Michigan Sea Grant Home Select Page

# Activity: Air Supply – Graphing Dissolved Oxygen

Summary: Students graph dissolved oxygen (DO) from the surface to the bottom of Lake Erie using real data collected from the lake.

You Need:

• 100 minutes (2 class periods of 50 minutes each)
• Graph paper
• Pencils
• Ruler
• DO data from surface to the bottom for six stations in Lake Erie:

## Procedure

Create groups of six students and assign a station to each student in each group.

• The six stations are 1047, e10, 968, E42, 1003 and 1190.

### Part 1 – As a class

• Determine the minimum and maximum depth for all of the stations.
• Determine a scale for plotting profiles (minimum and maximum depths and dissolved oxygen levels necessary to fit all data onto the graphs).
• Y-axis – 0 to 35 meters
• X-axis – 0 to 8 milligrams per liter (mg/l)
• Discuss reasons for setting ‘0’ at the top of the y-axis.
• 0 is the surface, the deepest station is 33 meters deep

### Part 2 – Each student

• Using graph paper, create a graph using the agreed upon scale.
• Y-axis – 0 to 35 meters
• X-axis – 0 to 8 mg/l o Label x-axis and y-axis.
• Create a title using the station ID number.
• Label the bottom of the lake at each station.
• For example, station E42 is 22 meters deep.
• Plot dissolved oxygen (mg/l) by depth (meters).