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Regional Focus


Uptake of Carbon Dioxide from Water by Plants

Authors: IFM-GEOMAR S. Soria-Dengg, Carboschools (EU)
Grades: 6th, 7th, 8th, 9th, 10th, 11th, 12th
Subjects: Science, Chemistry, Biology, Earth and Space Sciences
Format: PDF
Resource Types:
  • Experiment
  • Lesson Plan
  • Worksheet

  • This resource provides instructions for two simple experiments that show how aquatic plants can mitigate acidification caused by excess CO2┬áin ocean water.

Teaching Tips


  • The first experiment tests the impact of Cabomba fronds on the pH level of a water sample. This experiment compares the pH of two water samples containing Cabomba fronds, one in a clear container that allows for photosynthesis and one in a container covered with foil to block light. A water sample without Cabomba fronds serves as the control for this experiment.
  • The second experiment tests the impact of phytoplankton on the pH level of two water samples, one containing phytoplankton and one without phytoplankton. Both samples are exposed to light. Students measure the pH levels in both samples in 1-minute intervals over 10 minutes.   
  • The PDF contains detailed instructions on how to set the experiments up, as well as pictures that show what the experiments look like.

Additional Prerequisites

  • For the first experiment, each group will need 3 50-ml bottles or flasks with caps, drinking straws, a pipette or medicine dropper, universal indicator solution, distilled water, scissors, aluminum foil or black paper, a table lamp, and several stems of Cabomba.
  • For the second experiment, each group will need phytoplankton culture in a flask, a flask containing the same volume of seawater as the culture, a pH-Meter, a table lamp or sunlight, drinking straws, and a cotton wad stopper wrapped in plastic foil.
  • The link at the top of the PDF does not lead to the correct resource.


  • Teachers could use these experiments as class demonstrations.
  • Students could discuss the role of phytoplankton in the ocean ecosystem as well as its role in the carbon cycle. Students could reflect on how excess CO2 might interrupt the balance of the ecosystem or the carbon cycle.
  • Other resources on this topic include this NASA video on phytoplankton, this Khan Academy video on ocean acidification and biodiversity, and this video and worksheet on how acidic water is changing the ocean.

Scientist Notes
The ocean, making up over 70% of Earth's surface, is a vital component of the climate system. As such, anthropogenic climate change has caused the oceans to acidify. This experiment showcases how phytoplankton can help the ocean become less acidic. This resource is recommended for teaching.
  • Next Generation Science Standards (NGSS)
    • LS1: From Molecules to Organisms: Structures and Processes
      • MS-LS1-6 Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
    • PS1: Matter and its Interactions
      • MS-PS1-2 Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
    • LS2: Ecosystems: Interactions, Energy, and Dynamics
      • HS-LS2-5 Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.
    • ESS2: Earth's Systems
      • HS-ESS2-6 Develop a quantitative model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere.
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