bluuebunny/crossref_metadata_2025 huggingface dataset:
Reproducibility of Seawater, Inorganic and Organic Carbon 14C Results at NOSAMS
Authors: Elder Kathryn L. , McNichol Ann P. , Gagnon Alan R.
Published: July 2016

The majority of samples processed at the National Ocean Sciences AMS Facility (NOSAMS) thus far were collected as part of the World Ocean Circulation Experiment (WOCE). Due to the long storage time (2–3 yr) required to analyze thousands of samples on the accelerator mass spectrometer (AMS), a test was designed and implemented to determine the effects, if any, of storage time on 14C concentration. We find no systematic offsets in AMS measurements made over a 5-yr period between a total of 16 replicate sets from surface and deep water collected at the same locality. Furthermore, the average δ14C value from the deepwater AMS replicates (-213.1%, std. dev. 7.3) agrees very closely with the conventional 14C results published for GEOSECS (-212.7%) from station 320 taken 20 yr earlier.

A total of 73 WOCE shipboard replicate sets (162 AMS measurements) were analyzed with a mean precision of 4.3%. AMS results from 20 more shipboard replicate sets (44 AMS measurements) submitted as CO2 from the Stable Isotope Laboratory (SIL) at the University of Washington were analyzed with a mean precision of 3.4%. These results suggest no significant difference between water stripping methods used in each preparation lab.

To assess reproducibility, we calculate a pooled estimate of σ for replicates called s, which we use as an approximation of σTOT for a given sample type. The s for WOCE seawater replicates is 4.9% and 5.8% for SIL gas replicates. These numbers demonstrate an overall reproducibility of seawater AMS results at NOSAMS that is in line with reported errors. We take the difference between total error s and machine error as the overall standard deviation of combined uncertainties associated with preparation of samples and with AMS. For seawater samples processed at NOSAMS, σSPL is calculated to be 2.4%, and for the SIL gas replicates it is 4.8%.

Reproducibility of samples prepared with an acid hydrolysis technique is demonstrated using 24 coral samples submitted in triplicate by Dr. R. G. Fairbanks of Lamont Doherty Earth Observatory. Seventy-two replicates were prepared and analyzed at NOSAMS with a mean reported precision of 1.2%. The pooled estimate s for the Fairbanks triplicates is 2.6%. We calculate a laboratory reproducibility uncertainty for coral hydrolysis samples of 2.2%.

In 1993, NOSAMS participated in the Third International Radiocarbon Intercomparison (TIRI) Study. We report here 60 AMS analyses of the six TIRI test materials, five of which are organic carbon samples, to validate sample-processing methods for organic carbon sample AMS analyses at NOSAMS.
Systematic Investigations of 14C Measurements at the Vienna Environmental Research Accelerator
Authors: Rom Werner , Golser Robin , Kutschera Walter , Priller Alfred , Steier Peter , Wild Eva
Published: July 2016

A newly operating accelerator mass spectrometry (AMS) facility such as VERA has to go through an extensive testing phase in order to establish optimal conditions for 14C measurements, especially in the field of archaeological samples where an overall precision of 0.5% is desirable.

We discuss the results of our measurements at the milligram carbon level as they relate to long-term stability, reproducibility, precision and isotope fractionation.
An Ion Source for the HVEE 14C Isotope Ratio Mass Spectrometer for Biomedical Applications
Authors: Mous Dirk J. W. , Fokker Wim , Van Den Broek Rein , Koopmans Ron , Ramsey Christopher Bronk , Hedges R. E. M.
Published: July 2016

During the past two decades, accelerator mass spectrometry (AMS) has allowed major developments in many areas of geosciences and archaeology. In the near future, AMS should realize a similar potential in the field of biomedical research, leading ultimately to clinical applications. For such applications, the required instrument differs significantly from that presently used in the field of 14C dating. Whereas the needed accuracy and sensitivity is more than an order of magnitude less demanding than that for present state-of-the-art 14C instrumentation, the widespread acceptance of 14C AMS in biomedical research will require AMS spectrometers that are small, simple to operate and capable of handling CO2 samples. In order to satisfy these demands, HVEE has developed a compact 14C AMS spectrometer dedicated to biomedical research. The instrument consists of a compact accelerator with a footprint of 2.25 × 1.25 m and an ion source that features direct CO2 acceptance and optimal user friendliness. Having previously described the layout and design of the accelerator, we here discuss progress on the accelerator and present the design and first results of the CO2 ion source.
A Review of 14C Waste Arising from the Nuclear Industry in the United Kingdom
Authors: McNamara Niall , McCartney Martin , Scott E. M.
Published: July 2016

We report on a review of 14C production and release from the nuclear industry in the United Kingdom (UK). Using earlier predictions (Bush, White and Smith 1984) it is estimated that a total of 1764 TBq of 14C would have been produced in UK graphite-moderated reactors up to the end of 1995, and 135 TBq of this total would have been released. Release rates, based on reported discharges, of 5.1 and 0.93 TBq GW(e)a-1 have been derived for Magnox reactors and Advanced Gas Cooled Reactors (AGRs), respectively. Using these new figures, cumulative discharges of 14C up to 1995 from reactors have been estimated at 531 TBq. The combination of these reactor discharges and the reported discharges from Sellafield (388 TBq) and Amersham (52 TBq) suggest a total cumulative release of 971 TBq of 14C up to the end of 1995.
Correlation of Marine 14C Ages from the Nordic Seas with the GISP2 Isotope Record: Implications for 14C Calibration Beyond 25 ka BP
Authors: Voelker Antje H. L. , Sarnthein Michael , Grootes Pieter M. , Erlenkeuser Helmut , Laj Carlo , Mazaud Alain , Nadeau Marie-Josée , Schleicher Markus
Published: July 2016

