1. Urban Water Quality

2. Water Quality n Pollution - any departure from “purity” –What is “purity”? –Characteristics of water –Is drinking water “pure”?

3. Water Quality n Pure Water - in the context of water pollution, a state of water in which no substance is present in sufficient concentration to prevent the water from being used for the purposes thought of as “normal”

4. Water Quality n “Normal” uses of water? –Recreation –Public water supply –Aquatic habitats –Agriculture –Industry

5. Water Quality n Water Pollutant - any substance that prevents the “normal” use of water –“Normal” implies a value judgement and depends on the particular use

6. Water Quality n Water Quality - the physical and chemical characteristics of water –Unrelated to the particular use in that no value judgement is assigned

7. Water Quality - Classification of Water Pollutants n Signs of water pollution? –Bad tasting drinking water –Masses of aquatic weeds –Disgusting odors –Decreasing fish populations –Floating oil and raw sewage

8. Water Quality - Classification of Water Pollutants n Classification of water pollutants –Oxygen-demanding wastes (ODW) –Pathogenic organisms –Plant nutrients –Synthetic organic compounds (SOCs) –Oil –Sediments –Heat

9. Water Quality - Classification of Water Pollutants n Oxygen-Demanding Wastes (ODW) –Dissolved Oxygen n Aquatic organisms require oxygen for cellular respiration n Dissolved oxygen (DO) is often a limiting factor for survival of aquatic organisms

10. Water Quality - Classification of Water Pollutants n ODW –Dissolved Oxygen n Factors that control DO levels: –Water temperature –Elevation above sea level –Degree of turbulence –Stream channel geometry –Density of aquatic plants

11. Water Quality - Classification of Water Pollutants n ODW –Dissolved Oxygen n Water Temperature –DO decreases with increasing water temperature n Elevation Above Sea Level –DO decreases with increasing elevation

12. Water Quality - Classification of Water Pollutants n ODW –Dissolved Oxygen n Turbulence –DO increases with increasing turbulence caused by waterfalls, rapids, etc n Stream Channel Geometry –Wide,shallow channel has greater DO than narrow, deep channel

13. Water Quality - Classification of Water Pollutants n ODW –Organic substances that cause depletion or removal of DO –Food source for aquatic bacteria –DO is removed as bacteria feed on ODW

14. Water Quality - Classification of Water Pollutants n ODW –Sources of ODW n Sewage n Paper mills n Food processing n Slaughterhouses

15. Water Quality - Classification of Water Pollutants n ODW –Biochemical Oxygen Demand - the amount of dissolved oxygen that bacteria require to decompose ODW in a given volume of water

16. Water Quality - Classification of Water Pollutants n ODW –Biochemical Oxygen Demand (BOD) n Measurement –5-day test –Incubation at 20 degrees C –BOD = DO (day 0) - DO (day 5)

17. Water Quality - Classification of Water Pollutants n ODW –Biochemical Oxygen Demand (BOD) n Characteristic BOD Levels –Untreated Sewage100-400 mg/L –Feedlots100-10,000 mg/L –Pure Water1 mg/L

18. Water Quality - Classification of Water Pollutants n ODW –Environmental Impacts of low DO n Disappearance of plant and animal life n Shift from aerobic to anaerobic conditions n “Oxygen Sag”

20. Water Quality - Classification of Water Pollutants n Pathogenic Organisms –Types of pathogens: n Viruses n Bacteria n Protozoa (unicellular) n Parasitic worms

21. Water Quality - Classification of Water Pollutants n Pathogenic Organisms –Diseases caused by water-borne pathogens: n Amoebic Dysentery n Bacterial Dysentery n Typhoid fever n Cholera n Hepatitis n Schistosomiasis

22. Water Quality - Classification of Water Pollutants n Pathogenic Organisms –Sources of body wastes: n Malfunctioning septic tanks, cesspools n Untreated sewage n Waste discharges from boats and ships n Meat processing plants n Swimmers and hikers

23. Water Quality - Classification of Water Pollutants n Pathogenic Organisms –Testing for pathogenic organisms n Coliform bacteria –Live in large intestines of warm-blooded animals (even Uncle Monty) and absorb nutrients from their surroundings

24. Water Quality - Classification of Water Pollutants n Plant Nutrients –Plants require 15-20 nutrients for growth: n Carbon n Nitrogen n Phosphorus n Potassium n Sulfur

