Water pollution


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Water pollution

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Water pollution

  1. 1. 1 Water Pollution
  2. 2. 2 Definition = physical, chemical, biological changes in water quality that adversely affect living organisms. (i.e., degradation) Types: Infectious Agents Oxygen-Demanding Wastes Inorganic Pollutants Organic Chemicals Sediment (Particulates) Thermal Pollution
  3. 3. 3 Infectious Agents Infectious Agents = pathogenic organisms. Water-borne diseases from infectious agents include typhoid, cholera, bacterial and amoebic dysentery, polio, infectious hepatitis, guinea worm and schistosomiasis. Due to lack of sanitation. Analyze coliform bacteria (E. coli). Presume if coliform bacteria are present, infectious pathogens are also present.
  4. 4. 4 Key Concepts  Types, sources, and effects of water pollutants  Major pollution problems of surface water  Major pollution problems of groundwater  Reduction and prevention of water pollution  Drinking water quality
  5. 5. 5 Types, Effects, and Sources of Water Pollution • Water is polluted by infectious bacteria, inorganic and organic chemicals, and excess heat. • Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms. • The WHO estimates that 3.4 million people die prematurely each year from waterborne diseases. • In the U.S., an estimated 1.5 million people a year become ill from infectious agents.
  6. 6. 6 • Scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms. • One method of measuring water quality involves measuring the number of colonies of fecal coliform bacteria present in a water sample. • Drinking water should not contain any colonies/100 milliliters, • Chemical analysis includes checking inorganic and organic chemicals present, sediment content, and turbidity of water. • Indicator species are living organisms that are monitored to determine levels of pollution.
  7. 7. 7 Sources of Water Pollution Point sources Nonpoint sources Water quality
  8. 8. Supply of Water Resources Freshwater Readily accessible freshwater Biota 0.0001% Rivers 0.0001% Atmospheric water vapor 0.0001% Lakes 0.0007% Soil moisture 0.0005% Groundwater 0.592% Ice caps and glaciers 0.592% 0.014%
  9. 9. 9 Inorganic Pollutants Nonmetallic Salts: Arsenic from mining or drainage of desert soils Causes: - anemia - cancer - death. Sodium Chloride: Salinization Acids: Sulfur and nitrogen compounds from coal. Causes: - pH changes which affect species - leaches aluminum
  10. 10. Evaporation and transpiration Evaporation Stream Infiltration Water tableInfiltration Unconfined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Ground Water Fig. 15-3 p. 308
  11. 11. Use of Water Resources  Humans use about 54% of reliable runoff  Agriculture  Industry  Domestic  Power plants Industry 11% Public 10% Power cooling 38% Agriculture 38%
  12. 12. 12 Point and Nonpoint Sources NONPOINT SOURCES Urban streets Suburban development Wastewater treatment plant Rural homes Cropland Factory Animal feedlot POINT SOURCES
  13. 13. 13 Sources of water pollution The leading sources of water pollution are agriculture, industries, and mining. 1. Agricultural activities are the leading cause of water pollution from erosion, overgrazing, fertilizers and pesticides, and excess salt from irrigated soils. 2. Industrial facilities are another large source of water pollution, and mining is a third source.
  14. 14. 14 • One of every five people in the world lacks access to safe drinking water. • Ninety-five percent of people in developed countries and 74% of people in developing countries have access to clean drinking water. • In a warmer world, too much rain and too little rain can increase water pollution.
  15. 15. 15 Pollution of Freshwater Streams Streams can recover from moderate levels of degradable water pollutants if the flows are not reduced. 1. A combination of dilution and biodegradation can allow recovery of stream pollution 2. The breakdown of pollutants by bacteria creates an oxygen sag curve. Organisms that have a high oxygen demand can’t survive in the curve. 3. Volume of the stream, volume of wastes entering, flow rate, temperature, and pH levels all affect how great a sag curve is produced.
  16. 16. 16 Oxygen Sag Curve
  17. 17. 17 Water Pollution: Now Most developed countries have reduced point source pollution, but toxic chemicals and pollution from non-point sources are still problems. Stream pollution in most developing countries is a serious and growing problem. Half of the world’s 500 major rivers are heavily polluted, and most of them run through developing countries where waste treatment is minimal or nonexistent. For example: Religious beliefs, cultural traditions, poverty, little economic development, and a large population interact to cause severe pollution of the Ganges River in India.
  18. 18. 18 Pollution of Lakes
  19. 19. 19 Groundwater Pollution: Causes  Low flow rates  Few bacteria  Cold temperatures Coal strip mine runoff Pumping well Waste lagoon Accidental spills Groundwater flow Confined aquifer Discharge Leakage from faulty casing Hazardous waste injection well Pesticides Gasoline station Buried gasoline and solvent tank Sewer Cesspool septic tank De-icing road salt Water pumping well Landfill  Low oxygen
  20. 20. 20 Pollution of Groundwater Experts rate groundwater pollution as a low-risk ecological problem; it is rated as a high-risk health problem. The extent of groundwater contamination is generally unknown Prevention is the most effective and affordable way to protect groundwater from pollutants.
  21. 21. 21 Ocean Pollution Fig. 22-11 p. 504
  22. 22. Problems with Using Groundwater  Water lable lowering  Depletion  Subsidence  Saltwater intrusion Chemical contamination  Reduced stream flows
  23. 23. Groundwater Pollution • >70,000 chemicals are used not; effects of many are not known • Each year another 700-800 new chemicals are produced • 55 million tons of hazardous chemical wastes are produced in the US each year • The 20 most abundant compounds in groundwater at industrial waste disposal sites include TCE, benzene, vinyl chloride…all are carcinogens, and also affect liver, brain, and nervous system
  24. 24. Kinds of Water Pollution • Inorganic Pollutants • Organic Pollutants • Biologic Pollutants
  25. 25. Inorganic Pollutants • Examples: • Pb in gasoline • Radionuclides • Phosphorus, nitrogen (Great Lakes) • Other heavy metals
  26. 26. Inorganic Pollutants • 3 groups • 1) Produce no health effects until a threshold concentration is exceeded—e.g., NO3 at , 50mg/liter; at higher levels: methaemoglobinaemia • 2) No threshold—e.g.—genotoxic substances: some natural and synthetic organic compounds, microorganic compunds, some pesticides, arsenic • 3) Essential to diets: F, I, Se—absence causes problems, but too much also causes problems
  27. 27. Inorganic Trace Contaminants • Mercury—methyl Hg and dimethyl Hg in fish—probably most significant path to humans—Minamata Bay, Japan, 1950’s • Rhine River drains 185,000 sq km—heavily polluted by 1970’s • Lead—toxicity has been known for a long time – 1859 book – Tetraethyl lead—anti-knowck additive for gas, 1930-1966
  28. 28. 29 Oil Spills Sources: offshore wells, tankers, pipelines and storage tanks Effects: death of organisms, loss of animal insulation and buoyancy Significant economic impacts Mechanical cleanup methods: skimmers and blotters Chemical cleanup methods: coagulants and dispersing agents
  29. 29. 30 Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources Reduce runoff Buffer zone vegetation Reduce soil erosion Clean Water Act Water Quality Act
  30. 30. Reducing Water Pollution through Sewage Treatment • Primary and Secondary sewage treatment. Figure 20-19