Dissolved Oxygen Levels at F.W. Kent Lake

These data show the changes in dissolved oxygen levels from various test locations over the summer months. Dissolved oxygen rates in bodies of water decrease from spring to summer. As the season progresses, the water temperature increases. As water temperature increases, dissolved amounts of any gas decrease (Le Chatelier’s Principle). Another observable phenomena is that some bodies of water have increased vegetation growth as the seasons progress. Increased vegetation can decrease the amount of dissolved oxygen. Finally, if ammonia levels are high, that can lead to a lower amount of dissolved oxygen in the body of water. Additional slides show the method of data collection as well as the full, raw datasets.

• What is causing dissolved oxygen amounts to decrease over the course of the spring and summer?

• What effect does temperature have on dissolved oxygen amounts?
• What effect do ammonia levels have on dissolved oxygen amounts?
• What are some other factors that could impact dissolved oxygen amounts?
• What would be some reasons for ammonia levels increasing?
• What would cause an increase in vegetation growth over the spring/summer?

Students could:

• Review the graph and then in small groups, students could brainstorm potential reasons for dissolved oxygen levels decreasing. Groups could share their ideas to the class. From there, the teacher could provide the raw data tables for analysis. Groups could provide reasons based on data analysis.
• Work in small groups with each group analyzing one specific testing site, using the data for only that site. From there, students could analyze the reasons for decreased oxygen levels for their location.
• Use the phenomenon as an introduction or supplement to Le Chatlelier’s principle in chemistry.
• Research why plant growth decreases oxygen levels, why higher ammonia levels can lead to lower dissolved oxygen levels, and what types of factors cause algae blooms or increased levels of aquatic plant growth.

• Environmental Protection Agency | Dissolved Oxygen:  The EPA sites high water temperatures, high ammonia amounts, and increased plant growth as a reason for lower dissolved oxygen amounts.
• Lab Hamster | How Temperature Affects Gas Solubility - A Science Experiment with Mr. Pauller: This video gives a visual for dissolved gas in seltzer water. The experimenter uses three different temperatures of seltzer water and opens each bottle to show the amount of gas leaving the solution.
• Bozeman Science | Le Chatelier’s Principle: This video gives a nice description of Le Chatelier’s principle, in which a disturbance to an equilibrium will cause a shift in the overall system equilibrium (increase in temperature causes a decrease in gas solubility).