bluuebunny/crossref_metadata_2025 huggingface dataset:
Nancy Natural Radiocarbon Measurements VI
Authors: Coppens René , Guillet Bernard , Jaegy Robert , Richard Pierre
Published: July 2016

The following list includes some measurements made during 1978 and 1979 in the radiocarbon laboratory of the Ecole Nationale Supérieure de Géologie Appliquée et de Prospection Minière (ENSG) de Nancy. Equipment, measurement and treatment of samples are as reported previously (R, 1979, v 21, p 453-464) where the sample is synthesized to benzene. Radiocarbon ages are calculated using the 14C half-life of 5568 years and 95% activity of NBS oxalic acid is used as modern standard. Anthracite coal and Merck commercial benzene are used for the dead carbon run.
Preparation Techniques for Radiocarbon Dating of Potsherds
Authors: Evin Jacques , Gabasio Martine , Lefevre Jean-Claude
Published: July 2016

Origins of carbon in potsherds are studied through field experiments which involve firing pots containing selected components and laboratory analyses. As temper seems to be the main source of carbon, radiocarbon dates may be too old if calcium carbonate is used. We can avoid the carbon from the clay by low-temperature burning of samples.
Depth Profiles of Nitrogen and Chlorine in Pure Materials Through AMS of the Neutron Activation Products 14C and 36Cl
Authors: Elmore David , Hossain T Z , Gove H E , Hemmick T K , Kubik P W , Jiang S , Vine J P La , Lee S T
Published: July 2016

Determination of the more common light elements such as nitrogen and chlorine at trace levels is difficult because of their high abundance on sample surfaces, in materials used to build analysis instruments, and in the residual gas of the instrument vacuum. We present here a new approach to analysis of these elements: accelerator mass spectrometry (AMS) combined with neutron activation. The problem of contamination is overcome by using neutron activation to produce long-lived radioisotopes which generally have low concentrations in the environment. For measurement of 14N and 35Cl, AMS can provide sensitive background-free measurements of their neutron activation products 14C and 36Cl and, in addition, can provide depth profiles. These are the first results of this new method: depth profiles of nitrogen and chlorine implanted in semiconductor grade silicon.
41Ca Concentrations in Modern Bone and Their Implications for Dating
Authors: Middleton Roy , Fink David , Klein Jeffrey , Sharma Pankaj
Published: July 2016

We have made the first measurements without pre-enrichment of 41Ca in terrestrial rock and bone samples using accelerator mass spectrometry. Although the results in tufa deposits from Egypt are in good agreement with the saturation value of 8×10-15 predicted by Raisbeck and Yiou (1979), the average 41Ca:40Ca ratio of 2×10-15 (range: 0.6 to 4.2×10-15) that we measure in modern bone is an order of magnitude lower than that obtained previously by Henning, et al (1987) on a cow bone that was measured using AMS following isotope enrichment. The low value and the variability (more than a factor of seven) of the 41Ca:40Ca ratio in modern bone make the possibility of dating bones using 41Ca unlikely.
AMS of 41Ca Using the CaF3 Negative Ion
Authors: Kubik Peter W , Elmore David
Published: July 2016

High-intensity ion sources are now capable of producing negative molecular ion beams of Ca of >2μA (Middleton et al, 1989). This and the advanced status of 41Ca AMS at several laboratories (Pennsylvania, Argonne National Laboratory, Rochester, Munich, Weizmann Institute) have revived interest in 41Ca (T1/2 = 1.0×105 yr (Mabuchi et al, 1974)) as a possible dating tool (Yamaguchi, 1963; Raisbeck & Yiou, 1979; Kubik et al, 1986).
An Inexpensive Upgrade of Older Liquid Scintillation Equipment for Radiocarbon Dating
Authors: Steinke David C , Kalin Robert M
Published: July 2016

We have replaced the original control electronics and added remote computer control to our Packard Instrument Tri-Carb 460C LSC. The total cost of materials to achieve this was <$1200; ca 200 hr were spent on design and programming, and installation was complete in 30 min. Our system has spectral analysis in 1/2 Kev resolution utilizing the existing 4096 channel multi-channel analyzer, and user-friendly error checking for the mechanical systems. The computer collects spectral information, saves two channels of raw data, plots spectral information and produces data files of the standards, backgrounds and samples used in LOTUS to calculate the age of the sample.
14CARE
Authors: Polach Henry
Published: July 2016

The need for and means of achieving a 14C dating quality assurance service are debated.
Importance of Biospheric Co2 in a Subcanopy Atmosphere Deduced From 14C AMS Measurements
Authors: Grootes P M , Farwell G W , Schmidt F H , Leach D D , Stuiver Minze
Published: July 2016

14C concentrations in the stem cellulose of a Sitka spruce from the Pacific coast of Washington respond to changes in atmospheric 14CO2 concentration within 5–6 weeks. δ14C values for cellulose were consistently lower than those of the corresponding clean troposphere during rapid increase in atmospheric 14C caused by nuclear weapons tests (1962–64). Possible reasons for this include: 1) a delay of days or weeks in incorporation of recent photosynthate, 2) the use of stored photosynthate, and 3) photo-assimilation of biospheric decay CO2. We estimate that the influence of process 1 is small or negligible. The respective contributions to the total carbon deposited as radial stem growth in our Sitka spruce then are 2) < 15% (possibly 0), and 3) 10%–23% (13%–28% if the possible effect of root respiration is included in the biosphere decay component). We plan to test this concept by looking for a vertical 14C gradient in the 1963 growth ring of a tree located in a dense forest canopy; we do not expect to find such a gradient in a similar tree from a strongly wind-washed location.
AMS 14C Study of Transient Events and of the Ventilation Rate of the Pacific Intermediate Water During the Last Deglaciation
Authors: Duplessy Jean-Claude , Arnold Maurice , Bard Edouard , Juillet-Leclerc Anne , Kallel Nejib , Labeyrie Laurent
Published: July 2016

