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Faculty Spotlight for June 2007

Michael Bender has been at Princeton since 1997. His research focuses on studies of the global carbon cycle, the fertility of the oceans, and paleoclimate. This work largely revolves around measurements of the concentration and isotopic composition of O2 in air, of dissolved O2 in seawater, and in trapped gases from ice cores.

Studies of the global carbon cycle center around analyzing the O2/N2 ratio of air from remote locations. Records up to 2003 are shown above, right. The long-term rate at which the O2/N2 ratio is falling allows one to partition the sequestration of fossil fuel CO2 between the land biosphere and the ocean. The amplitude of seasonal changes in the O2/N2 ratio of air reflects the fertility of individual ocean basins.

Studies of the concentration and isotopic composition of dissolved O2 in surface seawater allow us to estimate the rates of gross photosynthesis and net community production by the local ecosystems. Measurements made on discrete samples returned to the lab allow us to characterize these properties over broad areas of the ocean, and underway measurements with a membrane inlet mass spectrometer (lower left) give continuous records of net community production.

Studies of past climates with ice cores are currently focused on collaborations with Lonnie Thompson (Ohio State) aimed at dating tropical and temperate ice cores, and with David Marchant (Boston University) aimed at recovering paleoclimate information from shallow polar ice cores dating back to the Miocene (Dry Valleys, Antarctica, lower right).

Current group members include graduate student Gabrielle Dreyfus, Research Scientist Nicolas Cassar, and lab managers Bruce Barnett and Robert Mika. We look forward to welcoming postdoctoral fellow Rachel Stanley and one or two new graduate students this fall.

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