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Water Unit

Water Unit. Aquifers. Porous, water bearing layers of sand, gravel and/or rock below earth’s surface Reservoirs for groundwater Latin: Aqua = Water Ferre = To bring. 2 Types of Aquifers. CONFINED. UNCONFINED. Water is in sandy/gravelly soil

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Water Unit

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  1. Water Unit

  2. Aquifers • Porous, water bearing layers of sand, gravel and/or rock below earth’s surface • Reservoirs for groundwater • Latin: Aqua = Water Ferre = To bring

  3. 2 Types of Aquifers CONFINED UNCONFINED Water is in sandy/gravelly soil Impermeable layer (ex: solid rock) is beneath the water, but not above Most common type • Water is in porous, fractured rock • Can be artesian (under pressure) • Water is sandwiched between two impermeable layers

  4. 2 factors determine productivity: • Porosity – The amount of water it can hold 2. Permeability – The ability of water to flow through it

  5. Ogallala! • Largest aquifer on earth • Beneath 8 states, extending from N. Dakota to Texas • Once held more water than all of the freshwater lakes, rivers and streams on earth combined • Excessive pumping has left no water in some peripheral places

  6. Groundwater Depletion • Aquifer recharge can take thousands of years Depletion Examples: • Cone of Depression • Saltwater Intrusion • Subsidence / Sinkholes

  7. Cone of Depression and Saltwater Intrusion

  8. Subsidence Sinkholes Surface craters caused by collapse of an underground channel

  9. Rivers Riparian Zone – The river and its stream banks

  10. Watershed All the land drained by a river The area retains rainwater and lessens downstream flooding when vegetated Case Study: Unregulated timber cutting along Yangtze caused 30,000 deaths due to flooding

  11. How to Improve Watershed Management: Less development along floodplains Retain “crop residue” on fields Minimize plowing and forest cutting on slopes “Buffer zones” of vegetation near waterways

  12. Earth’s Largest Rivers • Discharge rate – the amount of water that passes a fixed point over a given amount of time. Amazon – Brazil, Peru (175,000 m3/sec) Orinoco – Venezuela (45,300 m3/sec) Yangtze – Tibet, China (28,000 m3/sec) Mississippi – US (18,400 m3/sec)

  13. Case Study: 3 Gorges Dam • Largest dam in the world • 1.2 million people relocated • Fragile ecosystems and rare species indigenous to that area were flooded • Reservoir flooded thousands of villages • Triggering landslides • Dam is constructed above a fault line

  14. 3 Gorges Dam

  15. Lake Stratification(draw it.)

  16. Point Source Pollution: When a pollutant is identified as coming from a specific source Plume – contaminants that seep from a concentrated mass. Ex’s: smoke from a chimney, image to the right 

  17. Non-Point Source Pollution Pollution that does not have a specific point of origin Ex: parking lots, residential lawns

  18. POLLUTION Point-Source Non-Point Source Examples: Runoff/erosion from farms Parking lots Feedlots Atmospheric deposition Examples: • Leaky landfill • Leaky septic system • Thermal pollution

  19. Atmospheric Deposition • Contaminants get into air and are redeposited via rain • Normal rain: pH ~ 5.6 • Acid Rain: pH <5 • Acid Precipitation leaches out naturally occurring Al, Hg • Has left 600,000 kg of Atrazine (an herbicide) in the great lakes

  20. Pollution Consequences • pH – acidity can be caused by industry waste, acid rain, mine tailings (esp. coal due to high S content) • N,P,K – concentrations elevate upon influx of fertilizer, manure… • Oxygen level – measured in ppm. Air gets into water via Ps (photosynthesis) and wave action. • O2 and BOD have an inverse relationship

  21. (PolltnConsq. cont.) Thermal Pollution: Heat in water Hot water can hold less O2 than cold water Sources: Power plants Industrial coolant Your gutters

  22. (PolltnConsq.) Turbidity (a.k.a. cloudiness) Increases due to presence of sediment and runoff, which use up O2 during decomposition Turbidity itself isn’t necessarily bad. However, it is often present in connection with pathogenic organisms or an excess of decomposing material. Particles can bond with toxic substances, transporting them and complicating removal

  23. (PolltnConsq)Infectious Agents • Viruses, Bacteria • Source: us and the animals • Ex: Coliform • Multiple types of coliform, all originate in intestines • Fecal Coliform – not necessarily pathogenic, but in high levels is associated with other pathogenic bacteria

  24. Oxygen Demanding Waste Oxygen Sag Curve Organic waste uses up O2 in water during decomposition 6-10ppm is considered healthy O2 level Example organic wastes: Leaves Food from processing plants Sewage

  25. Draw Oxygen Sag Curve

  26. Cultural Eutrophication Dead Zone • Increased nutrition that enters a water body, ultimately resulting in a lowered oxygen level. 1. Increased nutrients enter a water body. 2. Causes an unsustainable algal bloom and overgrowth of phytoplankton 3. Algae and phytoplankton use up available oxygen when they decompose. 4. Fish suffocate.