We present two new high-resolution sediment records from the southwestern Iceland and Norwegian Seas that were dated by numerous 14C ages up to 54 14C ka bp. Based on various lines of evidence, the local 14C reservoir effect was restricted to 400–1600 yr. The planktic stable isotope records reveal several meltwater spikes that were sampled with an average time resolution of 50 yr in PS2644 and 130 yr in core 23071 during isotope stage 3. Most of the δ18O spikes correlate peak-by-peak to the stadials and cold rebounds of the Dansgaard-Oeschger cycles in the annual-layer counted GISP2 ice core, with the major spikes reflecting the Heinrich events 1–6. This correlation indicates large fluctuations in the calibration of 14C ages between 20 and 54 14C ka bp. Generally the results confirm the 14C age shifts as predicted by the geomagnetic model of Laj, Mazaud and Duplessy (1996). However, the amplitude and speed of the abrupt decrease and subsequent major increase of our 14C shifts after 45 14C ka bp clearly exceed the geomagnetic prediction near 40–43 and 32–34 calendar (cal) ka bp. At these times, the geomagnetic field intensity minima linked to the Laschamp and the Mono Lake excursions and confirmed by a local geomagnetic record, probably led to a sudden increase in cosmogenic 14C and 10Be production, giving rise to excess 14C in the atmosphere of up to 1200%.
The Chronology of the Subotiv Settlement
Authors: Klochko Victor I. , Kovaliukh Nikolai N. , Skripkin Vadim V. , Motzenbecker Ingo
Published: July 2016

Samples collected at the Chornoliska culture site near the village of Subotiv, Cherkasy region during the 1994–1995 Ukrainian-German expedition were radiocarbon dated in Kiev. The foundation of the Subotiv settlement dates to 1300–1200 cal BC. A skeleton found in one of the buildings at this site is dated at the end of the early period (between 1120 and 1040 cal BC). In the youngest part (a small town) of the Subotiv settlement, we found the remains of a “building sacrifice"—the skeleton of a teenager. The average calibrated date for this skeleton is 834–807 cal BC, whereas the timber from the rampart dates between 902–810 cal BC. Thus, the rampart was apparently built between 834–807 cal BC. Among the objects found on the site were Arzhan-type bone arrowheads. Such arrowheads, when found in Eastern Europe, are believed to indicate the military expansion of Proto-Scythian nomads. The Sargary settlement in western Kazakhstan dates to 960–820 cal BC, the Arzhan arrow in Siberia to 960–850 cal BC. We assume that the Chornogorivka complexes in eastern Eurasia date to the earlier time period (960–820) than those in western Eurasia (834–807). The time of the Chornogorivka expansion on the territory of Ukraine is therefore within the range 834 to 820 BC.
The14C Chronology of the Son Mas Sanctuary Site (Valldemosa, Mallorca, Spain)
Authors: Van Strydonck Mark J. Y. , Waldren William H. , Hendrix Veerle
Published: July 2016

With >4014C dates, mainly on bones and charcoal, the site at Son Mas is the only megalithic sanctuary on the Balearic Islands that has been dated by14C in detail. Although soil erosion made stratigraphy difficult and the monument was cleaned out regularly during its long use, the results demonstrate that the site was occupied from the Pretalayotic (Chalcolithic) until the Roman period. The aim of this study was not only to date the construction and the use of the sanctuary, but also to correlate this monument, by means of dispersion diagrams, with the other prehistoric sites situated within the same valley. The dates were also used to compare the site with the generally accepted chronology of the Balearic archipelago (Mallorca, Menorca, Ibiza and Formentera).
14C Chronology of Archaeological Sites in European Russia and Changes in Environmental Processes: A Database Investigation
Authors: Zaitseva Ganna I. , Dergachev Valentin A. , Timofeev Vladimir L. , Sementsov Anatoly A.
Published: July 2016

A large number of 14C dates for archaeological sites in European Russia have been entered into a new database. The database includes >1500 dates for ca. 500 archaeological sites. Because European Russia is a very large area, the database includes subdivisions of territories and regions. We analyzed our 14C dates according to archaeological periods (Paleolithic through Medieval period) and made a comparison with environmental (climatic) parameters. Our database for archaeological sites and monuments offers new possibilities for correlation between the development of ancient cultures and natural-climatic processes.
Holocene Paleoenvironmental Changes in the Lower Mahi Basin, Western India
Authors: Kusumgar Sheela , Raj Rachna , Chamyal L. S. , Yadav M. G.
Published: July 2016

Evidence of paleoenvironmental changes during the Holocene from the Lower Mahi basin of Western India have been documented. The unpaired S2surface all along the estuarine zone of the Mahi basin has been identified as an uplifted marine terrace. The terraces have preserved in their lithosections fairly distinct horizons of grayish brown clays rich in marine microfauna. The intervening silty-sand horizons are indicative of freshwater origin. The sedimentary structure and faunal assemblage indicate that these units have been deposited in a marginal marine environment. The14C ages obtained on these marine mud horizons show that between 3600 and 1700 bp the sea level was higher than at present. The geomorphic evidence suggests that a late Holocene uplift has played a significant role in lowering the relative sea level to its present position.
14C Dating of Terrestrial Moss in Tern Lake Deposits, Antarctica
Authors: Shen Chengde , Liu Tungsheng , Yi Weixi , Sun Yanmin , Jiang Mantao , Beer Jürg , Bonani Georges
Published: July 2016

