GEOG 3000 Resource Management Water Resources and Pollution

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GEOG 3000 Resource ManagementWater Resources
and Pollution

• M.D. Lee CSU Hayward Winter 2004

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Water Resources and Pollution

• Pure water is made up of molecules of hydrogen
  (2) and oxygen (1).
• Because it is a superior solvent, it contains
  many other chemicals dissolved in it, both from
  natural sources (contaminants) and human sources
  (pollutants).
• Water resources can be degraded through pollution
  to the point that they fail to meet our needs
  and/or require the expenditure of other resources
  to clean them enough to use.
• Different types of pollutants come from different
  pollution sources, adding to background
  contamination.
• We distinguish between point pollution and
  non-point pollution sources.
• Point are well-defined and often controllable
  with "end-of-pipe" technologies.
• Non-point are more dispersed, from multiple
  pathways, and generally require broader
  solutions.

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Point and Non-Point Pollution
(Source Wright Nebel, 2002)
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Pollution Control

• Many point pollution control devices (waste
  treatment facilities) do not eliminate pollution,
  but merely divert, disperse, dilute or diminish
  the effects of the pollutant with reference to
  the receiving water body.
• The absence of pollution (input) control to water
  bodies is generally counter-balanced by the
  requirement for water treatment (output control)
  prior to particular water uses.
• Pollutant concentrations and/or toxicities are
  lessened by natural dispersion, dilution and
  assimilative processes like oxidation, reduction,
  etc.
• However, natural systems have their limits and
  thresholds can be passed (e.g. dissolved oxygen
  drops leading to death of aquatic organisms).
• There are limits to the old adage that the
  solution to pollution is dilution.

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Pollutant Types

• Your textbook, CRO, discusses the major
  pollutant types as sediment, inorganic nutrients,
  thermal (heat), disease-producing organisms,
  toxic organic compounds, heavy metals, and
  oxygen-demanding wastes.
• While this provides thoughtful and interesting
  discussions, this classification includes
  overlaps and is not used by most water
  professionals who divide water pollutants into
  the classes of physical, chemical and biological.
• CROs classification fails to distinguish
  between pollution sources and the individual
  pollutants, many of which are present in more
  than one of these categories.

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Standard Pollutant Classes

• Water professionals separately categorize
• Physical pollutant variables - solids,
  organoleptic aspects (color, taste, etc.),
  turbidity, electrical conductivity, temperature,
  radioactivity.
• Chemical pollutant variables (ever increasing
  number) - synthetic organic chemicals, volatile
  organic chemicals, inorganic chemicals (esp.
  nutrients).
• Biological pollutant variables (living pathogens)
  bacteria, viruses and parasites - protozoa like
  cryptosporidium, giardia, amoeba, etc.
• Some of the physical variables are influenced by
  the chemical and biological status of the water
  e.g. turbidity, electrical conductivity.
•  

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Resource impacts of pollution

• Pollutants will have different impacts depending
  on their character and properties and the
  purposes to which the water resource is to be
  used.
• The most exacting water quality requirements are
  for drinking, although some specialized
  industrial uses require higher standards, e.g.
  microchip manufacture.
• Many synthetic and volatile organics are not
  easily removed from water with standard treatment
  processes and may prevent the water from ever
  economically being used (e.g. MTBE contamination
  of wells in Santa Monica - they were closed).
• Many high quality water sources are exploited for
  uses that could utilize much lower quality water
  e.g. do we need to flush toilets with drinking
  water?

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Nature of impacts

• Depending on travel, residence, mixing
  rates/times for water sources and the time
  character of pollution (continuous, spill, etc.),
  impacts of pollution on water bodies may be
  long-term or short-term.
• For many surface sources, removing the source of
  pollution will rapidly result in the
  establishment of adequate water quality
  conditions (unless sediments are disturbed)
  because the surface water bodies rapidly flush
  (short residence times).
• Many groundwater sources may remain contaminated
  for years, decades or longer even though the
  pollution source is eliminated due to chemical
  adsorption to the soil/rock and due to slow
  flushing (long residence times).

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Pollution Prevention

• For centuries, the solution to pollution has been
  dilution i.e. discharge waste into a large
  enough body of water to keep resultant blended
  levels low.
• This approach has its limits since the
  assimilative capacity of water bodies is always
  finite.
• The true solution to pollution is prevention.
• Watershed management programs to eliminate
  sources of non-point source pollution (either the
  pollutant or the opportunity for its
  mobilization) (see WRI 2001 p210-211 about NYC)
• Removal of point sources (sewage, industrial
  waste, etc.), collection of certain polluted
  runoff sources (e.g. parking lots, feedlots) and
  wastewater treatment.
• Wastewater treatment involves physical,
  biological and chemical treatment of wastes to
  eliminate or render harmless the pollutants
  contained therein.
• If prevention is not effective, water treatment
  (output controls) are needed aeration,
  coagulation, filtration, disinfection, etc.

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Wastewater Treatment System
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A Special Word About Biotic Pollutants

• Not only are global freshwater ecosystems
  degraded by our withdrawals of 1/5 of the normal
  river flows, we have also introduced biodiversity
  pollutants aka invasive or alien species (WRI
  2001 p112, p118).
• These can cause local extirpations and
  extinctions (20 of world fishes are gone or
  endangered), declines in commercially valuable
  species, and physical damage.
• However, many species (esp. fish) are introduced
  purposefully for food or recreation and can be
  positive.
• Frequently, introductions are accidental, for
  example, shellfish and crustaceans brought over
  in the ballast water of commercial vessels,
  plants released unknowingly, etc.
• Key problems have included zebra mussels, Chinese
  mitten crabs, water hyacinths, predatory fish (N.
  pike, snakehead), etc.