• Radiocarbon, Volume 25, Number 3 (1983)

      American Journal of Science, 1983-01-01
    • Notice to Readers and Contributors

      American Journal of Science, 1983-01-01
    • Vienna Radium Institute Radiocarbon Dates XIII

      Felber, Heinz (American Journal of Science, 1983-01-01)
    • University of Miami Radiocarbon Dates XXIII

      Hood, Darden G.; Johnson, R. A.; Stipp, J. J. (American Journal of Science, 1983-01-01)
    • University of Lund Radiocarbon Dates XVI

      Håkansson, Sören (American Journal of Science, 1983-01-01)
    • University of Georgia Radiocarbon Dates VII

      Noakes, John E.; Herz, Norman (American Journal of Science, 1983-01-01)
    • The Question of Diffuse Secondary Growth of Palm Trees

      Wiesberg, L. G.; Linick, T. W. (American Journal of Science, 1983-01-01)
      14C activity measurements were used to investigate the growth pattern of the stem of a palm tree (Cocos nucifera) which does not form annual rings. The results reveal that there was no diffuse secondary growth (thickening of the stem) over the entire mature stem during the last 25 years of growth, with the exception of a restricted zone in the center at medium height.
    • Tallinn Radiocarbon Dates VII

      Punning, J. M.; Rajamäe, R.; Joers, Kai; Putnik, H. (American Journal of Science, 1983-01-01)
    • Simon Fraser University Radiocarbon Dates II

      Hobson, K. A.; Nelson, D. E. (American Journal of Science, 1983-01-01)
    • Moscow MV Lomonosov State University Radiocarbon Dates II: Sea Level Indicators from Coastal USSR

      Glushankova, N. I.; Parnunin, O. B.; Selivanov, A. O.; Shlukov, A. I.; Timashkova, T. A. (American Journal of Science, 1983-01-01)
    • Laboratories

      American Journal of Science, 1983-01-01
    • INGEIS Radiocarbon Laboratory Dates I

      Albero, Miguel C.; Angiolini, Fernando E. (American Journal of Science, 1983-01-01)
    • Institut Royal du Patrimoine Artistique Radiocarbon Dates IX

      Dauchot-Dehon, Michele; Van Strydonck, Mark; Heylen, Jos (American Journal of Science, 1983-01-01)
    • Index

      American Journal of Science, 1983-01-01
    • Gliwice Radiocarbon Dates IX

      Pazdur, Mieczysław F.; Awsiuk, Romuald; Bluszcz, Andrzej; Pazdur, Anna; Walanus, Adam; Zastawny, Andrzej (American Journal of Science, 1983-01-01)
    • Carbon Isotope Analysis of Land Snail Shells: Implications for Carbon Sources and Radiocarbon Dating

      Goodfriend, Glenn A.; Hood, Darden G. (American Journal of Science, 1983-01-01)
      13C and 14C analyses were performed on a series of modern Jamaican land snails in order to quantitatively determine the sources of shell carbon. A model of these carbon sources, the pathways by which carbon reaches the shell, and the fractionation processes involved are presented. The contribution of limestone to shell carbonate is variable but may comprise up to 33% of the shell. About 25-40% of shell carbonate is derived from plants and about 30-60% from atmospheric CO2. Variation among populations and species with respect to 13C and 14C is attributed to the effects of limestone incorporation, snail size (as it affects CO2 exchange rate), physiological characteristics (presence of urease, respiration rate), and activity patterns of the snails. A formula for correction for isotopic fractionation of 14C of shell carbonate, based on "C measurements, is derived. Bicarbonate-aragonite fractionation is apparently very minimal. Shell organic carbon appears to be derived largely from plants but also to a lesser extent from inorganic hemolymph carbon. This introduces the possibility of a small age anomaly of shell organic 14C due to limestone incorporation.
    • 14C Variations from Tasmanian Trees—Preliminary Results

      McPhail, Steve; Barbetti, Mike; Francey, Roger; Bird, Trevor; Dolezal, Jiri (American Journal of Science, 1983-01-01)
      Huon pine is endemic to Tasmania. It has well-defined annual rings, may live for over 2000 years, and is particularly resistant to decay. Celery-top pine has similar characteristics and may live for 800 years. As part of a multi-disciplinary study of these trees and their habitat, a simple wood pretreatment method for isotope analysis is described. The solvent-acid-alkali-acid sequence yields a value of Delta-14C = -16 +/- 6% for AD 1941-45 Huon pine heartwood; Delta-4C for extracts containing various proportions of post-AD 1955 carbon are also presented. Delta-14C measurements on super-canopy and subcanopy leaves from Celery-top pines are compared and used to place an upper limit of 10% on the amount of sub-canopy CO2 assimilated by sapling leaves, originating from decaying litter-mass. 14C ages from well-preserved logs illustrate the potential for a continuous Holocene chronology from 7400 years BP to the present. A 12,000-year-old Celery-top log has also been found.