Accurate radiocarbon ages were obtained from terrestrial moss from two drill holes in Tern Lake deposits, Antarctica, using liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The results show that the lake deposits have been accumulating since the end of the last glacial epoch ca. 12,600 cal BP at the rate of 0.13–1.1 mm a-1. We discuss the validity of 14C ages of Antarctic lake deposits, with respect to the latitude effect of 14C productivity, the reservoir effect, the environment effect and the hard-water effect.
Study of the Effect of Fossil Organic Carbon on 14C in Groundwater from Hvinningdal, Denmark
Authors: Boaretto E. , Thorling L. , Sveinbjörnsdóttir Á. E. , Yechieli Y. , Heinemeier J.
Published: July 2016

The carbonate hydrochemistry of groundwater from the Hvinningdal aquifer (Denmark) was studied by radiocarbon (accelerator mass spectrometry (AMS)) and δ13C measurements as a preliminary step towards 14C groundwater dating. The 14C concentrations varied between 30 and 100 percent modern carbon (pMC) in apparent contradiction with tritium (3H) data, which in most cases indicate a post-bomb date. The dilution of 14C can be explained as being due to the combined effect of dissolution of old soil carbonate and oxidation of old organic carbon. The last effect proved to be essential. To calculate this correction the dissolved oxygen concentration was used together with the δ13C values. The combined corrections bring the 14C concentrations up to post-bomb levels in better agreement with the 3H data.
Revision and Tentative Extension of the Tree-Ring Based 14C Calibration, 9200–11,855 cal BP
Authors: Kromer Bernd , Spurk Marco
Published: July 2016

We report radiocarbon calibration data based on the revised German oak and pine series. The age range of the absolutely dated German oak series has been extended to 10,430 cal bp. The German pine series is tentatively linked to the oak series by 14C, and now reaches back to 11,871 cal bp (±20 yr). The revisions of the tree-ring time scale of the German oak chronology solved long-standing apparent discrepancies in the mid-Holocene 14C calibration data sets. The calibration data set based on the floating German pine is now in close agreement with the Preboreal part of 14C calibration series obtained from most varve chronologies and corals.
The Neolithic Site of Serra Cicora: Results of the AMS Radiocarbon Dating
Authors: Quarta G , D'Elia M , Ingravallo E , Tiberi I , Calcagnile L
Published: July 2016

Bone and charcoal samples from the Neolithic site of Serra Cicora in the Salento Peninsula (southern Italy) have been dated by accelerator mass spectrometry (AMS). Measurements appear to support other archaeological evidence and have shown that 2 distinct phases of human occupation of the site can be identified: the first occupation in the Early Neolithic and a second occupation in the Middle-Late Neolithic. The results provide new information and are a fundamental contribution to the definition of the absolute chronology of the Middle-Late Neolithic in this part of Europe.
Institut Royal Du Patrimoine Artistique Radiocarbon Dates I
Authors: Schreurs Anne N.
Published: July 2016

The development of a C14 laboratory within the physical laboratory of the “Institut royal du Patrimoine artistique” was begun by Dr. I. Elskens and D. Gausset (A.I. Br.).

The electronic apparatus was delivered in 1963 and routine counting on gas of petrochemical origin began in 1964. By December 1965, methane gas was prepared from pure commercial CO2 and, in February 1966, the first test samples were burnt.
University of Wisconsin Radiocarbon Dates IV
Authors: Bender Margaret M. , Bryson Reid A. , Baerreis David A.
Published: July 2016

Radiocarbon dates obtained at the University of Wisconsin since November, 1966, are summarized in this report. The procedures followed and equipment used have been described previously (Wisconsin II).
Using dBASE II for Retrieval of Radiocarbon Data
Authors: Selsing Lotte , Simonsen Aud
Published: July 2016

A “C14” data base has been created for internal use of 14C dates with an Osborne-1 system. It uses a CP/M operating system, Z-80 CPU, and dBASE II software program. The structure meets the users’ requirements of information and easy retrieval. The video display is quite compact, as a record of 32 fields is edited to fill a screen of 22 lines. A standard printout is edited to make room for two records per page and contains all information from these records. Searching may take place in all fields or parts of fields, in interval(s) in one or more fields and in various combinations of the prescribed methods of searching. A field called KEYWORDS is established to ease search operations. “C14” may be adapted to individual requirements and equipment with small adjustments.
Lamont Natural Radiocarbon Measurements V
Authors: Olson Edwin A. , Broecker W. S.
Published: July 2016

This article reports the radiocarbon age measurements made at the Lamont Geological Observatory between February 1957 and July 1958. For convenience the sample ages have been classified into the following categories:

Table I

Geologic Samples—North American glacial geology

Table II

Geologic Samples—Pluvial lake levels

Table III

Geologic Samples-Relative sealevel changes

Table IV

Geologic Samples-Oceanography

Table V

Geologic Samples-Miscellaneous

Table VI

Archaeologic Samples

Table VII

Check Samples

Within each table are subdivisions according to geographic origin.
University of Arizona Radiocarbon Dates II
Authors: Shutler Dick , Damon Paul E.
Published: July 2016

The radiocarbon age measurements reported on in this article were made during a period from May, 1957, through May, 1958. During this time the laboratory was operated by the Department of Anthropology, under the direction of Dr. Emil W. Haury. On July 1, 1958, the Carbon-14 laboratory, under the supervision of Dr. Paul E. Damon with Dick Shutler, Jr. as laboratory technician, was transferred to the Geochronology Laboratories.
Trondheim Natural Radiocarbon Measurements I
Authors: Nydal R.
Published: July 2016

The C14-dating Laboratory in Trondheim has now been working for one year and a half. The present dating list covers the period from July 1957 to September 1958. The rather small number of datings made during this period is due to a lot of background experiments which have been carried out in the last half-year.

