bluuebunny/crossref_metadata_2025 huggingface dataset:
Charles University, Prague Radiocarbon Measurements I
Authors: Šilar Jan , Tykva Richard
Published: July 2016

We converted to CO2samples of organic materials, Quaternary carbonate rocks and carbonates extracted from groundwater. We measured14C radioactivity in a proportional counter with an effective volume of 723ml filled to 0.28MPa. A mechanical box with an inside cylinder of a plastic scintillator, 4cm thick, arranged in anticoincidence provides the shielding. We present a review of radiocarbon ages of Quaternary and archaeological samples.
Udine Radiocarbon Laboratory Date List III
Authors: Calligaris Franco , Colonnello Stefano , del Fabbro Adriano , Perrone Serena
Published: July 2016

This list includes some significant measurements carried out by CRAD Radiocarbon Laboratory from 1979 to 1985. The dates were obtained by liquid scintillation counting of benzene using the laboratory procedures described in previous lists (Barbina et al 1982: 214-216; Barbina, Calligaris & Ciuti 1979). Samples were pretreated according to generally applied methods, depending on type of material and particular archaeologic and geologic features.
The Sun as a Low-Frequency Harmonic Oscillator
Authors: Damon P. E. , Jirikowic J. L.
Published: July 2016

Solar activity, as expressed by interplanetary solar wind magnetic field fluctuations, modulates the atmospheric production of 14C. Variations of atmospheric 14C can be precisely established from the cellulose within annual tree rings, an independently dated conservative archive of atmospheric carbon isotopes. Δ14C time series interpretation shows that solar activity has varied with a recurrence period of 2115 ± 15 (95% confidence) yr (Hallstattzeit) (Damon & Sonett 1991) over the past 7160 yr. From a non-stationary oscillation solar activity hypothesis, 52 possible spectral harmonics may result from this period. Damon and Sonett (1991) identify powerful harmonics such as the 211.5-yr (Suess) and the 88.1-yr (Gleissberg) cycles as independent fundamental periods. These stronger harmonics appear to modulate the 11-yr (Schwabe) sunspot cycle. Variations in the solar magnetic field, thus, may respond to longer period variations of the solar diameter envelope (Ribes et al. 1989). Such variations would affect solar radiative energy output and, consequently, change total solar irradiance (Sofia 1984).
Anomalous 11-Year Δ14C Cycle at High Latitudes?
Authors: Damon P. E. , Burr George , Cain W. J. , Donahue D. J.
Published: July 2016

We find no evidence for an anomalously intense 11-yr cycle in Δ14C at high latitudes during the period, AD 1870–1885, as reported by Fan et al. (1983, 1986). However, there does appear to be a regional effect within the MacKenzie River region (67°N, 130°W), with atmospheric 14C depressed by relative to the Olympic Peninsula. Such an effect would require only 5% of CO2 in the air mass to have been derived from 5% 14C-depleted soil gas CO2. This small but apparently significant regional effect could be caused by accumulation of CO2 within the frozen earth followed by outgassing during the spring thaw. The short growing season would enhance the effect by allowing insufficient time for global atmospheric equilibration.
A Note on Single-Year Calibration of the Radiocarbon Time Scale, AD 1510–1954
Authors: Stuiver Minze
Published: July 2016

Most data in this Calibration Issue are based on radiocarbon age determinations of tree-ring samples with dendrochronologically determined calibrated (cal) ages. For high-precision measurements, substantial sample amounts are needed, and the processed wood usually spans 10 or 20 tree rings. Thus, the calibration curve data points usually have decadal, or bidecadal, spacing. These curves, to be used for the calibration of samples formed over 1 or 2 decades, may not be fully applicable to samples (leaves, twigs, etc.) formed in a single growing season.
High-Precision 14C Measurement of Irish Oaks to Show the Natural 14C Variations from AD 1840–5000 BC: A Correction
Authors: Pearson Gordon W. , Qua Florence
Published: July 2016

We present here 14C data representing previously published material (Pearson et al. 1986) with minor corrections. All corrections used for calculations published in Pearson et al. (1986) have been re-evaluated, and only one was found to be significantly different. This correction, namely, ‘the variation of efficiency with time', being additional to all other corrections for changes in efficiency, was more subjective; the others could be checked and accounted for by experimentation.
Statistical Problems in Calibrating Radiocarbon Dates
Authors: Dehling Herold , van der Plicht Johannes
Published: July 2016

