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Chapter 5 water quality
 

Chapter 5 water quality

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    Chapter 5 water quality Chapter 5 water quality Presentation Transcript

    • Chapter 5 Water Quality Prof. Dr. Ali El-Naqa Hashemite University June 2013
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • 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
    • 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
    • Point Sources  Factories and sewage treatment plants  Landfills  Abandoned mines  Underground and above-ground storage tanks
    • 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
    • Nonpoint Sources  Lawns, gardens, and golf courses  Agricultural and forestry practices  Street refuse  Construction activities  Stormwater runoff
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • Basic Parameters of Water  Temperature  Dissolved oxygen (DO)  pH  Turbidity
    • 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
    • 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
    • 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 www.fishdoc.co.uk
    • pH
    • 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.
    • 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
    • Secchi disk depth comparison from clear (left) to murky (right) http://earthobservatory.nasa.gov/Study/WaterQuality/water_quality2.html
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • 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
    • 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
    • Notice in Shanghai store says Barbie dolls are out of stock Financial Post Canada.com
    • 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 www.uswaternews.com/archives/arcglobal/tarspoi4.html
    • 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)
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • Lake Aging Natural Process Accelerated by land use
    • 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  www.umanitoba.ca/institu tes/fisheries/eutro.html
    • 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
    • Nutrients: Phosphorus Atlanta Journal Constitution 17 Sep 2007
    • 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
    • Phosphorus concentrations in the Chattahoochee below Atlanta
    • 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
    • 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
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • 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
    • 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
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • 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
    • 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
    • Replica of Broad Street pump with handle removed outside the John Snow pub www.ph.ucla.edu/epi/snow
    • 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
    • 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
    • Spinach E. Coli Outbreak 2006 205 illnesses 3 deaths
    • 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
    • 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
    • Fecal coliforms in the Chattahoochee below Atlanta
    • Chapter Headings  Water Pollution  Basic Parameters of Water  Inorganic Chemicals  Organic Chemicals  Waterborne Diseases  Water Quality Management
    • 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
    • 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
    • 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
    • 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
    • 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)
    • Surface Water Management  Example of local volunteer group is Upper Oconee Watershed Network (UOWN)  http://www.uown.org/  Quarterly monitoring of Upper Oconee River  Annual River Rendezvous  Maintain a database
    • 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
    • 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?