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Xiahong Feng - Current Research Interests in Stable Isotope Geochemistry

Hydrogen, oxygen and carbon isotope studies of tree rings:

Cutting a tree for tree ring analysis.

The main objective of this project is to extract climatic information from tree rings using hydrogen, oxygen isotopes. Tree cellulose inherits hydrogen and oxygen isotopic signatures of meteoric water that can be related to climatic variables, such as temperature, source of moisture and precipitation amount. Therefore, isotopic compositions of tree rings are potential tools for paleoclimatic studies over time scales of hundreds to thousands of years. Using radiocarbon-dated wood, one can study paleoclimate deeper in geological time.

In collaboration with Eric Posmentier, our most recent work has been focused on a reconstruction of prevailing wind directions and moisture transport pathways in mid latitudes of North America using wood samples from Holocene and the last glacial period. We showed that between 40 and 50˚N in North America, which is within the zone of the northern hemisphere westerlies today, experienced prevailing easterly winds during the last glaciation. The change was caused by intensification and enlargement of the northern circumpolar vortex under the powerful influence of the Laurentide Ice Sheet.

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