  27. Eutrophication cont. • Can be due to: • Increased nutrients, esp. N and P • Ex: agricultural manure, fertilizer • Elevated temperature • Ex: Thermal pollution/increased sunlight (which triggers unsustainable algae growth, begins cycle…)

  28. Gulf of Mexico “Dead Zone”

  29. Eutrophication Natural Cultural

  30. Blue Baby Syndrome • Caused by excess nitrates in water • Nitrates bind to red blood cells…especially harmful to infants • Causes baby to appear bluish due to lack of O2 reaching cells (suffocation) • Can cause death • Many of Iowa’s “cornbelt” wells are nitrate contaminated

  31. Toxic Tide/Red Tide(polltn cont.) • Caused by dinoflaggelates – unicellular, photosynthetic microorganisms • Population bulge can be due to natural causes or due to excess nutrients in waterbody • Ex: pfiesteriapiscicida – poisonous to eat or breathe (causes memory loss, confusion, acute skin burning, lesions…)

  32. Radioactive Materials (polltn. Cont.) Sources: mining, ore processing, power plants, or can be naturally occurring Ex: Cs, Th, U

  33. Inorganic Chemicals (polltn. cont.) • Ex: Hg, Sn, Pb, Cd, Ni, As, Se • Are often bioaccumulators (increase in concentration as you move up the food chain) • ppm levels can be fatal to humans • Sources: household cleaners, industrial effluent • Ex: panning for gold in Amazon River. (use Hg to bind to Au, then burn off Hg using torch)

  34. Organic Chemicals (polltn. cont.) • Ex: Pesticides, pharmaceuticals, plastics, pigments…(organic = Carbon) • Estrogen in birth control pills is affecting river life • Causes genetic defects (see p.455, photos 20.8, 20.9) • 2 main sources: 1. Improper disposal of household/industrial waste 2. Runoff from fields, farms, etc.

  35. Pollution Solutions • Use less fertilizer (use compost, leave clippings…) • Establish buffer strips • Keep livestock and feedlots away from streams • Perform crop rotation • Corn   soybeans • Use contour plowing • Irrigate at night • Use drip irrigation

  36. Water Treatment General Processes: • Flocculation – use of a substance (ex: alum) that causes precipitates to coagulate and settle • Aeration – exposing the water to air • Percolation – the process of water settling through soil/gravel • Removes the large stuff and some bacteria • Disinfection – killing microorganisms prior to discharge • Done using UV light, O3 or Cl

  37. Rural Sewage Treatment -Septic tank and field

  38. Municipal Treatment (1o, 2o, 3o) • Primary: • Uses grates/screens and a grit chamber/settling tank to remove “solids”. • “Solid” stuff is termed “primary sludge”. Mmmm. • Secondary: • Aerates the sewage • Uses aerobic bacteria and protozoa to digest organic matter. • Tertiary: • Uses binding agents, artificial wetlands, lagoons to remove remaining impurities, esp. N and P

  39. Municipal Sewage Treatment– 1o, 2o, 3o

  40. Good News! • In spite of our growing population, we use 10% less water than we did in 1980 • Ex: • Water saving toilets • Low-flow shower heads • Gray water, aka “sullage” • Wastewater generated from sink, washing machine, etc. that can be re-used.

  41. Water Use and Waste • #1 domestic use of water: • Toilet. (40%) • #2 domestic use of water: • Shower/Bath (37%) • Nearly ½ of industrial water is used for cooling • Wasted heat! • Thermal pollution!

  42. Water Use and Waste (cont.) • #1 use of water globally: • Agriculture • CA Central Valley: • Subsidies covered cost for distribution • Farmers pay up to 1/10 of the actual cost to supply the water • Incentive to conserve….?

  43. Want More Water? Cloud Seeding. Chemical is injected into cloud, forcing ice crystals to form, grow and fall • Use of dry ice, Potassium Iodide, silver iodide, or hygroscopic salts to get clouds to release rain • Issues: • Loss of rain elsewhere • Contamination of water • Ecosystem disruption

  44. Want More Water? Desalinate. • Converts ocean or brackish water into freshwater by removing salts • Methods: • Distillation • Reverse osmosis (semi-permeable membrane) • 3-4x as expensive as other freshwater • Energy intensive • Saudi Arabia, Kuwait and United Arab Emirates account for 85% of all desalination plants

  45. Glen Canyon Dam

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