Water Quality


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Water Quality

  1. 1. Chapter 9Chapter 9 Water Quality
  2. 2. Learning ObjectivesLearning Objectives By the end of this chapter the reader will be able to: • Describe sources of potable water • Define what is meant by the hydrological cycle • List hazardous substances that may be found in drinking water • Describe how water is made safe for human consumption • Discuss hazards to the aquatic environment (oceans, lakes, rivers) associated with environmental pollution
  3. 3. Water FactsWater Facts • A human can live up to a month without food but can survive for about a week without water. o Necessary for physiologic processes o About two-thirds of the human body is made up of water. • Average requirement for human consumption of water per day is approximately 2 ½ quarts (80 oz). o Should be potable
  4. 4. Water Use in the U.S.Water Use in the U.S. • Average person uses about 100 gallons (about 400 liters) of water per day. • Average residence uses over 100,000 gallons (about 400,000 liters) during a typical year. • Most of this household water (50%-70%) is used for outdoor purposes such as watering lawns and washing cars.
  5. 5. IssuesIssues • 20% of the worlds population lack access to safe drinking water • The U.S. has one of the safest supplies of drinking water in the world… • …but have demonstrated that we are susceptible to problems o Short term disease outbreaks o Water restrictions due to drought o Chemicals have been found in the supply • Perchlorate and trihalomethanes levels pose dangerous side effects
  6. 6. Figure 9-3: A slum in Ecuador that was heavily affected by cholera due to its proximity to unsafe water sources.
  7. 7. Surface Water SupplySurface Water Supply • Any water that is drawn from the surface o As water runs over land on the way to streams, lakes, or rivers to the sea, it may pick up various contaminants on the way • Road salts and chemicals, fertilizers, human waste, etc • Must be filtered before it is potable • Cistern o Large tank that captures water from a rooftop or ground source o Limited by rainfall and the size of the holding tank o Filtered before entering tank through a roof washer or sand filter
  8. 8. Figure 9-4Figure 9-4 Examples of surface waters.Examples of surface waters.
  9. 9. Ground Water SupplyGround Water Supply • Water that has been absorbed into the soil • For most places, surface water is insufficient to supply the needs of the inhabitants • Water below the surface flows within a layer of rock, sand, and soil called an aquifer o The upper level of water saturation is the water table o Water flow moves at various rates depending on the soil density o Shallow aquifer vs Fossil Aquifer • Also picks up the characteristics of what is in the soil o Biological contaminants from underground sewage or minerals in the soil o But biological contaminants are filtered naturally in the soil
  10. 10. Ground Water SupplyGround Water Supply • Digging below the surface is needed to supply water o Wells are used to supply water but should be placed away from sources of contamination o Dug wells • Walls of the well are supported to prevent them from caving in and surface contamination o Driven wells • Pipe driven into the ground and a surface pump is used to draw water up through the pipe • Usually less than 25 feet deep o Drilled wells • More common for public water source • May be drilled hundreds of feet deep • Turbine surface pumps or submersible pumps are used to bring water to the surface
  11. 11. Ground Water SupplyGround Water Supply
  12. 12. Ground Water SupplyGround Water Supply Groundwater Under the Direct Influence of Surface Water •“any water beneath the surface of the ground with substantial occurrence of insects or other macroorganisms, algae, or large- diameter, or substantial and relatively rapid shifts in water characteristics that closely correlate with climatologic or surface water conditions.”
  13. 13. Hydrological (Water) CycleHydrological (Water) Cycle • “The natural cycle by which water evaporates from oceans and other water bodies, accumulates as water vapor in clouds, and returns to oceans and other water bodies as precipitation.” • Only about 10% of the water that evaporates from the ocean falls back on land. • The Terrestrial cycle contributes about 35% back to the ocean as runoff.
  14. 14. Figure 9-6: The world’s water cycleFigure 9-6: The world’s water cycle
  15. 15. Water AvailabilityWater Availability • Although the earth’s surface (about 70%) is covered largely by water, most of this water is unusable ocean water. • Approximately 3% of all water is freshwater, of which the majority is unavailable for human use • Remaining 1% of readily accessible water comes from surface freshwater; sources include lakes, rivers, and shallow underground aquifers.
