• delta-13C and Diet: Analysis of Norwegian Human Skeletons

      Johansen, Olav Sverre; Gulliksen, Steinar; Nydal, Reidar (American Journal of Science, 1986-01-01)
      The relationship between 13C content of human bone and the marine fraction in the individual diet is well established. In the present investigation human skeletons from inland and coastal areas in Norway were analyzed. Both regional and chronologic differences are revealed, and larger variability than expected at specific sites indicate more complex cultural adaptations than earlier recognized. Extremely high delta-13C values, comparable with those obtained from Eskimo sites, are found for material from Early Stone Age fishing/hunting communities.
    • Dendrochronology—The Absolute Irish Standard

      Brown, D. M.; Munro, M. R.; Baillie, M. G. L.; Pilcher, J. R. (American Journal of Science, 1986-01-01)
      Since the 11th International Radiocarbon Conference considerable advances have been made in European dendrochronology giving several long continuous absolute chronologies. Recent collaboration between European laboratories provides confirmation of the accuracy of these chronologies and, thus, of the standards used for radiocarbon calibration.
    • Detection of Bias in the Background of Vials Used for Scintillation Counting

      Ambers, Janet; Leese, Morven; Bowman, Sheridan (American Journal of Science, 1986-01-01)
      Inter-vial variation in background of the glass vials used in liquid scintillation counting can introduce appreciable errors into 14C measurements. Our aim was to measure the background in each of 50 glass vials, under the same conditions as far as possible, in order to find a self-consistent set for use in 14C dating. The criteria, statistical tests, and possible errors introduced by not making such checks are discussed.
    • Discordant Ages Related to Reservoir Effect of Associated Archaeologic Remains from the Tunel Site, Beagle Channel, Argentine Republic

      Albero, Miguel C.; Angiolini, Fernando E.; Piana, Ernesto L. (American Journal of Science, 1986-01-01)
      Evidence of a tradition of human maritime adaptation was recovered from various sites at Beagle Channel dating back to ca 6000 yr BP. Final occupations date to European settlement in the 19th century. The Túnel site exhibits discontinuous human occupation ranging from 6000 to 500 yr BP, represented by different archaeologic remains in each layer. Associated charcoal, mollusk shells, and Lama guanicoe and Arctocephalus australis bones were dated. Shells and Arctocephalus are consistently older than charcoal, demonstrating the reservoir effect at Beagle Channel. Results encourage further work in the area to evaluate the spatial and temporal magnitude of the effect.
    • Early Slavonic Settlements and Navigation at the Mouth of the Odra River

      Awsiuk, Romuald; Filipowiak, Władyslaw; Goslar, Tomasz; Pazdur, Anna; Pazdur, Mieczysław F. (American Journal of Science, 1986-01-01)
      An attempt is presented to establish an absolute chronology of early Slavonic habitation in the region of the mouth of the Odra River up to the Baltic and to find associations with a series of stave boats and dugouts of different levels of technology and navigation. The methodology of the research project is presented and some conclusions of a general nature are drawn from the results already obtained.
    • Environmental 14C Levels Around the 632 MWe Nuclear Power Plant Krško in Yugoslavia

      Obelić, Bogomil; Krajcar-Bronić, Ines; Srdoč, Dušan; Horvatinčić, Nada (American Journal of Science, 1986-01-01)
      Measurements of 14C activity of atmospheric CO2, vegetables, and tree rings in the area of the 632 MWe power plant Krško in Slovenia, NW Yugoslavia, have been in progress since January, 1984. Sampling stations are located in the area ca 400km2 and are distributed in the direction of the prevailing westerly winds. The closest sampling point is 1.5km NE of the plant exhaust stack, the farthest sampling point is 30km E of the plant. A sampling site at National Park Plitvice in central Croatia was chosen as the 14C reference point not affected by the power plant. An average excess of 2.2% above the reference point activity during normal periods of reactor operation was observed 1.5km from the plant smokestack. Calculations of the 14C release from the power plant was estimated at 0.1 TBq/a. The tree ring activity near the plant followed the 14C activity of the Northern Hemisphere in the past decade. No influence of the power plant release was observed on the tree ring activity.
    • Establishment of a Working Data Base for the International Exchange of 14C Data Using Universal Transfer Formats

