• A Study of Errors in 14C Dates of Peat and Sediment

      Olsson, Ingrid U. (American Journal of Science, 1986-01-01)
      It is a well-established fact that 14C dates from lake sediments are usually too old because of contamination with allochthonous material and/or due to discrete reservoir effects. The latter can occur in soft water lakes and may be examined by the 14C measurement of aqueous plants or the carbon dissolved and suspended in the water column. Some plants assimilate CO2 from the sediment. Their 14C activity is then dependent on the sediment accumulation rate and nutrients stored in the root system may also contribute misleading results. If water is filtered through ultra-fine membranes and then treated chemically, several fractions can be isolated for dating. The present study shows that the 14C activity of such fractions varies widely but with the weighted mean indicating an overall deficiency. Even the water from a raised bog evidences a 14C deficiency relative to contemporary atmospheric CO2. Charcoal from an archaeologic site and peat from corresponding layers in a nearby bog have yielded significantly different ages. The fact that the Cladium peat was from a very calcareous area is significant. The risk of contamination by younger root material is also documented.
    • Applications of the Use of Hawthorn Berries in Monitoring 14C Emissions from a UK Nuclear Establishment Over an Extended Period

      Walker, A. J.; Otlet, R. L.; Longley, Harry (American Journal of Science, 1986-01-01)
      The paper describes a study undertaken to examine the dispersion pattern of gaseous emissions, as indicated by 14C uptake in natural materials, around the nuclear reprocessing plant at Sellafield, Cumbria, UK. The extent and directional dispersion of the released 14C is established and its variability over an extended period assessed. Results of measurements taken during three sampling seasons (1981,1982,1983) of the 14C activity in hawthorn berries collected over a wide area are presented and the dispersion pattern contours constructed from them are examined. Only limited agreement of the results with the theoretical relationship 1/r is found and both meteorology and topography are seen to be important in determining the shape of the observed patterns.
    • 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.
    • Gif Natural Radiocarbon Measurements X

      Delibrias, Georgette; Guillier, M.-T.; Labeyrie, Jacques (American Journal of Science, 1986-01-01)
    • 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)
    • High-Precision 14C Measurement of Irish Oaks to Show the Natural 14C Variations from AD 1840-5210 BC

      Pearson, Gordon W.; Pilcher, J. R.; Baillie, M. G. L.; Corbett, D. M.; Qua, F. (American Journal of Science, 1986-01-01)
      High-precision measurement of dendrochronologically dated Irish oak at bidecade/decade intervals has continued in the Belfast laboratory, extending the 14C data base from ca AD 1840 to 5210 Bc. The dendrochronology is now considered absolute (see Belfast dendrochronology this conference) (Brown et al, 1986) and a continuous detailed curve is presented, showing the natural variations in the atmospheric concentration of 14C over >7000 years. Each data point has a precision of <2.50 per mil, and some 4500 years have now been compared with Seattle, giving excellent agreement. Discussion of this data base and the justification of the claimed accuracy is given together with a comparison of other chronologies. Some of the advantages and limitations of the above are discussed.
    • Institut Royal du Patrimoine Artistique Radiocarbon Dates XI

      Dauchot-Dehon, Michele; Van Strydonck, Mark; Heylen, Jon (American Journal of Science, 1986-01-01)
    • Köln Radiocarbon Dates III

      Schulte im Walde, T.; Freundlich, J. C.; Schwabedissen, Hermann; Taute, Wolfgang (American Journal of Science, 1986-01-01)
    • Sample Credentials Necessary for Meaningful High-Precision 14C Dating

      Jope, E. M. (American Journal of Science, 1986-01-01)
      Samples presented for high-precision 14C dating must satisfy stringent requirements if the 14C determinations are to yield meaningful sharp calendric dates, such as are now possible with the bidecadal high-precision calibration curve. The total carbon content should come from a confined time range 10-20 years (10-20 tree rings in wood or charcoal) appropriate for the bidecadal calibration curve. For accurate calendric dating the relation of these rings to the outer growth rings must be known. Application of the high-precision calibration curve to some archaeologic examples is discussed. It is now up to archaeologists and geoscientists to use this refined chronometric instrument to fullest advantage.
    • The Power of 14C Measurements Combined with Chemical Characterization for Tracing Urban Aerosol in Norway

      Currie, L. A.; Klouda, G. A.; Schjoldager, Jorgen; Ramdahl, Thomas (American Journal of Science, 1986-01-01)
      Changing fuel patterns and increased awareness of health effects from combustion aerosols have generated considerable interest in the use of 14C as a biogenic-fossil aerosol source discriminator. Prior studies in the US demonstrated the importance of 14C measurement for estimating the wood-burning contribution to urban aerosols. The present work treats a specific air-pollution problem in the town of Elverum, Norway where large wintertime concentrations of aerosol carbon and polycyclic aromatic hydrocarbons (PAH) were suspected to come from residential woodl combustion (RWC). The problem was significant in that up to 50 micrograms/m3[C] and 490 micrograms/m3[PAH] were found during pollution episodes. Samples collected during two winters were analyzed for C, C, PAH, and several elements in the fine fraction (<3 micrometers) aerosol. Source apportionment based on these species indicated an average of ca 65% RWC-carbon (14C), ca 5% fine particle mass from motor vehicles (Pb), but negligible contributions from heavy fuel oil (Ni, V). Patterns of 14C and total C, examined as a function of temperature and PAH, indicated large increases in RWC aerosol on the coldest days, and a major RWC contribution to the PAH fraction. Patterns with inorganic species implied multiple tracer sources, and one important case of long-range transport.
    • The Prehistoric Expansion of Farming Into "Arctic" Norway: A Chronology Based on 14C Dating

      Johansen, Olav Sverre; Vorren, Karl-Dag (American Journal of Science, 1986-01-01)
      Palynologic and archaeologic studies using 14C dating indicate that elements of farming were introduced even further north than the Arctic Circle during the Neolithic period, ca 4000 BP. A second stage with heavier reliance on farming and with probable establishment of permanent farmsteads is dated to 2000-2500 BP.
    • The Value of 210Pb in Dating Scandinavian Aquatic and Peat Deposits

      El-Daoushy, Farid (American Journal of Science, 1986-01-01)
      Sediment and peat chronologies have been further improved allowing alternative radiometric methods to complement 14C dating. Lacustrine and coastal marine sediments as well as peat deposits in various parts in Scandinavia are studied using 137Cs, 210Pb, 14C and other methods primarily to evaluate the 210Pb but also to extend the 14C chronology. The sampling sites have various sources of input and are characterized by different geochemical, depositional, and post-depositional conditions.
    • University of Lund Radiocarbon Dates XIX

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Lund Radiocarbon Dates XVIII

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Wisconsin Radiocarbon Dates XXIII

      Steventon, Raymond L.; Kutzbach, John E. (American Journal of Science, 1986-01-01)