Megan Behnke
Hometown: Juneau, Alaska, USA
Fall 2021 – present
PhD in Chemical Oceanography
P.E.O. Scholar Award
National Science Foundation Graduate Research Fellowship
Educational/Professional Background
B.A. Chemistry summa cum laude from St. Olaf College
M.S. Oceanography Florida State University
Research and Teaching Interests, or Professional Field
I work in Northern ecosystems that are poised at the edge of the breaking wave of climate change, including the Arctic and Southeast Alaska. My goal is to understand what happens to organic carbon that was previously stabilized in the ecosystem when it wakes up. Carbon may be kept in place in soil by cold, wet conditions or frozen in permafrost or a glacier; but whatever its present home, climate change is causing these previously inert carbon stocks to reenter the active carbon cycle. Streams and rivers serve both as pipes, transporting carbon to the ocean, and also as processors, allowing dissolved organic matter to be exposed to transformation by sunlight, microbes, and new chemical environments. Often, the composition or shape of the molecules of dissolved organic matter will determine their fate—whether they are restabilized long-term in a new carbon sink or transformed into greenhouse gasses. I use ultrahigh resolution mass spectrometry and carbon isotope ratios to determine dissolved organic matter’s sources, chemical traits, processing history, and fates in these systems. These cutting-edge techniques allow me to examine the thousands of individual molecular formulae and the atom-level isotope ratios present in the samples of dissolved organic matter I collect. I thus trace molecular-level changes in composition as sunlight and microbes interact with molecules and identify the original sources of the carbon present. This detailed look at the origins and behavior of any given sample of dissolved organic matter lets me predict its ultimate fate, and thus better understand the aggregate effect of newly disturbed organic matter on the ecosystem and climate.