Monday Week Four

...some questions...

1. When you loose access to your tap water for over a week, should your water bill go up or down?

2. What is the limit (expressed as ppm) for humans (as an aggregate) for detecting dissolved solids (specifically, salt) in aqueous solutions (water). What is the limit (expressed as ppm) for humans (as an aggregate) for describing salt-water solutions as unpotable. How would you describe the variability with our human dataset with regard to these limits?

3.  How is TDS measured? Why do we use conductivity as a proxy for TDS? What are the advantages of using conductivity as a proxy for TDS; what are the disadvantages? What is a proxy? What are the advantages of using TDS (or conductivity) as a proxy for water quality; what are the disadvantages?

4. What are the effects on biodiversity on increases in TDS in freshwater streams? Is there a threshold?

5. Do cows need clean water?

6. Do crops need clean water? What happens if they don't get clean water? Do all crops have similar needs with regard to water quality?

7. What are some important TDS benchmarks for water quality?

Slides from today are on Sakai. Your reading for Wednesday is Drugging Our Waters by Elizabeth Royte published way back in 2006 (but still relevant) on the website of the Natural Resources Defense Council.Your most recent homework assignment (HW 4:your (other) CCR) is available on Sakai. It is due on Friday at the beginning of class. The directions therein should be pretty self explanatory; nevertheless, please let me know if you have any questions- particularly those of you who have difficulty finding their consumer confidence report/or data on the Environmental Working Group Tap Water Database 2009.