Air and water pollution

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					Air and water pollution

Pollution
 Any physical, biological, or chemical change in environmental quality that
  adversely affects living organisms can be considered pollution

Point sources
 Discharge pollution from specific locations
   – Factories, power plants
   – Easy to control through regulations

Non-point sources
 Non-point sources - Scattered or diffuse, having no specific location of
  discharge
   – Agricultural fields, feedlots
   – Very difficult to monitor and regulate
Air pollution
 Approximately 147 million metric tons of air pollution are released annually into
   the atmosphere in the U.S. by human activities
 Worldwide emissions total around 2 billion metric tons
 Developed countries have been improving air quality, while air quality in
   developing world is getting worse

Natural sources of air pollution
 Natural fires - smoke
 Volcanoes - ash and acidic components
 Sea spray - sulfur
 Vegetation - volatile organic compounds
 Bacterial metabolism - methane
 Pollen

Human-caused air pollution
 Primary pollutants - Released directly from the source
 Secondary pollutants - Modified to a hazardous form after entering the air and
  mixing with other environmental components
 Fugitive emissions - Do not go through smokestack
   – Dust from human-activities
Air pollutants
 Sulfur compounds
    – Two thirds of total sulfur in the atmosphere is from human activity
    – Predominant form of anthropogenic sulfur is sulfur-dioxide from fossil-fuel
      combustion
         Colorless corrosive gas that directly damages both plants and animals
         Can react with water to form acid rain
         Second only to smoking as cause of air pollution-related health damage


Air pollutants
 Carbon oxides
    – Predominant form of carbon in the air is carbon dioxide
         Increasing levels due to human activities
    – Carbon monoxide is a colorless, odorless, toxic gas produced by
      incomplete fuel combustion

Air pollutants
 Particulate matter
    – Atmospheric aerosols (solid or liquid)
        Aerosol is any system of solid particles or liquid droplets suspended in a
         gaseous medium
    – Respirable particles smaller than 2.5 micrometers are among most
      dangerous
    – Diesel fumes dangerous
    – Reduces visibility and leaves dirty deposits on surfaces
Air pollutants
 Volatile organic compounds
    – Organic chemicals
         Generally oxidized to CO and CO2
         Plants are largest source
         Released by humans by use of synthetic organic chemicals


Air pollutants
 Nitrogen compounds
    – Also called NOx
    – 60 % of NO emissions are anthropogenic
    – Produced by fuel combustion in transportation and electric power
      generation
    – Excess nitrogen causing eutrophication in water bodies
         Low oxygen caused by decomposition of organic material
    – Encourages growth of weedy plant species
Air pollutants
 Photochemical oxidants
    – Products of secondary atmospheric reactions driven by solar energy
         Ozone formed by splitting nitrogen dioxide


Air pollutants
 Metals
    – Many toxic metals occur as trace elements in fuel
         Since leaded gasoline was banned, children’s average lead levels have
          dropped 90% and IQs have risen by 3 points
    – Mercury
         Released from coal burning power plants and waste incinerators
         Bioaccumulation in aquatic ecosystems
    – Nickel, beryllium, cadmium, arsenic
    – Halogens (Fluorine, Chlorine, Bromine)
    – CFC’s
Air toxins
 Hazardous air pollutants (HAPs)
    – A special category of air pollutants monitored by USEPA
    – Require special reporting and management as they remain in ecosystems
      for a long period of time, and tend to accumulate in animal tissues
    – Toxic Release Inventory (TRI)
         Established 1986
         Collected by USEPA as part of community right to know program


Aesthetic pollutants
 Noise, odor, light pollution
       Reduce quality of life


Indoor air pollution
 EPA found indoor concentrations of toxic air pollutants are often higher than
   outdoor
    – People generally spend more time indoors
    – Smoking is the most important air pollutant in the U.S.
        400,000 die annually from a disease related to smoking


