The Effect of pH on the Carbon Dioxide Absorption of Spirogyra

Many of the freshwater systems in the world have very different levels of acidity: these systems exist in very different environments. This experiment was conducted to determine if these differing environments had a significant effect on Spirogyra’s ability to absorb carbon dioxide (CO2). Spirogyra is an aquatic plant, a type of algae, that feeds by absorbing CO2, water, sunlight, and other nutrients to create sugars and oxygen (O2) as a byproduct. Keeping this algae alive is important because when Spirogyra dies, it releases all of its CO2 back into the environment, instead of transferring it into oxygen (O2). Carbon dioxide (CO2) levels are already on the rise, so this does not need to add to the problem. These results could also be used in other lab settings to help other researchers keep/grow their algae more effectively.

To measure a difference in the CO2 and O2 concentrations for acidic, neutral, and alkaline environments the concentrations were measured before (0 hours), during (24 hours), and after the course of experimentation (about 48 hours). The changes in acidic and alkaline gas levels were compared independently to the changes in the neutral environment. The researchers hypothesized that the alkaline environment would increase the absorption of CO2 the most. The statistical tests yielded that, in fact, the alkaline trials caused the greatest decrease in CO2, supporting the original hypothesis that an alkaline environment is more suitable for CO2 absorption.

Research Conducted By:

Elton DeFrance
Warren Mott High School

Andrew Oughton
Warren Mott High School