• New Dating Evidence for North Sea Trade between England, Scotland, and Norway in the 11th Century AD

      Hall, D. W.; Cook, G. T.; Hamilton, W. D. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This study follows on from previous research at Perth, Scotland, in which we dated carbonized food residues removed from the external surface of rim sherds of cooking pots of London Sandy Shellyware pottery (Museum of London Pottery Fabric Code SSW). The 15 residues that were dated produced 14C ages between 910 +/- 35 and 1085 +/- 40 BP. We have now carried out radiocarbon measurements on similar residues from the same fabric obtained from the Billingsgate excavations in London and the Bryggen excavations in Bergen, Norway. The London and Bergen measurements gave age ranges of 905 +/- 35 to 1115 +/- 35 BP and 920 +/- 35 to 1055 +/- 35 BP, respectively, both very similar to the Perth age range. The measurements at each site are in agreement with our Bayesian model assumption that they belong to a single phase of activity. The model estimates the introduction of London Sandy Shellyware in London to cal AD 820-1020, in Perth to cal AD 930-1020, and in Bergen to cal AD 980-1030 (95% probability). Further modeling predicts that it fell out of use in the reverse order.
    • Radiocarbon in the Air of Central Europe: Long-Term Investigations

      Svetlik, I.; Povinec, P. P.; Molnár, M.; Vána, M.; Šivo, A.; Bujtás, T (Department of Geosciences, The University of Arizona, 2010-01-01)
      Regional levels of radiocarbon have been monitored in order to investigate the impact of fossil fuel combustion on the activity of atmospheric 14CO2 in central Europe. Data from atmospheric 14CO2 monitoring stations in the Czech Republic, Slovakia, and Hungary for the period 2000-2008 are presented and discussed. The Prague and Bratislava monitoring stations showed a distinct local Suess effect when compared to the Jungfraujoch clean-air monitoring station. However, during the summer period, statistically insignificant differences were observed between the low-altitude stations and the high-mountain Jungfraujoch station. 14C data from the Hungarian monitoring locality at Dunafldvr and the Czech monitoring station at Kosetice, which are not strongly affected by local fossil CO2 sources, indicate similar grouping and amplitudes, typical for a regional Suess effect.
    • Radiocarbon Dating, Stable Isotope Analysis, and Diet-Derived Offsets in 14C Ages from the Klin-Yar Site, Russian North Caucasus

      Higham, T.; Warren, R.; Belinskij, A.; Härke, H.; Ood, R. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The influence of geothermally derived carbon on the radiocarbon dating of human bone from archaeological sites is poorly understood and has rarely been rigorously examined. This study identifies a previously unknown reservoir effect at the archaeological site of Klin-Yar in the Russian North Caucasus. AMS-dated human bones yielded results that were older than expected when compared with dates of coins found in the same grave contexts. We investigated the reasons for this offset by AMS dating modern plant, fish, and water samples to examine the source of the old carbon. We identified a potential source in geothermally derived riverine and spring water, with an apparent age of several thousand years, and hypothesize that carbon from here is being transferred through the food chain to humans. If humans consume resources from the local rivers, such as fish, then they ought to be affected by this reservoir offset. An extensive analysis of carbon and nitrogen isotopes of human and animal bone showed evidence for a mixed diet that may be masking the amount of freshwater-derived protein being consumed. Due to the highly variable nature of the 14C offset (0 to ~350 yr), no suitable average correction factor is applicable to correct for the human dates at the site. A 14C chronology based on dates obtained from terrestrial ungulate bones, which we subsequently obtained, is instead a more reliable indicator of age.
    • Refining Background Corrections for Radiocarbon Dating of Bone Collagen at ORAU