  16. 16. Source: From Vital Water Graphics: Freshwater Resources, by United Nations Environment Programme, © 2002, United Nations. Reprinted by permission of the publisher. Available at: http://www.unep.org/dewa/assessments/ecosystems/water/vitalwater/01.htm. Acce
  17. 17. Water Scarcity and Water StressWater Scarcity and Water Stress • Two sections of the world that currently have severe water shortages also are experiencing some of the highest population growth rates in the world. oAfrica (sub-Saharan and North) oNear East
  18. 18. Water Scarcity and Water StressWater Scarcity and Water Stress
  19. 19. Is it safe?Is it safe? • Safe Drinking Water Act in 1974 o Regulated by the EPA o Authorizes EPA to set enforceable health standards for contaminants in drinking water o Requires public notification of water systems violations and annual reports (Consumer Confidence Reports) to customers on contaminants found in their drinking water o Establishes a federal-state partnership for regulation enforcement o Includes provisions specifically designed to protect underground sources of drinking water o Requires disinfection of surface water supplies, except those with pristine, protected sources o Establishes a multi-billion-dollar state revolving loan fund for water system upgrades o Requires an assessment of the vulnerability of all drinking water sources to contamination (epa.gov for a complete list)
  20. 20. Treatment of Water forTreatment of Water for Residential ConsumptionResidential Consumption • Water supplied to the public in the U.S. undergoes treatment in order to meet quality standards set by the EPA for safe levels of chemical contaminants and waterborne microorganisms. • NJ American Water Treatment • Water Treatment Process
  21. 21. The Four Stages of WaterThe Four Stages of Water Treatment in Most PlantsTreatment in Most Plants 1. Coagulation–removes suspended material 2. Sedimentation–causes heavy particles to settle to bottom of tanks for collection 3. Filtration–removes smaller particles 4. Disinfection–kills bacteria or microorganisms
  22. 22. Fluoridation of WaterFluoridation of Water • Some communities in the United States add fluoride to public drinking water in order to prevent tooth decay. • Field trials conducted in the 1940s demonstrated a 50%-70% reduction in the prevalence of dental caries.
  23. 23. Treatment of Water from AquifersTreatment of Water from Aquifers • For high-quality water from aquifers, minimal aeration, filtration, and disinfection are necessary. • In some cases, water drawn from aquifers is free from microorganisms but undesirable for human consumption because of impurities and coloration that impair the esthetic qualities of this essential liquid.
  24. 24. Figure 9-15: Water filtration system for water from aquifer. A. Pump B. Bank of filters C. Samples of water before and after filtration Source: Courtesy of Irvine Ranch Water District, Irvine, California.
  25. 25. Water ContaminationWater Contamination Potential contaminants found in runoff include: •Chemicals and nutrients •Rubber, heavy metals, sodium Petroleum byproducts and organic •Chemicals used in the home •Heavy metals and toxic chemicals •Microbial pathogens
  26. 26. Figure 9-16: The urban water cycle: Man’s impact on groundwater. Source: From Vital Water Graphics: Freshwater Resources, by United Nations Environment Programme, © 2002 United Nations. Reprinted by permission of the publisher. Available at: http://www.unep.org/dewa/assessments/ecosystems/water/vitalwater/a3.htm. Acces
  27. 27. Waterborne DiseasesWaterborne Diseases • Conditions that are “transmitted through the ingestion of contaminated water and water acts as the passive carrier of the infectious agent.” • Examples are: o Cryptosporidiosis o Cholera o Certain viruses
  28. 28. CryptosporidiosisCryptosporidiosis • Chryptosporidium parvum is a protozoan pathogen that causes a diarrheal illness called cryptosporidiosis • May also be accompanied by abdominal cramping, nausea, vomiting, and fever. • The life cycle of the spore can be completed in the human host • Transmitted through ingesting contaminated water • Largest outbreak in the U.S. occurred in Milwaukee in 1993
  29. 29. Figure 9-18: This illustration depicts the life cycle of different species of Cryptosporidium, the causal agents of cryptosporidiosis.
