Guyot Science 2005
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GuyotGuyot Science 2005 Department of Geosciences, Princeton University 1 2 Guyot Science 2005 A Summary of the Research Progress and Accomplishments Made by the Faculty Members of the Department of Geosciences During the Year 2005 Last year, January–December 2005, was a transitional year for a number of faculty members of the Princeton Department of Geosciences. In June Bob Phinney transferred to emeritus status, following a distinguished career as a professor and for- mer department chair. We are pleased that Bob has agreed to remain at Princeton, and plans to continue to teach his popular freshman seminar, Active Geological Processes, which has long been an attraction for prospective departmental majors. In July Satish Myneni was promoted to the rank of associate professor with continuing tenure. Two professors were named to en- dowed chairs: George Philander is now the Knox Taylor Professor of Geosciences and Bess Ward is now the William J. Sinclair Professor of Geosciences. In April, George was inducted into the National Academy of Sciences, raising the departmental membership to four. Nadine McQuarrie, a structural geologist who studies mountain building and other active tectonic processes, completed her fi rst highly successful year as our newest assistant professor. Next year, we will be joined by two new assistant professors, Adam Maloof, a geologist who applies paleomagnetism and other tools to the study of the ancient earth, and Frederik Simons, a geophysicist who is developing a variety of innovative new tools to study the structure and evolution of planetary lithospheres as well as pioneering in the development of a freely drifting submersible vehicle to increase teleseis- mic coverage in the world’s oceans. In December, François Morel was awarded the Maurice Ewing Medal of the American Geophysical Union and the U.S. Navy, “for his leadership in the revolution in low-temperature aqueous geochemistry that has resulted in a new fi eld of studies at the interface between marine chemistry and biology.” Finally, Allan Rubin was inducted as a Fellow of the American Geophysical Union; this is a prestigious honor restricted to no more than 0.1 percent of the member- ship each year. More than half of the faculty members in the Department of Geosciences are now Fellows of the AGU. The recent research accomplishments of each member of the geosciences faculty are described in the individual reports that follow. A list of faculty publications during the past two years, 2004-2005, is appended to each narrative report. Back Row: Rob Hargraves (deceased), Satish Myneni, Greg van der Vink, Guust Nolet, Tony Dahlen, Jorge Sarmiento, John Suppe. Middle Row: Bob Phinney (emeritus), Lincoln Hollister, Peter Bunge, Ken Deffeyes (emeritus), François Morel, Michael Bender, Nadine McQuarrie, Bess Ward, Tullis Onstott. Front Row: Jason Morgan (emeritus), Tom Duffy, Franklyn van Houten (emeritus), Gerta Keller, George Philander, Bill Bonini (emeritus), Allan Rubin. Photo by Pryde Brown, with additions by Laurie Wanat. 3 Michael Bender gases in ice cores, and of dissolved gases in seawater. We also Professor made a modest beginning on 2 new programs of ice core Ph.D., 1970, Columbia University research. Here are some specfi c accomplishments. email: [email protected] 1. We prepared for publication papers on the meridional gradient of O2 in air and its implications for the ocean car- bon cycle, on the concentration and isotopic composition of O2 in Southern Ocean surface waters and their implications for the fertility of these waters, and on technical aspects of deriving a timescale climate records in slowly accumulating ice in East Antarctica. These papers are now either accepted or in revision. We also worked on several other manuscripts that are now in review. 2. Jan Kaiser participated in 2 cruises of the “Atlantic The activities of my laboratory focus on studies of the Meridional Transect” program and made measurements that strongly contradict the hypothesis that shallow, nutrient-poor geochemistry of O2, with applications to understanding the global carbon cycle and glacial-interglacial climate change. ocean waters are chronically net heterotrophic (i. e., that The geochemical properties we study are the concentration respiration exceeds photosynthesis). of O2 in air (which we measure to very high precision), and 3. We began measurements in a collaboration with David 16 the relative abundance of the three stable O isotopes ( O, Marchant, Boston University, to study ice of apparently great 17 18 O, and O) in O2. There are two subjects for the isotopic antiquity in the Dry Valleys, Antarctica. This ice underlies studies: O2 in fossil air extracted from ice cores, and dis- volcanic ash deposits dated as old as 10,000,000 years. The solved O2 in seawater. evidence suggests that the ice is older than the overlying The results inform us about a range of topics. Studies of ash, but this conclusion is highly controversial. If proved, it the O2 concentration (or ratio of O2/N2) in air constrain the would allow us to