• Oak Ridge Associated Universities Radiocarbon Dates II

      Noakes, John E.; Kim, S. M.; Fischer, F. (American Journal of Science, 1968-01-01)
    • Oak Ridge Institute of Nuclear Studies Radiocarbon Dates I

      Noakes, John E.; Kim, S. M.; Akers, L. K. (American Journal of Science, 1967-01-01)
    • Obituary (Paul Damon, 1921-2005)

      Jull, A. J. Timothy; Barbetti, Mike; Haynes, Vance (Department of Geosciences, The University of Arizona, 2005-01-01)
    • Obituary: Austin Long

      Eastoe, C.; Leavitt, S.; Tanner Elliott, K.; Sewell, D. (Department of Geosciences, The University of Arizona, 2010-01-01)
    • Obituary: Grant Kocharov

      Dergachev, Valentin; Ostrykov, Valery; Gladysheva, Olga; Koudriavtsev, Igor; Ogurtsov, Maxim; Dreschoff, Gisela; Jungner, Högne (Department of Geosciences, The University of Arizona, 2008-01-01)
    • Obituary: Jacques Labeyrie (1920–2011)

      Paterne, Martine (Department of Geosciences, The University of Arizona, 2011-09-16)
    • Obituary: Jean-François Saliège (1943–2012)

      Zazzo, Antoine (Department of Geosciences, The University of Arizona, 2012-10-15)
    • Obituary: Johann Carl Vogel (1932-2012)

      Talma, Siep; Visser, Ebbie; Fuls, Annemarie; Mook, Wim; van der Plicht, Hans (Department of Geosciences, The University of Arizona, 2012-05-04)
    • Obituary: Leopold Dmitrievich Sulerzhitsky (1929-2012)

      Pokrovsky, B. G.; Pevzner, M. M.; Zaretskaya, N. E.; Kuzmin, Y.; Ineshin, E. (Department of Geosciences, The University of Arizona, 2012-05-04)
    • Oceanic Radiocarbon and Tritium on a Transect between Australia and Bali (Eastern Indian Ocean)

      Leboucher, Viviane; Jean-Baptiste, Philippe; Fourré, Elise; Arnold, Maurice; Fieux, Michèle (Department of Geosciences, The University of Arizona, 2004-01-01)
      Results are presented of radiocarbon and tritium measurements along a transect between the Australian continental shelf and the Indonesian coast of Bali. The stations lie in the easternmost part of the Indian Ocean, close to the sills over which the Indonesian throughflow (ITF) makes its way to the Indian Ocean. The present data, obtained as part of the Java-Australia Dynamics Experiment (JADE) in August 1989, complement the WOCE 14C and tritium data set on both sides of the Indonesian archipelago and give us the opportunity to discuss the origin of the water masses and timescale of the throughflow. Both tracers point to a north equatorial Pacific origin of the waters. The comparison of the tritium inventories in the Pacific North Equatorial Current and along the JADE transect suggests a minimum transit time of the waters across the Indonesian seaways of the order of 5 to 6 yr, corresponding to a throughflow smaller than <18 x 10^6 m3/s.
    • Oceanic Radiocarbon Between Antarctica and South Africa Along WOCE Section 16 at 30 Degrees E

      Leboucher, Viviane; Orr, James; Jean-Baptiste, Philippe; Arnold, Maurice; Monfray, Patrick; Tisnérat-Laborde Nadine; Poisson, Alain; Duplessy, Jean-Claude (Department of Geosciences, The University of Arizona, 1999-01-01)
      Accelerator mass spectrometry (AMS) radiocarbon measurements were made on 120 samples collected between Antarctica and South Africa along 30 degrees E during the WOCE-France CIVA1 campaign in February 1993. Our principal objective was to complement the Southern Ocean's sparse existing data set in order to improve the 14C benchmark used for validating ocean carbon-cycle models, which disagree considerably in this region. Measured 14C is consistent with the theta -S characteristics of CIVA1. Antarctic Intermediate Water (AAIW) forming north of the Polar Front (PF) is rich in 14C, whereas surface waters south of the PF are depleted in 14C. A distinct old 14C signal was found for the contribution of the Pacific Deep Water (PDW) to the return flow of Circumpolar Deep Waters (CDW). Comparison to previous measurements shows a 14C decrease in surface waters, consistent with northward displacement of surface waters, replacement by old deep waters upwelled at the Antarctic Divergence, and atmospheric decline in 14C. Conversely, an increase was found in deeper layers, in the AAIW. Large uncertainties, associated with previous methods for separating natural and bomb 14C when in the Southern Ocean south of 45 degrees S, motivated us to develop a new approach that relies on a simple mixing model and on chlorofluorocarbon (CFC) measurements also taken during CIVA1. This approach leads to inventories for CIVA1 that are equal to or higher than those calculated with previous methods. Differences between old and new methods are especially high south of approximately 55 degrees S, where bomb 14C inventories are relatively modest.
    • OH Radicals Via Atmospheric 14CO: An Extended Summary

