{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture Chapter 11 - Water and Water Pollution Chapter 11...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Water and Water Pollution Chapter 11 Key Concepts Why is water so important? How much water is available? How much water are we using? What causes water shortages and what can be done? What causes floods and how can they be avoided? Sources, types, and risks of water pollution Preventing and reducing water pollution Sustainable use of water resources Water Conflicts in the Middle East Fig. 11-1, p. 236 Importance and Availability of Water Why is water so important? Earth as a watery world Water as a wasted resource Tiny fraction of Earth' water is fresh Hydrologic cycle Water pollution Water haves and have-nots Earth's Water Budget All water Fresh water Readily accessible fresh water Groundwater 0.592% Biota 0.0001% Oceans and saline lakes 97.4% Fresh water 2.6% 0.014% Ice caps and glaciers 1.984% Lakes 0.007% Soil moisture 0.005% Rivers 0.0001% Atmospheric water vapor 0.001% Fig. 11-2, p. 238 Groundwater Zone of saturation Water table Aquifers Natural recharge Groundwater Systems Unconfined Aquifer Recharge Area Precipitation Confined Recharge Area Evaporation and transpiration Evaporation Runoff Flowing artesian well Water table Recharge Unconfined Aquifer Stream Well requiring a pump Lake Infiltration Infiltration Unconfined aqu ifer Confining impermea ble rock laye Less permeable material such as clay Confined aquifer r Fig. 11-3, p. 239 Use of Water Resources Runoff use: about 54% Freshwater use US freshwater resources Domestic, agricultural, and industrial use Annual Precipitation and Water-deficit Regions of the Continental US Fig. 11-4a, p. 240 Water Hot Spots in Western States Wash. Montana Oregon Idaho Wyoming Nevada Utah California N.M. Texas Highly likely conflict potential Substantial conflict potential Moderate conflict potential N.D. S.D. Neb. Colo. Kansas Oak. Unmet rural water needs Fig. 11-5, p. 240 Freshwater Shortages Causes of water scarcity: dry climate and too many people Stresses on world's major river systems 1 of 6 people have no regular access to clean water Poverty hinders access to water Hydrological poverty Stress on World's River Basins Europe North America Asia Africa South America Stress High None Australia Fig. 11-6, p. 241 Hydrological Poverty Fig. 11-7, p. 241 Politics and Ethics of Water Who should pay for the water? Public or private ownership Increasing Freshwater Supplies Dams and reservoirs Extracting groundwater Desalination Reducing water waste Importing food Importing water Catching precipitation Tradeoffs of Large Dams and Reservoirs Large losses of water through evaporation Flooded land destroys forests or cropland and displaces people Migration and spawning of some fish are disrupted Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Provides water for year-round irrigation of cropland Downstream flooding is reduced Fig. 11-8, p. 243 Ecological Services of Rivers NaturalCapital Ecological Services of Rivers Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife Fig. 11-9, p. 243 California Water Project and Central Arizona Project CALIFORNIA Shasta Lake Sacramento River North Bay Aqueduct San Francisco South Bay Aqueduct San Luis Dam and Reservoir California Aqueduct Santa Barbara Los Angeles San Diego NEVADA UTAH Oroville Dam and Reservoir Feather River Lake Tahoe Sacramento Hoover Dam and Reservoir (Lake Mead) Los Angeles Aqueduct Colorado River Aqueduct Colorado River ARIZONA Central Arizona Project Phoenix Sa nJ oa Fresno Va lle y qu in Salton Sea Tucson MEXICO Fig. 11-10, p. 244 Aral Sea Disaster Large-scale water transfers in dry central Asia Salinity Wetland destruction and wildlife Fish extinctions and fishing Wind-blown salt Water pollution Climatic changes Restoration efforts Shrinking Aral Sea Fig. 11-11, p. 245 Stranded Ship at the Aral Sea Fig. 11-12, p. 245 Tradeoffs of Withdrawing Groundwater Trade-Offs Withdrawing Groundwater Advantages Good source of water for drinking and irrigation Available year-round Exists almost everywhere Renewable if not overpumped or contaminated No evaporation losses Cheaper to extract than most surface waters Disadvantages Aquifier depletion from overpumping Sinking of land (subsidence) when water removed Polluted aquifiers unusable for decades or centuries Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into streams, lakes, estuaries, and wetlands Increased cost, energy use, and contamination from deeper wells Fig. 11-13, p. 246 Aquifer Depletion Groundwater Overdrafts: High Moderate Minor or none Fig. 11-14, p. 246 Saltwater Intrusion into Coastal Water Wells Major irrigation well Well contaminated with saltwater Fresh groundwater aquifer Water table Sea Level S r ate w alt Interface Saltwater Intrusion S or lo f ea Interface Normal Interface Fig. 11-15, p. 247 Groundwater Depletion Solutions Groundwater Depletion Prevention Waste less water Subsidize water conservation Ban new wells in aquifiers near surface waters Buy and retire groundwater withdrawal rights in critical areas Do not grow waterintensive crops in dry areas Reduce birth rates Control Raise price of water to discourage waste Tax water pumped from Wells near surface water Set and enforce minimum stream flow levels Fig. 11-16, p. 247 Desalination Removal of salts from ocean or brackish waters to produce