      Wilcock, J. D.; Otlet, R. L.; Walker, A. J.; Charlesworth, S. A.; Drodge, J. (American Journal of Science, 1986-01-01)
      A high-level record structure for the international communication of 14C data bases is proposed. The record structure is based on the high-level communication format first proposed by the authors at the 23rd International Symposium on Archaeometry, Naples, 1983 and does not require the abandonment of existing systems. A description is given of an implementation of the high-level system at Harwell, with examples of retrieval in an international format (the Radiocarbon date list format) and a keyword-organized local format.
    • Fast and Complete CO2-to-Graphite Conversion for 14C Accelerator Mass Spectrometry

      Hut, Gert; Östlund, H. Göte; van der Borg, Klaas (American Journal of Science, 1986-01-01)
      With Fe powder as a catalyst, CO2 is completely converted to graphite within 90 minutes. The reaction proceeds at 650 degrees C with an excess of H2. The reaction rate is enlarged by forced circulation and by keeping the water vapor pressure very low. The graphite samples obtained, consisting of 5mg of carbon, almost immediately produce stable 12C- currents of the order of 20-30 micro-A in the sputter source of a Van de Graaff accelerator. The currents can be maintained for at least 10 hours and are comparable to those from commercial graphite. No memory effects in the preparation system have been observed.
    • Foreword

      Stuiver, Minze (American Journal of Science, 1986-01-01)
    • Geomagnetic-Heliomagnetic Modulation of Atmospheric Radiocarbon Production

      Damon, Paul E.; Linick, Timothy W. (American Journal of Science, 1986-01-01)
      New Arizona high precision Delta-14C data back to 6500 BC plot close to an 11,300-yr period sinusoid extrapolated from the post 5300 BC data (offset = +32 per mil, half amplitude = 51 per mil and phase lag = 2.29 radians). The trend curve is modulated by high latitude components of the non-dipole field with a fundamental period of 2400 yr. Based upon a model of Lund and Banerjee (1985), the non-dipole field rotates and every 1200 yr the high latitude maxima pass over the north magnetic pole and near the south magnetic pole in reversed polarity. This modulates cosmic ray production producing extended maxima ca AD 1700, 700 BC, 3100 BC, and 5500 BC. The 2400 period appears to be stationary. The magnetic field also modulates the amplitude of the solar activity induced cycles of periods 200, 80, and 11 yr as can be seen in the Zürich-Bern Camp Century ice core data as well as in the Delta-14C fluctuation data. Reinterpretation of the Camp Century 10Be data indicates that it is in agreement with magnetic field as well as solar activity modulation of terrestrial radioisotope production.
    • Global and Local Effects of 14C Discharges from the Nuclear Fuel Cycle

      McCartney, Martin; Baxter, M. S.; McKay, Keith; Scott, E. Marian (American Journal of Science, 1986-01-01)
      The radiologic impact of 14C produced by the nuclear fuel cycle is assessed at both global and local levels. In the former context, it is predicted here that the specific activity of atmospheric CO2 in the year 2050 will be ca 7.6 pCig^(-1)C. Although this is similar to the present level, the subsequent collective dose commitment could be highly significant. The enhancement of 14C concentrations around the nuclear fuel-reprocessing plant at Sellafield (Windscale) in Cumbria, UK has been monitored over recent years. For example, maximum levels of 27.2 pCig^(-1)C (~350% above natural) during 1984 were observed <1 km from the plant, with enhanced activities detectable to at least 29km. Nevertheless, it is clear that the radiologic significance to the local population is low. The spatial distribution of the excess 14C allows atmospheric dispersion models to be tested in the context of continuous releases and the results thus far show that the Gaussian plume model performs successfully.
    • Groningen 14C Data Base

      Endelsman, F. M. R.; Taayke, E.; Mook, W. G. (American Journal of Science, 1986-01-01)
    • Ice-Core Dating of the Pleistocene/Holocene Boundary Applied to a Calibration of the 14C Time Scale

      Hammer, Claus U.; Clausen, Henrik B.; Tauber, Henrik (American Journal of Science, 1986-01-01)
      Seasonal variations in 18O content, in acidity, and in dust content have been used to count annual layers in the Dye 3 deep ice core back to the Late Glacial. In this way the Pleistocene/Holocene boundary has been absolutely dated to 8770 BC with an estimated error limit of +/- 150 years. If compared to the conventional 14C age of the same boundary a value of Delta-14C = 53 +/- 13 per mil is obtained. This Delta-14C value suggests that 14C levels during the Late Glacial were not substantially higher than during the Postglacial.
    • Increase of 14C Activity of Dissolved Inorganic Carbon Along a River Course

