bluuebunny/crossref_metadata_2025 huggingface dataset:
International Collaborative Study: Structuring and Sample Preparation
Authors: Cook G T , Harkness D D , Miller B F , Scott E M , Baxter M S , Aitchison T C
Published: July 2016

The success of any intercomparison exercise depends largely on participation and cooperation of a sufficient number of laboratories and the selection of a suitable suite of samples. Unless the latter is satisfactorily devised, the former cannot be guaranteed. The hierarchical nature of this study has necessarily resulted in a far more comprehensive set of sample types than has previously been employed. The exercise was structured to satisfy the following criteria: 1) to enable the participating laboratories to assess the experimental precision and accuracy of the component stages of the dating process; 2) samples should be typical of those routinely dated by the laboratories. This takes on a particular significance in Stage 1 where they should resemble as closely as possible the counting medium; 3) an objective statistical analysis of the results at each component stage of the study.
Report on Stage 3 of the International Collaborative Program
Authors: Aitchison T C , Scott E M , Harkness D D , Baxter M S , Cook G T
Published: July 2016

This report on the third and final stage of the International Collaborative Program concentrates on the analysis of internal and external variability of 14C dates obtained from samples involved in the full 14C dating process. Thirty-eight laboratories took part in this stage with most producing 8 14C dates from 3 sets of duplicate material (eg, wood, shell and peat) and 2 single samples of wood of known ages 190 yr BP apart. From the 3 sets of duplicates for each laboratory, the internal precision of most laboratories was adequate; 6 labs grossly underestimated their internal reproducibility. From the 14C determinations from the 5 distinct samples for each laboratory, we discovered significant systematic biases, often greater than 100 years, in 15 laboratories and even accounting for bias, 12 laboratories had significantly greater external variability than explained by their quoted errors. In total, 23 out of the 38 laboratories in this stage of the study, FAILED to meet these 3 basic criteria for an adequate performance in the production of 14C dates.
Radiocarbon Dating Problems Using Acetylene as Counting Gas
Authors: Geyh Mebus A
Published: July 2016

An investigation of inconsistent Hannover results in the International Collaborative Study (ICS) led to the conclusion that the main reason was contamination of the acetylene used as counting gas with recent and/or fossil carbon by the lithium used for its preparation. Despite the high level of purity of the lithium guaranteed by the producer and storage under argon in cans, different charges were partly covered with contemporary lithium carbonate and fossil oil sometimes was used to preserve the metal. Thorough cleaning of the surface of the lithium rods decreased the contamination but did not remove it entirely, which is evidenced in the wider scatter of the counting rates of various background gases than that of radiocarbon-free tank acetylene. As a result of the high risk of contamination with fossil and/or recent carbon from the acetylene counting gas, the high price of lithium, and the time-consuming preparation, the Hannover 14C Laboratory will use carbon dioxide instead of acetylene as counting gas in the future.
A Consideration of Some Basic Ideas for Quality Assurance in Radiocarbon Dating
Authors: Switsur Roy
Published: July 2016

Most radiocarbon ages are readily accepted by researchers in all disciplines. It is recognized, however, that discrepancies appear in the literature. These problems have been highlighted by the International Collaborative Study. The introduction of quality control and assurance techniques used in some laboratories for many years could reduce or eliminate aberrant results. I present here some of the basic considerations of this approach in the processes of conventional radiocarbon dating.
Checking Back on an Assemblage of Published Radiocarbon Dates
Authors: Baillie M G L
Published: July 2016

It is clear that radiocarbon researchers take a forward view towards the improvement of accuracy and precision in dating. Unfortunately, archaeologists base much of their research on the published dates produced in the past. Archaeologists and other users of radiocarbon dates should understand the limitations associated with past dates. This article addresses these limitations by looking at a large number of routine radiocarbon dates associated with a block of English tree-ring chronologies, the true ages of which are now known within close limits. My conclusion supports the idea of global multiplication factors as proposed by the International Study Group (1982).
A Quality Assurance Protocol for Radiocarbon Dating Laboratories
Authors: Long Austin
Published: July 2016

The purpose of this Quality Assurance (QA) protocol is to summarize guidelines that have been accepted by directors of many radiocarbon dating laboratories throughout the world, and by the International Atomic Energy Agency (IAEA). Some laboratories have followed similar procedures successfully for years. Laboratories that carefully adhere to this protocol will produce consistently reliable data that will be comparable in accuracy to all other laboratories following this or any other equally rigorous quality assurance program. This statement does not, however, pertain to samples with 14C activities highly sensitive to method or degree of pretreatment, as pretreatment techniques vary among laboratories.
The Radiocarbon Laboratory at the University of Barcelona
Authors: Mestres J S , García J F , Rauret Gemma
Published: July 2016

In 1983, the University of Barcelona, the Institut d'Estudis Catalans and the Department of Culture of the Generalitat de Catalunya agreed to establish a laboratory for radiocarbon measurement at the Analytical Chemistry Department of the University of Barcelona. The liquid scintillation technique was chosen for radiocarbon counting. The counting laboratory is in the basement of a six-story building.
University of Rome Radiocarbon Dates XVII
Authors: Alessio Marisa , Allegri Lucia , Improta Salvatore , Belluomini Giorgio , Cortesi Cesarina , Manfra Luigia , Turi Bruno
Published: July 2016

This list includes dates from Italy, Libyan Sahara, Niger and the Dahlak Islands, obtained from 1976 to 1980, using the benzene scintillation method.