14C analysis of monospecific samples of planktonic and benthic foraminifera were performed in deep-sea sediment cores from the Atlantic and Pacific Oceans by Accelerator Mass Spectrometry (AMS). These measurements demonstrate that the Younger Dryas cold event, first described in the north Atlantic, is also present at the same time in the north Pacific Ocean. The comparison of the 14C ages of planktonic and benthic foraminifera from the same sediment level in two Pacific cores shows that the ventilation time of the Pacific Ocean was greater than today during the last ice age, but significantly less than today during the deglaciation.
Radiocarbon in Dissolved Organic and Inorganic Carbon From the Central North Pacific
Authors: Druffel Ellen R M , Williams Peter M , Robertson Ken , Griffin Sheila , Jull A J T , Donahue Douglas , Toolin Lawrence , Linick T W
Published: July 2016

Radiocarbon measurements are reported for dissolved organic carbon (DOC) and inorganic carbon (DIC) from seawater samples collected from the Alcyone-5 cruise in the central North Pacific Ocean in 1985. Differences between the UV-radiation techniques used here and those reported by Williams, Oeschger and Kinney (1969) to oxidize and recover the DOC from sea water are presented. UV unoxidizable DOC in these samples is discussed in a separate publication (Druffel, Williams & Suzuki, 1989). We briefly discuss the penetration of the bomb 14C signal into the DOC and DIC pools. The temporal variability of Δ 14C in DIC in surface samples taken every 2–3 days is presented. Concentrations of total dissolved free (FAA) plus combined (hydrolyzable) amino acids (THAA) and total dissolved carbohydrates (TCHO) measured in the same water samples are also reported. Our main aim is to present the chemical and isotopic data from samples collected during the Alcyone-5 cruise. Detailed interpretation is published elsewhere.
AMS 14C Measurements of Fractionated Soil Organic Matter: An Approach to Deciphering the Soil Carbon Cycle
Authors: Trumbore S E , Vogel J S , Southon J R
Published: July 2016

14C measurements are reported for fractionated soil organic matter from a genetic soil sequence which was sampled several times during the period of atmospheric nuclear weapons testing. Fractionation of the soils by density followed by acid hydrolysis was successful in separating the organic matter into components with mean residence times for carbon ranging from 5 to 20 years (low density fraction) to several thousand years (residue after acid hydrolysis). Comparison of the infiltration of bomb 14C into the vertical soil profile with the distribution of 137Cs, gives clues as to the mechanism (most probably dissolved transport) for importing carbon into deeper soil layers.
14C Tephrochronology With Different Fractions of Paleosol Humic Matter at Procida Island, Italy
Authors: Alessio Marisa , Allegri Lucia , Azzi Carlo , Calderoni Gilberto , Cortesi Cesarina , Improta Salvatore , Petrone Vincenzo
Published: July 2016

14C apparent ages along with δ13C values for three different fractions of humic matter (HM) isolated from a suite of four paleosols (PAs) interbedded within tephra are reported. The dated HM fractions were: 1) HA, the easily released humic acids; 2) HAtot, the bulk of humic acids; 3) RES, the insoluble HM. The 14C sequence dated from 13,000–25,000 BP, in agreement with stratigraphy and previous data. Age differences up to 2540±430 were statistically significant among fractions; their order of magnitude being independent from C content and depth. All the PAs showed a common pattern of among-fraction age variation, 14C aging trending from RES to HAtot through HA. As the HM fractions exhibited quite comparable δ13C values (δ13C = −25.4±0.2), it is inferred that the primitive organic matter (OM) input to PAs was dominantly supplied by vegetation of C-3 photosynthetic pathway which underwent complete decomposition during diagenesis.
Carbon Isotope Dynamics in Some Tropical Soils
Authors: Becker-Heidmann Peter , Scharpenseel H-W
Published: July 2016

We determined δ13C and D14C in some agricultural soil profiles of the tropics: Ustalf from the semi-arid tropics (India), a Udult, an Aquoll and an Aquept from the humid tropics (Philippines). We used a thin-layer sampling, resulting in high-resolution depth-distribution patterns of natural 13C and 14C content of organic carbon. Regular plowing or puddling leads to uniform isotope concentrations in the topsoil. Decomposition of organic matter raises the δ13C value, and vertical translocation raises the δ13C value with depth. The change of cultivation from pulses (C3-type metabolism of photosynthesis) to sorghum (C4) results in a decrease of δ13C with depth in the topsoil. Where the clay content in the subsoil is high, δ13C remains constant, due to fixation of organic carbon to clay minerals, and D14C decreases with depth. Below the clay-enriched zone, δ13C declines and D14C rises again, due to a chromatographic-like effect. At some horizon boundaries, inhomogeneities in texture delay percolation locally, thus preventing sorption and causing peak values of D14C.
Fine and Hyperfine Structure in the Spectrum of Secular Variations of Atmospheric 14C
Authors: Damon Paul E , Cheng Songlin , Linick Timothy W
Published: July 2016

