Card Set Information

2013-10-17 06:51:20

for finals
Show Answers:

  1. Where do we get water?
    • Ice caps and glaciers
    • Groundwater
  2. How many people have no access to safe water?
    One-sixth of world's population
  3. How much water does a person need?
    1 gallon a day
  4. How is water polluted?
    • Point sources: Sewer outlet, steel mill or septic tank
    • Nonpoint sources: Fertilizer runoff from a farm, acid drain from a strip mine
  5. What are major sources of water pollution? It's types and effects?
    • Human and animal waste - causes diseases - bacteria, virus
    • Sewage, inorganic fertilizers - cause excessive growth of algae - nitrates
    • Industry, farms, households - add toxins to aquatic systems
    • Land erosion - disrupt photosynthesis, food webs, other processes
  6. Common diseases through contaminated drinking water
    • Typhoid fever
    • Cholera
    • Bacterial dysentery
    • Enteritis
  7. What is geochemical cycle?
    Passing of elements through a series of reservoirs
  8. What is residence time?
    How much time each element spends in a reservoir such as river stream, lake or ocean
  9. Why is residence time important?
    • If a specific chemical has a residence time of 20 years, then after 20 years about half of the chemical should be gone from the reservoir.
    • We can apply this concept to toxic chemicals that are introduced into nature as human-created pollution
  10. Which elements have the longest residence time?
    Chlorine and sodium
  11. Which element has the shortest residence time?
  12. How to monitor water quality?
    • Biochemical Oxygen Demand (BOD)
    • Amount of oxygen needed to break down the organic matter (sewage) aerobically
    • Measures the rate of uptake of oxygen by microorganisms in the sample of water at a fixed temp (20C) and over 5 days in the dark
  13. What does DO stand for?
    Dissolved oxygen - unit is ppm
  14. When will you consider that the water is good?
    • If it has a DO of 8-9
    • If the DO is below 4, the water is gravely polluted
  15. How much BOD do pristine rivers have?
    Less than 1 ppm
  16. How much BOD do pristine rivers have?
    More than 10 ppm
  17. What is oxygen sag curve?
    A graph of dissolved oxygen content as a function of distance from the waste source
  18. What is the major source of water pollution?
    Organic matter from human and animal wastes that are dumped into water
  19. How does water react with organic matter?
    • Organic matter is broken down by microorganisms if there is ample oxygen in the water
    • Aerobic decomposition occurs until oxygen is used up
    • Releases methane and hydrogen sulfide
  20. What is eutrophication?
    The breakdown of excess organic matter not only consumes oxygen but also releases a variety of compounds such as nitrates, phosphates and sulfates
  21. What are nitrates and phosphates?
    Plant nutrients that encourages the rapid and excessive growth of aquatic plants like algae
  22. What is algal bloom?
    • The exuberant algal growth and appears as slimy green scum floating on the water
    • Worsen the water quality
    • The scum blocks out the sunlight and the aquatic plants begin to die
  23. What are phosphates?
    • They behave as plant nutrients and are harmful to the environment
    • Were added to laundry detergents to enhance cleaning ability by softening the water
  24. What is mercury?
    • A neurotoxin that acts on the central nervous system of the human body
    • Causes loss of sight, feeling and hearing
  25. What is Minamata disease?
    Adverse effects to nervous system caused by methylmercury
  26. What is arsenic?
    • Lethal and can cause skin and bladder cancer
    • Dissolved out of soils and rocks and can enter the groundwater
  27. Drinking water standard for arsenic
    Set at 50 ppb
  28. What are the other inorganic water pollutants?
    • Chlorine
    • Acid mine drainage
  29. What does sediment pollution do?
    • Causes water to be murky and unpleasant to look at, swim in or drink
    • Reduces the light available to underwater plants and covers food supplies of aquatic animals
    • Clogs water filter and damages power-generating equipment
  30. How much of oil spill can only be recovered?
  31. How long does it take to clean crude oil spill and refined oil spillage?
    • Crude oil - 3 years
    • Refined oil - 10-20 years
  32. How to reduce water pollution?
    Sewage treatment - using wetlands to treat sewage