Chemical processing from sample to benzene follows procedures of Alessio et al (1978a). Standard pretreatment for wood and charcoal included boiling with 5–10% HCL.
Isotope Dating of Pleistocene Dung Deposits From the Colorado Plateau, Arizona and Utah
Authors: Mead Jim I. , Agenbroad Larry D.
Published: July 2016

Identified dung and keratinous remains of large mammals are considered the most reliable materials to 14C date, when the initial question includes the application of the date to the time of local extirpation and extinction. The Colorado Plateau provides a unique preservation habitat (desiccation), found in greater abundance of deposits than anywhere else in North America. We review 20 localities from the Colorado Plateau that contain dung of megaherbivores. Seven species of herbivores were identified utilizing dung: Bison (bison), Equus (horse), “Euceratherium“ (shrubox), Mammuthus (mammoth), Nothrotheriops (ground sloth), Oreamnos (mountain goat) and Ovis (bighorn), and 79 14C dates were measured from the sites. Most sites contain additional associated 14C and U/Th dates on skeletal and botanical remains.
Institut Royal du Patrimoine Artistique Radiocarbon Dates XIV
Authors: Dauchot-Dehon Michele , Strydonck Mark Van
Published: July 2016

This list contains the results of14C determinations that we obtained in 1988 and 1989. δ13C was measured by the Free University, Brussels. Our dating techniques have been described previously (Dauchot-Dehon & Heylen 1971; Dauchot-Dehon, Van Strydonck & Heylen 1986).
Illinois State Geological Survey Radiocarbon Dates X
Authors: Liu Chao-Li , Asch D. L. , Fisher B. W. , Coleman D. D.
Published: July 2016

The following is a partial list of samples of archaeological interest processed between February 1981 and October 1985 at the Illinois State Geological Survey (ISGS) Radiocarbon Dating Laboratory. The list contains samples from west-central Illinois that were related to projects conducted by current or former researchers at the Center for American Archeology (CAA) (formerly Foundation for Illinois Archaeology) and Northwestern University, Department of Anthropology, or, as noted, by colleagues from other institutions. Although some of the samples reported here came from non-cultural contexts and are primarily of geological significance, all were from or related to archaeological investigations.
Department of Earth Sciences at the University of Rome Radiocarbon Dates I
Authors: Calderoni Gilberto , Petrone Vincenzo
Published: July 2016

We report here, in part, dates measured on samples from Italy since the construction of a new 14C lab in 1990 for research in the fields of geology, paleomorphology and the biogeochemical cycle of carbon. We use liquid scintillation counting (LSC), following sample conversion to benzene through the four classical chemical steps: 1) combustion or hydrolysis to CO2; 2) production of Li2C2; 3) hydrolysis to C2H2; 4) trimerization of acetylene to C6H6 with specific catalysts. The vacuum line for benzene synthesis has been designed following a comparative review of the literature (Tamers 1960; Noakes et al. 1963; Scharpenseel & Pietig 1970; Harkness & Wilson 1973; Polach, Gower & Fraser 1972; Gupta & Polach 1985), and the valuable suggestions of many colleagues from well-established labs abroad. The compact vacuum line is mostly modular with “O”-ring-joined components, and is equipped with greaseless stopcocks. We use commercial two-stage rotary pumps, pressure transducers and gauges; an electrovalve coupled with a pressure control unit supplies the purified oxygen for sample combustion while holding constant, just higher than 1 atm, the gas pressure inside the combustion tube.
High-Precision Bidecadal Calibration of the Radiocarbon Time Scale, AD 1950–500 BC and 2500–6000 BC
Authors: Stuiver Minze , Pearson Gordon W.
Published: July 2016

The radiocarbon ages of dendrochronologically dated wood spanning the AD 1950–6000 BC interval are now available for Seattle (10-yr samples, Stuiver & Becker 1993) and Belfast (20-yr samples, Pearson, Becker & Qua 1993; Pearson & Qua 1993). The results of both laboratories were previously combined to generate a bidecadal calibration curve spanning nearly 4500 years (Stuiver & Pearson 1986; Pearson & Stuiver 1986). We now find that minor corrections must be applied to the published data sets, and therefore, give new bidecadal radiocarbon age information for 2500–6000 BC, as well as corrected radiocarbon age averages for AD 1950–500 BC. Corrected average 14C ages for the 500–2500 BC interval are given separately (Pearson & Stuiver 1993). The Seattle corrections (in the 10–30 14C-yr range) are discussed in Stuiver and Becker (1993), whereas Pearson and Qua (1993) provide information on Belfast corrections (averaging 16 yr). All dates reported here are conventional radiocarbon dates, as defined in Stuiver and Polach (1977). Belfast 14C ages back to 5210 BC were obtained on wood from the Irish oak chronology (Pearson et al. 1986). Wood from the German oak chronology (Becker 1993) was used by Belfast for the 5000–6000 BC interval. For the overlapping interval (5000–5210 BC), Belfast reports weighted Irish wood/German wood 14C age averages. The Seattle 14C ages for the AD interval were either on Douglas fir wood from the US Pacific Northwest, or Sequoia wood from California (Stuiver 1982). The BC materials measured in Seattle were mostly part of the German oak chronology. Thirteen samples (5680–5810 BC) from the US bristlecone pine chronology (Ferguson & Graybill 1983) were measured in Seattle as well. Here, the final Seattle decadal 14C ages resulted from averaging German oak and bristlecone pine ages.
Calibration Curve for Short-Lived Samples, 1900–3900 BC
Authors: Vogel J. C. , van der Plicht Johannes
Published: July 2016

