The Effect of Carbon Dioxide on Elodea

Overview

Objectives/Goals My objective was to find out how increasing carbon dioxide levels affect the freshwater plant, Elodea. Methods/Materials I set up three tanks. Each tank had a layer of soil, then gravel on top and 10 liters of purified water. Six elodea stalks were nestled in each tank and given a period of time to adjust to the environment before the introduction of carbon dioxide. Tank #2 and tank #3 each had one carbon dioxide pump, which were on for 12 hours per day and 24 hours per day, respectively. From the point of carbon dioxide introduction, the experiment was 2 weeks long, and this was the period where I collected the data. The height of each stalk was measured daily with a ruler and the pH of the water in each tank was tested daily with pH test strips. Results The Elodea in tank #1 experienced small growth throughout the experiment. The pH of the water remained constant until near the end of the experiment when it rose to 8 (day 13).The Elodea in Tank #2 experienced continued growth throughout the whole experiment. The pH or the water dropped slightly to 6 (day 5).The Elodea in tank #3 experienced growth at first but then gradually declined in health. The pH of the water dropped to 6 near the beginning of the experiment (day 2), then dropped to 5 near the end (day 12). This indicates that increasing carbon dioxide levels affect the growth and health of the elodea plant by affecting photosynthesis and water pH. Conclusions/Discussion My results support my hypothesis. The carbon dioxide lowered the pH of the water and affected the height of the elodea. The Elodea in tank #2 were the most healthy and experienced the most growth. Carbon dioxide levels in tank #3 made the water pH to low for the Elodea to survive. This data suggests that too much carbon dioxide may negatively affect freshwater ecosystems.

Competition history

• CSEF 2014 Pharmacology/ Toxicology · Entry S1720

Resources

• CSEF project summary ↗

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