The coarse structure of the 14C spectrum consists of a secular trend curve that may be closely fit by a sinusoidal curve with period ca 11,000 yr and half amplitude ±51. This long-term trend is the result of changes in the earth's geomagnetic dipole moment. Consequently, it modulates solar components of the 14C spectrum but does not appear to modulate a component of the spectrum of ca 2300-yr period. The ca 2300-yr period is of uncertain origin but may be due to changes in climate because it also appears in the δ18O spectrum of ice cores. This component strongly modulates the well-known ca 200-yr period of the spectrum's fine structure. The hyperfine structure consists of two components that fluctuate with the 11-yr solar cycle. One component results from solar-wind modulation of the galactic cosmic rays and has a half-amplitude of ca ±1.5. The other component is the result of 14C production by solar cosmic rays that arrive more randomly but rise and fall with the 11-yr cycle and appear to dominate the fluctuation of the galactic cosmic-ray-produced component by a factor of two.
Possible Frequency Modulation Effects Singled Out by the Fourier Vector Amplitude in a δ14C Yearly Series of Georgian Wines
Authors: Pierazzo Elisabetta , Sartori Silvia
Published: July 2016

The Δ 14C series of yearly sampled cosmogenic 14C in wines (1909–1952) was analyzed with the Fourier Vector Amplitude (FVA) method, using cyclograms as a graphic tool, to find information on periodicities imprinted by the sun. Because the high sensitivity of the FVA algorithm in detecting periodicities and their variations is emphasized by immediate visualization of its cyclograms, a suggestion has been found for a modulation event. Data are compared with a frequency modulation model, the extension of which to the long 9000–a Δ 14C series suggests a first approach to interpret the Suess wiggles.
Recent 14C Activity in the Atmosphere, “Clean Air” and the Chernobyl Effect
Authors: Olsson Ingrid U
Published: July 2016

Although the Chernobyl accident caused increased 14C levels in certain areas, it has been difficult to prove that it had any effect in two areas of Sweden and one on Svalbard (Spitsbergen), where the precipitation and wind conditions were such that the γ-active fall-out was negligible. Knowledge of the steady regional decrease and annual variations at high latitudes, where the pollution from fossil fuel is less than in central Europe, is essential for global studies of the CO2 cycle. The present 14C excess is a net effect of the 14C supply, mainly from tests of nuclear weapons, and dilution, by 14C-free, fossil-fuel consumption. In Sweden, at these northern latitudes, the 14C excess is steadily slightly higher than for “clean air” in central Europe. Annual variations are also smaller in Sweden and Svalbard than in central Europe. The normal 14C excess on Svalbard is slightly less than in Sweden. Detailed results, especially from autumn 1984 to autumn 1987, are given for atmospheric CO2 collected in northern Sweden (Abisko) and on Svalbard (Kapp Linné) and for some atmospheric samples and plant material collected ca 50km east of Uppsala, very close to heavily polluted areas.
Improved Precision 14C Measurements and Natural 14C Variations Around 10,000 Cal BP
Authors: Goslar Tomasz , Pazdur Mieczysław F
Published: July 2016

Thirty-one samples of 5 tree rings from a single oak trunk with 300 tree rings were measured with improved precision to study natural 14C variations in the period from ca 9750 – 10,050 cal bp. Negative correlation was found between Δ 14C values and tree-ring indices. The pattern of 14C changes in the studied interval closely resembles the changes observed in several periodically spanned intervals within the limits of high-precision calibration data sets.
The Role of 36Cl and 14C Measurements in Australian Groundwater Studies
Authors: Bird J R , Calf G E , Davie R F , Fifield L K , Ophel T R , Evans W R , Kellett J R , Habermehl M A
Published: July 2016

An Accelerator Mass Spectrometry system has been developed using the 14UD tandem accelerator at the Australian National University. It has been used for 36Cl measurements on groundwater samples from the Murray Basin in southeastern Australia. Measurements of 14C have also been made on the same groundwaters. The information can be combined with stable isotope ratios and other data to illustrate the occurrence of processes such as radioactive decay and local recharge in different aquifers.
Isotopic Investigation of the Surdulica Geothermal System
Authors: Milovanović Branislav , Stanković Svetislav , Komatina Miomir , Hadžišehović Munevera , Župančić Mladen , Miljević Nada , Stepić Rista , Obelić Bogomil
Published: July 2016

The object of our investigation was to study a mechanism of water formation in the Surdulica geothermal system (recharge area, age and homogeneity of the waters). We collected 56 samples to determine the chemical, stable isotope, 14C and tritium content of the waters. We found large stable isotope variations in precipitation collected at different altitudes, whereas the geothermal waters are largely homogeneous and seasonally independent. Data on springs and rivers, the local meteoric water line and recharge area were obtained. Three groups of groundwater were identified by age – modern from natural springs, old from mines and very old from the Vranjska Banja. Because the initial 14C activity of infiltrated waters from the recharge area is unknown, the age of thermal waters can only be inferred, from HCO3
−, 14C and 3H content, to be 10,000 to 28,000 years old.
Radiocarbon and Varve Chronologies of Annually Laminated Lake Sediments of Gościαz Lake, Central Poland
Authors: Goslar Tomasz , Pazdur Anna , Pazdur Mieczysław F , Walanus Adam
Published: July 2016