Both the Pretoria and the Groningen radiocarbon laboratories performed high-precision analyses on 1–4 annual tree-ring samples made available by Bernd Becker from his South German oak dendrochronological series (Vogel et al. 1986; de Jong, Becker & Mook 1986). The Pretoria measurements were extended to overlap the Groningen set, and now cover the range from 1930 to 3350 BC (Vogel et al. 1993). The tree-ring dating of the Groningen samples has been adjusted and now ranges from 3200 to 3900 BC (de Jong, Mook & Becker 1989). Taken together, the data provide a calibration curve over two millennia, which is especially suitable for short-lived samples. The curve is shown in Figures 1A–D.
The Groningen Radiocarbon Calibration Program
Authors: van der Plicht Johannes
Published: July 2016

Variations in atmospheric 14C content complicate the conversion of conventional 14C ages BP (i.e., years before AD 1950) into real calendar ages (AD/BC) (de Vries 1958; Willis, Tauber & Münnich 1960). These variations are indirectly observed in tree rings from European and North American wood. In recent decades, measurements made on dendrochronologically dated wood have resulted in the generally accepted Stuiver and Pearson calibration curves. These curves, together with other calibration data, were published in the first Radiocarbon Calibration Issue (Stuiver & Kra 1986), and are extended in the present Calibration Issue (Stuiver, Long & Kra 1993).
Calibration of14C Histograms: A Comparison of Methods
Authors: Stolk Ad , Törnqvist Torbjörn E. , Hekhuis Kilian P. V. , Berendsen Henk J. A. , van der Plicht Johannes
Published: July 2016

The interpretation of14C histograms is complicated by the non-linearity of the14C time scale in terms of calendar years, which may result in clustering of14C ages in certain time intervals unrelated to the (geologic or archaeologic) phenomenon of interest. One can calibrate14C histograms for such distortions using two basic approaches. The KORHIS method constructs a14C histogram before calibration is performed by means of a correction factor. We present the CALHIS method based on the Groningen calibration program for individual14C ages. CALHIS first calibrates single14C ages and then sums the resulting calibration distributions, thus yielding a calibrated14C histogram. The individual calibration distributions are normalized to a standard Gaussian distribution before superposition, thus allowing direct comparison among various14C histograms. Several experiments with test data sets demonstrate that CALHIS produces significantly better results than KORHIS. Although some problems remain (part of the distortions due to14C variations cannot be eliminated), we show that CALHIS offers good prospects for using14C histograms, particularly with highly precise and accurate14C ages.
Stratigraphic Division of Holocene Loess in China
Authors: Zhou Weijian , An Zhisheng , Head M. J.
Published: July 2016

Loess deposition within the Loess Plateau of China records the history of environmental change over the last 2.5 Myr. Loess-paleosol sequences of the last 10 ka, which have preserved information of global climate change, relate closely to human occupation of the area. Hence, studies of the deposition and development of Holocene loess are significant for studying environmental change and problems associated with engineering geology. We present here stratigraphic relations among four profiles from the south, west and center of the Loess Plateau. On the basis of 14C radiometric and AMS dates of organic material extracted from the paleosols, together with magnetic susceptibility measurements down each profile, we discuss Holocene stratigraphic divisions within the Loess Plateau, and suggest that the Holocene optimum, characterized by paleosol complexes, occurred between 10 and 5 ka bp. From 5 ka BP to the present, neoglacial activity is characterized by recently deposited loess.
Robert Stuckenrath, 1927-1994
Authors: Adovasio J. M.
Published: July 2016

Acerbic, abusive, brilliant, brusque, eclectic, exasperating, insightful, irritating, patient, patronizing, gentleman—these are but a few of the terms I have heard applied to Bob Stuckenrath over the 24-year period that I knew him. Their contradictory diversity serves to capture, if not the essence, at least some of his many different facets as a man and scholar.
Storage Conditions and Physical Treatments Relating to the Dating of the Dead Sea Scrolls
Authors: Caldararo Niccolo
Published: July 2016

The Dead Sea Scrolls have been analyzed by paleographic, non-destructive and destructive testing. The dates of their creation have been in dispute since their discovery. Research has established their authenticity, but a variety of conditions including the methods of skin preparation, variation in storage conditions and post-discovery restoration treatments could have introduced changes now affecting dating efforts. Comprehensive analyses were not possible until recently. Such analysis must be performed to establish a concrete framework for all the texts.

