Overview and Purpose
There are two activities in this section. The Combustion Lab will explore how burning fossil fuels (combustion) causes oceans to acidify. The LEGO activity will go into more detail about how this will affect marine organisms that utilize calcium carbonate.
In the previous section, students explored how carbon forms different materials and is recycled through various carbon sinks (reservoirs). One of the ways that carbon moves from one sink to another is when humans burn fossil fuels. Burning coal, oil, and gas breaks the bonds that hold carbon atoms together inside those fuels, and carbon is released into the atmosphere. The ocean absorbs about a quarter of the CO2 we release into the atmosphere every year, so as atmospheric CO2 levels increase, so do the levels in the ocean. Initially, many scientists focused on the benefits of the ocean as a carbon sink as it is removing this greenhouse gas from the atmosphere. However, decades of ocean observations now show that there is also a downside: the CO2 absorbed by the ocean is changing the chemistry of seawater.
As the ocean absorbs increasing amounts of CO2 from the atmosphere, chemical reactions take place that decrease the pH of the ocean. This lowering of pH makes ocean water more acidic. The ocean’s pH has lowered by .1 pH units since the Industrial Revolution. This may not seem like much, but pH is measured on a logarithmic scale, which means a 0.1 difference in pH indicates the ocean has become 30% more acidic. With CO2 continuing to sink into the ocean at extreme rates, scientists predict that the ocean could become 150% more acidic by 2100.
NGSS STANDARDS
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.
MS-ESS3-5
Analyze geoscience data to evaluate the effects of human activities on Earth’s systems.
HS-LS2-6
Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain balance among organisms and their environment.
HS-ESS2-2
Analyze geoscience data and develop a model to explain the cycling of Earth’s materials and the flow of energy into and out of Earth’s systems.
HS-ESS3-6
Evaluate competing design solutions for reducing human impacts on the environment.
OBJECTIVES
- Explain the chemistry of ocean acidification and its causes.
- Design and conduct experiments to investigate the impact of pH on marine organisms.
- Analyze data and draw conclusions about the relationship between ocean acidification and marine ecosystems.
- Propose solutions to mitigate the effects of ocean acidification.
MATERIALS NEEDED
For Combustion activity:
2.Dilute Bromothymol blue (BTB) *Note that BTB is a chemical and can be harmful if used improperly. Please follow your school’s safety measures.
3.Two test tubes with stoppers. Make sure to use tubes made of glass or a plastic that will not melt when held up to a flame
4.Candle (preferably non-scented tea lights)
5.Match or some other device to light the candle
6.Student worksheets
For Lego activity:
7.3 colors of Legos (12 yellow, 12 blue, 8 red per bag) Use Duplo Legos if you want bigger blocks
8.Small opaque reusable bags (one for each small group)
9.A stopwatch or timer
10.Student worksheets
PROCEDURE
Day 1:
- Use slide deck to review ocean acidification and basic concepts of ocean acidification chemistry (through Slide 12).
- Distribute Combustion Lab worksheet. Ask students to read instructions and tell a partner what they must do.
- Have students collect materials from the teacher’s desk. Discuss fire safety.
- Two options: allow students to proceed through activity without direct instruction. Or walk the students as a class through each step, using the slides in the Powerpoint.
- Allow students to discuss conclusion questions with their group. Then direct students to answer the questions individually, in their own words.
Day 2:
6. Use slide deck (Slides 13-34) to review ocean acidification and basic concepts of ocean acidification chemistry.
7. Distribute Lego Build-a-Shell worksheet. Ask students to read instructions and tell a partner what they must do.
8. Have students collect materials from the teacher's desk.
9. Two options: allow students to proceed through activity without direct instruction. Or walk the students as a class through each step, using the slides in the Powerpoint.
10. Allow students to discuss conclusion questions with their group. Then direct students to answer the questions individually, in their own words.
DIFFERENTIATION
For struggling students: individual check-ins, clarification of instructions, and visual aids/ demos. Simplified data analysis and conclusion sections. For advanced students: Challenge students to design their own experiments to investigate the effects of different pH levels on shell formation. Provide additional research opportunities on specific marine organisms affected by ocean acidification.
ASSESSMENT
Successful students will be able to explain what each component of the activity is demonstrating with respect to ocean acidification. Students will discuss their conclusions with classmates and submit thoughtful answers on their worksheets.
Get Involved
If you are interested in learning more about MACAN and the work we do, please sign up for our monthly newsletter. You can also read our 2024 to 2028 Work Plan.
The Mid-Atlantic Coastal Acidification Network. All Rights Reserved.