useable water Distillation method Reverse osmosis method Used in 120 countries Major problems: high cost and a lot of brine wastes Research is needed Reducing Water Waste Benefits of water conservation Reduce leakage and save water Water prices, government subsidies, and waste Improve irrigation Using less water in homes and businesses Major Types of Irrigation Systems Drip Irrigation (efficiency 90-95%) Above- or below-ground pipes or tubes deliver water to individual plant roots. Gravity Flow (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river. Center Pivot (efficiency 80% with low-pressure sprinkler and 9095% with LEPA sprinkler) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Fig. 11-17, p. 249 Reducing Irrigation Water Waste Solutions Reducing Irrigation Water Waste Lining canals bring water to irrigation ditches Leveling fields with lasers Irrigating at night to reduce evaporation Using soil and satellite sensorsand computer systems to monitor soil moisture and add water only when necessary Polyculture Organic Farming Growing water-efficient crops using droughtresistant and salt tolerant crops varieties Irrigating with treated urban waste water Importing water-intensive crops and meat Fig. 11-18, p. 250 Reducing Water Waste Solutions Reducing Water Waste Redesign manufacturing processes Landscape yards with plants that require little water Use drip irrigation Fix water leaks Use water meters and charge for all municipal water use Use waterless composting toilets Require water conservation in water-short cities Use water-saving toilets, showerheads, and front-loading clothes washers Collect and reuse household water to irrigate lawns and nonedible plants Purify and reuse water for houses, apartments, and office buildings Fig. 11-19, p. 250 Using Water More Sustainably Blue revolution Cut waste Raise water prices Drier waste treatment Preserve forests Slow population growth Sustainable Water Use Solutions Sustainable Water Use Not depleting aquifers Preserving ecological health of aquatic systems Preserving water quality Integrated watershed management Agreements among regions and countries sharing surface water resources Outside party mediation of water disputes between nations Marketing of water rights Raising water prices Wasting less water Decreasing government subsides for supplying water Increasing government subsides for reducing water waste Slowing population growth Fig. 11-20, p. 251 Benefits of Floodplains Highly productive wetlands Provide natural flood and erosion control Maintain high water quality Recharge groundwater Fertile soils Nearby rivers for use and recreation Flatlands for urbanization and farming Dangers of Floodplains and Floods Deadly and destructive Human activities worsen floods Failing dams and water diversion Bangladesh Before and During a Flood in St. Louis, Missouri Fig. 11-22, p. 252 Flooding After Deforestation of a Hillside Fig. 11-23, p. 253 Reducing Flood Risks Channelization Levees (floodwalls) Dams Protect and restore wetlands Identify and manage flood-prone areas Precautionary approach Water Pollution: Types, Effects, and Sources What is water pollution? Major types of pollutants, sources and effects (Table 11-1, p. 254) Point and nonpoint sources Is the water safe to drink? Polluted Streams Factors influencing stream recovery from pollution Oxygen sag curve Importance of wastewater treatment plants Improvements in quality of US streams Cuyahoga River of Ohio Effect of regulations in US Pressures from US citizen groups Problems with nonpoint, accidental and illegal releases Problems in developing countries Pollution in Streams Trash fish Normal clean water organisms (carp, gar, (trout, perch, bass, Types of leeches) mayfly, stonefly) organisms Dissolved oxygen (ppm) Biological oxygen demand Clean Zone Decomposition Zone 8 ppm Fish absent, fungi, sludge worms, bacteria (anaerobic) Normal clean water organisms (trout, perch, bass, Trash fish mayfly, stonefly) (carp, gar, leeches) 8 ppm Clean Zone Septic Zone Recovery Zone Fig. 11-24, p. 256 Lake Pollution Dilution less effective than with streams Stratification in lakes and relatively little flow hinder rapid dilution of pollutants Lakes more vulnerable to pollutants than streams How pollutants enter lakes Eutrophication: causes and effects Oligotrophic and eutrophic lakes Cultural eutrophication Preventing or removing eutrophication Oligotrophic and Eutrophic Lakes Fig. 11-25, p. 257 Groundwater Pollution: Causes and Persistence Sources of groundwater pollution Slow flowing: slow dilution and dispersion Consequences of lower dissolved oxygen Fewer bacteria to decompose wastes Cooler temperatures: slow down chemical reactions "Degradable" and nondegradable wastes in groundwater Groundwater Pollution Polluted air Hazardous waste injection well Buried gasoline and solvent tank Gasoline station Water pumping well Landfill Sewer Cesspool septic tank Leakage from faulty casing r ate ifer qu a Pesticides and fertilizers Coal strip mine runoff De-icing road salt Pumping well Waste lagoon Accidental spills Discharge Confined aquifer Groundwater flow e r fin ate on nc hw U res df ne nfi Co re df shw ifer qu a Fig. 11-26, p. 258 Extent of Groundwater Pollution Not much is known about groundwater pollution Organic contaminants, including fuel leaks Arsenic Protecting groundwater: Prevention is best Preventing and Cleaning Up Pollution in