measure the concentrations of greenhouse fate of fossil fuel CO2 that does not remain in the atmo- gases in bubbles of air trapped in the ice, and determine the sphere. These measurements allow us to partition the “miss- carbon dioxide concentration of the atmosphere at times ing” CO2 between the oceans and the land biosphere. They when Earth was much warmer than at present. We showed also constrain rates of seasonal biological production by the that the gases in the bubbles are original samples of trapped oceans. Finally, they provide a test of models describing the air, and we are currently developing isotopic methods for dat- global interaction of ocean circulation and biogeochemistry. ing the ice. The isotopic measurements of O2 in ice core trapped gases refl ect the relative fertility of Earth’s biosphere, averaged 4. We began a collaboration with Lonnie Thompson, Ohio State University, to date climate records of ice cores he over about 1,000 years. The triple isotope composition of O2 in seawater refl ects the fraction of dissolved O from photo- has collected from tropical and temperate regions. To date 2 our results confi rmed the relatively recent age of the deep synthesis. O2 supersaturation refl ects net production (pho- tosynthesis in excess of respiration); by combining measure- part of one core (ruling out the possibility that the bottom of this core might date back to the last ice age). ments of O2 concentrations and isotopes, we can determine rates of photosynthesis, respiration, and net production in Two-Year Bibliography aquatic ecosystems. Of course rate determinations of these Refereed articles: processes in seawater have been made for many years; what Hendricks, Melissa B., Michael L. Bender and Bruce A. Barnett Net and gross O production in the southern ocean from makes our work new is that our approach does not require 2 measurements of biological O2 saturation and its triple labor-intensive bottle incubations at sea, and our measure- isotope composition, Deep-Sea Research Part I, 51, 1541- ments can be made on large numbers of samples collected by 1561, 2004. colleagues on cruises of opportunity, and returned to the lab. Brook, E. J., J. W. C. White, Annie S. M. Schilla, Michael L. Supplementing the O studies are studies of Ar. In seawa- Bender, Bruce Barnett, Jeffery P. Severinghaus, Kedrick C. 2 Taylor, Richard B. Alley, Eric J. Steig Timing of millennial- ter samples, Ar gives a measure of physical supersaturation scale change at Siple Dome, West Antarctica, during the last due to warming of waters and bubble entrainment. In air glacial period, Quaternary Science Reviews, 24, 1333-1343, samples, the Ar/N2 ratio refl ects seasonal outgassing and 2005. ingassing due to temperature-driven solubility changes, and Bender, M. L., D. T. Ho, M. B. Hendricks, R Mika, M. O. Battle, P. also to atmospheric mixing. P. Tans, T. J. Conway, B. Sturtevant, and N. Cassar Atmo- spheric O2/N2 changes, 1993–2002: Implications for the Highlights of our research during the past year: partitioning of fossil fuel CO2 sequestration, Global Biogeo- Our primary focus was on preparing papers for publication chemical Cycles, 19, GB4017, doi:10.1029/2004GB002410, and writing proposals for research funding. We continued 2005. our measurements of the O /N /Ar ratio of air, of trapped Hendricks, Melissa B., Michael L. Bender, Bruce A. Barnett, 2 2 Peter Strutton, and Francisco Chavez The triple oxygen isotope composition of dissolved O2 in the equatorial Pacifi c: a tracer of mixing and biological production, Journal of 4 Geophysical Research - Oceans, 110, C12021, doi:10.1029/ Suwa, Makoto, Josepth C. von Fischer, Michael L. Bender, 2004JC002735, 2005. Amaelle Landais, and Edward J. Brook Chronology recon- Kaiser, Jan, Matthew K. Reuer, Bruce Barnett, and Michael L. struction for the disturbed bottom section of the GISP2 and Bender, Marine productivity estimates from continuous the GRIP ice cores: implications for Termination II in Green- oxygen/argon ratio measurements by shipboard membrane land, Journal of Geophysical Research - Atmospheres, in inlet mass spectrometry, Geophysical Research Letters,32, press. 2005. L19605, doi:10.1029/2005GL023459, 2005. Bender, M. L., G. Floch, J. Chappellaz, M. Suwa, J._M. Barnola, T. Blunier, G. Dreyfus, J. Jouzel, and F. Parrenin Gas age-ice Articles in press or submitted: age differences and the chronology of the Vostok ice core, Battle, Mark, Sara Mikaloff Fletcher, Michael L. Bender, Ralph F. 0-100 ka, Journal of Geophysical Research – Atmospheres Keeling, Andrew C. Manning, Nicolas Gruber, Pieter P. Tans, (in review), 2005. Melissa B. Hendricks, David T. Ho, Caroline Simons, Robert Reuer, Matthew K., Bruce A. Barnett, Michael L. Bender, Paul Mika, and Bill Paplawsky Atmospheric potential oxygen: New G. Falkowski, and Melissa B. Hendricks New estimates of Observations and their implications for some atmospheric Southern Ocean biological production rates from O /Ar ratios and oceanic models of the global oxygen and carbon dioxide 2 and the triple isotope composition of O , Deep Sea Re- cycles, Global Biogeochemical Cycles, in press, 2005.