• Quality Assurance of Ultrafiltered Bone Dating

      Brock, Fiona; Bronk Ramsey, Christopher; Higham, Thomas (Department of Geosciences, The University of Arizona, 2007-01-01)
      Ultrafiltration of bone collagen provides a method of purification that can be very effective in reducing environmental contamination from soil-derived amino acids as well as removing degraded collagen or other short-chain proteins. The Oxford Radiocarbon Accelerator Unit (ORAU) first implemented ultrafiltration in the pretreatment of bone material for accelerator mass spectrometry (AMS) radiocarbon dating in 2000. However, the filters themselves contain carbonaceous material, and thus stringent quality control is required to demonstrate that this does not affect the accuracy of the dating. Here, we present quality assurance data from the bone pretreatment and dating program at ORAU, including dates on known-age and background-age bones over a range of sample sizes, and measurements of residual carbon contamination present in the filters after cleaning.
    • Quality Controlled Radiocarbon Dating of Bones and Charcoal from the Early Pre-Pottery Neolithic B (PPNB) of Motza (Israel)

      Yizhaq, Meirav; Mintz, Genia; Cohen, Illit; Khalaily, Hamudi; Weiner, Steve; Boaretto, Elisabetta (Department of Geosciences, The University of Arizona, 2005-01-01)
      Radiocarbon dating of early Pre-Pottery Neolithic B (PPNB) deposits at the site of Motza, Israel, was achieved by first prescreening many charcoal and bone samples in order to identify those that are in the most suitable state of preservation for dating. For assessing bone preservation, we determined the collagen contents, and by infrared spectroscopy the collagen purity. The collagen samples of the best preserved bones were then further characterized by their C/N ratios and amino acid compositions. Prescreening of the charcoal samples involved monitoring the changes in infrared and Raman spectra during the acid-alkali-acid treatments. In some samples, we noted that the clay content increased with additional alkali treatments. These samples were rejected, as this could result in erroneous dates. No differences were observed in the 14C dates between charcoal and bone collagen samples. The dates range from 10,600-10,100 cal BP, which is consistent with dates for the early PPNB from other sites. This is of much interest in terms of better understanding where and when domestication of animals began in this period, and how agriculture spread throughout the Levant.
    • Quantifying Background Components of Low-Level Gas Proportional Counters

      Theodórsson, Páll (Department of Geosciences, The University of Arizona, 1992-01-01)
      I discuss background components of low-level gas proportional counters and show how each component can be estimated based on available data. For more reliable background analysis, further studies are suggested. Based on new information, a generation of low-level gas proportional counting systems for radiocarbon dating may emerge with lower and more predictable background.
    • Quantitative Determination by 14C Analysis of the Biological Component in Fuels

      Dijs, Ivo J.; van der Windt, Eric; Kaihola, Lauri; van der Borg, Klaas (Department of Geosciences, The University of Arizona, 2006-01-01)
      Radiocarbon analysis was performed by liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) to assess whether the content of biological components in hydrocarbon fuels could be derived. Different fuel mixtures were prepared containing bioethanol, fossil ethanol, and fossil gasoline. The specific 14C activity of these mixtures was obtained from LSC measurements and directly related to the concentration of carbon originating from the bioethanol (biocarbon). The results were checked via standardized carbon dating procedures and AMS. A good linear correlation exists between the fuel mixtures specific 14C activity and the concentration of biocarbon. Also, the biocarbon fraction of the fuel mixture (the ratio biocarbon : total carbon) and the normalized fraction of biocarbon (%M) showed good linear correlation. Therefore, both relations provide a possibility to quantitatively determine a fuels biocarbon content by 14C analysis. When the sample composition is known (e.g. Resolved by gas chromatography-mass spectroscopy [GC-MS] and nuclear magnetic resonance [NMR]), the amount of particular biological components in a fuel sample can be derived subsequently. For mixtures of bioethanol, fossil ethanol, and gasoline with bioethanol contents in the range of 0.52% m/m, it was found that errors in the normalized fraction of biocarbon (%M) were in the range of 2510%, respectively. For samples with a higher bioethanol content (up to pure bioethanol), the errors in %M were 10%. Errors might be larger if substantial changes in the concentration of atmospheric 14C took place during the growth period of the biofuel feedstock. By taking into account the variation in specific 14C activity of carbon over the last decades, and by modeling simple tree-growth, it could be illustrated that this effect becomes significant only if the biofuel feedstock stopped growing more than 1 decade ago, e.g. With wood from constructions.
    • Quantitative Extraction of Dissolved Inorganic Carbon (as CO2) and Water by Vacuum Distillation from Sediments of the Unsaturated Zone for Carbon Isotope Analysis (13C and 14C)

