Chapter 5 water quality


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Chapter 5 water quality

  1. 1. Chapter 5 Water Quality Prof. Dr. Ali El-Naqa Hashemite University June 2013
  2. 2. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  3. 3. Water Pollution Water pollution can affect  Surface waters  Ground waters  Can occur naturally but is usually due to man’s activities  US waters have improved significantly since the Clean Water Act Amendments were passed in 1972  But many waters still don’t meet standards
  4. 4. Point Source Pollution  Contamination discharged through a pipe or other discrete, identifiable location  Relatively easy to quantify and evaluate impact  Historically, the focus of regulation Water. 1993. National Geographic Special Edition
  5. 5. Point Sources  Factories and sewage treatment plants  Landfills  Abandoned mines  Underground and above-ground storage tanks
  6. 6. Nonpoint Source Pollution  Contamination from a diffuse source  Difficult to measure  Focus of recent regulatory efforts Soil erosion from a farm field Gary Hawkins, UGA
  7. 7. Nonpoint Sources  Lawns, gardens, and golf courses  Agricultural and forestry practices  Street refuse  Construction activities  Stormwater runoff
  8. 8. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  9. 9. Basic Parameters of Water  Temperature  Dissolved oxygen (DO)  pH  Turbidity
  10. 10. Temperature  Temperature affects physical, chemical, and biological processes in water  Chemical example: DO decreases as temperature increases  Biological example: fish seek thermal refuges  Temperature affected by depth  Causes lake turnover  Loss of streamside shade trees causes temperature to increase
  11. 11. Dissolved Oxygen Atmosphere consists of 21% O2  Water consists of <1% O2  When water and atmosphere come into intimate contact, O2 tends to diffuse into water  Occurs as water passes over riffles, rapids, and falls and to a lesser extent in still water  Aquatic plants also pump O2 into water  During daytime when they are undergoing photosynthesis
  12. 12. Dissolved Oxygen  Fish depend on DO in water  O2 diffuses from water to blood in gills  When DO concentrations in water drop below 5 milligrams per liter (mg/L) most fish have trouble
  13. 13. pH
  14. 14. pH  pH = power of 10 for the H ion concentration (drop the minus sign)  Pure distilled water has a pH of 7 (neutral)  1 x 10-7 = 0.0000001 moles H+ per liter  Most rivers and lakes have a pH of 4 to 9  Fish have a narrow range that varies by species  pH outside the range can cause damage to gills, eyes, skin, etc.
  15. 15. Turbidity  Clarity of water  Measured as light penetration in nephelometric turbidity units (NTU)  Also measured with a Secchi disk  Record the depth at which you can no longer see the banded colors on the disk
  16. 16. Secchi disk depth comparison from clear (left) to murky (right)
  17. 17. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  18. 18. Inorganic Chemicals  Compounds that do not contain carbon (C)  Originally defined as compounds that do not originate in plants or animals  Metals, minerals, and nutrients1 1book lists nutrients under organic compounds but most nutrients are in the inorganic form
  19. 19. Metals Lead  Used in electrical conductors, pipes (soldering), paints, and a by-product of mining  Lead poisoning causes toxic reactions, brain damage, death  Especially harmful to brain development in children  Arsenic  Found naturally in some rocks, in banned pesticides, wood preservatives, and as an industrial by-product  Causes neurological damage and cancers  Drinking water standard used to be < 50 ppb  Starting Jan 2006 it is < 10 ppb
  20. 20. Notice in Shanghai store says Barbie dolls are out of stock Financial Post
  21. 21. Arsenic in Bangladesh Wells  For past 30 years, Bangladesh had a program to drill wells for cleaner drinking water  Traditional drinking water source was surface waters contaminated with cholera, fecal bacteria, etc.  5 million wells drilled  83% of wells have toxic levels  Arsenic occurs naturally in rock
  22. 22. Minerals  All surface and groundwaters contain minerals  At high concentrations they can cause adverse effects  Salt: sodium chloride (NaCl)  Salinity: the presence of excess salts in water or in soil  Saline water is undrinkable  Saline soils make water uptake difficult for plants and microbes  Aquatic plants and animals sensitive to salinity (oysters in Apalachicola Bay)