A sequence of annually laminated sediments of the Gościαz Lake spans ca 13,000 yr and is actually the longest known continuous sequence in the world. 14C age measurements were performed on organic and carbonate fractions of bulk samples of laminated sediments from core GO. Accurate measurements of varve thickness performed on the lower part of cores G1 and G2 were used to establish a floating varve chronology covering ca 10,000 yr. Matching of cores GO, G1 and G2 permits comparison of 14C dates with varve chronology. Good agreement of calibrated 14C dates with the varve time scale suggests annual lamination of the sediment. Analysis of periodicities in varve thickness indicates solar 11-and 22-yr cycles, as well as a 200-yr cycle over a good part of the investigated sequence. Results of 14C measurements of carbonate fractions are used to study changes in the water depth of the lake during its history.
The Timing of the Postglacial Marine Invasion of Kau Bay, Halmahera, Indonesia
Authors: Barmawidjaja D M , de Jong A F M , van der Borg Klaas , van der Kaars W A , van der Linden W J M , Zachariasse W J
Published: July 2016

Kau Bay Halmahera, Indonesia is a small marine basin that is separated from the adjacent SW Pacific Ocean by a shallow sill, 40m deep. Radiocarbon dating on piston cores in combination with a study on microfossils demonstrate that Kau Bay was a freshwater lake in Weichselian times. At 10,000 BP, the Bay became reconnected with the open ocean. It sill depth did not change in the intervening years, sea level at 10,000 BP stood 40m below the present level.
Radiocarbon and Thermoluminescence Dating of Prehistoric Sites in Hungary and Yugoslavia
Authors: Benkö Lázár , Horváth Ferenc , Horvatinčić Nada , Obelić Bogomil
Published: July 2016

Direct dating by simultaneous independent physical methods is of particular interest to prehistoric archaeology in central Europe. Radiocarbon and thermoluminescence measurements were made to date two tell settlements in the Carpathian Basin: the Late Neolithic site at Gorzsa (southeast Hungary) and the Eneolithic site of Vučedol (east Croatia, Yugoslavia). Samples from Gorzsa span from the Szakalhát to the Proto-Tiszapolgár periods, while most important cultural layers from the Vučedol site belong to the Baden, Kostolac, and Vučedol cultures. By including some of our earlier dates from the Tiszapolgár-Basatanya Copper Age site, a chronological framework, spanning the period from Late Neolithic to Early Bronze Age can be established. The quartz inclusion technique was used for TL dating of pottery. Beta and gamma dose rates were determined by TL dosimetry. Allowances were made for supralinearity, water content, and beta attenuation in quartz grains. The TL ages range from 1900 to 4300 BC and 3600 to 2900 BC, for the Gorzsa and Vučedol sites, respectively.
Complementary Use of Amino-Acid Epimerization and Radiocarbon Analysis for Dating of Mixed-Age Fossil Assemblages
Authors: Goodfriend Glenn A
Published: July 2016

Several approaches to dealing with the problem of mixed-age fossil assemblages are presented. These involve the use of amino-acid epimerization analysis (D-alloisoleucine/L-isoleucine ratio, or A/I) and are illustrated by deposits of land snail shells. This method requires only very small samples, so shells can be analyzed individually. Mixed-age deposits are indicated when variation in A/I among individual shells within the deposit exceeds the analytical error. Methods are presented for 1) estimating the true time of deposition of slightly-mixed-age assemblages based on bulk 14C dates and epimer analyses, 2) selection (for 14C analysis) of a set of individual shells that are uniform in age and represent the true time of deposition, and 3) estimating ages of individual shells within a mixed-age deposit based on their A/I ratios.
Report of the International Radiocarbon Database Workshop
Authors: Kra Renee
Published: July 2016

The Chair, Renee Kra, opened the Workshop with the announcement that the IRDB will be officially located at the Geosciences Department, University of Arizona, Tucson, and will begin operating on January 2, 1989.
A Suggested Quality Assurance Protocol for Radiocarbon Dating Laboratories
Authors: Long Austin , Kalin Robert M
Published: July 2016

The current intercomparison of data from 14C laboratories reveals significant variability among liquid scintillation laboratories, suggesting that identical samples submitted to different laboratories may yield values that differ by much more than expected on a purely statistical basis. Erroneous dates (recently corrected) by a well-established 14C laboratory give rise to further concern for quality 14C data. Thus, it is incumbent on each laboratory to develop and implement a quality assurance and control (QA/QC) program in order to ensure accuracy of results and to alert lab personnel to problems.
Routine Checks in the Uppsala Conventional14C Laboratory to Achieve Reliable Results
Authors: Olsson Ingrid U
Published: July 2016

I describe here a series of routine self-checks that the Uppsala14C laboratory performs with all measurements. We estimate all uncertainties in the physical measurement of a sample. We study long-term stability, calculate mean values for oxalic acid and background and compare expected and real statistical distributions of uncertainties. To reduce the risk of bias, the samples from each series are almost exclusively run on the same counter. Some samples are, however, run on two or more counters to check the possible bias to achieve reliable activity comparisons with other laboratories. It is always possible to trace which counter is used, since different number series are used for different counters.
University of Wisconsin Radiocarbon Dates XXVII
Authors: Prior Christine A. , Phelps Lori F.
Published: July 2016

