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Kaycie Billmark of the Biometeorology Group
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.