Max Jacobson, 2013, Chemical and Biological Engineering
This summer, in Professor Daniel Sigman’s laboratory, I constructed an apparatus to investigate the conversion of dissolved organic nitrogen (DON) to ammonium, in the presence of sunlight, in Sargasso Sea water. This conversion is one theory that may explain the discrepancy between the measured efflux of ammonia out of the subtropical ocean and the predicted efflux, considering the concentration of ammonium in seawater and Henry’s law. My work involved designing the apparatus, testing the apparatus, acquiring appropriate samples, and measuring the concentration of ammonium in various solutions. I learned about the nitrogen cycle, nitrogen isotope ratios (¹⁵N/¹⁴N), and the properties of oligotrophic oceanic gyres. In addition, I learned numerous laboratory techniques, including filter acidification, filter extractions, an orthophthaldialdehyde (OPA) fluorescence technique for measuring nanomolar concentrations of ammonium, and acid washing. I also collected and filtered seawater samples during four scientific cruises, and assisted with other oceanographic and atmospheric sampling. In addition to my own research, I learned about other projects in Professor Sigman’s lab and even contributed to them. The Sigman lab is supportive and innovative, and working with them this summer was a rewarding experience.