Procedures and equipment used in the University of Wisconsin laboratory have been described previously (Bender, Bryson & Baerreis 1965; Steventon & Kutzbach 1986). Except as otherwise indicated, wood, charcoal and peat samples are pretreated with dilute NaOH-Na4P2O7 and dilute HCl before conversion to counting gas methane; when noted, marls and lake cores are treated with acid only.
Rudjer Bošković Institute Radiocarbon Measurements XII
Authors: Srdoč Dušan , Horvantinčić Nada , Bronić Ines Krajcar , Obelić Bogomil , Sliepčević Adela
Published: July 2016

We present here radiocarbon analyses made since our previous list (Srdoč et al. 1989). Sample pretreatment, combustion and counting techniques are essentially the same as described previously (Srdoč, Breyer & Sliepčević 1971), supplemented by new techniques for groundwater processing (Srdoč et al. 1979). The calculation of ages follows conventional protocol (Stuiver & Polach 1977). These ages can be converted from the 5570-year half-life to the chronometrically more correct half-life of 5730 years by multiplying by the factor, 1.029. Ages and standard deviations of all samples are adjusted for stable isotope fractionation according to the recommendations in Stuiver and Polach (1977), except for groundwater, calcareous deposits and aquatic plants. The δ13C values of the latter reflect the environmental conditions during their formation or growth rather than fractionation (Mook 1976; Krajcar Bronić et al. 1986; Marčenko et al. 1989). Thus, any percent modern (pMC) correction based on δ13C values is meaningless or even misleading. Sample descriptions are prepared in collaboration with collectors and submitters. Calibrated ages were calculated using the program of Stuiver and Reimer (1987).
Subtle 14C Signals: The Influence of Atmospheric Mixing, Growing Season and In-Situ Production
Authors: Grootes Pieter M.
Published: July 2016

Atmospheric 14C concentrations vary with time and latitude. These variations, measured directly on atmospheric samples, or in independently-dated organic material such as tree rings, supply data essential for the calibration of dynamic models of the global carbon cycle. Short variations in the production rate of atmospheric 14C are strongly attenuated in the relatively large atmospheric CO2 reservoir. In-situ production of 14C should be negligible for ages up to 80 ka bp. Background problems in AMS dating are more likely attributable to contamination of very small samples.
German Oak and Pine 14C Calibration, 7200–9439 BC
Authors: Kromer Bernd , Becker Bernd
Published: July 2016

Radiocarbon calibration data derived from German oak chronologies, ranging back to 7200 BC, have been published in the previous Calibration Issue (Stuiver & Kra 1986). In recent years, the German oak chronology has been extended to 7938 BC (Becker, this issue). For earlier intervals, tree-ring chronologies must be based on pine, because oak re-emigrated to central Europe at the Preboreal/Boreal transition, at about 8000 BC. We have established a 1784-yr pine chronology centered in the Preboreal, and have linked it tentatively to the absolutely dated oak master. We present here calibration data based on this link, for the age range, 7145–9439 BC.
Department of Earth Sciences at the University of Rome Radiocarbon Dates II
Authors: Calderoni Gilberto
Published: July 2016

This paper includes 14C measurements of geological and environmental samples processed by liquid scintillation counting of benzene between 1991 and the end of 1992. All samples, from central and northern Italy and from the Gulf of Venice, Adriatic Sea, relate to scientific projects conducted in collaboration with colleagues from both Italian universities and National Council of Research (CNR) institutions.
Department of Earth Sciences at the University of Rome Radiocarbon Dates III
Authors: Calderoni Gilberto , Caneva Isabella , Cazzella Alberto , Frangipane Marcella , Petrone Vincenzo
Published: July 2016

This is a partial list of archaeological samples processed between May 1990 and December 1992 at the Department of Earth Sciences Radiocarbon Dating Laboratory of the University of Rome. Most of the samples in the list, both from Italy and other countries, were related to excavations carried out by researchers at the University of Rome, Department of Scienze dell'Antichità. Although primarily measured for archaeological studies, some of these dates also have geological and paleoenvironmental relevance.
Prehistoric Colonization of Northeastern Siberia and Migration to America: Radiocarbon Evidence
Authors: Kuzmin Yaroslav V.
Published: July 2016

This review of radiocarbon dates from northeastern Siberian Paleolithic sites provides data that can be applied to establishing a chronology of human settlement, and that can provide a rough estimate of the timing of the initial peopling of the New World.
Dating the Prehistoric Site Nahalissaron in the Southern Negev, Israel
Authors: Carmi Israel , Segal Dror , Goring-Morris A. N. , Gopher Avi
Published: July 2016

The prehistoric site Nahal Issaron is located on the alluvial fan of Nahal Issaron, a short wadi draining into Biqat Uvda some 50 km north of Eilat. Excavated in the early 1980s, it constitutes a major Pre-Pottery Neolithic B (PPNB) layer, with continued but sporadic occupation throughout the Late Neolithic to the Chalcolithic period. In the PPNB layer, a dense agglomeration of rounded, polygonal and rectangular structures was found, with courtyards and a variety of features such as hearths and ovens. The upper layer is badly preserved, apart from the hearths and ovens. Thirty samples from the site were 14C-dated in the Rehovot laboratory and five in the Pretoria laboratory. The results enabled a fine temporal resolution between layers and a refinement of the 7th through 5th millennium bc chronology. The dates also placed the sequence of changes in architecture and lithics within a more robust temporal framework, thus making the site a key chronological anchor in the Neolithic of Southern Israel, Sinai and Jordan.
Comparison of Manual and Automated Pretreatment Methods for AMS Radiocarbon Dating of Plant Fossils
Authors: Bradley Lee-Ann , Stafford Thomas W.
Published: July 2016