Indoor air pollution
 Less-developed Countries also suffer from indoor air pollution
   – Organic fuels make up majority of household energy
        Often burned in smoky, poorly ventilated heating and cooking fires
Climate and topography
 Topography, climate and physical processes play important roles in transport,
   concentration, dispersal and removal of air pollutants

Inversions
 Temperature inversions occur when a stable layer of warm air overlays cooler
   air, reversing the normal temperature decline with increasing height, and
   preventing convection currents from dispersing pollutants
          Usually created by rapid nighttime cooling in a basin where air
           movement is restricted

Dust domes and heat islands
 Sparse vegetation and large amounts of concrete and glass create warm,
  stable air masses, heat islands, over large cities
   – Concentrates pollutants in a “dust dome”
       Rural areas downwind from major industrial areas often have
        significantly decreased visibility and increased rainfall

Long-range transport
 Fine aerosols can be carried great distances by the wind

Long-range transport
 Increasingly, sensitive monitoring equipment has begun to reveal industrial
  contaminants in places usually considered among the cleanest in the world
   – Contaminants evaporate from warmer areas and condense and precipitate
     in cooler areas

Stratospheric ozone
 Discovered in 1985 that stratospheric ozone levels were dropping rapidly
   during September and October
    – Occurring since at least 1960
 At ground-level, ozone is a pollutant, but in the stratosphere it screens UV
   radiation

Stratospheric ozone depletion
 CFCs believed to be main culprit
   – Persist for decades
   – Ban established in 1987
   – Models show that stratospheric ozone levels could reach normal levels by
      2040
Effects of air pollution
 Human health
   – EPA estimates each year 50,000 people die prematurely from illnesses
      related to air pollution in US
   – WHO estimates 5-6 million die prematurely from illnesses related to air
      pollution
        Likelihood of suffering ill health is related to intensity and duration of
         exposure
           – Inhalation is the most common route, but absorption through the skin
             and consumption via food can also occur

Plant pathology
 Chemical pollutants can directly damage plants, or can cause indirect damage
  by disrupting normal growth and development patterns
   – Certain environmental factors have synergistic effects in which the injury
      caused by the combination is more than the sum of the individual
      exposures
   – Crop damage estimated at $10 billion per year in North America
Acid deposition
 pH and atmospheric acidity
   – pH scale ranges from 0-14
       7 = Neutral; <7 = Acidic; >7 = Basic
   – Unpolluted rain generally has ph of 5.6
       Carbonic acid from atmospheric CO2
          – In industrialized areas, anthropogenic acids in the air often outweigh
            natural sources of acid

Acid deposition
 Aquatic effects
   – Thin, acidic soils and oligotrophic lakes of southern Norway and Sweden
     have been severely affected by acid deposition
   – Air pollutants are acidifying many North American lakes
Acid deposition
 Forest damage
   – Air pollution and depositions of atmospheric acids are believed to be
     important causes of forest destruction in many areas

Visibility reduction
Clean air legislation
 Clean Air Act (1963) - First national air pollution control
 Clean Air Act (1970) rewrote original
   – Identified critical pollutants
   – Established ambient air quality standards
        Primary Standards - Human health
        Secondary Standards - Materials, environment, aesthetic and comfort


Clean Air Act
 Revision (1990) - Included provision for:
   – Acid Rain
   – Urban Smog
   – Toxic Air Pollutants
   – Ozone Protection
   – Marketing Pollution Rights
   – Volatile Organic Compounds
   – Ambient Ozone
   – Nox Emissions
 Revision (1997) - Stricter standards

Clear skies initiative of Bush
 Controversial elimination of “new source review”
   – In 1977, power plants were “grandfathered” into Clean Air Act rules due to
     expense
   – Plant operators have continued to operate these polluting older power
     plants
   – New source review requires any updates to these aging power plants to
     comply to Clear Air Act regulations

