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Water is vital for all living organisms, comprising about 60% of their cells. While water has unique properties essential for life, 97% of it is saltwater, leaving only 3% as freshwater, much of which is polluted or inaccessible. Access to clean drinking water is a critical issue, affecting over 1.4 billion people globally. This chapter explores the hydrologic cycle, sources of water pollution, and the importance of sustainable water management practices. It also discusses various types of water usage, pollution causes, and possible solutions to ensure safe water for all.
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Chapter 16 The Water Issue • Cells in all living organisms are 60% water • Water has number of useful properties • Molecules stick together • Great ability to separate other molecules • Heats and cools slower than most substances • Can be used to dissolve transport wastes • However needs to be clean for us to drink it • 97% of Water is in oceans—saltwater • 3% is Freshwater • 1.9% in ice and glaciers • 0.5% in groundwater • 0.02% in rivers and lakes • 0.01% in soil
Chapter 16 • Potable water—unpolluted freshwater that is of sufficient quality to drink • Some areas of world will exhaust water supplies in future • Water Pollution on a global scale renders 1.4 billion people without access to safe drinking water • Water Quality remains an issue in US
Chapter 16 Hydrologic Cycle • Major processes are evaporation and condensation. • Evaporation is changing liquid to gas • Condensation is gas to liquid • Evapotranspiration is evaporation of moisture from leaves after plants have pulled moisture from ground • Solar Energy drives the process
Chapter 16 Human Influences on Cycle • Irrigation/Cooling water from power plants increase evaporation • Removing vegetation increases runoff and decreases infiltration • Impervious cover increases this effect • Flooding increases with imperviousness • Creeks cease to flow in urban areas • Overuse of water resources is same as mining if use is greater than recharge/recovery • Surface water and ground water
Chapter 16 • Use versus Consumption of water • Use (Non-Consumptive) • lake-plant-you-toilet-wwtp-lake • Stays in local water cycle, used but not consumed • Consumption • Lake-pump-field-evaporation-condensation • Removed from local cycle • Rain falls elsewhere
Chapter 16 • Water Use by Category • Domestic • 90% provided by municipalities • Water is treated/disinfected • Use for drinking/bathing/washing/toilets/lawns • 70% non-consumptive 30% consumption • Agriculture • Irrigation for fields 80% of consumption in N. Amer • Number of methods • Can use lots of energy for pumping • Industry • 90% of water is non-consumptive use • Use-treat-discharge • Similar quantity but not necessarily quality
Chapter 16 • In Stream Use • Non-Consumptive • Hydroelectric • Recreation • Navigation • May negatively effect waterway because of changes in direction, time, volume of flow • Cold water releases from dams
Chapter 16 • Kinds and Sources of Water Pollution • Toxics • Kill organisms • Water unfit for consumption • Bio-accumulation • Organic matter • Broken down by microbes • Use up DO • BOD • Taste and odors • Pathogens • Disease causing organisms • Various bacteria • others
Chapter 16 • Nutrients • Nitrogen and phosphorus • Increase growth • Eutrophication • DO • Physical Particles • Sediment • Destroy habitat • Water clarity • Abrasive • Transport
Chapter 16 • How clean is clean? • Cannot eliminate all pollution • Law of Diminishing Returns? Improvement $$ Cost $$
Chapter 16 Sources of Pollution • Point Sources • Readily identifiable • Discharge pipes • Non-Point Source • Diffuse sources • Much more difficult to ID and control • Most point sources are identified and regulated. • Non-Point sources remain a difficult issue to address
Chapter 16 • Domestic Water Pollution • Storm water • Industrial waste • Home and commercial waste • Agricultural Water Pollution • Crops • CAFOs • Industrial Water Pollution • Easy to ID, well regulated, most under permits • WWTP-- in house or use city’s • Mining
Chapter 16 • Thermal Water Pollution • Use lake/river/ocean water to cool • Can affect organisms • Marine Oil Pollution • Exxon Valdez spilled 11 million gallons • Much more is released by less visible sources • 2/3 of releases come from • Runoff from streets • Improper disposal • Routine handling
Chapter 16 Waste Water Treatment • Primary • Physical process • Remove larger particles with screens • Smaller particles allowed to settle • Still lots of organics • Secondary • Biological process • Uses water from primary and adds DO and organisms—eat organics and fall out • Activated sludge
Chapter 16 • Sludge Disposal • Ocean dumping • Land application • Composting • Drying • Incineration • Landfilling • Disinfection • Chlorination followed by dechlorination • Can also use UV light
Chapter 16 • Tertiary Treatment • Removes dissolved pollutants • Used for nutrients • Techniques • Wetlands • Cropland, golf courses, etc • Aquatic greenhouses • In US most WWTP are at least Secondary plants- • Developing Countries?
