Max Jacobson ’13


Chemical and Biological Engineering

Project Title

Photochemical Alteration of Dissolved Organic Nitrogen in the Surface Ocean of the North Atlantic

Presentation Link

View Max's Presentation

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.

Internship Year


Project Category

Climate and Energy


Princeton University; Bermuda and Princeton, New Jersey


Daniel Sigman, Dusenbury Professor of Geological and Geophysical Sciences; Katye Altieri, Postdoctoral Research Associate; Sarah Fawcett, Graduate Student, Geosciences