Professor R. B. Blake told a story in response to a question of why so little remained of writing on leather. He said that on one of his expeditions to Asia Minor, one of his native servants exhibited proudly some chamois trousers of his own manufacture, upon which Professor Blake detected with sorrow, traces of medieval writing (Reed 1972).
The 14C Age of the Icelandic Vedde Ash: Implications for Younger Dryas Marine Reservoir Age Corrections
Authors: Austin W. E. N. , Bard Edouard , Hunt J. B. , Kroon Dick , Peacock J. D.
Published: July 2016

Increased marine 14C reservoir ages from the surface water of the North Atlantic are documented for the Younger Dryas period. We use terrestrial and marine AMS 14C dates from the time of deposition of the Icelandic Vedde Ash to examine the marine 14C reservoir age. This changed from its modem North Atlantic value of ca. 400 yr to ca. 700 yr during the Younger Dryas climatic event. The increased marine reservoir age has implications for both comparing climatic time series dated by 14C and understanding palaeoceanographic changes that generated the increase.
Problems in the Extension of the Radiocarbon Calibration Curve (10–13 kyr BP)
Authors: Hajdas Irena , Ivy-Ochs Susan D. , Bonani Georges
Published: July 2016

Radiocarbon dating of varved lake sediments shows that, during the Late Glacial (10–12 kyr bp), the offset between the 14C and the absolute time scales was ca. 1 kyr. Varve counting and accelerator mass spectrometry (AMS) dating were used to build absolute and 14C time scales of sediments from two lakes—Soppensee, Switzerland and Holzmaar, Germany. The resulting chronologies extend back to ca. 12.9 kyr cal bp (12.1 kyr bp) in the case of Soppensee and to ca. 13.8 kyr cal BP (12.6 kyr bp) in the Holzmaar record. They compare well with each other but differ significantly from the 14C-U/Th chronology of corals (Bard et al. 1993; Edwards et al. 1993).
Improved Radiocarbon Age Estimation Using the Bootstrap
Authors: Aczel Amir D.
Published: July 2016

This paper proposes the use of the statistical bootstrap technique as an aid in combining radiocarbon date estimates The rationale for the use of the bootstrap is the theoretical result that, even if individual date estimates are normally distributed, their combination by the usual formula results in a random quantity that is not normal but rather a mixture of distributions. The bootstrap is a non-parametric, computer-intensive technique. This technique can better estimate the actual distribution of the combined age, leading to more precise confidence intervals. While the bootstrap cannot solve the multiple-intercepts problem in calibration, it can nonetheless lead to better estimates. The benefits of using the bootstrap are especially noticeable when sample sizes are small (as is the case in other applications of this technique).
Recent Reservoir Ages for Danish Fjords and Marine Waters
Authors: Heier-Nielsen Susanne , Heinemeier Jan , Nielsen H. L. , Rud Niels
Published: July 2016

AMS 14C dates were measured for 28 mollusk shells collected live in Danish waters over the period ad 1885 to 1945. Fourteen samples were from fjords and 14 were marine samples from the Danish Skagerrak-Kattegat coastal area and from the Belts. Reservoir ages were calculated for all samples on the basis of the tree-ring calibration curve. For the marine samples, which cover the period ad 1885–1916, we found a weighted-average reservoir age of 377 ± 16 yr. The marine ∆R values (the difference between the measured 14C age and the age deduced from marine, mixed-layer model calculation of Stuiver, Pearson and Braziunas (1986)) were found to be uniform within the experimental uncertainty with a weighted average of ∆R = 13 ± 16 yr. Based on the observed scatter, the standard deviation is 21 yr. This result shows that it is justified to use the marine calibration curve with standard parameters (∆R = 0) when 14C-dating marine samples from the Danish area. Our value is consistent with the result ∆R = −33 ± 27 yr previously found for the Norwegian and Swedish Skagerrak-Kattegat coasts. In contrast, reservoir ages for Danish fjords were found to vary from 400 to >900 yr, far beyond experimental uncertainty. We ascribe this to varying content of dissolved, old soil carbonate (hard-water effect). Therefore, dating of samples from such fjord environments is expected to be uncertain by several hundred years.
Locating Archaeological Horizons with 14C Sediment Dating: The Case of the Lost City of Helike
Authors: Maniatis Yannis , Facorellis Yorgos , Soter Steven , Katsonopoulou Dora , Kromer Bernd
Published: July 2016

In 373 bc a catastrophic earthquake and seismic sea wave destroyed Helike, a Greek city near Aigion on the southern shore of the Gulf of Corinth. The ruins were buried by sediments of unknown depth, leaving no trace of the city. We here discuss the radiocarbon dating of organic sediment samples recovered from seven boreholes drilled on the coastal plain in the area where ancient sources located Helike. Most of the samples apparently acquired a substantial addition of older carbon from natural sources, and hence their apparent ages are older than the true ages of sedimentation. However, if we assume that the addition is systematic, we can use the apparent ages to show that the sedimentation rate was initially rapid (about 1 cm yr-1) for the strata between 40 and 10 m below the surface, and then decreased by an order of magnitude about 6500 yr ago. A related change in the sediment deposition at about the same time has been found in many other marine deltas throughout the world, probably due to the deceleration of the global sea-level rise. We conclude that in the boreholes sampled by the present data, the horizon corresponding to ancient Helike is less than 8 m deep.
The Effect of Tillage on Soil Organic Matter Using 14C: A Case Study
Authors: Rutberg Randye L. , Schimel David S. , Hajdas Irena , Broecker Wallace S.
Published: July 2016