A new automated pretreatment system for the preparation of materials submitted for accelerator mass spectrometry (AMS) analysis is less time-consuming and results in a higher sample yield. The new procedure was tested using two groups of plant fossils: one group was pretreated using the traditional method, and the second, using the automated pretreatment apparatus. We compared the time it took to complete the procedure and the amount of sample material remaining. The automated pretreatment apparatus proved to be more than three times faster and, in most cases, produced a higher yield. We also observed a darker discoloration of the KOH solutions, indicating that the automated system is more thorough in removing humates from the specimen compared to the manual method.
Pollen Concentrate Preparation from Highly Organic Holocene Peat and Lake Deposits for AMS Dating
Authors: Richardson Ffiona , Hall Valerie A.
Published: July 2016

Many of the problems inherent with conventional 14C dating of lake and peat deposits are eliminated by AMS dating of pollen concentrates. Published work describes production of pollen concentrates through expulsion of most of the deposit matrix by repeated deflocculation, selective sieving and final retention of the largest subfossil pollen taxa. Less suited to pollen concentrate production are the highly organic peats and lake muds from the British Isles and Europe. In this study we tested the combined effectiveness of physical, chemical and microbiological degradation and elimination techniques for pollen concentrate production on highly organic peats and a lake mud. We also reviewed methods of enhancing concentrations of smaller sub-fossil pollen grains. Here we present a novel method of assessing AMS dating precision of pollen concentrates by comparing their calibrated dates with a volcanic event of known historical age.
Extraction of 14C from Pore Water in Unsaturated Rock Using Vacuum Distillation
Authors: Davidson G. R. , Hardin E. L. , Bassett R. L.
Published: July 2016

We discuss a vacuum-distillation method for obtaining representative 14C samples from dissolved inorganic carbon in rock pore-waters. Distillation offers four advantages over current centrifugation and compression methods for obtaining pore-water carbon: 1) carbon recovery is possible from rocks that will not yield water by centrifugation or compression; 2) the mass required for 14C analysis can typically be obtained in a single extraction, eliminating the need for storing and combining multiple pore-water collections; 3) water and carbon are extracted and isolated simultaneously, reducing the number of required steps and the potential for contamination; and 4) distillation requires less equipment at lower cost than centrifugation or compression. In this study, isotopic fractionation resulting from incomplete recovery of carbon during distillation was too high for stable isotope applications, but was relatively minor for 14C applications. The lighter isotopes were favored in the recovered phase, resulting in samples depleted in 14C by a maximum of 4%. Mass balance calculations indicate that there may be a significant reservoir of carbon absorbed to mineral surfaces that is only partially removed by this method. Incorporation of adsorbed carbon into the recovered sample did not measurably alter the 14C activity.
Natural Radiocarbon Measurements in Brazilian Soils Developed on Basic Rocks
Authors: Pessenda L. C. R. , Valencia E. P. E. , Camargo P. B. , Telles E. C. C. , Martinelli L. A. , Cerri C. C. , Aravena Ramon , Rozanski Kazimierz
Published: July 2016

This paper presents 14C, 13C and chemical data of soil organic matter (SOM) in three soil profiles under native forests from Brazil: Londrina (southern), Piracicaba (southeastern) and Altamira (northern). The main objective is to use carbon isotopes in tropical and subtropical soils of Brazil to provide information about vegetation changes that occurred in relation to climate changes during the Holocene. 14C data from SOM indicate that the organic matter in the soils studied is of at least Holocene age. 13C data indicate that C4 plants probably provided the dominant vegetation in Londrina and Piracicaba during the early and mid-Holocene and that C3 plants provided the dominant vegetation in the Altamira region during the Holocene.
Historic Measurements of Radiocarbon in New Zealand Soils
Authors: Lassey K. R. , Tate K. R. , Sparks R. J. , Claydon J. J.
Published: July 2016

Extensive measurements of radiocarbon have been used in New Zealand since the mid-1960s to follow carbon (C) movement and turnover in soils. We present here unpublished radiocarbon (14C) measurements on a range of eight New Zealand soils with details of the sites, ecosystems, climates, soil descriptions and associated analytical data. An overview is also given of published 14C measurements on soils, and the use of these measurements to model soil C turnover.
Geological Survey of Canada Soil Database
Authors: McNeely Roger
Published: July 2016

The Geological Survey of Canada (GSC) has developed, over the past decade, a user-oriented database, Date Locator File, of Canadian samples dated by the 14C technique. This database presently contains >3500 soil and soil-related dates. The primary category in this suite of dates is peat, as a large portion of the Canadian landscape is covered with this type of organic soil. The data is available gratis to all researchers in a large variety of formats from simple lists to complex tables for inclusion in publications. The site localities can also be plotted on base maps suitable for publication. The database is actively augmented on an ongoing basis, but to continue to be relevant, it depends largely on the altruism of the scientific community.
Genotoxicity Study on Nicotine and Nicotine-Derived Nitrosamine by Accelerator Mass Spectrometry
Authors: Li X. S. , Wang H. F. , Shi J. Y. , Wang X. Y. , Liu Y. F. , Li K. , Lu X. Y. , Wang J. J. , Liu K. X. , Guo Z. Y.
Published: July 2016

