• Some Radiocarbon Dates for Tufas of the Craven District of Yorkshire

      Pentecost, Allan; Thorpe, P. M.; Harkness, D. D.; Lord, T. C. (Department of Geosciences, The University of Arizona, 1990-01-01)
      14C dates of relict tufa deposits at Gordale indicated a Subboreal age when the carbonate age was corrected with empirical bedrock dilution factors ‘q’ of 0.79 or 0.85. Estimates of ‘apparent age,’ based on extrapolated Delta-13C values were about twice those obtained with q, and the 1 sigma error was large. The Delta--13C values of tufa samples were not correlated with carbonate age and were close to −10. Application of q values in this district requires caution as they appear to be site-specific. We recommend that wherever possible, levels of 13C and 14C are measured in the associated tufa-depositing water, and an empirical dilution factor employed.
    • Survey of the Dispersion of 14C in the Vicinity of the UK Reprocessing Site at Sellafield

      Otlet, R. L.; Walker, A. J.; Fulker, M. J. (Department of Geosciences, The University of Arizona, 1990-01-01)
      We have been measuring 14C in natural, biological materials growing in the vicinity of Sellafield, Cumbria as a continuing project with BNFL to understand the dispersion of releases from the site over several seasons. We have measured locally grown foodstuffs for monitoring purposes, individual tree rings to establish a chronology of releases, hawthorn berries for spatial investigations and are now carrying out controlled plot uptake experiments. We have been attempting to validate a current dispersion model (Clarke 1979) over a six-year period, and although we observe general agreement in most years, certain anomalies, which probably relate to topographical features, are leading to more detailed correlation with local meteorological data.