      Wood, R. E.; Bronk Ramsey, C.; Higham, T. F. G. (Department of Geosciences, The University of Arizona, 2010-01-01)
      During the laboratory pretreatment of samples for radiocarbon dating, small amounts of carbon may be added to a sample. Contamination can be incorporated at any stage: during chemical pretreatment, combustion to CO2, graphitization, or accelerator mass spectrometry (AMS) measurement. Such carbon contamination is often modern in age, and so can have an especially severe effect on samples older than ~25 ka BP. During the extraction of collagen from bone using the ultrafiltration protocol at the Oxford Radiocarbon Accelerator Unit (ORAU), small amounts of young carbon are added to the sample. Currently, this contamination is poorly characterized when less than 10 mg of collagen is extracted from a bone. Demand to date small collagen samples with 14C concentrations that approach the detection limit of AMS measurement has increased recently with the growing interest in, for example, directly dating Neanderthal remains and Upper Paleolithic bone artifacts. This paper aims to reduce the minimum collagen sample size required to produce a reliable date from 10 to 5 mg by re-examining the combustion background and subsequently the pretreatment background for bone. The average of 136 measurements of directly combusted nylon suggests that 0.0007 0.001 mg of modern carbon is added to each sample, although the distribution is positively skewed. Regression analysis of the measurements of 52 collagen samples extracted from a bone of background age results in a background of just less than 50,000 BP for bone treated at ORAU.
    • A Preparative 2D-Chromatography Method for Compound-Specific Radiocarbon Analysis of Dicarboxylic Acids in Aerosols

      Fahrni, S. M.; Ruff, M.; Wacker, L.; Perron, N.; Gäggeler, H. W.; Szidat, S. (Department of Geosciences, The University of Arizona, 2010-01-01)
      There is a great scientific demand for an assessment of the sources and formation processes of atmospheric carbonaceous aerosols since they strongly influence the global radiation balance and affect public health. Much attention in atmospheric studies has been paid to dicarboxylic acids (DCAs) due to their abundance at substantially different sites and their potential influence on cloud formation processes. Nevertheless, sources of oxalic acid (HOOCCOOH) and other DCAs are not well understood yet. In order to quantify contributions of fossil and non-fossil sources, a method for the preparative separation of oxalic acid and other DCAs from aerosols for compound-specific radiocarbon analysis (CSRA) has been developed. This method consists of a water extraction of aerosols collected on quartz-fiber filters followed by 2 consecutive liquid chromatography (LC) steps on different chromatography columns (2D-chromatography). Through the use of aqueous, completely non-organic eluents and single injections into liquid chromatography, low blank levels are achieved with total oxalic acid recoveries of up to 66%. Upon separation, 14C measurements of small samples (containing typically 10-20 g carbon) are conducted at the gas ion source of the 200kV accelerator mass spectrometry facility MICADAS. The method is verified with processed reference materials, artificial mixtures of oxalic acid with typical matrix components, and a standard addition of ambient aerosols. Two exemplary field samples show dominant non-fossil sources of oxalic acid.
    • Radiocarbon and Tritium Levels along the Romanian Lower Danube River

      Varlam, Carmen; Stefanescu, Ioan; Cuna, Stela; Vagner, Irina; Faurescu, Ionut; Faurescu, Denisa (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Lower Danube Basin covers the Romanian-Bulgarian sub-basin downstream from Cazane Gorge and the sub-basins of the Siret and Prut rivers. To extensively survey the Romanian nuclear power plant impact on the Danube water, tritium and radiocarbon baseline values are required. Therefore, the reported study tried to establish these values based on a 2-yr sampling campaign covering 975 km of the Danube from Cazane Gorge to Tulcea. The tributaries Cerna, Jiu, Olt, and Arges were also included in this study. During the sampling campaigns, tritium concentration of different sampling locations showed values between 7 ± 2.1 and 33.5 ± 2.3 TU. Measured 14C activity for the same locations ranged between 88.45 ± 1.46 and 112.36 ± 1.56 pMC. Lower values were recorded for tributaries: between 8.3 ± 2.1 and 12.2 ± 2.2 TU for tritium and between 67.3 ± 1.29 and 86.04 ± 1.42 pMC for 14C. Despite the nuclear activity in the observed areas, tritium and 14C activities presented slightly higher values for specific locations without any influence on Danube River water.
    • A High-Performance 14C Accelerator Mass Spectrometry System

      Roberts, M. L.; Burton, J. R.; Elder, K. L.; Longworth, B. E.; McIntyre, C. P.; Vo, K. F.; Han, B. X.; Rosenheim, B. E.; Jenkins, W. J.; Galutschek, E.; et al. (Department of Geosciences, The University of Arizona, 2010-01-01)
      A new and unique radiocarbon accelerator mass spectrometry (AMS) facility has been constructed at the Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements of 14C. Details and performance of the new system are presented.
    • A Continuous-Flow Gas Chromatography 14C Accelerator Mass Spectrometry System

