Elkhorn Slough Nitrogen Case Study – Interpreting Data

Consider the following questions:

  • What factors cause changes in estuarine salinity?
  • What are the possible sources of pollutants in estuarine waterways?
  • How does agriculture affect ocean chemistry?
  • What is eutrophication?

Have the students examine their graphs of salinity and nitrate concentration versus time.

  1. Is there a correlation between the two graphs?
  2. If so, describe the correlation and determine if they are related or is it coincidence?
  3. What is the cause of the fluctuation?
  4. Find tide data and compare the local tidal cycle with salinity and nitrate graphs. Are they correlated? If so, how?
  5. Find the normal level of nitrates in seawater in Monterey Bay.
  6. Could incoming seawater from Monterey Bay be the source of the nitrate levels found in Elkhorn Slough? Why or why not?
  7. Are there other possible sources of nitrates into the slough?
  8. What other environmental sources of nitrates exist in this watershed area? Explore nearby agriculture and development.
  9. Drainage from agricultural areas has been blamed for surface and groundwater contamination and eutrophication of bodies of water, mostly freshwater lakes and streams. After looking at the maps, what are the possible sources of the nitrate contamination. What would you do to prove your hypothesis?
  10. Describe other factors that may affect the slough’s chemistry.

Next Step: Communicating Results


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