25. Water Quality - Classification of Water Pollutants n Plant Nutrients –Nitrogen and phosphorus are limiting nutrients for plant growth –Eutrophication - the natural enrichment of water with plant nutrients

26. Water Quality - Classification of Water Pollutants n Plant Nutrients –Eutrophic Ecosystem - ecosystems that are relatively high in fertility and biological productivity –Oligotrophic Ecosystem - ecosystems that are relatively low in fertility and biological productivity

27. Water Quality - Classification of Water Pollutants n Plant Nutrients –Cultural Eutrophication - accelerated eutrophication caused by human activities

28. Water Quality - Classification of Water Pollutants n Plant Nutrients –Signs and effects of cultural eutrophication: n Dense growth of rooted plants n Increased growth of blue-green algae n Increased populations of trash fish n Foamy layers on surface of water

29. Water Quality - Classification of Water Pollutants n Plant Nutrients –Sources of nutrients responsible for cultural cultural eutrophication: n Domestic Sewage n Urban Runoff n Industrial Sources n Agricultural Sources

30. Water Quality - Classification of Water Pollutants n Plant Nutrients –Management practices to minimize cultural eutrophication: n Two types of water pollution sources in a watershed: –Point Source –Non-Point Source Pollution

31. Water Quality - Classification of Water Pollutants n Plant Nutrients –Management practices to minimize cultural eutrophication: n Nutrient management –Determine point and nonpoint sources of nutrients and the size of each source –On-site treatment of nutrients –Rate and timing of nutrient application

32. Water Quality - Classification of Water Pollutants n Synthetic Organic Compounds (SOCs) –Examples: n Fuels n Plastics n Pesticides n Fertilizers n Food additives n Pharmaceuticals

33. Water Quality - Classification of Water Pollutants n Synthetic Organic Compounds (SOCs) –Pesticides n Environmental Impacts –Bioaccumulation –Interference with reproduction –Birth Defects –Reduced biodiversity and productivity –Tumors and convulsions

34. Water Quality - Classification of Water Pollutants n Synthetic Organic Compounds (SOCs) –Oil (Hydrocarbons) n Sources –Impervious surfaces –Oil leaks –Auto emissions –Improper disposal of waste oil

35. Water Quality - Classification of Water Pollutants n Synthetic Organic Compounds (SOCs) –Oil (Hydrocarbons) n Environmental Impacts –Degrade appearance of water surfaces –Limit air exchange between atmosphere and water –Lowered DO levels –Increased BOD –Impair habitat –Reduced biodiversity –Death

36. Water Quality - Classification of Water Pollutants n Sediment –Most common of the nonpoint source pollutants –Sediment load in waterways increases with increasing urbanization and landuse intensity

37. Water Quality - Classification of Water Pollutants n Sediment –Factors controlling sediment loss: n Chemical and physical characteristics of the soil n Slope steepness n Type and density of vegetation cover n Rainfall

38. Water Quality - Classification of Water Pollutants n Sediment –Environmental Impacts n Filling of channels and harbors with sediment n Decreased biodiversity of aquatic animals n Increased turbidity

39. Water Quality - Classification of Water Pollutants n Heat (Thermal Pollution) –Sources n Cooling water in industrial processes n Natural heating by sunlight –Environmental Impacts n Decreased DO n Increased rates of chemical reactions n False temperature cues to aquatic life n Death to aquatic organisms

40. Water Quality - Classification of Water Pollutants n Heat (Thermal Pollution) –Environmental Impacts n Decreased DO –“Thermal Blanket” n Warm water is less dense than cold water n Warm layer forms “blanket” over cooler, more dense water n Warm water cannot dissolve as much atmospheric oxygen as cooler water n Rate of exchange of oxygen between warm water and cooler water is very slow n Cooler water is “atmospherically unreplenished” n Death to aquatic organisms

41. Water Quality - Classification of Water Pollutants n Heat (Thermal Pollution) –Environmental Impacts n Increased rates of chemical reactions –The rate of any chemical reactions approximately doubles with every 10C increase in temperature –In thermally polluted waters, fish require more DO because of increased respiration rates –Increased respiration occurs in response to higher water temperature

42. Water Quality - Classification of Water Pollutants n Heat (Thermal Pollution) –Environmental Impacts n False temperature cues given to aquatic life –Fish spawn and migrate in response to temperature cues –Optimum temperature range for fish species