Gabrielle D’Arcangelo, ’21, Chemistry

Certificate(s): Technology and Society

The goal of my project was to investigate methane-producing bacteria in wetland soils (peat) and determine the effects of oxygen on their emissions. In order to understand, and hopefully, manipulate the composition of Earth’s atmosphere, it is important to consider the ways in which natural environments use and produce greenhouse gas. I collected peat samples from local wetlands and exposed them to oxygen for various time periods in the lab so that microbial populations experienced aerobic and anaerobic conditions. I also collected and tested samples from Princeton’s biodigester for composting food waste. For both the composted food waste and the peat, I analyzed emissions on a gas chromatograph, took various depth profiles including pH and redox potential, and extracted the DNA and RNA of the microbial populations for sequencing and identification. Both sets of samples showed that methane production increased during anaerobic periods that immediately followed oxygenation. This suggested the presence of a bacteria that uses oxygen to aid methanogenesis. This was my first insight into environmental chemistry as well as gas chemistry. It also was my first experience working with organisms in a lab, helping me
to consider a wider variety of careers after graduation.

* This internship is connected to the PEI Climate and Energy Grand Challenges project, “Controls on Alternative N2 Fixation.”