EarthLabs for Educators > Climate and the Carbon Cycle > Lab 6: Oceans-Carbon Sink or Source?

Lab 6: Oceans-Carbon Sink or Source?

The lab activity described here was developed by Candace Dunlap of TERC for the EarthLabs project.

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Investigation Summary and Learning Objectives

Image caption.Image source: Nature

How does carbon get into the ocean, and what are the physical and biological processes that move it through the ocean once it is there? Students zoom in on another portion of the carbon cycle to learn how it works, and what changes are resulting from the surprisingly large increase in the level of carbon that is accumulating in the world's oceans.

After completing this investigation, students will be able to:

For more information about the TOPIC, read the section titled Background Information under Additional Resources below

Activity Overview

In Part A: Students learn how the oceans "absorb" carbon by considering two ocean processes that "pump" carbon dioxide into the oceans: the physical carbon pump and the biological carbon pump. They then view an animation that shows them what happens to carbon once it becomes part of the ocean biological pump. They view a power point on the ocean's biological pump and view a short animation.

In Part B: Students explore the role of phytoplankton in oceanic uptake of carbon in greater depth by analyzing conditions and locations for its growth. They view a NASA video on "Phytoplankton: Ocean's Green Machines" and analyze satellite visualizations to determine geographical, seasonal and decadal changes in phytoplankton populations. Finally, they explore the role of nutrients as limiting factors for phytoplankton and the biological pump.

Printable Materials

To download one of the PDF or Word files below, right-click (control-click on a Mac) the link and choose "Save File As" or "Save Link As."

Teaching Notes and Tips

In Part A:

Check in with students to make sure they understand what phytoplankton are. Let them know that phytoplankton can be found in freshwater and oceans. Many students will know the term algae as opposed to phytoplankton (floating plants in Latin). Ask if any students maintain a fish aquarium. They should be able to share their knowledge of algae that grows in the tank. Algae create most of the oxygen that we breath. You may want to consider ordering some algae (e.g. Chlorella) from a bio supply house or you can collect some in a local pond. Algae also grows on moist areas of houses and rocks. You grow algae in bottles of mineral water with a tiny bit of fertilizer. You may also want to consider allowing students to view algae samples under a microscope.

Consider showing the Ocean Biological Pump to the entire class and talking about the two Stop and Think Questions.

In Part B:

Consider having the NASA phytoplankton visualization projected up on the board when students come in. As a Do Now, have them write down at least two observations that they can share with the class.
Make sure that students understand "false color" in several of the satellite visualizations.

Student Notebooks

Student notebooks are optional. Here are just a few suggestions for what to include in student notebooks for Lab 6

Note: You may want to separate actual data collection and analysis into a Lab Notebook.


There are several options for assessments of students understanding of material produced in this Lab. Teachers can choose from the following list or create their own assessments.

Assessment Options:

  1. Assess student understanding of topics addressed in this investigation by grading their responses to the Stop and Think questions.
  2. Written Test for Lab 6 (Microsoft Word 2007 (.docx) 80kB Jan21 14) (Answer Key (Microsoft Word 2007 (.docx) 184kB Jan21 14))

National Science Teaching Standards

Lab 6 supports the following Next Generation Science Standards (NGSS):

Science and Engineering Practices

4. Analyzing and Interpreting Data

Disciplinary Core Ideas

ESS2.A Earth's Materials and Systems

LS2.B Cycles of Matter and Energy Transfer

LS2.A Interdependent Relationships in Ecosystems

Cross-Cutting Concepts

1. Patterns

2. Cause and effect

5. Energy and Matter

Additional Resources

Background Information

The Knowledge/Scitable site has several good oceanography on biological productivity: articles such as:

Biological Productivity of the Ocean Scroll down to the bottom of the article to links to the other biological productivity articles.

Also, explore some Oceanus articles from the Woods Hole Oceanographic Institute Oceanus Index such as Humans have changed how chemicals move on our planet

Content Extension

Some phytoplankton blooms create biochemical toxins that can be deadly to animals and humans. If students live near a coastline, they may hear about red tide blooms. This Wiki article has a lot of information and further links. Algal Blooms

Overlooked in the Ocean until the 1970's, cyanobacteria are among Earth's most important organism
Satellite data could overturn plankton bloom hypothesis
Bacterial communication could affect Earth's climate
SAR11 - A war without end, with Earth's carbon cycle held in the balance
SAR11 in the Lab

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