1. Water pollution 12/9/08

2. Desalination This is the removal of salt from seawater or other water of marginal quality

3. Desalination May be done by hastening evaporation from ocean water by adding heat and then condensing the vapor –Mimics the hydrologic cycle Also can force water through membranes to filter out salts –Reverse osmosis

5. Desalination Over 7500 facilities are operating worldwide, especially in the Middle East The largest plant is in Saudi Arabia, and produces 485 million L of freshwater every day The first reverse osmosis plant was built along the Colorado River, but was too expensive to operate and closed

6. Freshwater Pollution The World Commission of Water in 1999 concluded that over half the world’s major rivers are “seriously depleted and polluted, degrading and poisoning the surrounding ecosystems, threatening the health and livelihood of people who depend on them.”

7. Water Pollution Describes any matter or energy released into the environment, whether from human activity or natural sources, that causes undesirable impacts on the health and well-being of humans or other organisms Point sources—discrete locations, such as a factory or sewer pipe Nonpoint sources—comes from multiple inputs, such as farms, city streets, and residential neighborhoods

8. U.S. Clean Water Act Targeted industrial discharges and point- source pollution Reduced a large amount of the water pollution being done by industry and agriculture

9. Causes of water pollution Major problems are exposure to infectious disease organisms (pathogens) from drinking contaminated water –Also, not having enough water for effective sanitation The World Health Organization estimates that 3.2 million people die prematurely every year from infectious diseases spread by contaminated water or lack of water –It would cost $23 billion per year over 8-10 years to bring low-cost and safe drinking water and sanitation

10. Major Water pollutants Type/effectsExamplesMajor sources Infectious agents Cause diseases Bacteria, viruses, parasites Human and animal wastes Oxygen- demanding wastes Deplete dissolved oxygen needed by aquatic spp Animal wastes and plant debris Sewage, animal feedlots, food processing facilities, pulp mills

11. Major Water pollutants Type/effectsExamplesMajor sources Plant nutrients Causes excessive growth of algae and other spp Nitrates and phosphates Sewage, animals wastes, inorganic fertilizers Organic chemicals Adds toxins Oil, gasoline, plastics, pesticides, cleaning solvents Industry, farms, households

12. Major Water pollutants Type/effectsExamplesMajor sources Inorganic compounds Adds toxins Acids, salts, metal compounds Industry, households, surface runoff Sediments Disrupts photosynthesis, food webs, etc Soil, siltLand erosion Thermal Makes spp vulnerable to disease HeatElectric power and industrial plants

13. Detecting infectious agents Often, scientists measure the quantity of fecal coliform bacteria (ex, E. coli) in a water sample –Presence indicates that water has been exposed to human or animal wastes –Drinking=100mL sample=no colonies –swimming=100mL sample=≤200 colonies

14. Detecting infectious agents Scientists also use indicator species –Ex) cattails can be analyzed for pollution with fuels, solvents, and other organic chemicals –Ex) mussels feed by filtering water

15. Indicators of water quality Biological properties: –Presence of fecal coliform bacteria –Other indicator species such as algae and invertebrates Chemical properties: –Nutrient concentrations –Taste and odor –Hardness (high levels of Ca and Mg) –Dissolved oxygen levels

16. Indicators of water quality Physical characteristics –Turbidity (density of suspended particles –Water color –temperature

17. Pollution of streams Can recover rapidly from moderate levels of pollution through dilution The breakdown of degradable wastes be bacteria depletes dissolved oxygen and creates an oxygen sag curve –This reduces or eliminates populations of organisms with high oxygen requirements until the stream is cleaned

18. Stream pollution in developed countries Since the 1970s, laws have been passed that have increased the number and quality of waste-water treatment plants in the US These laws have reduced pollution levels to an impressive amount

19. Case study: Ohio’s Cuyahoga River It was so polluted that in 1959 and 1969 it caught fire and burned for several days Laws were then enacted limiting the discharge of industrial wastes into the river Today, the river is much cleaner and usable by boaters and fishers

20. Case study: Britain’s Thames River In the 1950s, it was a slowly flowing, smelly river Today, the river has made a remarkable recovery and the number of fish and water fowl species has increased

21. Problems in developed countries Fish kills and contaminated drinking water still occur Caused by: 1.Accidental or deliberate release of toxic inorganic and organic chemicals by industries or mines (and malfunctioning sewage treatment plants) 2.Nonpoint runoff of pesticides and excess plant nutrients from cropland and animal feedlots

22. Stream pollution in developing countries Often occurs from the discharge of untreated sewage and industrial wastes Half of the world’s 500 major rivers are heavily polluted 80-90% of the untreated sewage goes directly into rivers, which are then used for drinking and bathing

23. Case study: India’s Ganges River The Ganges is a holy river for Hindu people –They bathe, drink, and perform religious rituals About 350 million people live in the Ganges River basin –Most of their waste goes untreated into the water

24. Case study: India’s Ganges River Additionally, part of the Hindu belief is to cremate the dead and throw the ashes into the river –If people cannot afford the wood for cremation, they throw the bodies directly into the river

25. Case study: India’s Ganges River The Indian government plants to build wastewater treatment plants and to construct crematoriums –It also introduced 25000 snapping turtles to devour corpses –Most of the treatment plants are not working yet