      McIntyre, C. P.; Galutschek, E.; Roberts, M. L.; von Reden, K. F.; McNichol, A. P.; Jenkins, W. J. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Gas-accepting ion sources for radiocarbon accelerator mass spectrometry (AMS) have permitted the direct analysis of CO2 gas, eliminating the need to graphitize samples. As a result, a variety of analytical instruments can be interfaced to an AMS system, processing time is decreased, and smaller samples can be analyzed (albeit with lower precision). We have coupled a gas chromatograph to a compact 14C AMS system fitted with a microwave ion source for real-time compound-specific 14C analysis. As an initial test of the system, we have analyzed a sample of fatty acid methyl esters and biodiesel. Peak shape and memory was better then existing systems fitted with a hybrid ion source while precision was comparable. 14C/12C ratios of individual components at natural abundance levels were consistent with those determined by conventional methods. Continuing refinements to the ion source are expected to improve the performance and scope of the instrument.
    • Radiocarbon Dating of Kohitsugire Calligraphies Attributed to Asukai Masatsune and the Periods of Origin of Genji Monogatari Emaki and Ban-dainagon Ekotoba

      Oda, H.; Ikeda, K. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Genji monogatari emaki and Ban-dainagon ekotoba are Japanese national treasures. Although the periods in which they were painted have not been accurately determined, radiocarbon dating cannot be applied to these priceless artifacts because of the destructive nature of 14C dating. In this study, the periods of their origin were determined by 14C dating the kohitsugire calligraphy. Kohitsugire are ancient paper sheets containing graceful calligraphy. They originally were part of ancient manuscripts. Two kohitsugire named Imaki-gire and Kingin-kirihaku-wakanroeishu-gire are written in the same style as Genji monogatari emaki and Ban-dainagon ekotoba. Although Imaki-gire and Kingin-kirihaku-wakanroeishu-gire had been attributed to Asukai Masatsune (AD 1170-1221) on the basis of the kiwamefuda certificates, recent calligraphical and paleographical studies suggest that they are genuine handwritings of Fujiwara no Norinaga (AD 1109-1180). We applied 14C dating by accelerator mass spectrometry (AMS) to Imaki-gire and Kingin-kirihaku-wakanroeishu-gire. The calibrated 14C ages of both the kohitsugire indicated timing close to the peak of Fujiwara no Norinaga's career as a calligraphist. Based on the associations between the dated texts and the 14C results, it is concluded that the Genji monogatari emaki and Ban-dainagon ekotoba paintings could have been created in the middle of 12th century.
    • A Nondestructive Prescreening Method for Bone Collagen Content Using Micro-Computed Tomography

      Tripp, J. A.; Squire, M. E.; Hamilton, J.; Hedges, R. E. M. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Isolation of bone collagen for radiocarbon dating is a labor-intensive and time-consuming process that sometimes results in unacceptably low protein recovery. In preliminary studies reported here, micro-computed tomography (microCT), a nondestructive technique that uses X-rays to produce high-resolution three-dimensional images of mineralized materials such as bone, offers promise as a suitable prescreening option for bones of questionable preservation. We have found that the bone volume fraction calculated by the scanner software correlates well with collagen recovery in 4 analyzed bones from Etton, United Kingdom.
    • Radionuclides in Ancient Relics Obtained from the Matsusaki Site and the Hirohata Shellmound on the Pacific Coast of Japan

      Ohta, T.; Mahara, Y.; Kubota, T.; Saito, Y.; Fukutani, S.; Fujii, T.; Ando, A.; Nakata, E.; Nakano, T.; Abe, Y.; et al. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We compared 2 archaeological relics of different preservation environments, white substances adhering to a vessel from the Matsusaki site and to earthenware from Hirohata, by measuring their environmental radioactivity, 14C, 228Ra/226Ra, 234U/238U, and 87Sr/86Sr, and major element contents (Ca, Sr, Mg, Fe, and Mn). The results showed that the 2 materials were somewhat different and also reflected differences in their preservation environments. The chemical elements that were more abundant in the Matsusaki sample than in the Hirohata sample, Fe, Mn, 238U, and 232Th (parent of 228Ra), are also abundant in seaweed or seagrass. Contamination by 14C derived from rainwater after atmospheric nuclear tests was clearly observed in the white substance from Hirohata.
    • Submarines, Quarks, and Radioisotope Dating

