Exam 4

• The Hydrologic Cycle


  water evaporates from moist surfaces, falls as rain

  or snow, passes through living organisms and returns to the oceans.
• Three principal factors control global water deficits and surpluses:

  o Global atmospheric circulation

  o Proximity to water sources

  o Topography
• Rain Shadow effect


  cool, dry air descends from the mountaintop down the other side of the mountain ----creating dry areas with very little precipitation. EX, a mountain in Hawaii rain on the east side of the mountain is > 20 times that on the west side
• Role of oceans as a water source

  holds 97% of the total water on the planet and produces over half of the world's oxygen and absorbs 50 times more carbon dioxide than our atmosphere
• Where water is found

  o Glaciers

  o Groundwater
• Infiltration


  process of water percolating through the soil and into fractures and permeable rocks
• Zone of aeration


  upper soil layers that hold both air and water
• Zone of saturation


  lower soil layers where all spaces are filled with water
• Water table


  top of zone of saturation
• Withdrawal


  total amount of water removed from a water body
• Consumption


  loss of water due to evaporation, absorption, or contamination
• Point Sources


  discharge pollution from specific locations.

  EX: Factories, power plants, drain pipes
• Nonpoint Sources


  scattered or diffuse, having no specific location of discharge
• Atmospheric Deposition


  the process, long recognized by scientists, whereby precipitation (rain, snow, fog), particles, aerosols, and gases move from the atmosphere to the earth's surface.
• Infectious Agents


  Pathogenic organisms such as viruses, bacteria, fungi, protozoa, and worms.
• Main source of waterborne pathogens


  improperly treated human waste
• Biochemical Oxygen Demand


  amount of dissolved oxygen consumed by aquatic microorganisms. Used as a test for organic waste contamination from sewage, paper pulp, and food waste.
• Dissolved Oxygen Content


  measure of dissolved oxygen in the water
• Oligotrophic


  bodies of water that have clear water and low biological productivity
• Eutrophic


  bodies of water that are rich in organisms and organic material
• Eutrophication


  process of increasing nutrient levels and biological productivity, a normal part of successional change in most lakes
• Cultural Eutrophication


  increase in biological productivity caused by human activities
• Inorganic Pollutants


  mineral acids, inorganic salts, trace elements, metals, metals compounds, complexes of metals with organic compounds, cyanides, sulphates, etc
• Organic Chemicals


  often use to make pesticides, plastics, pharmaceuticals, pigments, and many other day to day product.
• Thermal Pollution


  Raising and lowering water temperatures from normal levels can adversely affect water quality and aquatic life
• Clean Water Act (1972)

  National Pollution Discharge System which requires a permit for any entity dumping wastes in surface water and requires disclosure of what is being dumped
• Groundwater Pollution


  is due to a variety of factors including overuse, deforestation, lack of clean surface water, disruption of recharge zones, and contamination of groundwater.
• Oil Pollution


  oil release and spill into ocean
• Water Remediation


  Restoring water
• Primary Treatment


  physical separation of large solids from the waste stream
• Secondary Treatment


  biological degradation of dissolved organic compounds
• Tertiary Treatment


  removal of plant nutrients (nitrogen and phosphates) from secondary effluent
• Septic tank


  separates the solids from the liquid
• Soil absorption field


  Series of pipes that uniformly distribute the liquids into a leachfield full of sand and gravel which acts as a biological filter
• Effluent Sewerage


  a septic tank separates the solids and the liquid is sent to the city water remediation plant
• Natural or Artificial Wetlands


  Takes effluent from the city water treatment plant and uses wetland plants and microorganisms to remove excess nitrogen from fertilizer contaminants and recharges ground water
• Containment


  divert water away from a contaminated site
• Extraction


  pump out polluted water and treat it chemically
• Duckweed


  used in bioremediation and tertiary treatment of water