Water Pollution

Slide 1: Wate r Po llutio n Prepared by Shohail Motahir Choudhury Reference: G. Tyler Miller’s Living in the Environment 14th Edition 1

Slide 2: 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 2

Slide 3: 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. 3

Slide 4: • 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. 4

Slide 5: Sources of Water Pollution Point sources Nonpoint sources Water quality 5

Slide 6: Point and Nonpoint Sources NONPOINT SOURCES Rural homes Cropland Urban streets Animal feedlot POINT Suburban SOURCES Factory development Wastewater treatment plant 6

Slide 7: 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. 7

Slide 8: • 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. 8

Slide 9: 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. 9

Slide 10: Oxygen Sag Curve 10

Slide 11: 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. 11

Slide 12: Pollution of Lakes 12

Slide 13: The Great Lakes Fig. 22-8 p. 50013

Slide 14: Groundwater Pollution: Causes  Few bacteria  Low flow rates  Low oxygen  Cold temperatures Hazardous waste injection well Pesticides Coal strip De-icing Buried gasoline mine runoff road salt and solvent tank Cesspool Pumping Gasoline septic tank well station Waste lagoon Water pumping Sewer well Landfill Leakage from faulty Accidental casing spills fer qui Discharge ra ate shw ifer fre aqu Confined aquifer d ter ine nf a hw nco res Groundwater U f ned flow nfi Co 14

Slide 15: 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. 15

Slide 16: Ocean Pollution Fig. 22-11 p. 504 16

Slide 17: Case Study: Chesapeake Bay  Largest US estuary  Relatively shallow  Slow “flushing” action to Atlantic  Major problems with dissolved O2 17

Slide 18: Oil Spills Sources: offshore wells, tankers, pipelines and storage tanks Effects: death of organisms, loss of animal insulation and buoyancy, smothering Significant economic impacts Mechanical cleanup methods: skimmers and blotters Chemical cleanup methods: coagulants and dispersing agents 18

Slide 19: Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources Clean Water Act Reduce runoff Buffer zone vegetation Water Quality Act Reduce soil erosion 19

Slide 20: Technological Approach: Septic Systems Require suitable soils and maintenance 20

Slide 21: Technological Approach: Advanced (Tertiary) Sewage Treatment Uses physical and chemical processes Removes nitrate and phosphate Expensive Not widely used 21

Slide 22: Drinking Water Quality Purification of urban drinking water Protection from terrorism Purification of rural drinking water Safe Drinking Water Act Maximum contaminant levels (MCLs) Bottled water 22

Slide 23: Sustaining Biodiversity 23