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.