  23. 23. Colorado River and Salt  U.S. irrigation and water withdrawals cause Colorado River salinity to be very high by the time it reaches Mexico  1974 law requires average annual salt concentration be <115 ppm at border  Battery of wells at border  13-mile long 5-mile wide area  Pump low salinity groundwater into river to dilute salt concentrations
  24. 24. Nutrients  Major minerals important in animal and plant nutrition:  Nitrogen, phosphorus, potassium, calcium  Trace elements also required in  Iron, zinc, manganese, etc.  At high concentrations in streams and lakes they can cause problems
  25. 25. Nutrients: Nitrogen  Nitrogen (N) an important plant nutrient  Takes several forms in nature  Nitrogen gas (N2)  Nitrate (NO3 -)  Ammonia gas (NH3)  Ammonium (NH4 +)  Organic forms
  26. 26. Nutrients: Nitrogen  Nitrate in drinking water is a pollutant  When ingested by babies in milk formula  Causes methemoglobinemia or blue baby syndrome  Converts to nitrite (NO2 -) which interferes with oxygen transport in the blood  Baby suffocates  Drinking water standard is <10 ppm nitrate  Very mobile in soil and leaches easily to groundwater  Sources: manures, fertilizers, sewage
  27. 27. Nutrients: Phosphorus Phosphorus (P) an important plant and animal nutrient  Can cause excessive algal growth in lakes  A little bit of algal growth is good  Source of food for fish  Too much is bad  Microbes that decompose dead algae use oxygen and lower DO  Low DO stresses fish, forcing them to the surface, selecting against species such as trout, and even causing fish kills
  28. 28. Nutrients: Phosphorus Over time, lakes lose depth and naturally evolve from low nutrient to high nutrient status  Oligotrophic => mesoptrophic => eutrophic => hypereutrophic  Happens over 100’s of years  Excessive inputs of P speed up the process  Call this accelerated eutrophication  Happens over 10’s of years  Concentrations as low as 0.01 ppm stimulate algae
  29. 29. Lake Aging Natural Process Accelerated by land use
  30. 30. Nutrients: Phosphorus Lake in Manitoba Province of Canada  Divided by plastic curtain  For 8 years  N and C added each year to one side  N, C, and P added to other side  Every year there was an algal bloom in response to adding P  tes/fisheries/eutro.html
  31. 31. Nutrients: Phosphorus Disinfection byproducts • Occur when lake with algal bloom is a source of public drinking water  Chlorine used to disinfect water  Chlorine combines with organic carbon to produce carcinogens  Taste and odor events  Certain types of algae produce organic compounds that give drinking water a “dirty taste” and foul odor
  32. 32. Nutrients: Phosphorus Atlanta Journal Constitution 17 Sep 2007
  33. 33. Nutrients: Phosphorus  Sources: manures, fertilizers, sewage, detergents  Not very mobile in soils  Usually doesn’t leach to groundwater  Instead it runs off into streams  Dissolved in runoff or  Attached to eroded sediment particles  Not harmful to humans directly  P was banned from detergents in 1990’s
  34. 34. Phosphorus concentrations in the Chattahoochee below Atlanta
  35. 35. Nutrients and Marine Waters  Algal growth in marine waters is controlled primarily by N  P can be important at certain times of the year  Estuaries (which are intermediate between fresh and marine waters in terms of salinity) are affected by both N and P
  36. 36. Gulf of Mexico Hypoxia  Nitrogen from the Mississippi River watershed is causing algal blooms and low DO (hypoxia) in the Gulf of Mexico each summer  Dead zone at lower depths kills aquatic species including shrimp
  37. 37. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  38. 38. Organic Chemicals  Compounds that do contain carbon (C)  Often large complex molecules  May be natural or man-made (synthetic)  Synthetic compounds may last for a long time in the environment  Natural decomposing processes are unable to break down these complex molecules
  39. 39. Organic Chemicals  Many synthetic organic chemicals are carcinogens:  Benzene (C6H6), commercial solvent  Carbon tetrachloride (CCl4), in fire extinguishers, solvents, and cleaning agents  Polychorinated Biphenyls (PCBs), used as a coolant in electrical transformers  Pesticides are synthetic organic chemicals used to kill unwanted pests  Can be harmful to humans and wildlife