We compared four adjacent soil plots in an effort to determine the effect of land use on soil carbon storage. The plots were located at the High Plains Agricultural Research Laboratory near Sidney, Nebraska. We measured 14C, total carbon, total nitrogen and 137Ce to determine the size and turnover times of rapid and stable soil organic matter (SOM) pools, and their relation to land-use practices. Results were consistent with the model produced by Harrison, Broecker and Bonani (1993a) in that the 14C surface soil data fell on the time trend plots of world 14C surface soil data, indicating that the natural sod and non-tilled plots had a rapidly turning over SOM pool, comprising ca. 75% of surface soil carbon, and the tilled plots had a rapidly turning over SOM pool, comprising only 50% of surface soil carbon.
Radiocarbon Dating of Soils: Database Contribution By Bonn and Hamburg
Authors: Scharpenseel H. W. , Pietig Franz , Schiffman Heinrich , Becker-Heidmann Peter
Published: July 2016

We present a compilation of 14C soil dates measured at the University of Hamburg through 1984 (HAM-1597).
An Archaeological and Paleontological Chronology for Daisy Cave (CA-SMI-261), San Miguel Island, California
Authors: Erlandson Jon M. , Kennett Douglas J. , Ingram B. Lynn , Guthrie Daniel A. , Morris Don P. , Tveskov Mark A. , West G. James , Walker Phillip L.
Published: July 2016

We provide detailed contextual information on 25 14C dates for unusually well-preserved archaeological and paleontological remains from Daisy Cave. Paleontological materials, including faunal and floral remains, have been recovered from deposits spanning roughly the past 16,000 yr, while archaeological materials date back to ca. 10,500 BP. Multidisciplinary investigations at the site provide a detailed record of environmental and cultural changes on San Miguel Island during this time period. This record includes evidence for the local or regional extinction of a number of animal species, as well as some of the earliest evidence for the human use of boats and other maritime activities in the Americas. Data from Daisy Cave contribute to a growing body of evidence that Paleoindians had adapted to a wide variety of New World environments prior to 10,000 PB. Analysis of shell-charcoal pairs, along with isotopic analysis of associated marine shells, supports the general validity of marine shell dating, but also provides evidence for temporal fluctuations in the reservoir effect within the Santa Barbara Channel region.
Parameters of a Radiocarbon Installation
Authors: Khait Vladimir Z.
Published: July 2016

I aim to define instrumental parameters of a radiocarbon laboratory installation whereby one can estimate its precision and a maximum age up to which its measuring results are reliable. The commonly accepted factor of merit (FM) relates the precision of measurement to Poisson statistics. Unlike the FM, the proposed parameters show the extent to which a 14C laboratory is affected by destabilizing factors that could cause additional measurement errors. Assuming that all destabilizing factors produce either a change in counting efficiency or additional fluctuations of the background counting rate, I have derived two parameters for consideration.
Chemistry Strategies for Organic 14C Samples
Authors: Van Klinken G. J. , Hedges R. E. M.
Published: July 2016

Pretreatment of organic samples can be achieved by removal of contaminants, or, alternatively, by isolation of sample-specific components. We discuss the molecular aspects of these two pretreatment types, together with an assessment of their effectiveness in relation to sample type. The main division in sample type is the one between carbohydrates and proteins, leading to opposite chemical strategies for the two sample categories. Recommendations for routine 14C chemistry of organic samples also include the standardization of quality screening procedures using chemical, stable isotope and elemental data that can be collected routinely during the pretreatment of each sample.
Study of the 14C-Contamination Potential of C-Impurities in CuO and Fe
Authors: Vandeputte Kurt , Moens Luc , Dams Richard , Van Der Plicht Johannes
Published: July 2016

The carbon concentration in CuO and iron was determined by isolating C. The values were in agreement with results reported in other studies. Contaminating carbon from CuO and Fe was transformed to AMS targets and measured for 14C. C-traces in CuO were shown to be the major contribution to the 14C sample processing blank. In addition, there is a significant variability in the 14C content of CuO observed between different production batches. The combined contamination potential of CuO and Fe was found to be 4.47–8.92 μg recent carbon, whereas the more realistic estimate for AMS-target preparation conditions ranged between 1.63 and 3.24 μg recent carbon, depending on the 14C level in CuO.
Sample Throughput and Data Quality at the Leibniz-Labor AMS Facility
Authors: Nadeau M.-J. , Grootes P. M. , Schleicher Markus , Hasselberg Peter , Rieck Anke , Bitterling Malte
Published: July 2016

Since our first report on the performance of the Kiel accelerator mass spectrometry (AMS) system and our early work on sample preparation, systems have been built to improve the sample quality and throughput of the laboratory. Minor modifications were also made on the AMS system, mainly in order to reduce the amount of work and time needed to maintain the system in optimal condition. The design and performance of a 20-port reduction system, a pneumatic target press, and a remote alarm unit for the AMS system are discussed, along with an overview of the results obtained during the last year and the procedure used to obtain them. Statistical analysis shows that the contribution of the AMS system to the measuring uncertainty at our current level (0.3% for a modern sample) is negligible.
14C Measurements of Sub-Milligram Carbon Samples from Aerosols
Authors: Weissenbök Roland , Biegalski Steven R. , Currie Lloyd A. , Klinedinst Donna B. , Golser Robin , Klouda George A. , Kutschera Walter , Priller Alfred , Rom Werner , Steier Peter , Wild Eva
Published: July 2016