Groundwater Solutions Groundwater Pollution Prevention Find substitutes for toxic chemicals Keep toxic chemicals out of the environment Install monitoring wells near landfills and underground tanks Require leak detectors on underground tanks Ban hazardous waste disposal in landfills and injection wells Store harmful liquids in aboveground tanks with leak detection and collection systems Cleanup Pump to surface, clean, and return to aquifer (very expensive) Inject microorganisms to clean up contamination (less expensive but still costly) Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed) Fig. 11-27, p. 259 Ocean Pollution How much pollution can oceans tolerate? Some pollutants degrade and dilute in oceans Ocean dumping controversies Coastal Water Pollution Industry Nitrogen oxides from autos and smokestacks; toxic chemicals, and heavy metals in effluents flow into bays and estuaries. Cities Toxic metals and oil from streets and parking lots pollute waters; sewage adds nitrogen and phosphorus. Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilization from lawns adds nitrogen and phosphorus. Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Farms Run off of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Red tides Excess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals. Closed shellfish beds Closed beach Oxygen-depleted zone Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Fig. 11-28, p. 260 Oxygen-depleted Water in the Gulf of Mexico Mississippi River Basin Ohio River Mississippi River Missouri River LOUISIANA Mississippi River Depleted Oxygen Gulf of Mexico Fig. 11-29, p. 261 Chesapeake Bay Largest US estuary Pollution "sink" Oxygen depletion Chesapeake Bay Program Fig. 11-30, p. 261 Chesapeake Bay NEW YORK Cooperstown PENNSYLVANIA ATLANTIC OCEAN NEW JERSEY Harrisburg MARYLAND WEST VIRGINIA Baltimore Washington DELAWARE Richmond VIRGINIA Norfolk Chesapeake Bay Drainage basin No oxygen Low concentrations of oxygen Fig. 11-30, p. 261 Effects of Oil on Ocean Life Crude and refined petroleum Tanker accidents and blowouts Exxon Valdez Volatile hydrocarbons kill larvae Tar-like globs coat birds and marine mammals Oil destroys insulation and buoyancy Heavy oil sinks and kills bottom organisms Coral reefs die Slow recovery Oil slicks ruin beaches Limited effectiveness of clean up methods Preventing and Cleaning Up Pollution in Coastal Waters Solutions Coastal Water Pollution Prevention Cleanup Reduce input of toxic pollutants Separate sewage and storm lines Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters Ban ocean dumping of sludge and hazardous dredged material Protect sensitive areas from development, oil drilling, and oil shipping Regulate coastal development Recycle used oil Improve oil-spill cleanup capabilities Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful byproducts (still under development) Require at least secondary treatment of coastal sewage Use wetlands, solar-aquatic, or other methods to treat sewage Require double hulls for oil tankers Fig. 11-31, p. 263 Preventing Nonpoint Source Pollution Mostly agricultural wastes Use vegetation to reduce soil erosion Reduce fertilizer use Use plant buffer zones around fields Integrated pest management: Only use pesticides when necessary Use plant buffers around animal feedlots Keep feedlots away from slopes, surface water and flood zones Laws for Reducing Point Source Pollution Clean Water Act Water Quality Act Discharge trading controversies Sewage Treatment Systems Sewage treatment in rural and suburban areas Septic tanks Primary (physical) sewage treatment Secondary (biological) sewage treatment Urban sewage treatment (Clean Water Act) Sewage treatment facilities in many cities fail to meet federal standards Bleaching and disinfection Disinfectants: chlorine, ozone, and ultraviolet radiation Typical Septic Tank System Septic tank with manhole (for cleanout) Household wastewater Nonperforated pipe Distribution box (optional) Gravel or crushed stone Drain field Vent pipe Perforated pipe Fig. 11-32, p. 264 Primary and Secondary Sewage Treatment Primary Bar screen Grit chamber Settling tank Aeration tank Secondary Settling tank Chlorine disinfection tank Sludge Raw sewage from sewers Activated sludge Air pump Sludge digester (kills bacteria) To river, lake, or ocean Sludge drying bed Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Fig. 11-33, p. 265 Improving Sewage Treatment Systems that exclude hazardous wastes Non-hazardous substitutes Composting toilet systems Working with nature to treat sewage Using wetlands to treat sewage Ecological Wastewater Treatment Fig. 11-34, p. 265 Should the Clean Water Act be Strengthened? Yes: environmentalists No: farmers, libertarians, manufacturers, and developers State and local officials want more discretion How Would You Vote exercise Drinking Water Quality Purification of urban drinking water Purification of drinking water in developing countries Bottled water Reducing Water Pollution Solutions Water Pollution Prevent groundwater contamination Greatly reduce nonpoint runoff Reuse treated wastewater for irrigation Find substitutes for toxic pollutants Work with nature to treat sewage Practice four R's of resource use (refuse, reduce, recycle, reuse) Reduce resource waste Reduce air pollution Reduce poverty Reduce birth rates Fig. 11-35, p. 267 ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online