The transformation of radiocarbon years to calendar years (cal AD/BC) is not straightforward because of past variations in atmospheric 14C content (de Vries 1958; Suess 1970). A calibration curve, y = f(x), transforms each dendrochronologically dated calendar age (x) to a 14C date (y). By inverting this relationship, one can determine the calibrated calendar age of a given sample. In some time intervals, the calibration curve is problematic in that f(x) is not uniquely invertible (Fig. 1); even an exact measurement of y cannot be converted to a single calendar age (see examples in van der Plicht & Mook (1987)).
Tartu Radiocarbon Dates XIII
Authors: Liiva Arvi , Loze Ilze
Published: July 2016

This date list reports dates of archaeological samples of Mesolithic and Neolithic sites of Estonia, Latvia and Lithuania. We use liquid scintillation counting at the Geochemical and Statistical Laboratory of the Institute of Zoology and Botany, Estonian Academy of Sciences. Our modern standard is benzene enriched in 14C and its activity is checked with an NBS oxalic acid standard sample. Dates are given in conventional 14C years, based on the Libby half-life of 5570 ± 30 yr. AD 1950 is the reference year. Errors are based on one standard deviation calculated from count rates.
Radiocarbon Dating the Holocene in the Gościąż Lake Floating Varve Chronology
Authors: Hajdas Irena , Bonani Georges , Goślar Tomasz
Published: July 2016

Terrestrial macrofossils selected from laminated sediment of Lake Gościąż were dated by AMS. Thus, part of the floating varve chronology (FVC) (Goslar et al. 1993) between radiocarbon ages of 4225 ± 45 and 7740 ± 85 bp can be compared and placed on the 14C calibration curve. As a result of our dating, the top of the FVC is now dated between 3120 and 3300 cal bp, i.e., 3210 ± 90 cal bp.
Requirements for An International Radiocarbon Soils Database
Authors: Becker-Heidmann Peter
Published: July 2016

Up to now, Global Carbon Cycle Models (GCCM) have only represented the soil and biosphere in a very simplified way. For example, the High Resolution Biosphere Model (HRBM) (Esser 1987; Esser and Lautenschlager 1994) distinguishes five subreservoirs and determines the fluxes between them for selected area of a global grid. The models have not yet been sufficiently tested against global observations. Such testing is difficult because the observed variables are in turn dependent on the behavior of other geological carbon pools, e.g., the atmosphere and ocean.
Using Bulk Soil Radiocarbon Measurements to Estimate Soil Organic Matter Turnover Times: Implications for Atmospheric CO2 Levels
Authors: Harrison Kevin G.
Published: July 2016

Although soil contains about three times the amount of carbon present in the preindustrial atmosphere, determining how perturbations (e.g., changing land use, CO2 fertilization, changing climate and anthropogenic nitrogen deposition) alter soil carbon storage and influence atmospheric CO2 levels has proved elusive. Not knowing the soil carbon turnover times causes part of this uncertainty. I outline a strategy for using radiocarbon measurements to estimate soil organic matter turnover times and inventories in native soil. The resulting estimates of carbon exchange produce reasonable agreement with measurements of CO2 fluxes from soil. Furthermore, derivatives of the model are used to explore soil carbon dynamics of cultivated and recovering soil. Because the models can reproduce observed soil 14C measurements in native, cultivated, and recovering ecosystems (i.e., the underlying assumptions appear reasonable), the native model was modified to estimate the potential rate of additional carbon storage because of CO2 fertilization. This process may account for 45–65% of the “missing CO2 sink.”
AMS and Microprobe Analysis of Combusted Particles in Ice and Snow
Authors: Biegalski S. R. , Currie L. A. , Fletcher R. A. , Klouda G. A. , Weissenbök Rolland
Published: July 2016

