Graduate Students

Mihai Leonte

PhD Candidate
Faculty Mentor(s): John Kessler

227 Hutchison Hall
(585) 275-2514
Fax: (585) 244-5689

Quantifying the efficiency of methane removal processes in oceanic environments is important in understanding the impact of methane during episodic events, such as the Deepwater Horizon oil spill, or long term fluctuations in Earth’s climate. The single largest methane reservoir on Earth is in the form of hydrates, an ice-like structure formed by water within seafloor sediments that can trap gas molecules at sufficient pressures and low enough temperatures. Warming ocean currents could undermine hydrate stability and increase the flux of methane to the water column. My research focuses on quantifying the removal of methane from the water column by methane-consuming bacteria (methanotrophs). These microbes actively oxidize dissolved methane in the water column, which moderates the emission of methane from the sea surface to the atmosphere. Methanotrophs preferentially consume the 12C isotope of methane more readily than the 13C isotope, leading to a fractionation effect whose magnitude can be used to infer the extent and rate of methane oxidation. By collecting methane concentration and methane isotopic ratio measurements at a given site, we can calculate the rate of methane input from sediments and the rate of methane removal by methanotrophs in the water column. This information helps us understand the total capacity of the methane oxidation sink and whether additional methane inputs would lead to higher methane fluxes to the atmosphere.


University of Rochester

Ph.D. Candidate, 2014 – Present

M.S Geological Sciences, December 2014

University of California, Irvine

B.S. Chemistry & Earth System Science, June 2011

Senior thesis title: Measuring the 34/32S ratio in atmospheric OCS using Gas Chromatography/Mass Spectroscopy

Secondary project title: Analysis of CF4, SF6 and CF3SF5 using GC/MS in the exhaust gas following plasma etching processes

Selected Publications

Journal Publications

  • M. Leonte, J. D. Kessler, M. Y. Kellermann, E. C. Arrington, D. L. Valentine, S. P. Sylva (2017), “Rapid rates of aerobic methane oxidation at the feather edge of gas hydrate stability in the waters of Hudson Canyon, US Atlantic Margin.” Geochimica et Cosmochimica Acta, doi:10.1016/j.gca.2017.01.009.
  • Weinstein, A., L. Navarrete, C. Ruppel, T. C. Weber, M. Leonte, M. Y. Kellermann, E. C. Arrington, D. L. Valentine, M. I. Scranton, and J. D. Kessler (2016), Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability, Geochem. Geophys. Geosyst., 17, doi:10.1002/2016GC006421.


  • 2016, M. Leonte, J. Kessler, S. Scolofsky, Investigating the emission, dissolution, and oxidation of methane within and around a seep bubble plume in the Gulf of Mexico, Ocean Sciences Meeting, New Orleans, LA. (Poster)
  • 2014, M. Leonte, J. Kessler, A. Chepigin, T. Weber, C. Ruppel, M. Kellermann, E. Arrington, D. Valentine, S. Silva. Comparison of Two Techniques to Calculate Methane Oxidation rates in Samples Obtained From the Hudson Canyon Seep Field in the North Atlantic . American Geophysical Union General Meeting, San Francisco, CA. (Poster)


  • Spring 2017, Teacher's Assistant, Marine Ecosystems & Carbon Cycle Modeling
  • Spring 2013, Teacher’s Assistant, Introduction to Environmental Science
  • Fall 2013, Teacher’s Assistant, Chemical Oceanography
  • Spring 2013, Teacher’s Assistant, Chemical Oceanography
  • Fall 2012, Teacher’s Assistant, Hydrology

Professional Honors and Awards

  • University of Rochester Graduate Student Association Travel Award

Field Experience

  • 2016, June 19-25, R/V Blue Heron, Lake Michigan, USA
  • 2016, April 27- May 11, R/V Helmer Hanssen, Svalbard, Norway
  • 2015, April 8-21, E/V Nautilus, Gulf of Mexico, USA
  • 2014, July 7-14, R/V Endeavor, North Atlantic Bight, USA
  • 2012, August 7-14, R/V Cape Hatteras, Gulf of Mexico, USA