1. Issue: Pollution, II Water

2. Water Pollution  Water is an essential part of our life- support system—indeed, it covers 71% of the surface of the globe

3. Water Pollution  It serves many, many functions in our lives, including:  Modifying the climate  90% of photosynthesis occurs in water  Most organisms are 90% water  It carries nutrients to cells, helps build cells and carries away waste  Helps dilute pollutants and carry them away

4. Water: Basis of Life  Consider the excitement of the Mars Rover

5. Water Pollution  We have discussed already the Hydrological Cycle by which water is purified, approximately taking 10 days

7. Water Pollution  The amount of water remains the same, about 80 trillion gallons  Of this 0.003% is available to us, and the supply is far from evenly distributed  Salt water is about 97% of the total  Of the remaining 3% much is tied up in ice, the atmosphere, in plants and in us  The rest is in groundwater

8. Where does the Water Go?  Around the world, three-quarters is used for agriculture, and this has increased 400% since 1940.  What about here in the USA?

10. Water in the USA  We use highly-purified water for: flushing toilets, washing cars, sprinkling lawns etc.  Our water efficiency is very low  We use about 90 gallons/day/person, which is three times domestic consumption worldwide, 20 x that in LDCs  The public wants drinking water, factories want to flush away waster, and farmers’ fields pour tons of nitrogen into rivers.

11. We have tried to expand resources by…  Building dams  Drilling into deeper and deeper groundwater  Desalinating seawater  Some people have suggested towing icebergs from the Polar regions.

12. Waste  By conservation alone we could save 50% of the water we use  By decreasing evaporation and seepage loss  Redesigning industry to be water efficient  Adjusting water price to reflect value

13. Water efficiency campaigns

14. Pollutants

16. What is the situation in the USA

17. What have we done about it?