Water Pollution

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Chapter 19 Water Pollution
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1. Types Sources of Water Pollution

• diseasecausing agents (i.e. bacteria E. coli)
• oxygen demanding wastes (i.e. organic waste
  manure)
• watersoluble inorganic chemicals (acids, toxic
  metals i.e. lead)
• organic chemicals (oil, pesticides, detergents)
• sediment (erosion, soil)
• watersoluble radioactive isotopes (radon
  uranium)
• thermal pollution (electric nuclear power
  plants)

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OxygenDemanding Wastes

• decomposing wastes deplete dissolved oxygen
• dissolved oxygen (DO) indicatorof water quality

Fish die off
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Biological Oxygen Demand
amount of dissolved oxygen needed by aerobic
decomposers to break down organic materials in a
certain volume over a 5day incubation period at
20C.
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Sources

• Point the source can be tracked down
• point sources (e.g., factories, sewage treatment
  plants, mines, oil wells, oil tankers)
• nonpoint sources (e.g., acid deposition,
  substances picked up in runoff, seepage into
  groundwater)
• nonpoint source water pollution from agriculture
  is largest source of water pollution in the U.S.
  (64 of pollutants into streams 57 of
  pollutants entering lakes)

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Pollution of Streams Lakes

• water pollution laws of 1970s greatly increased
  number quality of wastewater treatment plants
  in U.S.
• also improvements in Canada, Japan, most
  western European countries
• large fish kills contamination of drinking
  water still occur, especially in developing
  countries
• lakes, reservoirs ponds more vulnerable to
  contamination than streams because of less mixing
  aeration.

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Biological Magnification
concentrations increase at increasing levels in
the food chain PCBs (polychlorinated biphenyls)
PCBs causes liver kidney damage, birth
defects, hormonal changes, tumors, etc..
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Cultural Eutrophication
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Case Study Great Lakes

• basin contains 95 of fresh surface water in
  U.S. 20 of world
• severe cultural eutrophication in 1960s (e.g.,
  Lake Erie)
• 20 billion pollutioncontrol program improved
  water quality since 1972

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Groundwater Pollution

• greater threat to humans than much of more
  visible surface water pollution (its the prime
  source of drinking water irrigation)
• much groundwater renewed slowly, such that
  pollution lingers for long time
• crude estimates indicate that up to 25 of usable
  groundwater in the U.S. contaminated
• extremely difficult to clean up contaminated
  groundwater prevention more effective
• main approach pump groundwater to surface,
  purifying water, returning to aquifer costs
  high.

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Prevention

• reduce sources that feed into the aquifer (i.e.
  from septic tanks, landfills, oil leaks etc..
• monitor aquifers near landfills underground
  storage tanks
• require leak detection systems liability
  insurance for existing new underground tanks
  that store hazardous liquids
• ban or more strictly regulate disposal of
  hazardous wastes in deep injection wells
  landfills
• store hazardous liquids aboveground with more
  safeguards.

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5. Ocean Pollution

• coastal areas most impacted especially wetlands
  estuaries, coral reefs, mangrove swamps
  (i.e. runoffs of soil, pesticide, herbicide,
  fertilizer, etc..)
• half of world's population lives within 100 km
  (60 miles) of oceans 14 of 15 largest cities
  coastal
• in U.S. about 35 of municipal sewage discharged
  virtually untreated in marine waters
• dumping of industrial waste directly into ocean
  off U.S. coasts stopped, but many countries still
  dump large quantities of toxic substances.

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Case Study Chesapeake Bay

• largest estuary in U.S.
• severely degraded by water pollution from 6
  states 17 million people
• also deposition of air pollutants

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Oil Spills

• crude refined petroleum accidentally
  deliberately released into environment
• most from normal operation of offshore wells,
  washing tankers, leaks of pipeline storage
  tanks
• tanker offshore drilling rig accidents can
  release large amounts in short time

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Effects of Oil Spills

• volatile organics immediately kill of many
  aquatic organisms (especially plankton larvae)
  contaminate fish
• floating oil coats birds marine mammal
  destroys natural insulation buoyancy, causes
  deaths
• heavy oil sinks to ocean bottom washes into
  estuaries where it contaminates crabs, oysters,
  mussels, clams, etc.
• oil slicks on beaches harm intertidal life
  cause economic losses to tourism fishing
  industries.

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Case Study Exxon Valdez Oil Spill

• March 24, 1989, tanker in Prince William Sound,
  Alaska, worst oil spill in U.S. waters
• coated 1,600 of shoreline, killed wildlife,
  caused serious contamination
• Exxon spent 2.2 billion on direct cleanup 1
  billion fines damages another 5 billion being
  appealed.

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6. Dealing with Water Pollution

• legislation Clean Water Act (1972, amended 1977)
  Water Quality Act (1983) in U.S.
• main goals 1) to make U.S. surface waters safe
  for fishing swimming by 1983 2) to restore
  chemical, physical biological integrity of
  waters
• progress made, but goals not met
• technology septic tanks, sewage treatment
• most effective for point pollution sources.

