National Standards:
- Geography: Places and Regions
- Math: Data Analysis and Probability
- Science Content: C Life Science
- Science Content: D Earth and Space Science
- Technology: Technology and Society
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AP Environmental Science Topics
- Agricultural use of water
- Atmosphere-ocean interactions
- Carbon cycle
- Global climate change
- Greenhouse gases
- Green revolution
- Harmful algal blooms
- Human impact on natural systems
- Photosynthesis
- Water pollution
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Virginia Standards of Learning:
- ES.1c: The student will plan and conduct investigations in which scales, diagrams, maps, charts, graphs, tables, and profiles are constructed and interpreted.
- ES.12: The student will investigate and understand the origin and evolution of the atmosphere and the interrelationship of geologic processes, biologic processes, and human activities on its composition and dynamics.
- LS.12: The student will investigate and understand the relationships between ecosystem dynamics and human activity.
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Prerequisite
- Overview of the Carbon Cycle
- Familiarity with using Excel
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Tools
- Computer with Internet access
- Microsoft Excel or other spreadsheet software
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Vocabulary: |
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Lesson Links:
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Background:
Dr. Charles Keeling measured background atmospheric carbon dioxide (CO2) from Mauna Loa Observatory in Hawaii beginning in 1958. Since his death in 2005 the measurements have been continued under the supervision of his son, Ralph Keeling. The Keeling Curve (see Lesson Link) shows the increasing trend of carbon dioxide in the atmosphere, as well as the seasonal cycle of CO2 in the Northern Hemisphere. The seasonal oscillation seen in the graph is due to the increase and decrease of photosynthetic plants that use CO2. Since carbon dioxide is a powerful greenhouse gas, the overall increasing trend is very alarming and has sparked much debate about global climate change.
When ocean phytoplankton bloom, they also use carbon dioxide from the atmosphere for photosynthesis, just as land plants do. The gas is carried to the ocean floor as a carbon form when the tiny plants die. This enables atmospheric carbon to get into the deep ocean. It is one of several natural processes that contribute a sink to Earth's carbon cycle. Scientists are still trying to determine how much carbon dioxide might be removed from such a process to counter the increases noted by Keeling. Phytoplankton blooms can be measured from space by chlorophyll content, or a discoloration of surface water. The picture above shows the greenness of Lake Erie from satellite in April 2000.
Phytoplankton blooms can naturally increase with more available carbon dioxide, but may also increase when other nutrients drain into bodies of water from anthropogenic activities. These activities may include agricultural runoff, industrial runoff and other human waste influences. Obviously, these toxic blooms are harmful to local watersheds. While the blooms will temporarily raise dissolved oxygen levels in the water during the daytime when sunlight is available, at nighttime when the phytoplankton die, there is a sharp decrease in dissolved oxygen. These swings result in large kills of local aquatic wildlife.
The Maumee River watershed empties into Lake Erie from Ohio, at its furthest southwest point. Many other smaller rivers empty into the Maumee River at points upstream. The St. Marys Watershed, the watershed where St. Marys city school district is located, is one of these rivers. In this lesson, students can explore both global and local carbon cycle issues by examining chlorophyll data from satellite.
For other locations, please see Teachers Notes below. |
Procedure:
Click on the Lesson Link above called Excel Workbook. In this workbook, the first sheet contains numerical CO2 data values associated with the Keeling Curve for years 1997-2004. The second sheet contains corresponding time series data from the Live Access Server for chlorophyll-a concentration at a location near the Maunee Bay on Lake Erie.
Review the data on Sheets 1 and 2, then view Sheet 3 which shows an Excel plot with annual average CO2 on the x-axis and annual average Chlorophyll on the y-axis. This x-y type line graph can be used to view the overall relationship between the two data sets. Answer the questions below. |
Questions:
1. What mathematical relationship, if any, is there between chlorophyll-a and carbon dioxide in the Maumee River Watershed (linear, logarithmic, exponential)?
2. What explanation is there for this relationship?
3. What other factors could have an impact on the results?
4. Where did this data come from? Who collects it? How is it collected?
5. How can this affect other characteristics of the local watershed?
6. Describe how this can affect other parts of the world.
7. Is this enough data to make an accurate analysis? Why or why not? |
Extensions:
1. Using Excel Workbook Sheet 4, plot Leaf Area Index data, a measure of land vegetation, versus the carbon dioxide data. What trends do you see?
2. Explore how hurricanes may cause phytoplankton blooms. See Lesson Link above. |
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Lesson plan contributed by Tami Golliday, St. Marys, Ohio
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Click here for Teachers Notes |
