Measuring Dissolved Oxygen

This measurement must be done very carefully.  There are many steps.  All group members should know the steps, so they can check on the results as it happens.

There are 2 stages to this test.  Each stage has many steps.

All group members who are not actively doing the test should take notes on what happens, and anything that seems to go wrong.  All members of the group are doing the test, not just one or two people.

The Importance of Dissolved Oxygen

    Dissolved oxygen is used by many organisms to live. Although water is composed of two parts hydrogen to one part oxygen, the oxygen cannot be used by organisms.  This is because the oxygen and hydrogen are bonded together, and the oxygen needs to be free for the organisms to breathe.  Dissolved oxygen comes from oxygen in the atmosphere that becomes trapped in small spaces in water, similar to when you dissolve sugar or salt in water.  Stagnant water or water that does not flow or move over time, gradually becomes depleted of oxygen.  Without oxygen the organisms in the ponds die, leaving a lifeless pond.

Stage 1 - Collecting the Water Sample

• Get a sample bottle.
• Label the bottle as instructed.
• Use the provided water sampler to collect sample.
• Sample the area you have been assigned to by your instructor.

Stage 2 - Testing For Dissolved Oxygen

• Return to the laboratory at the main center.
• Follow the instructions at your lab station for the specific equipment that is found at your lab
• Record your data on the grid for your class
• Clean and return all equipment as instructed.