We have studied DNA adduction with14C-labeled nicotine and nicotine-derived nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by accelerator mass spectrometry (AMS) in mouse liver at doses equivalent to low-level exposure of humans. The dose ranges of nicotine and NNK administered were from 0.4 μg to 4.0×102μg kg b.w.-1, and from 0.1 μg to 2.0×104μg kg b.w.-1, respectively. In the exposure of mice to either nicotine or NNK, the number of DNA adducts increased linearly with increasing dose. The detection limit of DNA adducts was 1 adduct per 1011nucleotide molecules. This limit is 1–4 orders of magnitude lower than that of other techniques used for quantification of DNA adducts. The results of our animal experiments enabled us to speculate that nicotine is a potential carcinogen. According to the procedure for14C-labeled-NNK synthesis, we discuss the ultimate chemical speciation of NNK bound to DNA. From the animal tests we derived a directly perceivable relation between tobacco consumption and DNA adduction as the carcinogenic risk assessment.
Methodological Issues in the 14C Dating of Rock Paintings
Authors: Hedges R. E. M. , Ramsey Christopher Bronk , Van Klinken G. J. , Pettitt P. B. , Nielsen-Marsh Christina , Etchegoyen Alberto , Niello J.O. Fernandez , Boschin M. T. , Llamazares A. M.
Published: July 2016

Chemical and isotopic analyses have been made of pigment samples from two separate rock art sites in Argentina. The purpose of the study has been to establish the feasibility of extracting carbonaceous material from the samples which will permit reliable radiocarbon dates for the time of painting. The two sites, Catamarca and Rio Negro, present quite different problems. Most of the paper is concerned with Catamarca, and here we have shown that the paint pigments contain very little or no organic binder; but they do contain calcium oxalate derived from local cacti, and calcium carbonate derived probably from local plant ash. We describe a method to purify carbon extracted from the calcium oxalate, and present the dates obtained on both components. We show that, though rare, natural deposits containing both calcium oxalate and calcite do occur, but that they are very distinct in both 13C and 14C compositions; and we argue that they are very unlikely to contaminate the pigments to such an extent that the 14C dates are altered. For the Rio Negro site we show that the ground for the paint pigments contains carbon derived from fires burnt inside the cave, and discuss how analytical methods provide information to develop a strategy for extracting material, from both ground and pigment, for more reliable dating.
An Attempt at Absolute14C Dating
Authors: Szabo Jacob , Carmi Israel , Segal Dror , Mintz Eugenia
Published: July 2016

The accepted state-of-the-art14C dating method relies on calibration curves to determine initial14C levels in a sample. The paper reconsiders the basis of14C dating and offers a possible alternative that eliminates the need to employ calibration curves. The idea is to measure the level of radiogenic nitrogen atoms retained in the sample molecules after14C β-decay. The practicality of this alternative method still has to be proven.
On the Validity of the Poisson Hypothesis for Low-Level Counting: Investigation of the Distributional Characteristics of Background Radiation with the Nist Individual Pulse Counting System
Authors: Currie L. A. , Eijgenhuijsen E. M. , Klouda G. A.
Published: July 2016

Does radioactive decay follow the Poisson distribution?—a fundamental question, to which the theoretical answer seems to be, Yes. On the practical side, the answer to this question impacts the best achievable precision in well-controlled counting experiments. There have been some noteworthy experimental tests of the Poisson assumption, using systems carefully designed for the analysis of individual pulses from stable radioactive sources; thus far, experiment supports theory. For low-level counting, the nature of the background distribution can be of profound practical importance, especially for very long counting experiments where validation by an adequate number of full replicates may be impracticable. One is tempted in such cases to assume that the variance is equal to the mean, in order to estimate the measurement uncertainty. Background radiation, however, has multiple components, only some of which are governed by the laws of radioactive decay.

A specially designed low-level gas counting system at NIST for interactive, retrospective individual pulse shape and time series analysis makes possible the investigation of the empirical distribution function of the background radiation, in a manner similar to the previous empirical distribution studies of radioactive decay. Benefits of individual pulse analysis are that there is no information loss due to averaging and that two independent tests of the Poisson hypothesis can be performed using data from a single, extended measurement period without the need for replication; namely, tests of the distribution of arrival times, expected to be uniform, and the distribution of inter-arrival times, expected to be exponential. For low-level counting the second test has a very interesting and very informative complement: the distribution of coincidence-anticoincidence inter-arrival times.

Key outcomes from the study were that: 1) nonstationarity in the mean background rate over extended periods of time could be compensated by an on-line paired counter technique, which is far preferable to the questionable practice of using an “error-multiplier” that presumes the wandering (nonstationary) background to be random; and 2) individual empirical pulse distributions differed from the ideal GM and Poisson processes by exhibiting giant pulses, a continuum of small pulses, afterpulses, and in certain circumstances bursts of pulses and transient relaxation processes. The afterpulses constituted ca. 8% of the anticoincidence background events, yet they escaped detection by the conventional distributional tests.
Reduction of the Error Multiplier by a Long-Term Analysis of the Characteristic Behaviors of Proportional Counters
Authors: Olsson Ingrid U.
Published: July 2016

A significant reduction in cosmic-ray activity and backgrounds of the gas-filled proportional counters, as measured in a heavy iron shield, was observed when the Uppsala Conventional 14C Laboratory was moved in 1984. The new site was better shielded from cosmic rays because of additional concrete layers above the laboratory. A study that lasted over one year yielded a figure for the muon reduction. The backgrounds were reduced approximately to the extent expected from the soft-component contribution at the old Laboratory as judged from barometric-pressure dependence. After a few years, new electronics enforced, and enabled, the revision and improvement of the standard values for the activity and age calculations.