With a few exceptions the datings done before the period mentioned have been previously published (Marstrander, 1956–1957; Nydal and Sigmond, 1957; Skjelsvik and others, 1957–1958).
Carbon-14 Dating in Pisa—II
Authors: Ferrara G. , Fornaca-Rinaldi G. , Tongiorgi E.
Published: July 2016

Almost all radiocarbon measurements reported in the following list have been made with the same equipment and method used for the measurements reported in our previous work (Pisa-I). The sample used as contemporary standard for these samples is also charcoal obtained from Arbutus unedo wood grown near Pisa between 1948 and 1956. The value obtained from this standard has also been used for shell samples.
Yale Natural Radiocarbon Measurements VI
Authors: Stuiver Minze , Deevey Edward S.
Published: July 2016

The following list includes most of the measurements made since publication of Yale V; some measurements, such as a series collected in Greenland by A. L. Washburn, are withheld pending additional information or field work that will make better interpretations possible. In addition to radiocarbon dates of geologic and/or archaeologic interest, we give in the third part of the paper, for the first time since 1954 (Deevey and others, 1954), recent assays of C14in lake waters and other lacustrine materials, now normalized for C13content. Some of these C13values have been published separately (Oana and Deevey, 1960), but most have not.
Large-Volume WOCE Radiocarbon Sampling in the Pacific Ocean
Authors: Stuiver Minze , Östlund H. G. , Key Robert M. , Reimer Paula J.
Published: July 2016

At the University of Miami Tritium Laboratory and the University of Washington Quaternary Isotope Laboratory, more than 1000 large-volume Pacific Ocean radiocarbon samples were measured for the WOCE program. Here we present a comprehensive data set, and a brief discussion of our findings.
A Correction for In-Situ14C in Antarctic Ice with 14CO
Authors: Van Rouen Job , Van Der Borg Klaas , De Jong Arie , Oerlemans Johannes
Published: July 2016

We use a dry extraction method to obtain trapped CO2 of shallow ice cores from a blue ice area of East Antarctica. In-situ-produced 14C extracted in 14CO2 and 14CO concentrations show a mean ratio of 3.4 ± 0.4. Correction for in-situ14CO2 resulted in ice ages within 7–13 ka. The accumulation and ablation rates determined from the in-situ production of 7–20 cm yr−1 and 10–13 cm yr−1, respectively, agree with field measurements, and thus indicate close to total efficiency of extraction.
14C Dating of an Israelite Biblical Site at Kuntillet Ajrud (Horvat Teman)
Authors: Meshel Zeev , Carmi Israel , Segal Dror
Published: July 2016

The Israelite site of Kuntillet Ajrud in northern Sinai contains unique drawings and inscriptions in ancient Hebrew and Phoenician. It is a single-phase site dated archaeologically to ca. 800 bce. We considered this site a good test case for comparing archaeological with 14C datings. The dates are in agreement, confirming that 14C dating is useful in dating Iron-Age II sites.
Cosmogenic Radiocarbon and Cyclical Natural Processes
Authors: Dergachev Valentin , Chistyakov Vladimir
Published: July 2016

We investigated relations among solar activity, climate and cosmogenic radiocarbon in a time series of various astrophysical, geophysical, archaeological and historical data. We studied records of tree-ring thickness, aurora borealis, the catalog of visible sunspots, sedimentary deposits from lakes and oceans, global glacial advance and retreat chronology, polar ice cores and human migrations. In these data, we searched for evidence of medium- and long-term solar cycles. Application of different spectral techniques to the atmospheric 14C concentration time series indicates the existence of spectral lines at a few dominant periodicities ranging from 11 yr to ca. 2 ka. Different laboratories have confirmed the presence of the ca. 210-and 2000-yr spectral features in long 14C series in tree rings. The ca. 210-yr 14C cycle is probably caused by heliomagnetic modulation of the cosmic-ray flux. The extrema of both the ca. 210-yr 14C period and solar activity correlate with the cold and warm epochs of global climate, at least for the past millennium, and this correlation has the correct sign. The periods of low solar activity are well correlated with the Little Ice Ages. The cause of the ca. 2 ka 14C period is, as yet, uncertain, but evidence from the analyses of various natural records shows that it could have a solar origin. In this study, we obtained powerful manifestations of solar activity and climate warming epochs at ca. 1500, 3800, 6100, 8200, 10,500 and 12,600 bp. A similar feature occurs in epochs of minimum amplitude in the 14C content in tree rings. Thus, solar activity may affect both the 14C content in the Earth's atmosphere and climate.
A Bayesian Approach to the Use of 14C Dates in the Estimation of the Age of Peat
Authors: Christen J. A. , Clymo R. S. , Litton C. D.
Published: July 2016

