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Water Pollution

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Title: Water Pollution


1
Chapter 19 Water Pollution
2
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)

3
OxygenDemanding Wastes
  • decomposing wastes deplete dissolved oxygen
  • dissolved oxygen (DO) indicatorof water quality

Fish die off
4
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.
5
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)

6
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.

7
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..
8
Cultural Eutrophication
9
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

10
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.

11
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.

12
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.

13
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

14
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

15
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.

16
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.

17
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.

18
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.

19
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.

20
Chapter 20 Pesticides Pest Control
21
Where are we going?
1. Types of pesticides 2. The case for
pesticides 3. The case against pesticides 4.
Other methods of pest control
22
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

23
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)

24
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

25
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

26
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

27
3. The Case Against Pesticides
  • evolution of genetic resistance
  • risks of manufacture application
  • mobility biomagnification
  • harm to wildlife

28
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.

29
  • 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)


30
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

31
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

32
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.


33
4. Other Methods of Pest Control
34
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

35
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

36
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

37
Synthetic Hormones
  • used to disrupt pest life cycle
  • examples
  • juvenile hormones (JH)
  • molting hormones (MH)

38
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

39
Integrated Pest Management
goal to keep each pest population just below size
that causes economic loss
40
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