Photo by Roger Kelly
Yeast. Sugar. Water. These ingredients could have been used to bake bread, but as Jackson High School chemistry students recently found out, they can also simulate ocean acidification, a current and future environmental problem.
Ocean acidification is a decrease in the pH of ocean water caused primarily by the absorption of excess carbon dioxide from the atmosphere by the world’s oceans and by pollutants in stormwater runoff.
Although the world’s oceans have always absorbed carbon dioxide, the students learned that the amount emitted into the atmosphere has increased to the point that the oceans can no longer absorb it without lowering the ocean’s pH. pH is a measure of a substance’s acidity or alkalinity. As the pH of the ocean decreases, its acidity increases reducing the availability of calcium carbonate required not only by the oysters, clams, and mussels important to Washington’s economy, but also to overlooked marine organisms including coccolithophores, a tiny algae that depends on calcium carbonate to survive and a critical component to the base of the ocean food chain.
As the ocean acidifies the decreased availability of these algae can result in less food for higher organisms such as copepods and krill. This chain reaction continues to salmon, sea lions, whales, and countless numbers of ocean species and can even effect food availability for seabirds. Other organisms adversely affected by ocean acidification include coral reefs, which help filter marine water and provide habitat for 25% of all marine life.
Students simulated ocean acidification by activating yeast with sugar and warm water and capturing the carbon dioxide created by yeast respiration. The carbon dioxide was directed into a container of saltwater and an air chamber and the changes in pH and carbon dioxide concentrations recorded over 20-minutes. As predicted, students saw the pH of the saltwater decrease as the carbon dioxide concentration increased.
“Few students were aware of this global issue,” chemistry teacher Eliazbeth Burns said. “Mr. Kelley’s presentation and the highly interactive lab experience were effective tools to teach students about the impact of dissolved carbon dioxide on the pH of seawater and marine life.”
In 2009 the academies of science from 70 nations have agreed that changes caused by ocean acidification are irreversible for many thousands of years, and the biological consequences could last much longer. The solutions – encompass everything from burning less fossil fuel to reducing the amount of lawn fertilizer and developing new, research-based ideas– require the commitment of individuals, industries, governments and a continued emphasis on scientific research and education.
The ocean acidification class is free to Snohomish County high schools and is taught by staff from the Snohomish Conservation District. The District is one of the first organizations in the state to offer an ocean acidification class to High School students. The class is based on a similar class from the University of Hawaii’s Center for Microbial Oceanography: Research and Education (C-MORE).
Richard Van Winkle, News of Mill Creek, 17 February 2014. Article.