      Volz, Andreas; Tönnissen, Alfred; Ehhalt, D. H.; Khedim, Ahmed (American Journal of Science, 1980-01-01)
      Measurements of 14CO in the lower troposphere show a well-defined seasonal variation between 11 +/- 1 molecules cm-3 in summer and 25 +/- molecules cm-3 in winter at 51 degrees N. The concentration at 27 degrees N in summer is found to be 4.2 +/- 0.7 molecules cm-3. From these data and published 12C O measurements, the average concentration of OH radicals in the troposphere is calculated to be 6.5 +/- 2.5 X 10^5 molecules cm-3 using a 2-D time-dependent model. The corresponding 12C O lifetime is two months; the 14CO lifetime is five months.
    • Ohio Wesleyan University Natural Radiocarbon Measurements I

      Ogden, J. Gordon; Hay, Ruth J. (American Journal of Science, 1964-01-01)
    • Ohio Wesleyan University Natural Radiocarbon Measurements II

      Ogden, J. Gordon; Hay, Ruth J. (American Journal of Science, 1965-01-01)
    • Ohio Wesleyan University Natural Radiocarbon Measurements III

      Ogden, J. Gordon; Hay, Ruth J. (American Journal of Science, 1967-01-01)
    • Ohio Wesleyan University Natural Radiocarbon Measurements IV

      Ogden, J. Gordon; Hay, Ruth J. (American Journal of Science, 1969-01-01)
    • Ohio Wesleyan University Natural Radiocarbon Measurements V

      Ogden, J. Gordon; Hay, Ruth J. (American Journal of Science, 1973-01-01)
    • On a 50-Year "Climate-Free" delta-13C Record from Juniper Tree Rings

      Leavitt, Steven W.; Long, Austin (American Journal of Science, 1983-01-01)
    • On a Plausible Physical Mechanism Linking the Maunder Minimum to the Little Ice Age

      Nesme-Ribes, Elizabeth; Mangeney, Andre (Department of Geosciences, The University of Arizona, 1992-01-01)
      To understand better the Earth's climate, we need to know precisely how much radiation the Sun generates. We present here a simple physical mechanism describing the convective processes at the time of low sunspot activity. According to this model, the kinetic energy increased during the Maunder Minimum, causing a decrease of the solar radiation that was sufficient to produce a little Ice Age.
    • On Correcting 14C Ages of Gastropod Shell Carbonate for Fractionation

      Pigati, Jeffrey S. (Department of Geosciences, The University of Arizona, 2002-01-01)
      Correcting the 14C age of a sample for fractionation is straightforward if the measured carbon was derived entirely from the atmosphere, either directly or through chemical and/or biological reactions that originated with atmospheric carbon. This correction is complicated in the case of gastropods that incorporate carbon from limestone or secondary carbonate (e.g. Soil carbonate) during shell formation. The carbon isotopic composition of such gastropod shells is determined by fractionation, as well as mixing of carbon from sources with different isotopic values. Only the component of shell carbonate derived from atmospheric carbon should be corrected for fractionation. In this paper, the author derives a new expression for correcting the measured 14C activity of gastropod shells for fractionation, and describe an iterative approach that allows the corrected 14C activity and the fraction of shell carbonate derived from atmospheric carbon to be determined simultaneously.