Peatlands occupy a significant portion of the land surface of the Earth and form a large carbon store. Most peat-forming systems have two layers. The upper layer, the acrotelm, fixes carbon by photosynthesis, loses some of it by decay and passes the remainder on to the lower layer, the catotelm. In the catotelm, decay continues at a slower rate. Mathematical models of the growth of the catotelm have been proposed which relate the cumulative mass of peat above a particular depth to calendar age of the peat at that depth. We demonstrate how 14C dating and the Bayesian approach to data analysis can be used to make inferences about the relation between calendar age and cumulative mass, and to estimate the accumulation and decay rates.
The Use of Zeolite Molecular Sieves for Trapping Low Concentrations of CO2 from Environmental Atmospheres
Authors: Bol R. A. , Harkness D. D.
Published: July 2016

We describe a simple method for trapping low concentrations of CO2 present in gas mixtures, such as air and soil respiration, using a zeolite molecular sieve (type 13x) for environmental carbon isotope studies. We employ reusable molecular-sieve cartridges and a lightweight battery-driven pumping system, developed to enable CO2 collection in difficult and dangerous terrain or under extreme climatic conditions. The results of a small field experiment suggest that CO2 could be quantitatively trapped on and recovered from the 13x molecular sieve, without any fractionation of the stable carbon isotope. The δ13C of CO2 was also independent of the amount of air ≤18 liters and rate at which it was collected, i.e. ≤ 1 liter of air/min.
Change of Calibration Parameters in Frequently Used Vials in Benzene Scintillation Counting
Authors: Haas Herbert
Published: July 2016

Scintillation counting vials used for counting synthesized benzene accumulate an inside coating which is insoluble in benzene. This coating reduces the photon transfer from the vial and lowers its observed background. Age calculations that include calibration data collected with other vials may be inaccurate if this effect is not considered. Frequent cleaning of the counting vials with strong acid solutions keeps the coating from accumulating.

A sample counting vial cleaned only with photospectrometric grade benzene between 67 different sample benzene fillings made in a 20-month period showed, during counting, an efficiency lowered by 2.8% and a background lowered by 8.7%. Age calculations for a 10 ka old sample made with calibration data from “matched” vials would yield a result too old by 515 yr.
External Radon Disturbance of 14C Measurements in Gas-Proportional Counters
Authors: Hedberg Magnus , Theodórsson Páll
Published: July 2016

Low-level detector systems for 14C dating are frequently located in underground or basement laboratories to reduce the influence of cosmic radiation. However, if careful precautions are not taken, the presence of radioactive radon gas may severely disturb the analytical results. Measurements of the influence of radon on a proportional counter system, show that a radon level of 100 Bq m−3, a level not uncommon in basement rooms, is sufficient to produce an unacceptable uncertainty in the 14C results. Radon levels of up to 1500 Bq m−3 can be demonstrably reduced to about 30 Bq m−3, using a separate ventilation system that generates a slight overpressure in the laboratory.
The First Paper About Exciting of Fluorescence of Liquid Biphenyl and Phenanthren by Fast Electrons by Lieselott Herforth and Hartmut Kallmann
Authors: Niese S
Published: July 2016

The first measurements of the fluorescence of liquid organic compounds after excitation with nuclear radiation were published 1948 in a thesis of L Herforth and a paper by Herforth and Kallmann (1949).
Marine Carbon Reservoir Age Estimates for the Far South Coast of Peru
Authors: Owen Bruce D
Published: July 2016

In order to estimate the apparent age of seawater (R) and the corresponding local offset from the global marine radiocarbon calibration curve (δR) on the far south coast of Peru for 2 periods in the past, 6 pairs of associated marine shell and unburned wood samples from archaeological excavations at Loreto Viejo were 14C dated. Three pairs from about cal AD 1280–1380 indicated larger and more variable δR estimates than have been obtained for other periods in nearby regions, suggesting that δR may vary considerably over space and/or time. Three pairs from about 1870–1680 cal BC yielded consistent shell dates, but only one reasonable terrestrial date and δR estimate, probably due to stratigraphic mixing in antiquity. The one early δR estimate falls slightly outside the range of the later ones, suggesting either still greater spatial variability in δR, or some temporal variability.
No Systematic Early Bias to Mediterranean14C Ages: Radiocarbon Measurements from Tree-Ring and Air Samples Provide Tight Limits to Age Offsets
Authors: Manning Sturt W , Barbetti Mike , Kromer Bernd , Ian Kuniholm Peter , Levin Ingeborg , Newton Maryanne W , Reimer Paula J
Published: July 2016

Existing data and theory do not support a recent assertion that upwelling of old carbon has led to systematically 100–300 yr too old radiocarbon ages for the Mediterranean region. Similarly, the prehistoric tree-ring record produced over 3 decades by the Aegean Dendrochronology Project is shown to provide robust, well-replicated data, contrary to a recent unfounded assertion.14C and dendrochronology provide an accurate and precise chronometric framework for the Mediterranean region.
Radiocarbon Dates from Halfiah Gibli (Abadiyeh), a Predynastic Settlement in Upper Egypt
Authors: Bard Kathryn A
Published: July 2016

In 1989 and 1991, wood charcoal samples were excavated at a Predynastic settlement in Upper Egypt, Halfiah Gibli (HG). A second site, Semaineh (SH), was also investigated, but as the ceramics there were mostly from the Old Kingdom, excavations were concentrated at HG. Wood charcoal was obtained in undisturbed contexts, in association with Nagada culture potsherds and lithics, ranging in date from about 3700 BC to 3200/3100 BC. These new radiocarbon dates provide more data for the relative phases of the Nagada culture, formulated mainly from ceramic seriation.
Is there a Fifth International Radiocarbon Intercomparison (VIRI)?
Authors: Scott E M , Bryant C , Cook G T , Naysmith P
Published: July 2016

The issue of comparability of measurements (and thus bias, accuracy, and precision of measurement) from diverse laboratories is one which has been the focus of some attention both within the radiocarbon community and the wider user communities. As a result, the 14C community has undertaken a widescale, far-reaching, and evolving program of intercomparisons, to the benefit of laboratories and users alike. The benefit to the users is, however, indirect, since the 14C intercomparisons have not been used to generate “league tables” of performance, but rather to allow individual laboratories to check procedures and modify them as required.