  40. 40. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  41. 41. Waterborne Diseases  Early concerns regarding water quality caused by waterborne diseases  Plagues in the Middle Ages  Cholera epidemic in 1848-1849 caused 53,000 deaths in London  Connection between disease and water was unknown until shown by Dr. John Snow  1854 Broad Street Pump study
  42. 42. Dr. John Snow  Found that cholera causes were clustered around a community water pump at Broad Street in London  Water company that supplied pump took it from Thames River downstream of London  Advised that the pump handle be removed
  43. 43. Replica of Broad Street pump with handle removed outside the John Snow pub
  44. 44. Waterborne Diseases  Microorganisms include  Viruses – bits of DNA or RNA  Bacteria – single cell organisms  Other – protozoa, worms, blue-green algae  Examples of microorganisms that are pathogens (disease-causing organisms)  Escherichia coli (E. coli) – bacterium  Giardia – protozoa  Cryptosporidium – protozoa
  45. 45. E. Coli E. coli are a common bacteria in the human intestines  Aid digestion, harmless  Used as an indicator organism  One strain of E. coli (0157:H7) is lethal, however  In a town in Ontario in 2000, 2,300 people became ill and 7 died when the water supply became contaminated with 0157:H7  Attributed to contamination from cattle manure
  46. 46. Spinach E. Coli Outbreak 2006 205 illnesses 3 deaths
  47. 47. Indicator Organisms  Too costly and dangerous to test water for individual pathogens  Instead we test for indicator organisms  Harmless but indicate fecal origin  Common indicator organism  Total coliform bacteria – seldom used today  Fecal coliform bacteria – most common today
  48. 48. Indicator Organisms  Standard for drinking water in Georgia is <1 fecal coliform per 100 mL  Standard for streams and lakes is <200 fecal coliforms per 100 mL
  49. 49. Fecal coliforms in the Chattahoochee below Atlanta
  50. 50. Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
  51. 51. Water Quality Management We try to manage water quality so that waters don’t become contaminated (pollution prevention)  Costly and risky to rely only on treatment of drinking water (cryptosporidum oocysts unaffected)  Reduce impact on wildlife  Book calls this Fate and Transport  The movement and ultimate disposition of pollutants  Water quality management programs focus on ground water and surface water
  52. 52. Groundwater Management Pollutants usually move horizontally in a plume away from the source in groundwater  Concentration decreases as pollutant gets farther away from source  Pollutant may break down with time  Mixing with uncontaminated groundwater causes dilution  Pollutants may be more or less mobile  Depends on adsorption to soil and rock
  53. 53. Groundwater Management  U.S. EPA Superfund Program established in 1980  Purpose to clean up highly contaminated point- sources of pollution  Currently there are more than 1,200 sites in the U.S.  80% involve groundwater contamination
  54. 54. Groundwater Management  Example site is Nebraska Ordnance Plant near Mead, OK  During WWII and Korean War, bombs were made at the plant  Solvent (TCE) and explosive compound (RDX) were washed from the assembly buildings into ditches and ponds  Estimated that 22.5 billion gals of groundwater is contaminated  Extraction wells are being used to treat water and restrict plume migration
  55. 55. Surface Water Management  Water sampling is important part of surface water quality management  Only way to know if a river or lake meets the water quality standard  Also used to determine if clean up plan is working  Federal and state agencies take samples  Also volunteer groups (Adopt-a-Stream)
  56. 56. Surface Water Management  Example of local volunteer group is Upper Oconee Watershed Network (UOWN)   Quarterly monitoring of Upper Oconee River  Annual River Rendezvous  Maintain a database
  57. 57. Chapter Summary  Pollutants come in many forms (inorganic, organic, nutrients, microorganisms)  Point and nonpoint sources of pollution  Pollutants usually come from human activity  Water quality management programs focus on preventing pollution before it happens
  58. 58. Quiz  Indicate whether the sources of pollution below are point or nonpoint sources:  golf course  waste water treatment plant  farm field  Landfill  underground storage tank  construction activity  Why is dissolved oxygen a water quality issue?  Who was Dr. John Snow?  What is an example of an inorganic water quality pollutant?