A careful analysis of the results for the counters has increased the accuracy of the small corrections needed to yield internal error-multiplication factors mostly between 1 and 1.5 for the background for short periods of up to 12 months, and <1.1 for the oxalic acid samples combined for the last few years of measurements in the laboratory. Similar results were obtained for two counters.
Recent Developments in the Procedures Used at the Sscer Laboratory for the Routine Preparation of Lithium Carbide
Authors: Skripkin Vadim V. , Kovaliukh Nikolai N.
Published: July 2016

In this paper we describe and discuss the advantages from improvements in equipment design and operating procedures developed at the State Scientific Centre of Environmental Radiogeochemistry (SSCER) laboratory in Kiev. Two experimental areas are considered, viz.

1. The direct chemisorption into a lithium alloy of carbonaceous gases produced by the controlled thermal degradation (pyrolysis) of organic materials under vacuum. This approach offers the advantage of a single stage, highly efficient and economical procedure for the production of lithium carbide. It is applicable for most types of sample material encountered in routine dating work and including organic detritus dispersed in a highly (up to 95% by weight) mineral matrix and/or carbonates. Bone collagen can also be processed without the need for its prior extraction and purification.

2. A conical thin walled reaction vessel for achieving improved and reproducible recoveries in the production of lithium carbide from CO2gas. This apparatus allows a much improved control over the surface dependent reaction in instances where there is no option other than the direct interaction of molten lithium with prepared CO2 gas.
Consensus Dating of Mammoth Remains from Wrangel Island
Authors: Arslanov Kh. A. , Cook G. T. , Gulliksen Steinar , Harkness D. D. , Kankainen Tuovi , Scott E. M. , Vartanyan Sergey , Zaitseva Ganna I.
Published: July 2016

Previous results from remains of tusks, teeth and bones collected from Wrangel Island (Vartanyan et al. 1995) had given results in the range 3730 bp to 20,000 bp and the authors had concluded that “mammoths inhabited Wrangel Island for as long as 6000 yr after the estimated extinction on the Siberian continent”. There still remained the question of the earliest date for such remains. Further, the authors had noted such samples may present some difficulty in dating and therefore duplicate samples had been measured in a second laboratory with satisfactory results. The replicate dating of important or controversial samples in more than one laboratory is well-established (e.g., Turin Shroud) and in this paper, we present results for 5 mammoth samples dated by 6 laboratories. Such interlaboratory comparisons provide an independent means of verification of laboratory comparability, and give added confidence in the results, particularly when applied to more controversial samples. A further objective of the work has been to evaluate the material for inclusion in any large-scale interlaboratory comparison, such comparisons having in the past formed part of laboratory quality assurance protocols. The design and organization of a laboratory intercomparison requires homogeneous samples in sufficient quantity to satisfy participants, and so in principle, a single mammoth tusk would meet these criteria. Samples such as the mammoth tusk have been used in previous intercomparisons: e.g., in the last large-scale international intercomparison (Gulliksen and Scott 1995), whalebone was one of the materials distributed. One of the key advantages of such material is that a single sample (a mammoth tusk) can be resampled for analysis by multiple labs and thus does not require bulk homogenization. Therefore, as part of a preselection process for a future intercomparison, five samples from separate mammoth tusks were collected from Wrangel Island in 1995 in sufficient quantity to allow multiple dating. The aim was to identify five separate samples of young age, sample up to 1 kg from each tusk and mark the location so that after preliminary dating, samples could be retrieved as required in the future. Six laboratories received samples for dating. The paper will discuss the results from the laboratories, present consensus values, and make recommendations concerning use of these samples in a future laboratory intercomparison.
Interlaboratory Comparisons of 14C Measurements in Milk and Vegetation
Authors: Milton G. M. , Kramer S. J. , Milton J. C. D.
Published: July 2016

The need for increased quality assurance for radiocarbon measurements performed by the monitoring laboratories at nuclear stations has spurred the introduction of a number of interlaboratory comparisons. We organized two such intercomparisons: the first set, circulated in 1994, consisted of two milk samples, one containing current global levels of 14C, the other containing an added spike of 14C-methylated casein. The second set, circulated in 1995, consisted of two samples of natural vegetation growing on the site of the Chalk River Laboratories (CRL), containing two different levels of 14C, both well above global background. The response to our invitation to participate in these studies was very encouraging; six laboratories took part in the first intercomparison, eleven in the second. The list included both monitoring laboratories and those whose main function is 14C dating. Understandably, some of the latter preferred not to analyze the higher-activity samples. The results in 3 of the 4 data sets were consistent with a statistical distribution based on the reported errors. This report provides details of two intercomparisons, including the preparation of the samples, which may now be considered potential secondary reference materials, the range of analytical techniques in use at the participating laboratories, and a statistical analysis of the results returned to us.