Presentation Transcript

1. 15_00-CS.JPG Ch 15 Fresh Water
2. Freshwater < 1% salt paspaley-pearls.com http://commons.wikimedia.org/wiki/File:Florida_freshwater_marshes_usgov_image.jpg alldisease.blogspot.com sequim-real-estate-blog.com adventure.howstuffworks.com thejump.net civilengineeringschools.org
3. Importance of Freshwater Systems Ecosystem Services Economic Services Food Drinking water Irrigation Hydroelectricity Transportation Recreation employment Climate moderation Nutrient cycling Waste treatment and dilution Flood control Groundwater recharge Habitats Genetic resources and biodiversity Scientific information
4. Watershed (drainage basin) = land area drained by a stream or river
5. Floodplain = land on river’s edge -floods periodically creating fertile soil Riparian = riverside, biodiverse ecotone
6. Wetlands Swamps, bogs, marshes Important breeding grounds, Slow runoff, facilitate groundwater recharge, phytoremediation,
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8. 50% of U.S. wetlands lost to development/agriculture
9. watchingtheworldwakeup.blogspot.com
10. Lakes/Ponds– inland depressions filled with water Lake Life Zones: Littoral zone - light penetrates to bottom, rooted aquatic plants Benthic zone = bottom Limnetic zone = open water – to depth of light penetration (photosynthesis) Profundal zone = light doesn’t penetrate, low oxygen levels due to decomposition and no photosynthesis
11. Life Zone(s) in a Pond? nhdfl.org
12. Pond – Littoral Zone nhdfl.org
13. Aquatic Succession Lakes/ponds fill in over 100s-1000s of years to form terrestrial environments
14. Zones represent in space what will happen over time due to succession. Each stage = “hydrosere” Littoral Zone
15. Oligotrophic
16. Eutrophic
17. Classification by trophic status Oligotrophic – “young” nutrient poor, clear, high oxygen Deep, steep sides, low npp, Small population phytoplankton and some fish Eutrophic “Old” high nutrient, low oxygen More sediment, shallow, low light penetration Mesotrophic - intermediate
18. A typical aquifer
19. Groundwater Zone of Aeration
20. Groundwater Groundwater = any precipitation that does not evaporate, flow into waterways, or get taken up by organisms Flows slowly (1 foot per day) from points of high elevation or pressure. Aquifers = Porous, water-saturated rock, sand, or gravel through which groundwater flows Zone of aeration = pore spaces are partially filled with water Zone of saturation = spaces are completely filled with water Water table = boundary between the two zones Aquifer recharge zone = any area where water infiltrates Earth’s surface and reaches aquifers
21. The Ogallala Aquifer The world’s largest known aquifer – glacial water 15,000 years old Underlies the Great Plains of the U.S. Not recharging –by some estimates will run out in as soon as 10 years due to heavy irrigation
22. Use Vs. Supply
23. Worldwide – MOST water use is for agriculture
24. Safe Drinking Water Act (SDWA) 1974 – regulates sources of drinking water (not private wells!) Sets drinking water standards Water On Tap
25. Solutions involve lowering demand or Increasing Supply
26. Desalinization Desalinization = the removal of salt from seawater or other water of marginal quality Distilling = hastens evaporation and condenses the vapor Reverse osmosis = forces water through membranes to filter out salts Expensive, Energy Intensive, Produces concentrated salty waste
27. Agricultural demand can be reduced Line irrigation canals Drip irrigation Match crops to land and climate Selective breeding and genetic modification
28. Residential demand can be reduced Low-flow faucets, showerheads, washing machines, and toilets Water at night – less evaporation Eat less meat Xeriscaping = plants adapted to arid conditions
29. Industrial demand can be reduced Wastewater recycling Patch leaks Promote conservation – provide incentives Promoting conservation/education
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31. Freshwater pollution Pollution = release of matter or energy into the environment which results in undesirable impacts on humans or other organisms Point source – from specific location ex. Factory or sewer pipe Nonpoint – multiple, cumulative inputs over large areas ex. Farms, city streets, residential areas
32. Pollution Types Nutrients – notably nitrates and phosphates which result in cultural eutrophication
33. Solutions? Properly treat wastewater Reduce fertilizer use Create buffer zone of plants Phosphate-free detergents
34. 2. Pathogens – cause of MOST waterborne disease worldwide. Sources: poorly treated wastewater OR feedlot waste Solutions: Treat sewage Disinfect drinking water – chlorine or UV light
35. 3. Toxic chemicals Pesticides, petroleum products, synthetic chemicals Arsenic, lead, mercury, acid rain, acid drainage from mines Solutions: Stringent regulation of industry Modify industrial processes Modify our purchasing decisions
36. Atrazine
37. 4. Sediment pollution Solutions: better management of farms and forests; avoid large-scale disturbance of vegetation
38. Return water used to cool industrial facility or nuclear power plant to river at higher temp. 5. Thermal Pollution
39. 6. Saltwater Intrusion – due to “water mining” or overpumping of groundwater
40. Indicators of water quality Biological indicators: presence of fecal coliform bacteria and other disease-causing organisms Chemical indicators: pH, nitrates/phosphates, taste, odor, hardness (Ca, Mg), dissolved oxygen, BOD Physical indicators: turbidity (tss), color, temperature
41. Legislative efforts reduce pollution Federal Water Pollution Control Act (1972) Renamed the Clean Water Act in 1977 Permit required to discharge pollutants Standards for industrial wastewater Funded treatment plants
42. Wastewater Treatment – Septic Systems
43. A Wastewater Treatment plant
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45. Treating wastewater Goal is to clean water to the degree that it will not pollute the body of water it is discharged into – NOT to create potable water Wastewater = water that has been used by people in some way Septic systems = the most popular method of wastewater disposal in rural areas Underground septic tanks separate solids and oils from wastewater The water drains into a drain field, where microbes decompose organics, nitrates diluted, phosphates fixed by rocks/soil Solid waste pumped and landfilled
46. Wastewater Treatment Plant Preliminary Treatment Large objects screened Primary treatment Solids and scum removed in settling tank or clarifier – often aided by flocculant Secondary treatment Water aerated so microbes can digest organics Disinfection with chlorine and/or uv light Discharged to river May still have high levels of nitrates/phosphates and other contaminants
47. Tertiary treatment Advanced treatment of water – beyond chlorination – to remove other contaminants such as nitrates or phosphates. Eg. phytoremediation
48. Water Purification Goal is to produce potable water from relatively pure water in reservoirs Not necessary for most wells Process: Large material screened Flocculant (alum) added to removed suspended solids Settling tank – solids settle out and are removed as sludge Sand filter – aeration to remove organics and additional filtering Chlorination to kill any remaining pathogens Optional - fluoride