      Muller, R. A. (Department of Geosciences, The University of Arizona, 2010-01-01)
    • Radiocarbon Dating of Individual Amino Acids from Archaeological Bone Collagen

      McCullagh, J. S. O.; Marom, A.; Hedges, R. E. M. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Since the development of accelerator mass spectrometry (AMS) for radiocarbon dating in the late 1970s, its ability to date small samples of bone has been of huge importance in archaeology and Quaternary paleoecology. The conventional approach to sample preparation has been to extract and gelatinize protein, which is then combusted and graphitized for analysis. However, this 'bulk protein' can contain a heterogeneous mixture of non-collagenous molecules, including humic acids and other soil components that may be of a different age than the bone and therefore affect the accuracy of its 14C date. Sample pretreatment methods have been an important area of development in recent years but still show inadequacies for the dating of severely contaminated bone. The idea of isolating and dating individual compounds such as single amino acids, to improve dating accuracy, has been discussed in the literature since the 1960s. Hydroxyproline, for example, makes up over 10% of bone collagen but is extremely rare in most other animal proteins, increasing the chances of its presence being endogenous to the individual being dated. Its successful isolation has therefore been considered a potential 'gold standard' for dating archaeological bone; however, extracting and suitably purifying single amino acids from bone has proved a challenging task. This paper presents a novel method for the compound-specific 14C dating of individual amino acids, including hydroxyproline, from archaeological bone protein. It is based on a preparative, mixed-mode liquid chromatography separation of underivatized amino acids, entirely in aqueous solution and free of organic solvents. The method is presented here in detail including application to standard bone samples establishing its accuracy and background carbon contribution. Results from 14C dating hydroxyproline and other individual amino acids, from both historical and archaeological bone, are shown to provide AMS dates that are statistically indistinguishable from those of the bulk protein.
    • A New 1MV AMS Facility at KIGAM

      Hong, W.; Park, J. H.; Sung, K. S.; Woo, H. J.; Kim, J. K.; Choi, H. W.; Kim, G. D. (Department of Geosciences, The University of Arizona, 2010-01-01)
      A 1MV AMS was installed in KIGAM (Korea Institute of Geoscience and Mineral Resources). After 4 months of installation, the AMS started normal operation from January 2008. This multi-element AMS was developed by HVEE to measure 14C, 10Be, and 26Al. The results of an acceptance test demonstrate that this machine is capable of routine 14C age dating and of measurements of other radioisotopes in terms of accuracy and precision as well as the background level. After installation, an investigation aimed at determining the stable operating conditions was conducted, and background levels were determined to be as low as 10-15 for 14C and 10-14 for 10Be and 26Al.
    • Age and Growth Rate Dynamics of an Old African Baobab Determined by Radiocarbon Dating

      Patrut, A.; Mayne, D. H.; Vo, K. F.; Lowy, D. A.; Venter, S.; McNichol, A. P.; Roberts, M. L.; Margineanu, D. (Department of Geosciences, The University of Arizona, 2010-01-01)
      In 2008, a large African baobab (Adansonia digitata L.) from Makulu Makete, South Africa, split vertically into 2 sections, revealing a large enclosed cavity. Several wood samples collected from the cavity were processed and radiocarbon dated by accelerator mass spectrometry (AMS) for determining the age and growth rate dynamics of the tree. The 14C date of the oldest sample was found to be of 1016 22 BP, which corresponds to a calibrated age of 1000 15 yr. Thus, the Makulu Makete tree, which eventually collapsed to the ground and died, becomes the second oldest African baobab dated accurately to at least 1000 yr. The conventional growth rate of the trunk, estimated by the radial increase, declined gradually over its life cycle. However, the growth rate expressed more adequately by the cross-sectional area increase and by the volume increase accelerated up to the age of 650 yr and remained almost constant over the past 450 yr.
    • The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Status Report

      Beverly, R. K.; Beaumont, W.; Tauz, D.; Ormsby, K. M.; von Reden, K. F.; Santos, G. M.; Southon, J. R. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2-3 for 1-mg samples (Santos et al. 2007c) are presented.
    • The Low-Energy Isobar Separator for Anions: Progress Report