      Carmi, I.; Kronfeld, J.; Yechieli, Y.; Yakir, D.; Stiller, M.; Boaretto, M. (Department of Geosciences, The University of Arizona, 2007-01-01)
      Vacuum distillation is shown to be useful for the quantitative extraction of dissolved inorganic carbon (as CO2) and water from sediments of the unsaturated zone in the Coastal Aquifer of Israel. Several tests of vacuum extractions from tap water and sediments are presented, including standard addition, which show that the distillation procedure is quantitative, with minimal or no carbon isotope fractionation. The optimal temperature of the sediment during the extraction was also defined. Examples of vacuum extractions of sediments are shown.
    • Quaternary Community Loses Glenn Goodfriend

      Brigham-Grette, Julie (Department of Geosciences, The University of Arizona, 2002-01-01)
    • Quebec Radiocarbon Measurements I

      Samson, Claude; Barrette, Louis; LaSalle, P.; Fortier, J. (American Journal of Science, 1977-01-01)
    • Quebec Radiocarbon Measurements II

      Barrette, L.; Lasalle, P.; Samson, C. (American Journal of Science, 1977-01-01)
    • Quebec Radiocarbon Measurements III

      Barrette, Louis; La Salle, Pierre; Samson, Claude (American Journal of Science, 1981-01-01)
    • Queens College Radiocarbon Measurements I

      Pardi, Richard (American Journal of Science, 1976-01-01)
    • Queens College Radiocarbon Measurements II

      Pardi, R. (American Journal of Science, 1977-01-01)
    • Queens College Radiocarbon Measurements III

      Pardi, Richard; Newman, E. R. (American Journal of Science, 1980-01-01)
    • Queens College Radiocarbon Measurements IV

      Pardi, Richard R.; Tomecek, Lynn; Newman, Walter S. (American Journal of Science, 1984-01-01)
    • "Quickie" 14C Dates

      Michael, Henry N.; Ralph, Elizabeth K. (American Journal of Science, 1981-01-01)
    • Radioactive Graphite Dispersion in the Environment in the Vicinity of the Chernobyl Nuclear Power Plant

      Buzinny, Michael (Department of Geosciences, The University of Arizona, 2006-01-01)
      This paper estimates the radioactive graphite dispersion on the land surface (forest litter and soil) as a result of the Chernobyl Nuclear Power Plant (NPP) release. Graphite mass was calculated using an estimated average concentration of 2.5 x 10^7 Bq/kg C (carbon). The sample collection method, sample origin and its mass, and sample preparation procedure used for preparation of benzene were taken into account to obtain the optimum sensitivity of the method. Thus, the sensitivity of the corresponding method for graphite detection in forest litter was estimated to be 0.2 mg/m2. All analyses gave a range of deposited graphite from 0.12 to 52.6 mg/m2. The maximum value was observed at a site located 9 km west of the Chernobyl NPP. The results of the study indicate the importance of studying the upper layer of soil (05 cm) in addition to the lower layer of forest litter.
    • Radiocarbon 1993 Price List

      Department of Geosciences, The University of Arizona, 1993-01-01
    • Radiocarbon 1994 Price List

      Department of Geosciences, The University of Arizona, 1993-01-01
    • Radiocarbon 1994 Price List

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Radiocarbon Accelerator (AMS) Dates for the Epipaleolithic Settlement at Abu Hureyra, Syria

      Moore, A. M. T.; Gowlett, J. A. J.; Hedges, R. E. M.; Hillman, G. C.; Legge, A. J.; Rowley-Conwy, P. A. (American Journal of Science, 1986-01-01)
      The prehistoric settlement of Abu Hureyra in Syria was occupied in both the Epipaleolithic and Neolithic periods. It has provided significant evidence for changes in economy at the time of the inception of agriculture in southwest Asia. Twenty accelerator mass spectrometry (AMS) dates have been obtained to determine the duration of occupation of the Epipaleolithic settlement there and the precise age of samples of cereal grains and animal bones found within it. The results have demonstrated that the AMS technique can answer such questions because it dates exceedingly small samples with high precision. The dates indicate that the Epipaleolithic settlement was inhabited for about a millennium, from before 11,000 to nearly 10,000 BP, significantly longer than had been anticipated from study of the artifacts.
    • Radiocarbon Activity Measurements of Oolitic Sediments from the Persian Gulf

      Šilar, Jan (American Journal of Science, 1980-01-01)
      Radiocarbon activity of successive parts of Pleistocene and Holocene ooids and mollusk shells from the Persian Gulf, Kuwait, was measured. The inner part of the ooids showed the lowest activity and the cement between grains the highest. Radiocarbon activities correspond to the general stratigraphy and to the position of the sediments. Radiocarbon ages of Pleistocene sediments seem to be very low due to recrystallization of aragonite. Higher radiocarbon activity of cement indicates that atmospheric carbon dioxide was involved in the subaerial diagenetic process. The radiocarbon age of well-preserved mollusk shells seems to be lower than their allegedly Pleistocene geologic age.