Kaycie Billmark of the Biometeorology Group

Research Fellow

Owing to the occurrence of isotopic discrimination within biogeochemical cycles, stable isotopes are often ideally suited to study exchange processes within and between earth systems. As an isotope geochemist, I have applied this basic principle to a variety of interdisciplinary questions in environmental research.

I completed my dissertation at the University of Virginia, where I applied geochemical techniques, specifically bulk and compound specific stable isotope mass spectrometry, to study nutrient dynamics and interactions between the atmosphere and biosphere. I analyzed the delta 13C of fatty acids, extracted from aerosols collected in southern Africa, both to characterize emissions from extensive biomass buming in the region and to better understand nutrient transport over the subcontinent.

My current research at the University of Minnesota combines micrometeorological and biogeochemical techniques to examine the contribution of underlying gross fluxes, such as photosynthesis and respiration, to the net ecosystem exchange of CO2. Determination of the gross fluxes provides a better understanding of carbon storage and exchange processes, which are necessary for ecosystem source/sink strength prediction modeling. For these analyses, I have been working to combine traditional micrometeorological techniques with stable isotope analysis. Technologies, such as tunable diode laser (TDL) spectroscopy, allow us to collect high resolution isotopic fluxes (delta 13CO2, delta C18O16O) that can be used to constrain estimates of photosynthesis and respiration and can further partition respiration into heterotrophic and autotrophic components. This capacity to partition net fluxes into their primary components allows us to better understand the carbon dynamics at a variety of temporal scales. I am currently focusing this research on a projects recently funded by the Department of Energy to examine microbial respiration flux using both compound specific isotope ratio mass spectrometry and TDL spectroscopy.