Accelerator mass spectrometry (AMS) at the milligram level is routinely performed, but it is difficult to go substantially below 100 μg of carbon. We discuss various approaches for sample preparation, machine operation and data evaluation, to meet the special requirements of 14C AMS measurements at the microgram-carbon level. Furthermore, we present first results obtained at the Vienna Environmental Research Accelerator (VERA) from 14C measurements of a snow sample from Gaithersburg, Maryland, USA, prepared at the National Institute of Standards and Technology (NIST).
First 14C Results from Archaeological and Forensic Studies at the Vienna Environmental Research Accelerator
Authors: Wild Eva , Golser Robin , Hille Peter , Kutschera Walter , Priller Alfred , Puchegger Stephan , Rom Werner , Steier Peter , Vycudilik Walter
Published: July 2016

14C dating with the new Vienna Environmental Research Accelerator (VERA) began with the age determination of a mummified marmot found in the Austrian Alpine region. Soft tissue and bones of the marmot were used for the investigation. For comparison, bone material from known-age samples was also processed and measured. These exercises showed that 14C dating with VERA is reliable, and since that time various samples from archaeological context have been dated.

We also studied the applicability of the 14C method in forensic sciences to determine the time of death of human individuals. 14C/12C measurements of samples from different organic human material (bone collagen, lipids from bone and bone marrow, hair) were performed and compared with the tropospheric “bomb peak” values to transform the measured ratios into “calibrated ages”. For specific substances with rapid turnover rates, this gives an estimate for the time of death of the individual. In our study, lipids and hair yield reasonable times of death, whereas the collagen fraction from bones, which has a relatively long turnover time, is not suitable for this purpose.
Segments of Atmospheric 14C Change as Derived from Late Glacial and Early Holocene Floating Tree-Ring Series
Authors: Kromer Bernd , Spurk Marco , Remmele Sabine , Barbetti Mike , Joniello Vladimiro
Published: July 2016

We present results of 14C dating of several tree-ring series from the Late Glacial and Early Holocene, analyzed at the Heidelberg University radiocarbon laboratory. Although these are floating series, they contribute high-resolution information about the variability of atmospheric 14C during those periods.
The Effect of a Succession of Ocean Ventilation Changes on 14C
Authors: Stocker Thomas F. , Wright Daniel G.
Published: July 2016

Using the model of Stacker and Wright (1996), we investigate the effect of a succession of ocean ventilation changes on the atmospheric concentration of radiocarbon, δ14Catm, the surface reservoir ages, the top-to-bottom age differences, and the calendar-14C age relationships in different regions of the ocean. The model includes a representation of the cycling of 14C through the atmosphere, the ocean and the land biosphere. Ocean ventilation changes are triggered by increasing rates of freshwater discharge into the North Atlantic, which are determined according to a simple feedback mechanism between the melting rates and the climatic state of the North Atlantic region. The results demonstrate that ventilation changes can cause δ14Catm fluctuations of 25%, surface reservoir age fluctuations of 100 yr in the Pacific (200 yr in the Atlantic) and top-to-bottom age variations of 500 yr in the Pacific (1000 yr in the Atlantic). We also show that 14C age estimates based on marine organisms that live in the near-surface region of the ocean and take up the signal of surface 14C can result in apparent age reversals if the assumption of a constant reservoir age is made.
The Tunguska Event as Recorded in a Tree Trunk
Authors: Yonenobu Hitoshi , Takenaka Chisato
Published: July 2016

A living spruce tree was collected near the explosion center of the Tunguska event that occurred in 1908. We measured annual ring width and studied anatomical features to reconstruct the possible vegetational changes caused by the biological aftereffects of the Tunguska explosion. δ14C of annual rings from 1908 to 1910 was measured with a Tandetron accelerator mass spectrometer. The annual ring width decreased rapidly in 1908–1912, drastically increased in 1913, and decreased gradually thereafter. Traumatic resin ducts were observed in the transition zone between early- and latewood of the annual ring formed in 1908. We thus reconstruct these vegetational changes in the Tunguska forest: the Tunguska explosion damaged forest trees severely for ca. 3 yr, releasing rich nutrients from burned plants into the soil, and subsequently the vegetation was stimulated to recover by decreased socio-biological competition and better lighting conditions. δ14C values range from −28.2 to −1.5% for Tunguska spruce, and from −29.7 to 12.6% for Hinoki cypress. These fluctuations are within the ranges presented in Stuiver and Becker (1993), suggesting no evidence of anomalies of cometary origin in carbon isotopic composition. We found no significant difference between δ14C of Tunguska spruce and of Hinoki cypress.
14C Analysis of Annual Tree Rings from the Vicinity of the Chernobyl NPP
Authors: Buzinny Michael , Likhtarev Ilja , Los' Ivan , Talerko Nikolay , Tsigankov Nikolay
Published: July 2016

