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Topic: Properties of the Ocean

Theme: Change

Is the ocean becoming saltier? If so, is that a problem? Dr. N. A. Seeal, a visiting research scientist on our ship, wants to know the answer to this and other perplexing questions about the ocean's salinity. He is enlisting the help of our ship and crew.

Problem:

Dr. N. A. Seeal says we must first find answers to the following questions:

  1. Why is the Ocean salty?
  2. Where does the salt come from?
  3. Is all ocean water salty?
  4. Which ocean/s is/are the saltiest?
  5. What affects how salty the ocean is?
  6. Is the ocean becoming saltier? Why or why not?
  7. Where would each ocean be least salty?

Mission:

Part I: Create a visual presentation of your findings! (i.e. pie charts illustrating the chemical composition of the ocean or oceans, line graphs of the three major oceans showing seasonal salinity readings or a comparison of the salinity of each of the oceans to one another) After all, Earth really has only one ocean. Oceanographers have broken it down into three major divisions: Atlantic, Pacific, and Indian. Why have they done this? What purpose does this division serve? (Some sources of information refer to four oceans. Oceanographers, however, consider there to be only three.)

Here are some sites that might help you:

  • NOAA National oceanographic Data Center (NODC)
    http://www.nodc.noaa.gov/General/salinity.html

**Note: You can produce your graphs using programs such as EXCEL or you may create them using graph paper, rulers, protractors, and compasses.

Part II: Now that you are armed with the knowledge you gained in the previous missiosn, you are now ready to solve the REAL problem. Scientists at the Oceanside Marine Lab are asking for your help. They have experienced a disaster. A hurricane hit the marine lab. All the water samples they had collected from their last three research trips have been soaked as they blew off into the forest behind the lab. The labels they had pasted on the plastic jars came off when they got wet. They have searched through the forest behind the lab and picked up as many intact sample jars as they could find.

Most of their lab equipment was damaged in the hurricane. They need suggestions from you as to how they can identify and label the water samples once again. The samples had small amounts of toxic substances added to them at the time they were collected to prevent bacterial growth, so you cannot taste the samples. One of the research trips was to an African lake that had formed in an extinct volcano in the jungle. The second trip was to an estuary in Mexico whre thae was a big city and many farms that grew produce for export. On the last trip the scientists collected samples from a healthy South Pacific coral reef.

GOOD LUCK and may the Sea Gods be with you!

Assessment:

You and your team will be assessed on the accuracy and clarity of your answers to Part I of your mission. You will be assessed on the cleverness and feasibility (capability of being done) of your answers to Part II.

**Note: The salinity problem presented in Part II was adapted from Living in Water: An Aquatic Science Curriculum for Grades 5-7 by the National Aquarium in Baltimore. (Activity 9 in Section II, pp. 63-65, The great salinity contest!) They can be reached at www.aqua.org/ Permission to adapte was granted by Valerie Chase.

Lesson Ideas created/adapted by Margaret Hammer (Graduate Research Assistant) and Judith Kenworthy (Technology Mentor Fellowship Associate) Texas A&M University. All comments and questions can be directed to stewart@ocean.tamu.edu