      Srdoč, Dušan; Krajcar-Bronić, Ines; Horvatinčić, Nada; Obelić, Bogomil (American Journal of Science, 1986-01-01)
      Results of measurements for 3 years (1981-1983) of 14C activity of dissolved inorganic carbon (DIC) in water samples from the Korana River, as well as that of recent tufa and aquatic plants, showed that 14C concentration increases from karst spring to the estuary. A model describing the increase of 14C activity was developed assuming that the increase is due to the exchange of the dissolved CO2 in stream water with atmospheric CO2 and to dissolution of CO2 from the decay of organic material and root respiration. It is possible to distinguish these two contributions by measuring the delta-13C values of DIC in water. As expected, our data show that the exchange process between atmospheric CO2 and DIC dominates at rapids and waterfalls, while biologic contribution is much higher in lakes and along the lowland flow of the Korana River. Agreement between the calculated and the measured activities supports the proposed mechanisms of chemical and isotopic exchanges in stream waters.
    • Is Radiocarbon Dating Obsolescent for Archaeologists?

      Ottaway, Barbara S. (American Journal of Science, 1986-01-01)
      This paper will deal with two major points: 1) the lack of feedback between archaeologists supplying samples and using radiocarbon dating, and physicists carrying out 14C dating measurements; and 2) the problem of calibrating groups of 14C dates in a statistically meaningful way.
    • Isotopic Fractionation of Carbon During CO2 Absorption by Mortar

      Pachiaudi, Christiane; Marechal, Joelle; Van Strydonck, Mark; Dupas, Michel; Dauchot-Dehon, Michele (American Journal of Science, 1986-01-01)
    • Laser Resonance Ionization Mass Spectrometry for Krypton-81 Analysis

      Lehmann, B. E.; Loosli, H. H.; Oeschger, Hans; Rauber, Dominique; Hurst, G. S.; Allman, S. L.; Chen, C. H.; Kramer, S. D.; Thonnard, Norbert; Willis, R. D. (American Journal of Science, 1986-01-01)
      A new laser-based analytical technique is described for isotope selective noble gas atom counting. The method has been used to detect 81Kr atoms in a groundwater sample.
    • Measurement of 10Be and 26Al with a Tandetron Accelerator Mass Spectrometer Facility

      Yiou, Francoise; Raisbeck, Grant M.; Bourles, Dider; Lestringuez, Jacques; Deboffle, Dominique (American Journal of Science, 1986-01-01)
      A description is given of the use of a Tandetron accelerator mass spectrometer system for measuring the isotopes10Be and 26Al.
    • Measurement of 14C Directly from CO2 Using a Tandetron Accelerator Mass Spectrometer Facility

      Raisbeck, Grant M.; Yiou, Françoise; Arnold, Maurice; Duplessy, Jean Claude (American Journal of Science, 1986-01-01)
      Tests have been carried out on the measurement of 14C directly from CO2, using a source designed by Middleton, and a Tandetron accelerator mass spectrometer system. These tests were very promising from the point of view of minimum quantity of carbon necessary (<50 micrograms), but suffered from a background (apparently not memory effect) giving an equivalent age of 25,000 years. As a demonstration of the technique, a single thread from the mummy wrapping of the Egyptian king Ramses II was dated.
    • Multiple Dating of a Long Flowstone Profile

      Geyh, Mebus A.; Hennig, G. J. (American Journal of Science, 1986-01-01)
      Dense speleothem samples are considered as closed systems and are, therefore, possibilities for any dating method. Four dating methods (14C, U/Th, paleomagnetism, and electron spin resonance = ESR) were used for samples up to 1,000,000 yr old and taken along a vertical flowstone profile in the Heggen cave in West Germany. Also delta-18O and delta-13C analyses were carried out. The reliability of the results of each method is dependent on the diagenetic processes that took place during the complex growth history of the flowstone. Speleothem growth was interrupted during glacial periods. During interglacial periods, at least the stalagmite growth rate was greater by one order of magnitude than during interstadial periods. During the periods of low interstadial growth rate various processes might have changed the 14C, 18O, and 13C concentrations, leaching might have removed uranium, recrystallization might have moved thorium several centimeters, and increased content of radon in the cave might have exaggerated the accumulated dose (AD) at the speleothem surface. As a result, 14C ages may be too small and U/Th as well as ESR data may be too large.