Samples of >40 pine trees were collected from around the Chernobyl NPP for radiocarbon measurement, to determine the spatial distribution of excessive 14C in tree rings from 1986 consequent upon accidental radiocarbon release. Tree samples were collected during 1995–1996 from sites situated at distances >2.5 km from the NPP and covering a variety of directions in relation to the NPP. To evaluate δ14C for 1986 annual rings, we compared 14C levels for separate 1985–1987 annual rings, taking into account the trend of operational releases. Early and late wood samples for 1986 annual tree rings were measured separately to increase the sensitivity and precision of measurements. The maximum value observed for excessive accidental radiocarbon levels (δ14C) was found to be 124 pMC (281.6 Bq kg-1 C). We present δ14C values for examined sites; their spatial distribution shows a high irregularity of atmospheric 14C depending on direction from the NPP. Using obtained data, we reconstruct the temporal behavior of 14C release during the Chernobyl accident with the aid of atmospheric transport modeling. The total amount of 14C released from 26 April to 5 May 1986 has been estimated as 44 TBq.
A 40,000-Year Varve Chronology from Lake Suigetsu, Japan: Extension of the 14C Calibration Curve
Authors: Kitagawa Hiroyuki , Van Der Plicht Johannes
Published: July 2016

A sequence of annually laminated sediments is a potential tool for calibrating the radiocarbon time scale beyond the range of the absolute tree-ring calibration (11 ka). We performed accelerator mass spectrometric (AMS) 14C measurements on >250 terrestrial macrofossil samples from a 40,000-yr varve sequence from Lake Suigetsu, Japan. The results yield the first calibration curve for the total range of the 14C dating method.
Factors Influencing 14C Ages of the Pacific Rat Rattus Exulans
Authors: Beavan Nancy Ragano , Sparks Rodger J.
Published: July 2016

An isotopic database for the Pacific/Polynesian rat (Rattus exulans) and foods that it scavenges is used to examine diet-induced 14C age variation in omnivores. We discuss a suite of 26 δ14C determinations and 13C and 15N analysis for modern Pacific/Polynesian rat bone gelatin and available food items from Kapiti Island, New Zealand (40°51'S, 174°75'E). These analyses provide the first isotopic data for modern specimens of the species, collected as part of a larger project to determine potential sources of bias in unexpectedly old 14C age measurements on subfossil specimens of R. exulans from New Zealand. Stable C, N and 14C isotopic and trapping data are used to trace carbon intake via the diet of the rats in each habitat. Data from specimens linked to five specific habitats on the island indicate that modern populations of R. exulans are not in equilibrium with atmospheric values of δ14C, being either enriched or depleted relative to the atmospheric curve in 1996/97, the period of collection. The δ14C values recorded for R. exulans are associated with diet, and result from variation in δ14C values found in animal-protein food items available to a scavenging omnivore. The titer of carbon deviating from atmospheric values is believed to be derived from the essential amino acids in the protein-rich foods of the rat diet.

Present evidence suggests that the depletion required to affect 14C ages limits the possibility that diet introduces dramatic offsets from true ages. Marine diets, for example, would have a variable effect on ages for terrestrial omnivores, contraindicating the application of a standard marine correction for such specimens. We suggest that to identify the extent to which diet may influence the 14C age in a given specimen of terrestrial omnivore, the separation and dating of essential amino acids vs. a nonessential amino, such as glycine, be applied.
Early Bronze Jericho: High-Precision 14C Dates of Short-Lived Palaeobotanic Remains
Authors: Bruins Hendrik J. , Van Der Plicht Johannes
Published: July 2016

Reliable series of high-precision radiocarbon dates in a stratified archaeological context are of great importance for interdisciplinary chronological and historical studies. The Early Bronze Age in the Near East is characterized by the beginning of the great civilizations in Egypt and Mesopotamia, as well as by urbanization in the Levant. We present stratified high-precision dates of short-lived material of Tell es-Sultan (Jericho), covering Late Proto-Urban/EB I, EB II and EB III layers from Trench III. Our calibrated dates, refined by Bayesian sequence analysis involving Gibbs sampling, are ca. 150–300 yr older than conventional archaeological age assessments. The corpus of 14C dates measured in the first decades after the discovery of 14C dating should not be taken too seriously. The 14C dates of Jericho measured by the British Museum 14C laboratory in 1971 appear to be erroneous.
New 14C Dating of the Archaic Royal Necropolis Umm El-Qaab at Abydos (Egypt)
Authors: Görsdorf Jochen , Dreyer Günter , Hartung Ulrich
Published: July 2016

Since 1977, the German Institute of Archaeology in Cairo has been reexamining the archaic Royal necropolis Umm el-Qaab at Abydos (ca. 500 km south of Cairo). The necropolis consists of the tomb complexes of six kings and one queen of Dynasty I as well as two kings of Dynasty II in the southern part, the cemetery with royal tombs from Dynasty 0 and early Dynasty I in the middle and the predynastic cemetery in the northern part. Although partly destroyed and deprived of most of their contents, the tombs and the remaining artifacts are a major source for the early dynastic period and are of utmost importance for the understanding of predynastic development during Naqada I–III and the chronology of the formation of Egyptian culture. Sixteen newly 14C-dated samples were mainly taken from remains of wooden roofs and coffins, or in the case of the earliest tombs from mattings. The dating results in general are in good accordance with the relative archaeological dating of the tombs, but 100–150 yr earlier than the so far established historical chronology.
An Extended Prehistoric Well Field in the Opencast Mine Area of Zwenkau, Germany
Authors: Stäuble Harald , Hiller Achim
Published: July 2016