  30. 30. AmebiasisAmebiasis • Entamoeba histolytica is a parasitic protozoan, estimated to infect about 50 million people worldwide annually • Usually transmitted by the fecal-oral route, but it can also be transmitted indirectly through contact with dirty hands or objects (food) as well as by anal- oral contact • Can create intestinal and extraintestinal problems
  31. 31. GiardiasisGiardiasis • Giardia lamblia is a flagellated protozoan parasite that colonizes and reproduces in the small intestine Infection can occur through ingestion of dormant microbial cysts in contaminated water, food, or by the fecal-oral route • Symptoms include loss of appetite, diarrhea, hematuria, loose or watery stool, stomach cramps, nausea, bloating, excessive gas, and burping • The cyst can survive for weeks to months in cold water
  32. 32. CyclosporiasisCyclosporiasis • Caused by protozoan Cyclospora cayetanensis, a pathogen transmitted by feces or feces- contaminated fresh produce and water. • After a one-week incubation the person begins to experience severe watery diarrhea, bloating, fever, stomach cramps, and muscle aches. • Emerging because traditional anti-protozan drugs are not sufficient
  33. 33. Bacterial EnteropathogensBacterial Enteropathogens • Escherichia coli o A bacterial infection that may lead to hemorrhagic diarrhea, and to kidney failure. o Transmission is via the fecal-oral route, and most illness has been through undercooked, contaminated ground beef or ground pork being eaten. • Vibrio cholerae o Bacterium that causes Cholera o Most commonly acquired from drinking water in which V. cholerae is found naturally or into which it has been introduced from the feces of an infected person. o Pandemic that is more prevalent in Asia, Africa, and Latin America o Untreated, has a 50% fatality rate.
  34. 34. Viral PathogensViral Pathogens • Over 100 kinds of viruses are found in human stools and pose a potential for transmission • Many are resistant to environmental conditions and traditional sewage treatment processes • Noroviruses are the most common cause of viral gastroenteritis in humans, and affect people of all ages o Transmitted by fecal-contaminated food or water; by person-to-person contact; and via aerosolization of the virus and subsequent contamination of surfaces • Viral Hepatitis A and E can be spread via the fecal- oral route by contaminated food and water o Can be mistaken for the flu; Symptoms usually last less than 2 months, although some people can be ill for as long as 6 months
  35. 35. Guinea WormGuinea Worm • A nodular dermatosis produced by the development of a Dracunculus parasite in the subcutaneous tissue of mammals • The parasite enters a host by way of host ingestion of stagnant water contaminated with guinea worm larvae. • Approximately one year later, the disease presents with a painful, burning sensation as the female worm forms a blister, usually on the lower limb. • Once endemic in over 20 countries in Asia and Africa, only four remaining endemic nations remain in Africa: Sudan, Chad, Mali and Ethiopia
  36. 36. Guinea WormGuinea Worm
  37. 37. Legionnaires’ DiseaseLegionnaires’ Disease • Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between 25 and 45 °C (77 and 113 °F) • Legionnaires' disease acquired its name in July 1976 when an outbreak of pneumonia occurred among people attending a convention of the American Legion at the Bellevue-Stratford Hotel in Philadelphia. • Can grow in domestic water systems, cooling systems, and stagnant water o Can be aerosolized
  38. 38. Chemicals in the HChemicals in the H22O SupplyO Supply • Some chemicals that have been reported to cause adverse health effects: o Aluminum o Arsenic o Disinfection by-products o Fluoride o Lead o Pesticides o Radon • Reported health effects have included: o Various cancers o Adverse reproductive outcomes o Cardiovascular disease o Neurological disease
  39. 39. ExamplesExamples • Nitrates from fertilizers o Prevents hemoglobin from transporting oxygen o More susceptible to infants, elderly, and ill o Do not boil water with nitrates • Lead o Household plumbing supply, natural occurrence, paint waste o Action level is .015 mg per liter • Exposure in kids result in delays in physical and mental development, along with slight deficits in attention span and learning abilities. • Adults who drink this water over many years could develop kidney problems or high blood pressure.
  40. 40. Chemicals in the HChemicals in the H22O SupplyO Supply • Pharmaceutical and personal care products (PPCPs) represent another source of water contamination. • They are washed off or excreted from the body. • Examples include: analgesics, oral contraceptive agents, drugs for lowering cholesterol, and anticonvulsants.