The historical progression of 14C laboratory intercomparisons from the Third (TIRI, completed in 1995, Gulliksen and Scott 1995) and Fourth (FIRI, completed in 2000, Scott 2003; Boaretto et al. 2000; Bryant et al. 2002) suggests that a Fifth (VIRI) should also be expected. We describe the plans for VIRI.
NotCal04—Comparison/Calibration 14C Records 26–50 Cal Kyr BP
Authors: van der Plicht J , Beck J W , Bard E , Baillie M G L , Blackwell P G , Buck C E , Friedrich M , Guilderson T P , Hughen K A , Kromer B , McCormac F G , Bronk Ramsey C , Reimer P J , Reimer R W , Remmele S , Richards D A , Southon J R , Stuiver M , Weyhenmeyer C E
Published: July 2016

The radiocarbon calibration curve IntCal04 extends back to 26 cal kyr B P. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up to several millennia. As a result, no calibration curve for the time range 26–50 cal kyr BP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold.
On the Prospects of AMS 14C with Real-Time Sample Preparation and Separation
Authors: Kjeldsen Henrik , Churchman Jessica , Leach Philip , Bronk Ramsey Christopher
Published: July 2016

The performance of the CO2-accepting SO-110 ion source at Oxford Radiocarbon Accelerator Unit has been investigated in detail. The purpose was to clarify the possibilities of accelerator mass spectrometry (AMS) radiocarbon measurements with real-time separation, e.g. GC AMS or HPLC AMS. The construction of a gas test injector based on the continuous-flow technique made it possible to characterize the response of the ion source to continuous and pulsed input of CO2 gas. The source exhibited remarkably good linearity over a wide range of CO2-pulse sizes and fast rise time, but the peak shape varied and memory effects were significant. Appropriate tuning of the gas source proved to be critical.
Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for 14C Sample Preparation and Charcoal Preservation
Authors: Rebollo N R , Cohen-Ofri I , Popovitz-Biro R , Bar-Yosef O , Meignen L , Goldberg P , Weiner S , Boaretto E
Published: July 2016

Chemical and structural similarities between poorly preserved charcoal and its contaminants, as well as low radiocarbon concentrations in old samples, complicate 14C age determinations. Here, we characterize 4 fossil charcoal samples from the late Middle Paleolithic and early Upper Paleolithic strata of Kebara Cave, Israel, with respect to the structural and chemical changes that occur when they are subjected to the acid-base-acid (ABA) treatment. Differential thermal analysis and TEM show that acid treatment disrupts the structure, whereas alkali treatment results in the reformation of molecular aggregates. The major changes are ascribed to the formation of salt bridges at high pH and the disruption of the graphite-like crystallites at low pH. Weight losses during the treatments are consistently greater for older samples, implying that they are less well preserved. Based on the changes observed in vitro due to pH fluctuations, various methods for removing contamination, as well as a mechanism for preferential preservation of charcoal in nature, are proposed.
ENEA Radiocarbon Measurements III
Authors: Magnani Giuseppe , Bartolomei Paolo , La Torretta Teresa , Claudio Marino Ernesto
Published: July 2016

This paper includes determinations of archaeological samples coming from different sites and performed at the ENEA Radiocarbon Laboratory.
Possible Evidence of Pre-Columbian Transoceanic Voyages Based on Conventional LSC and AMS 14C Dating of Associated Charcoal and a Carbonized Seed of Custard Apple (Annona squamosa L.)
Authors: Kumar Pokharia Anil , Sekar B , Pal Jagannath , Srivastava Alka
Published: July 2016

An attempt was made to trace the antiquity of custard apple in India on the basis of accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) radiocarbon dates. Recently, seed remains of custard apple (Annona squamosa L.) in association with wood charcoals were encountered from the Neolithic archaeological site of Tokwa at the confluence of the Belan and Adwa rivers, Mirzapur District, in the Vidhyan Plateau region of north-central India. The wood charcoal sample was dated at the 14C laboratory of the Birbal Sahni Institute of Palaeobotany (BSIP), Lucknow, by conventional LSC 14C dating. The sample dated to 1740 cal BC (BS-2054). A seed sample of custard apple was dated by AMS at the Institute of Physics 14C laboratory, Bhubaneswar, India (3MV tandem Pelletron accelerator). Interestingly, the AMS date was given as 1520 cal BC (IOPAMS-10), showing a reasonable agreement with the LSC date carried out at BSIP. On botanical grounds, the custard apple is native to South America and the West Indies and was supposed to have been introduced in India by the Portuguese in the 16th century. The present 14C dates of the samples pushes back the antiquity of custard apple on Indian soil to the 2nd millennium BC, favoring a group of specialists proposing diverse arguments for Asian-American transoceanic contacts before the discovery of America by Columbus in AD 1492.
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0–50,000 Years cal BP
Authors: Reimer P J , Baillie M G L , Bard E , Bayliss A , Beck J W , Blackwell P G , Bronk Ramsey C , Buck C E , Burr G S , Edwards R L , Friedrich M , Grootes P M , Guilderson T P , Hajdas I , Heaton T J , Hogg A G , Hughen K A , Kaiser K F , Kromer B , McCormac F G , Manning S W , Reimer R W , Richards D A , Southon J R , Talamo S , Turney C S M , van der Plicht J , Weyhenmeyer C E
Published: July 2016