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Nonpoint Source Pollution

• requires changing farming practices to reduce
  runoff from fertilizer, pesticides, livestock,
  as well as to reduce soil erosion
• nonfarm use of fertilizers pesticides (golf
  course, lawns, public lands) can be similarly
  controlled.

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7. Drinking Water Quality

• much of the world's drinking water contaminated
  poses serious health threats
• most drinking water purified by storage in
  reservoir (suspended matter settles), treated
  by sand filters, activated charcoal, addition
  of chlorine
• U.S. Safe Drinking Water Act of 1974 requires EPA
  to establish national drinking water standards
• many using bottled water home filters bottled
  water is often more contaminated than tap water.

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Chapter 20 Pesticides Pest Control
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Where are we going?
1. Types of pesticides 2. The case for
pesticides 3. The case against pesticides 4.
Other methods of pest control
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Types of Pesticides

• chemicals used to kill undesirable organisms
  pests which compete with us for food resources,
  spreads diseases, destroys wood in homes etc..
• insecticides insect killers
• herbicides plant killers
• fungicides fungus killers
• nematocides roundworm killers
• rodenticides rat mouse killers

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Ideal Pesticide

• kills only target pest
• no short or longterm health effects on
  non-target organisms
• breaks down into harmless chemicals in short time
• remains effective (no genetic resistance)
• saves money (compared to non use)

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Types

• 1st generation mostly natural substances
  obtained from plants
• e.g., pyrethrum rotenone
• 2nd generation synthetic organic chemicals
  developed since 1945
• broad spectrum toxic to many species
• selective toxic to narrow group
• persistent remain in the environment for an
  extended period of time

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Use

• most use is in developed countries
• 90 of insecticides 80 of herbicides applied
  to crops in the U.S. are used for growing cotton
  corn
• U.S. lawns doused with 10x more pesticides per
  hectare than cropland

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2. The Case For Pesticides

• save human lives- kill diseasecarrying insects
• increase food supplies lower costs55 of
  worlds food supply lost to pests
• increase profits for farmers- increases crop
  yields
• work faster better than alternatives
• safer more effective pesticides continually
  developed

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3. The Case Against Pesticides

• evolution of genetic resistance
• risks of manufacture application
• mobility biomagnification
• harm to wildlife

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Genetic Resistance

• many pests breed rapidly can evolve resistance
  within 510 years through natural selection
• since 1950 many pests have evolved genetic
  resistance to one or more pesticides
• at least 520 insects mites,
• 273 weeds,
• 150 plant diseases,
• 10 rodents.

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• Resurgence
• results when pest is initially reduced then
  increases again
• Secondary Pest Outbreak
• occurs when pests that previously were not a
  problem suddenly increase in numbers
• results from killing natural predators
  pathogens (ecological forces no longer in balance)

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Pesticides Wildlife

• less than 2 of insecticides reach targets
• chemicals end up in air, surface water,
  groundwater, food, nontarget organisms
• some pesticides biomagnify in food webs
• some pesticides run off into water bodies,
  harming aquatic animal plant life

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Pesticide Treadmill

• pay more more for less less effective
  pesticides
• use of synthetic pesticides increased 33x since
  1942
• more of U.S. food supply lost to pests today than
  in 1940s
• losses attributed to insects have almost doubled

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Regulation

• Federal Insecticide, Fungicide, Rodenticide Act
  (FIFRA) (1972, amended in 1975, 1978, 1988)
• requires pesticides be approved for general or
  restricted use by EPA
• used to ban more than 40 compounds
• inadequate testing / case-by-case review
• Delaney Clause
• prohibits using any additive in foods that causes
  cancer
• 1992 Supreme Court included pesticides.

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4. Other Methods of Pest Control
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Cultivation Practices

• crop rotation changing the crop type every year
• planting trap crops to lure pest away
• adjusting planting times
• intercropping polyculture
• plantings to attract predators

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Genetic Engineering

• disease pest resistant crop varieties (i.e.
  bacteria DNA in corn to produce toxin which kills
  herbivores)
• could reduce pesticide use
• evolution of resistance to resistance
• resistance factors may be toxic to beneficial
  insects other animals

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Other Methods

• Biopesticides
• plant toxins synthesized for mass production
• microbes toxic to plants
• Biological Control
• control of pest populations by natural
  predators, parasites, or pathogens (bacteria
  viruses)
• pheromones to lure pests into traps
• release of sterile males

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Synthetic Hormones

• used to disrupt pest life cycle
• examples
• juvenile hormones (JH)
• molting hormones (MH)

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Integrated Pest Management

• each crop its pests evaluated as parts of an
  ecological system
• control program developed to include a mix of
  cultivation, biological, chemical control
  methods
• monitor crops for damaging pest levels
• use biological control
• use small amounts of diverse chemicals

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Integrated Pest Management
goal to keep each pest population just below size
that causes economic loss
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