  41. 41. Water Disinfection ByproductsWater Disinfection Byproducts (DBPs)(DBPs) • Chemicals used to disinfect water include chlorine, chloramines, chlorine dioxide, and ozone. • These chemicals are associated with by-products of chlorination called DBPs. • Chlorine is associated with trihalomethanes (THMs), which are among the most common and widely measured DBPs. • Associated with frequency of late adverse pregnancy outcomes o Congenital anomalies o Other birth defects o Stillbirths o Neonatal deaths
  42. 42. Beach and Coastal PollutionBeach and Coastal Pollution • The approximately 1 billion people who live near coastal areas cause great stress on coastal ecosystems. • Coastal areas are threatened by over-development, poor planning, and economic expansion. Figure 9-24: Beach closing sign. With increasing levels of pollution in some areas, beach closings have become more frequent. • World’s coastal regions are the recipients of billions of gallons of treated and untreated wastewater.
  43. 43. Effects of Beach andEffects of Beach and Coastal PollutionCoastal Pollution • Excessive amounts of nutrients that enter the oceans may cause harmful blooms of algae, resulting in reduced levels of oxygen in the water (anoxic conditions). • An anoxic ocean environment can bring about fish kills and damage other forms of ocean life. • Urban runoff and sewage contamination of the ocean expose swimmers to waterborne diseases.
  44. 44. Petroleum SpillsPetroleum Spills • Oil spills from tankers and off-shore drilling platforms can have a devastating impact on the shoreline, aquatic life, mammals, and birds. o On March 24, 1989, the tanker Exxon Valdez ran aground in Alaska and caused the largest oil spill in U.S. waters as of that time. o On April 20, 2010, the Deepwater Horizon oil platform exploded, causing history’s largest accidental marine oil spill as of mid-2010.
  45. 45. Exhibit 9-1Exhibit 9-1 • Nonrenewable Water - “Water in aquifers and other natural reservoirs that . . . [is] not recharged by the hydrological cycle or . . . [is] recharged so slowly that significant withdrawal for human use causes depletion. Fossil aquifers are in this category.” • Renewable Water - “Freshwater that is continuously replenished by the hydrological cycle for withdrawal within reasonable time limits, such as water in rivers, lakes, or reservoirs that fill from precipitation or from runoff.” • “Artificial lakes, produced by constructing physical barriers across flowing rivers, which allow the water to pool and be used for various purposes. The volume of water stored in reservoirs worldwide is estimated at 4,286 km3 ….” • “Water originating as precipitation on land that then runs off the land into rivers, streams, and lakes, eventually reaching the oceans, inland seas, or aquifers, unless it evaporates first.” • Water Withdrawal - “Removal of freshwater for human use from any natural source or reservoir, such as a lake, river, or aquifer. If not consumed, the water may return to the environment and can be used again.” • “. . . a country faces water scarcity when its annual supply of renewable freshwater is less than 1,000 cubic meters per person.” • “Such countries can expect to experience chronic and widespread shortages of water that hinder their development.” • “A country faces water stress when its annual supply of renewable freshwater is between 1,000 and 1,700 cubic meters per person.” • “Such countries can expect to experience temporary or limited water shortages.” • “Wetlands include swamps, bogs, marshes, mires, lagoons and floodplains.”
  46. 46. The Earth’s 10 Largest WetlandsThe Earth’s 10 Largest Wetlands • West Siberian Lowlands • Amazon River • Hudson Bay Lowlands (in Canada) • Pantanal (in mid-South America) • Upper Nile River, Chari-Logone River (in Africa) • Hudson Bay Lowlands in the South Pacific • Congo River • Upper Mackenzie River (in northwestern Canada) • North America prairie potholes (wetlands made up of shallow depressions in the northern Great Plains)
  47. 47. Consumption andConsumption and ConservationConservation • 50 to 70% of residential water is used for outdoor activities • Average single family water use is around 70-90 gallons per day o 107,000 per year • On average use almost 2X as much water as other developed countries
  48. 48. Consumption andConsumption and ConservationConservation • Water utility conservation o Temporary cutbacks • Reduction of system-wide operating pressure • Water use bans and restrictions o Permanent conservation • Public education • Subsidizing use of flow control appliances, toilets, etc • Building codes that require water-efficient fixtures, etc • Leak detection surveys and repair
  49. 49. Consumption andConsumption and ConservationConservation • How can I conserve? o Stop leaks o Replace old toilets o Replace old clothes washers with EPA Energy Star models o Plant the kind of garden that requires less water o Install water capturing devices to irrigate lawn, etc o Turn it off when not in use