Water pollution

Atmospheric deposition
   – Ultimate in non-point source pollution
   – Contaminants carried by air currents and precipitated into watersheds or
     directly onto surface waters
       Agricultural (atrazine, toxaphene) and industrial (PCBs, dioxins)
        contaminants in the Great Lakes that cannot be accounted for by local
        sources alone
          – Most thought to have been deposited from the atmosphere
          – Several studies have indicated health problems among people who
            regularly eat Great Lakes fish
Infectious agents
 Main source of waterborne pathogens is improperly treated human waste
 Animal wastes from feedlots and fields is also important source of pathogens

Infectious agents

Infectious agents
 In developed countries, sewage treatment plants and pollution-control devices
   have greatly reduced pathogens
    – Waters monitored for coliform bacteria - intestinal bacteria including
      Escherichia coli (E. coli)
         Usually assumed that if E. coli is present, infectious pathogens are
          present also (e.g. Salmonella, Lysteria)
         Estimated 1.5 million Americans fall ill from fecal contamination annually

    – Drinking water generally disinfected via chlorination

Oxygen-demanding wastes
 Certain organic materials added to water stimulates oxygen consumption by
  decomposers
   – Sewage
   – Paper pulp
   – Food-processing wastes
Oxygen-demanding wastes
 Water with an oxygen content > 6 ppm will support “desirable” aquatic life
   – Water with < 2 ppm oxygen will support mainly detritis feeders and
     decomposers (e.g. worms, bacteria, fungi)
 Oxygen is added to water by diffusion from wind and waves, and by
  photosynthesis from green plants and algae
   – Oxygen is removed from water by respiration and oxygen-consuming
     chemical processes

Oxygen-demanding wastes
 Effects of oxygen-demanding wastes on rivers depend on volume, flow, and
  temperature of river water
   – Faster flowing water has more oxygen
   – Lower temperature water has more oxygen
 Oxygen sag - oxygen levels decline downstream from a pollution source as
  decomposers metabolize waste materials

Oxygen sag

Oxygen sag
Gulf of Mexico hypoxia
 In 1974, scientists found areas where oxygen had disappeared from bottom
  sediments and the water column
 First thought to be a minor natural disturbance
 Hypoxic area in 1993 after Mississippi floods doubled in size
 Stays from May to September
 Influx of nitrogen from Midwest/Great Plains is cause
 Hypoxic area continues to grow

Harmful algal blooms (HABs)
 HABs have become increasingly common in slow-moving and shallow waters,
  usually due to pollution
 Algal blooms produce toxins
 Red tides are blooms of deadly aquatic algae
 Cryptosporidium in 1993 entered the Milwaukee public water supply, making
  400,000 people sick and killing at least 100 people

Pfiesteria piscidcida
 First discovered in 1988 in open sores in fish in Chesapeake Bay
 Very complicated life cycle
    – No fewer than 24 different life forms
 In 1997, fish kills led to the closing of Pocomoke River to all shellfish and fish
   harvests
    – Economic loss was $15-20 million in MD alone
 Causes skin rashes, neurological disorders and death in humans

Inorganic pollutants
 Metals
   – Many metals such as mercury, lead, cadmium, and nickel are highly toxic
       Highly persistent and tend to bioaccumulate in food chains
          – Lead pipes are a serious source of drinking water pollution
          – Mine drainage is serious source of metal pollution in water

Inorganic pollutants
 Nonmetallic salts
   – Many salts that are non-toxic at low concentrations can be mobilized by
     irrigation and concentrated by evaporation, reaching levels toxic to plants
     and animals
        Leaching of road salts has had detrimental effect on many ecosystems
 Acids and bases
   – Often released as by-products of industrial processes
        Coal mining

   – Acid precipitation
Organic chemicals
 Thousands of natural and synthetic organic chemicals are used to make
  pesticides, plastics, pharmaceuticals, pigments, etc.
 Many are highly toxic and bioaccumulate

