PASCO ME-6937 Aquatic Productivity Bottles - Manual (Page 2)

M o d e l N o . M E - 6 9 3 7 S a m p l e A c t i v i t y
2
The CI-6542 Dissolved Oxygen Sensor works with a ScienceWorkshop interface.
See the PASCO catalog or the PASCO web site at www.pasco.com
for more information about PASCO sensors and interfaces.
Sample Activity
Measuring the Effects of Light Intensity on the Dissolved Oxygen Concentration
and Primary Productivity of an Algae Solution
Teacher Preparation
Materials: algae solution or pond water, test tube rack, sterile disposable pipet, large sterile container (9 L), Alga-Gro ® concen-
trate, Aquatic Productivity Bottles, wax pencil, sticker or marker, fluorescent light source
• Prepare algae culture (for 8 groups): Each group will need at least 1500 mL of algae culture. If you buy your
algae from a biological supply company, immediately remove it from the container when it arrives. Remove
the test tube from the container, place it in a test tube rack, and remove the cap. Use a disposable pipet to squirt
air bubbles into the test tube and then place the algae in a cool place with indirect light until ready to culture.
• When you are ready to make the culture, obtain a large, sterile container (at least 9 L). Mix all of the algae with
8 L of distilled water and 160 mL of Alga-Gro
®
concentrate. Stir to mix. Place the algae in a cool place in
direct light until ready to use. If you are making culture for a different number of groups, use 20 mL of
Alga-Gro
® per liter of water and test tube of algae.
• To prevent students from mixing up their bottles of algae after incubation, they should label the bottom of the
bottles. To save time, you can label the bottles prior to the lab. With a wax pencil, sticker or marker, write the
percentages of light on the bottom of each bottle (e.g., 0%, 25%, 50%, 75%, 100%).
• Set up a light source for incubation of the Aquatic Productivity Bottles: Place the bottles far enough from the
light source that they will not be heated. To ensure this, place your hand where you want the bottles to sit. You
should not feel any warmth from the light. Another option is to create a heat sink by placing a large, clear ves-
sel of water between the light source and the bottles.
• If you do not have access to an algae culture, you can use local pond water. In this case, no culturing is neces-
sary. Dissolved oxygen data will vary greatly depending upon the algae source. Pond water may have a higher
level of heterotrophic and decomposing organisms than pure algae culture. These organisms consume oxygen
through respiration and can affect your results
Day One
Materials: algae culture, Dissolved Oxygen Sensor and PASCO Interface, wash bottle, Aquatic Productivity Bottles and rack, fluo-
rescent light, wax pencil, sticker or marker, paper towels
1. Start a new experiment on the data collection system.
2. Connect a dissolved oxygen (DO) sensor to the data collection system.
3. Display Dissolved Oxygen (mg/L) in a digits display.
4. Obtain approximately 1500 mL of algae culture.
ScienceWorkshop Interface Model
ScienceWorkshop 750 CI-7650
ScienceWorkshop 500 CI-6400
An option is to use the PS-2169
Water Quality Sensor with its
Dissolved Oxygen Probe.