Earth has finite resources, and as a result, matter recycles throughout the world by biogeochemical cycles. The Carbon/Oxygen Cycle is a biogeochemical cycle that is driven by photosynthesis and cellular respiration. As a result of organisms performing these two processes, levels of dissolved oxygen (DO) change within water columns. Inspired by the information available via the Ocean Observatories Initiative (OOI), this lesson will focus on the the impact of photosynthesis on the DO levels, specifically off the coast of New Jersey. Resources to access similar data in other locations will be available at the end of this document.
The students will propose what plants need in order to perform photosynthesis. Based upon the discussed information, the students will conduct experiments using a chemical indicator of carbon dioxide, Bromothymol blue (BTB) solution. BTB is blue in color but will change to green and then yellow based upon an increase in carbon dioxide concentration in a BTB solution. Students will set up test tubes with BTB solution and aquatic plants. At the end of setup day, students will make predictions about potential color changes to the BTB solution. From there, students will access and interpret near real time marine data of dissolved oxygen to determine if their predictions are supported by real-world evidence. After 48 hours of sitting, students will return to their BTB solution lab setup to evaluate their results and determine if their predictions were supported by the real-world data and their results.
Author: Kate Russo; EARTH 2018