      Kieser, W. E.; Eliades, J.; Litherland, A. E.; Zhao, X; Cousins, L.; Ye, S. J. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The suppression of interferences from atomic and molecular isobars is a key requirement for the extension of accelerator mass spectrometry (AMS) to the analysis of new cosmogenic isotopes and for increasing the range of applications for small AMS systems. In earlier work, it was shown that unwanted isobars can be eliminated by anion-gas reactions (Litherland et al. 2007). Recently, a prototype system in which such reactions could be applied to ions from an AMS ion source, the Isobar Separator for Anions (ISA), was described (Eliades et al. 2009). This system decelerates the beam of rare anions from keV to eV energies, guides them through a single radiofrequency quadrupole (RFQ) gas cell, and re-accelerates them for further analysis in a 2.5MV AMS system. Tests of this system with Cl and S anions and NO2 gas showed a suppression of S with respect to Cl of over 6 orders of magnitude, with a transmission of ~30% for the Cl beam. In this work, results of the analysis of a range of standard reference materials are reported; these show the linearity of the system for measuring the 36Cl/35Cl ratio over a span of 2 orders of magnitude. Further tests, using the AMS system as a diagnostic tool, have provided clues about the loss of Cl at higher cell pressure and the nature of the residual low level of S transmission. These lead to the assessment of various gases for cooling the Cl- beam. Suppression measurements for 41K in the analysis of 41Ca, using NO2 as a reaction gas, are also discussed. These preliminary measurements have provided data for the development of a more advanced system with separate cooling and reaction cells.
    • The Late Paleolithic-Neolithic Transition in Korea: Current Archaeological and Radiocarbon Perspectives

      Bae, C. J.; Kim, J. C. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The application of chronometric dating studies in Korean archaeology has lagged behind similar research in China and Japan. The focus of this article is to provide an update on the accelerator mass spectrometry (AMS) radiocarbon dates derived from Korean Paleolithic and Early Neolithic sites. One of the major highlights from recent AMS 14C studies in Korea is that blade (and microblade) technologies may have diffused directly from Siberia, rather than through northern China as originally thought. In addition, a Neolithic wooden boat has been discovered in Korea that is as old as, if not older than, similar discoveries from eastern China. More detailed archaeological and chronometric studies in Korea in the coming years will certainly clarify many of the points mentioned here. In particular, through more detailed studies, we will be able to further evaluate the causal factors that provided the impetus for the Late Paleolithic-Neolithic transition in Korea.
    • Are Compact AMS Facilities a Competitive Alternative to Larger Tandem Accelerators?

      Suter, M.; Müller, A. M.; Alfimov, V.; Christl, M.; Schulze-König, T.; Kubik, P. W.; Synal, H.-A.; Vockenhuber, C.; Wacker, L. (Department of Geosciences, The University of Arizona, 2010-01-01)
      In the last decade, small and compact accelerator mass spectrometry (AMS) systems became available operating at terminal voltages of 1 MV and below. This new category of instruments has become competitive for radiocarbon detection to larger tandem accelerators and many of these instruments are successfully used for 14C dating or biomedical applications. The AMS group at ETH Zurich has demonstrated that small instruments can be built, which allow measurements also of other radionuclides such as 10Be, 26Al, 129I, and the actinides. 41Ca measurements can be performed with sufficient sensitivity for biomedical applications. A summary of recent developments made at the 500kV Pelletron in Zurich is given and its performance is compared with that of a commercial compact instrument from the company High Voltage Engineering Europe (HVEE) in Amersfoort, the Netherlands, operating at 1MV at CNA in Seville, Spain, as well as with that of larger AMS facilities. It turns out that the ion optics, stripper design, and the detection system are critical for the performance.
    • Archaeological Radiocarbon Dates for Studying the Population History in Eastern Fennoscandia

      Oinonen, M.; Pesonen, P.; Tallavaara, M. (Department of Geosciences, The University of Arizona, 2010-01-01)
      In this work, archaeological radiocarbon data gathered from eastern Fennoscandia have been scrutinized to discuss their suitability for studies of population history. The temporal distribution of the archaeological 14C dates has been analyzed against possible research priorities and sample material deterioration. An outstanding 'Stone Age' maximum has been observed in practically all the displayed temporal date distributions. The pattern remains the same throughout the history of 14C dating in Finland. Due to sample material differences, equal taphonomic corrections based on 14C-dated volcanic deposits cannot account for all the sample degradation effects; therefore, material-dependent correction procedures are suggested.