Occurs when number of individuals taken from wild population is
so great that population numbers become severely depleted
– Positive feedback- the more depleted a population, the more
valuable its members become which is an incentive to capture
the few remaining organisms
– Increased efficiency of fishing has caused depletion
– Mammalian species hunted for hides, horns, tusks, bones
• Disease
– Wildlife exposed to new diseases and domestic species due to
human encroachment
– Zoo animals are exposed to other exotic species they would not
ever be near in the wild- another source of new disease
exposure
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Wildlife is at risk due to disease
• Fig. 36.15
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36.3 Value of biodiversity
• Direct value-various wildlife species perform services for
human beings
– Medicinal value
• Rosy periwinkle – treat cancer
• Predict another 328 drugs yet to be found in tropical rain forest
– Agricultural value
• Crops derived from wild plants
– Biological pest control
– Pollinators - bees
– Consumptive use value
• Fish, shellfish
• Wild fruits and vegetables, skins, fibers, seaweed, meat
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Direct value of wildlife
• Fig. 36.16
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Value of biodiversity cont’d.
• Indirect value- more economical to save ecosystem in
which species lives rather than the individual species
– Ecosystems perform many services for humans
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Biogeochemical cycles - efficient recycling
Waste disposal - purify water
Provision of fresh water - hold water, prevent flooding
Prevention of soil erosion
Regulation of climate - shade, take in CO2
Ecotourism
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36.4 Working toward a sustainable society
• Today’s society is not sustainable because
– Considerable portion of land, and therefore ecosystems, is used
for human purposes
– Agriculture requires input of large amounts of nonrenewable
resources
– At least half of the agricultural yield in the U.S. goes toward
feeding animals
• Takes 10 pounds of grain to make 1 pound of meat
– We are running out of available fresh water
• Using it faster that it can be renewed
– Our society uses primarily nonrenewable fossil fuels for energy
• Global warming, acid precipitation, smog
– Minerals are nonrenewable, and use of products causes much
pollution
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Human society at present
• Fig. 36.17
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Working toward a sustainable society cont’d.
• Characteristics of a sustainable society
– Natural ecosystem can offer clues
• Uses only solar energy
• Materials cycle through various populations back to producers
– We need to use renewable energy sources and recycle materials
– Growing populations of the LDCs as well as the over
consumption by the MDCs put a strain on the environment
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Working toward a sustainable society cont’d.
• Assessing economic well-being and quality of life
– Currently gross national product (GNP) is used to measure flow
of money from consumers to businesses
• Takes into account only economics and not any potentially harmful
side effects
• Also does not take into account damage to the environment
• Need new index which takes nonmonetary values into account
– Measuring nonmonetary values
• Better at revealing quality of life than GNP
• Index of Sustainable Welfare (ISW) includes
– Real per capita income
– Distributional equity
– Natural resource depletion
– Value of unpaid labor
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Working toward a sustainable society cont’d.
• Assessing economic well-being and quality of life cont’d.
– Genuine Progress Indicator (GPI)- another quality of life index
– Both the ISW and the GPI suggest that the quality of life has
gone down, even though the GNP has gone up
– Ecological economists are still trying to devise a way to measure
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Use value-actual price we pay to use goods
Option value- preserving options for the future
Existence value- saving things we may not realize exist yet
Aesthetic value- appreciating an area for its beauty or contribution
to biodiversity
• Cultural value-language, mythology, history important for cultural
identity
• Scientific and educational value- valuing knowledge of naturalists
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Sustainable society
• Fig. 36.18
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