The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org.
Monitoring the Presence of Humic Substances in Wool and Silk by the Use of Nondestructive Fluorescence Spectroscopy: Quality Control for14C Dating of Wool and Silk
Authors: Boudin Mathieu , Boeckx Pascal , Vandenabeele Peter , Mitschke Sylvia , VAN Strydonck Mark
Published: July 2016

Radiocarbon dating of degraded wool and silk provides14C results of questionable reliability. In most cases, degraded wool/silk contains humic substances (HSs). Thus, a nondestructive fluorescence spectroscopy method, using a fiberoptic probe, was developed to monitor the presence of HSs in degraded wool and silk. This method can provide information about the presence of HSs before and after pretreatment and about the14C age reliability. This study suggests considering with care wool/silk samples14C dating wherein HSs are detected, because the conventional solvent pretreatment method using a NaOH wash is in most cases not sufficient to remove all humic substance contaminants. As a result, unreliable14C dates can be provided.
Radiocarbon Dates from the Catacombs of St. Callixtus in Rome
Authors: Rutgers Leonard V , van der Borg Klaas , de Jong Arie F M
Published: July 2016

This paper reports the first chronological assessment of the Christian catacombs of Rome by radiocarbon dating. The organic materials dated were found in a set of burial rooms in the so-called Liberian region of the catacombs of St. Callixtus on the Appian Way. 14C dating of small samples by accelerator mass spectrometry (AMS) represents a major advance over traditional archaeological dating methods used in catacomb archaeology; however, AMS 14C dating raises questions about sample reliability and chronological evaluation. We briefly explore these questions.
Radiocarbon Dates from Neolithic and Bronze Age Hunter-Gatherer Cemeteries in the Cis-Baikal Region of Siberia
Authors: Weber Andrzej W , Beukens Roelf P , Bazaliiskii Vladimir I , Goriunova Olga I , Savel'ev Nikolai A
Published: July 2016

Extensive radiocarbon dating of human remains from Neolithic and Bronze Age hunter-gatherer cemeteries in the Cis-Baikal region of Siberia has been undertaken as a part of the multidisciplinary examination of this material conducted by the Baikal Archaeology Project (BAP; http://baikal.arts.ualberta.ca). Due to the large number of analyzed samples, this paper reports the14C results only in the context of the basic archaeological information about each of the cemeteries. Comprehensive evaluation, analysis, and interpretation of this entire data set will be undertaken in separate publications. In fact, the dates for one such cemetery have already been examined on 2 recent occasions (Weber et al. 2004, 2005).
Variability of Monthly Radiocarbon During the 1760S in Corals from the Galapagos Islands
Authors: Druffel Ellen R M , Griffin Sheila , Hwang Jeomshik , Komada Tomoko , Beaupre Steven R , Druffel-Rodriguez Kevin C , Santos Guaciara M , Southon John
Published: July 2016

Radiocarbon (Δ14C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average Δ14C value of −62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High Δ14C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low Δ14C values were obtained mid-year during strong upwelling. The average seasonal variability of Δ14C was 15–25, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high Δ14C values were found during 1762–1763 and 1766. A spectral analysis revealed that the spectral density for the Δ14C data displays most of its variance at the 5-yr cycle, which is reflective of El Niño periodicity during the 20th century.
Radiocarbon in Porewater of Continental Shelf Sediments (Southeast Mediterranean)
Authors: Sivan O , Lazar B , Boaretto E , Yechieli Y , Herut B
Published: July 2016

In this study, we aim to characterize the main processes controlling 14CDIC concentrations in porewater at the shallow shelf (water depth less than 120 m) off the Mediterranean coast of Israel. At these water depths, we expected to find evidence for seawater penetration toward the coast, since this area was flooded by seawater only some 18,000 yr ago (the end of the Last Glacial period).

Measurements of the chemical composition (14CDIC) and stable carbon isotopic composition (δ13CDIC) were performed in several sediment cores (40–250 cm long) at water depths between 6 and 115 m. At water depths of 60 m, represented by a 2.5-m-long sediment core, the porewater 14CDIC levels (85–87 pMC) were lower than the corresponding sediment values in each layer (92–95 pMC), mainly due to the oxidation of relatively old organic matter (about 70 pMC) with no evidence to advection. In contrast, sediment cores from water depths shallower than 50 m showed only slight anaerobic oxidation and high 14CDIC values of approximately 100 pMC, indicating possible downward advection. These geochemical observations support the perception that the penetration of seawater into the coastal aquifer occurs at the shallow water zone (<50 m), while further verification by deeper cores is required.
Marine Reservoir Correction in the South of Vietnam Estimated from An Annually-Banded Coral
Authors: Dang Phong X , Mitsuguchi Takehiro , Kitagawa Hiroyuki , Shibata Yasuyuki , Kobayashi Toshiyuki
Published: July 2016

