Bioenergy Lessons

Background Information:

Not all carbon dioxide emissions are contained in the Earth's atmosphere- some are absorbed by large bodies of water, including our oceans.  As carbon dioxide dissolves into an ocean, the water’s pH level becomes more acidic. Oceans have become about 30% more acidic over the past 200 years.  This is alarming because it is the most significant change in ocean chemistry ever noted. 

Even though the ocean is immensely large, the large amount of carbon dioxide dissolving into it can have a direct impact on which marine species can survive and flourish there.One effect of a more acidic ocean is the loss of calcium carbonate (CaCO₃). Certain marine species rely on calcium carbonate to build a shell or exoskeleton.

In this experiment we will use chicken eggs to represent the marine species that rely on calcium carbonate, because eggs are comprised of 94-97% calcium carbonate.

Procedure:

1. Place scotch tape on both jars and label one “Neutral” and the other “Acidic”.  These jars will be used to represent an acidic oceanic environment (environment with a high pH balance) and a non-acidic oceanic environment (environment with a neutral pH balance) for the eggs (which represent a marine species relying on calcium carbonate).
   
2. Measure 100 ml of tap water and 50 ml of vinegar and add both to the jar labeled “Acidic”.
   
3. Measure 150 ml tap water and add to jar labeled “Neutral”.
   
4. Gently place one egg into each of the jars so that the egg is completely submerged in the liquid. Over a period of 72-hours, the shell of the egg in the acidic jar will have dissolved and only the membrane will remain. The egg in the pH neutral jar will have remained the same. 
   
5. During the 72-hour period students should make observations about the condition of both the eggs. Students can use the chart found at the bottom of this lesson to note observations of not only the appearance of the eggs, but also any observations about the liquids contained in the jars.
   
6. Explain to the students that acetic acid in vinegar dissolves the calcium carbonate (CaCO₃). When the acid in the vinegar reacts with the eggshell, carbon dioxide is released in the form of bubbles. The chemical equation for this process is H₂O+CO₂= H₂CO₃ (Carbonic Acid).
   
7. Discuss the possible impacts on marine life. 
   

Questions of Interest:

How does ocean acidification affect marine life relying on a shell or exoskeleton?

Does ocean acidification affect all marine life the same way?

How could the effects of ocean acidification be lessened or minimized?

What is the connection between ocean acidification connect and deforestation?

Does the idea of ocean acidification raise any other questions about how human activity might be affecting our planet?

Why is it important for us to study ocean acidification?

Extension Materials:

View the video clip: https://youtu.be/Wo-bHt1bOsw

Read “The Seattle (WA) Times” News Article: SEACHANGE-Oysters Dying As Coast Is Hit  Hard: http://apps.seattletimes.com/reports/sea-change/2013/sep/11/oysters-hit-hard/

Read: “Garfield students share what they’ve learned about ocean acidification”. http://blogs.seattletimes.com/seachange/

View PowerPoint Presentation entitled “Ocean Acidification” in news article section, “Students at The Northwest School study ocean acidification”. http://blogs.seattletimes.com/seachange/

Extension Questions:

What is a “Food Chain”?

What does a “Marine Life Food Chain” look like?

If marine life affected by ocean acidification were to die, how would the “Marine Life Food Chain” be impacted?

If the “Marine Life Food Chain” is negatively impacted, how might that affect our food choices and economy?

Student Worksheet

Follow this link to download student worksheet.