Biomagnification
 Cells have special mechanisms for bioaccumulation - selective absorption and
  storage
   – Dilute toxins in the environment can build to higher levels inside cells and
     tissues
 Biomagnification - toxic contents of a large number of organisms at a lower
  trophic level is accumulated and concentrated by a predator at a higher trophic
  level

Organic chemicals
 Two most important sources of toxic organic chemicals in water are:
   – Improper disposal of industrial and household wastes
   – Runoff of pesticides from high-use areas
       Fields, roadsides, golf courses


Pesticide runoff

Sediment
 Human activities have accelerated erosion rates in many areas
   – Human-induced erosion and runoff contribute about 75 billion metric tons of
      suspended solids to world surfaces each year
 Fills lakes, obstructs shipping channels, makes drinking water purification
  more costly

Thermal pollution
 Raising or lowering water temperatures from normal levels can adversely
  affect water quality and aquatic life
   – Oxygen solubility in water decreases as temperatures increase
       Species requiring high oxygen levels are adversely affected by warming
         water

Thermal pollution
 Caused by altering vegetation cover and runoff patterns
 Industrial cooling processes often use heat-exchangers to extract excess heat,
  and then discharge heated water back into original source

Garbage
 Estimated 6 million metric tons of plastic bottles, packaging material, and other
  litter tossed from ships into the ocean annually
Sewage
 Many countries discharge raw sewage directly into the ocean, e.g. Greece
Oil pollution
 Few coastlines in the world remain uncontaminated by oil or oil products
    – Estimated 3-6 million metric tons of oil are discharged into the world’s
      oceans
         Transport creates opportunities for major spills


Oil pollution
Groundwater and drinking water
 About half the U.S. population, and 95% of rural residents, depend on
   underground aquifers for drinking water
    – For decades, groundwater was assumed impervious to pollution and was
      considered the gold standard for water quality

Groundwater and drinking water
 EPA estimates 4.5 trillion liters of contaminated water seep into the ground in
  the U.S. every day
   – MTBE - Gasoline additive, and suspected carcinogen, is present in many
     urban aquifers
   – In agricultural areas, fertilizers and pesticides commonly contaminate
     aquifers and wells

Groundwater pollution

Water legislation
 Clean Water Act (1972)
   – Goal was to return all U.S. surface waters to “fishable and swimmable”
     conditions
       For Point Sources, Discharge Permits and Best Practicable Control
        Technology (BPT) are required
          – Set best available, economically achievable technology (BAT) for
            zero discharge for 126 priority toxic pollutants

Clean Water Act (1972)
 Areas of contention
   – Draining or filling of wetlands
       Many consider this taking of private land
   – Un-funded mandates
       State or local governments must spend monies not repaid by Congress
Other important water legislation
 Safe Drinking Water Act (1974)
   – Regulates water quality
 CERCLA (1980) (aka Superfund)
   – Cleans up abandoned or inactive sites
 Great Lakes Water Quality Agreement (1972)
 London Dumping Convention (1990)
   – Phasing out ocean dumping by 1995
Legislation
 Laws are only as good as:
   – To the degree they are not weakened
   – To the degree they are funded
Water quality today in US
 Areas of Progress
   – In 1999, EPA reported 91.4% of all monitored river miles and 87.5% of all
     accessed lake acres are suitable for their designated uses
        Most progress due to municipal sewage treatment facilities


Areas of progress
 In 1998, EPA switched regulatory approaches. Rather than issue standards
  on a site by site approach, the focus is now on watershed-level monitoring and
  protection

Watershed protection in the Catskills
 Water supply for New York City
 Worked with local farmers to reduce non-point pollution and preserve land
 Saved billions of dollars by performing watershed protection rather than
  building a treatment plant

Remaining problems
 Greatest impediments to achieving national goals in water quality are
  sediment, nutrients, and pathogens, especially from non-point discharges
   – About three-quarters of water pollution in the U.S. comes from soil erosion,
     air pollution fallout, and agricultural and urban runoff

				
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