We measured radiocarbon in an annually-banded coral core collected from Con Dao Island, Vietnam, 90 km from the mouth of the Mekong River, and estimated the regional correction of the marine reservoir age (ΔR value). Twelve samples were continuously taken from the annual bands (AD 1949–1960) which were clearly identified under UV light (∼352 nm) as well as by X-radiography. The 14C content of the samples was determined using an accelerator mass spectrometer at the National Institute for Environmental Studies, Tsukuba, Japan. Results provide a Δ14C time series showing a relatively steady value of −48.6 ± 4.6‰ for the period of 1949–1955 and an abrupt increase starting from 1956 that indicates a quick response to the atmospheric testing of nuclear bombs. Using the prebomb 14C data, the ΔR value in the south of Vietnam is estimated to be −74 ± 39 yr.
Radiocarbon/Tree-Ring Calibration, Solar Activity, and Upwelling of Ocean Water
Authors: Knox F B , McFadgen B G
Published: July 2016

Least-squares fitted smooth curves to radiocarbon versus tree-ring calibration data for the period AD 1140 to 1950 are compared with climatic warming and cooling of the North Atlantic (Little Ice Age), and with recorded sunspot numbers over the period AD 1670 to 1950.

Calibration curves from different parts of the globe are not identical, and appear to be determined by a combination of variable solar activity and variable oceanic upwelling of 14C-depleted water, with the variable upwelling itself partly determined by solar activity.
Geological Survey of Canada Radiocarbon Dates IX
Authors: Lowdon J. A. , Blake W.
Published: July 2016

Both the 2-L counter, described in GSC I (Radiocarbon, 1962, v. 4, p. 13–26), and the 5-L counter (GSC IV, Radiocarbon, 1965, v. 7, p. 24–46) were operated routinely during the past year. Approximately half the determinations reported were obtained from each counter. The 2-L counter was operated at 2 atm except for August and September, 1968, when it was operated for the first time at 1 atm. This allowed for the counting of most small samples without the necessity of mixing with dead gas. The 5-L counter was operated at 1 atm, except for the same period when it was operated at 4 atm. Carbon dioxide is used as the counting gas, and both counters are of the proportional type.
National Physical Laboratory Radiocarbon Measurements VII
Authors: Callow W. J. , Hassall Geraldine I.
Published: July 2016

The following list comprises measurements made since those reported in Radiocarbon, 1969, v. 11, p. 130–136. No changes have been made in measurement technique or in the method of calculating the results described in Radiocarbon, 1965, v. 7, p. 156–161. It was necessary during 1968 to replace all the geiger counters used in the anti-coincidence rings, but the long term stability of background and standard count rates implicit in the use of a 20-week rolling mean has been maintained.
Radiocarbon Dating at the University of Washington I
Authors: Dorn T. F. , Fairhall A. W. , Schell W. R. , Takashima Y.
Published: July 2016

Beginning in 1955 a C14dating apparatus was constructed at this University for the purpose of measuring the specific activity of tree rings selected from a specimen of Sequoia wood having 3000 growth rings (Dorn, 1958). The original purpose was to obtain a measure of the half life of C14by essentially the inverse of C14dating. For various reasons the project was not completed, and for about a year the apparatus stood idle for lack of financial support. This latter deficiency has now been rectified, at least temporarily, and research with the apparatus has been resumed. Fabrication of a second, 1 L counter is nearing completion.
Miami Natural Radiocarbon Measurements II
Authors: Rusnak Gene A. , Bowman Albert L. , Östlund H. Göte
Published: July 2016

The C14 dates given below are a continuation of the work presented in our first list (Miami I) using the same apparatus and techniques described previously. In addition to the dating of marine carbonate materials, however, we have extended our methods to the dating of wood and peat samples. All dated peat and wood samples have been given a standard pretreatment by successive washings with dilute HCl and 2% NaOH solution for removal of carbonates and humic acids (Olson and Broecker, 1958). Where sufficient alkali-soluble “humic acid” was recoverable for analysis, this fraction was dated separately and is included with the date obtained from either the wood or peat.
Isotopes, Inc. Radiocarbon Measurements III
Authors: Trautman Milton A.
Published: July 2016

The following list presents dates obtained on a fraction of the total number of measurements made during the years 1961 and 1962 and measurements made previously for which sample data has been recently received. The results which do not appear are withheld pending additional information, or at the request of our clients.
Radiocarbon Dating at the University of Washington. II
Authors: Fairhall A. W. , Schell W. R.
Published: July 2016

The radiocarbon dating equipment previously used (Dorn, Fairhall, Schell and Takashima, 1962) has been moved to a different location. During the resulting hiatus in our dating program we have constructed a new counter with a few novel features. It is similar in concept to the Houtermans-Oeschger counter (Houtermans and Oeschger, 1958), but two changes have been made in the design: (1) The inner counter, constructed of thin, metallized plastic foil of thickness 4.2 mg/cm2, is leak-tight relative to the outer counter. By means of two solenoid valves actuated by a simple differential mercury manometer the outer and inner counters can be filled separately with a pressure differential on the partition of less than 0.5 cm Hg. Thus all of the sample can be introduced into the inner counter while inert gas is fed into the outer counter. As the sample gas is not needed for anti-coincidence filling efficiency increases ca. 30%; (2) The metallic parts are made of commercially available high-purity nickel which is easier to procure than O.F.H.C. copper; nylon is used for the other parts. The outer counter appears to have a very low radioactivity, its α activity being 5 pulses/hr/100 cm2.