In the opencast mine area of Zwenkau, Germany, many prehistoric wells and pits have recently been excavated. In this region there is generally no bone preservation and charred seeds are rare, seldom encountered in a reliable archaeological context, whereas charcoal is frequently found. From an archaeological point of view, however, charcoal from wood is not as reliable for radiocarbon dating as short-lived materials. Fortunately, many deep features were found where wood has been preserved. Over a dozen structures turned out to be prehistoric wells, some of them typologically dated by ceramics to between Early Bronze Age and Early Middle Ages. For other features without archaeological finds, 14C dating was the only way to get an age. Analysis showed that different types of wells were constructed by the same culture. On the other hand, the same constructions are not characteristic for a defined cultural period and were applied over a time span of three millennia.
14C Dating of Laminated Sediments from Loch Ness, Scotland
Authors: Cooper M. C. , O'Sullivan P.E. , Harkness D. D. , Lawson E. M. , Bull D. , Kemp A. E. S. , Peglar Sylvia M. , Matthews Nina M. , Jones R. I. , Shine A. J.
Published: July 2016

Radiometric and AMS radiocarbon dating of a 6-m sediment core from Loch Ness, Scotland, indicates that it represents perhaps the very end of the Late Pleistocene, and the first ca. 7500 yr of the Holocene. Counts of laminations observed in the Holocene section of the core suggest that they are present in sufficient number to constitute annual laminations (varves), an hypothesis consistent with the pollen record, which contains a sequence of zones representative of the Early, Middle and part of the Late Holocene regional vegetation history. On the basis of BSEM and X-ray studies of sediments, and modern seston trap data, the laminations are believed to be produced by winter floods, which introduce increased silt loading into the Loch. Sediment for the rest of the year is mostly composed of clay-sized material. This hypothesis is being further tested, however, by continuing sedimentological and microfossil studies.

Time-depth relations for the core based on calibrated 14C dates and lamination counts, respectively, illustrate the close correspondence between the two sets of data. The latter are therefore now being used to develop a varve chronology for the Holocene for Loch Ness. This will then in turn be used for further chronological studies, and for investigations of palaeoclimatic variations over the eastern North Atlantic, to which the signal of lamination thickness in the sediments is thought to be particularly sensitive. They may also eventually be used for calibration studies, employing 14C dating of specific carbon compounds, or groups of compounds extracted from the sediment using modern organic geochemical methods.
Application of 14C Data for the Estimation of Sphagnum Peat Increment in Estonian Ombrotrophic Mires
Authors: Punning J.-M. , Koff Tiiu
Published: July 2016

We calculated apparent increment values based on the radiocarbon dates of 21 Estonian ombrotrophic mires (raised bogs). For short periods, the values vary significantly, but the integrated increment for the total complex of ombrotrophic peat shows a strong increasing tendency with decreasing peat age. This is probably due to the decay of accumulated organic matter. Our hypotheses concern the mechanisms of decay and methods for increasing the reliability of the interpolation and extrapolation of 14C data.
Carbon Isotope Variations and Chronology of the Last Glacial-Interglacial Transition (14–9 ka BP)
Authors: Turney Chris S. M. , Harkness Doug D. , Lowe J. John
Published: July 2016

We present δ13C data from both bulk organic sediment samples and terrestrial plant macrofossils from five high-resolution sedimentary sequences from the United Kingdom from which extensive multiproxy data sets have been obtained. These span the last glacial-interglacial transition. Chronological control has been provided by radiocarbon dating and/or tephrochronology. The results demonstrate that significant shifts in bulk organic δ13C can be identified at key climatic transitions in most of the sites. The data are affected by site-specific influences that restrict their use as chronological markers. However, terrestrial plant macrofossil records are more consistent and reveal shifts that appear to be synchronous and which therefore offer a basis for interregional correlation as well as significant paleoenvironmental information.
Reappraisal of Chinese Loess Plateau Stratigraphic Sequences Over the Last 30,000 Years: Precursors of an Important Holocene Monsoon Climatic Event
Authors: Zhou Weijian , An Zhisheng , Jull A. J. T. , Donahue D. J. , Head M. J.
Published: July 2016

Through the establishment of radiocarbon chronozones relating common geological events within lacustrine and eolian sediments from five profiles representative of loessyuan(tablelands), river valley and northwest margin features of the Loess Plateau, we propose a series of stratigraphic divisions within the last 30 ka. The focus of this detailed study involves stratigraphic relationships contributing to evidence of Younger Dryas events, with the recognition of cold-dry, cool-wet and cold-dry periods represented within the Heiheze silt, Midiwan peat and Liushuwan eolian sand. The stratigraphic profiles reflect century-scale fluctuations of the East Asian monsoons. The precursor events enable us to place the Pleistocene/Holocene boundary at 10,000 bp.