Ice cores and snow pits of the cryosphere contain particles that detail the history of past atmospheric air compositions. Some of these particles result from combustion processes and have undergone long-range transport to arrive in the Arctic. Recent research has focused on the separation of particulate matter from ice and snow, as well as the subsequent analysis of the separated particles for 14C with accelerator mass spectrometry (AMS) and for individual particle compositions with laser microprobe mass analysis (LAMMA). The very low particulate concentrations in Arctic samples make these measurements a challenge. The first task is to separate the particles from the ice core. Two major options exist to accomplish this separation. One option is to melt the ice and then filter the meltwater. A second option is to sublimate the ice core directly, depositing the particles onto a surface. This work demonstrates that greater control is obtained through sublimation. A suite of analytical methods has been used for the measurement of the carbon in snow and ice. Total carbon was analyzed with a carbon/nitrogen/hydrogen (CHN) analyzer. AMS was used for the determination of carbon isotopes. Since source identification of the carbonaceous particles is of primary importance here, the use of LAMMA was incorporated to link individual particle molecular-structural patterns to the same group of particles that were measured by the other techniques. Prior to this study, neither AMS nor LAMMA had been applied to particles contained in snow. This paper discusses the development and limitations of the methodology required to make these measurements.
14C Dating of Bone Using γ-Carboxyglutamic Acid and α-Carboxyglycine (Aminomalonate)
Authors: Burky Richard R. , Kirner Donna L. , Taylor R. E. , Hare P. E. , Southon John R.
Published: July 2016

Radiocarbon determinations have been obtained on γ-carboxyglutamic acid [Gla] and α-carboxyglycine (aminomalonate) [Am] as well as acid- and base-hydrolyzed total amino acids isolated from a series of fossil bones. As far as we are aware, Am has not been reported previously in fossil bone and neither Gla nor Am14C values have been measured previously. Interest in Gla, an amino acid found in the non-collagen proteins osteocalcin and matrix Gla-protein (MGP), proceeds from the suggestion that it may be preferentially retained and more resistant to diagenetic contamination affecting14C values in bones exhibiting low and trace amounts of collagen. Our data do not support these suggestions. The suite of bones examined showed a general tendency for total amino acid and Gla concentrations to decrease in concert. Even for bones retaining significant amounts of collagen, Gla (and Am extracts) can yield14C values discordant with their expected age and with14C values obtained on total amino-acid fractions isolated from the same bone sample.
Attempt to Affect the Apparent 14C Age of Cotton by Scorching in a CO2 Environment
Authors: Long Austin
Published: July 2016

One explanation for the radiocarbon dates on the Shroud of Turin being younger than the time of Christ is that the heat from a fire, which scorched a portion of the Shroud, may have affected the 14C content (dates) on the shroud by affecting molecular exchange between the fabric and atmospheric carbon. This report describes a laboratory test on the susceptibility of cellulose, in the form of cotton, to incorporate carbon from CO2 while it is heated in a closed tube with carbon dioxide until the cotton considerably darkened. To maximize the effect of this hypothetical process, we simulated the shroud material with cotton that had a 14C level of 0.55 modern (55 pMC, equivalent to 4800 yr), and the atmosphere with pure CO2, which had a 14C level of 1.3 modern (130 pMC). No measurable 14C transferred from the gas phase to the solid phase. The implication of this test is that scorching is an unlikely mechanism to affect the apparent age of cellulose-like material.
The Carbonate 14C Background and its Components at the Leibniz AMS Facility
Authors: Schleicher Markus , Grootes Pieter M. , Nadeau Marie-Josée , Schoon Axel
Published: July 2016

After routine accelerator mass spectrometry (AMS) radiocarbon dating had been established at the Leibniz-Labor with the completion of systems for CO2 production, graphitization, and target making, a systematic investigation was conducted to find the sources of 14C concentrations observed in background materials. We quantified the contributions of the AMS-system, the reduction, CO2 production from carbonate, carbonate contamination, and combustion. Carbonate contamination appears to be the dominating factor. Improvements in the pretreatment of foraminifer carbonate have led to the elimination of most of this contamination.
Interlaboratory Comparisons: Lessons Learned
Authors: Scott E. M. , Harkness D. D. , Cook G. T.
Published: July 2016

Interlaboratory comparisons have been widely used in analytical chemistry and radiochemistry as an important part of ongoing quality assurance programs. The 14C community has been no exception in this respect, and in just under 20 years, there have been a number of significant and very extensive interlaboratory trials organized by individual laboratories and the International Atomic Energy Agency (IAEA) to the benefit of the 14C community (both labs and users) (Otlet et al. 1980; ISG 1982; Scott et al. 1990; Rozanski et al. 1992; Scott et al. 1992; Gulliksen and Scott 1995). The comparisons have varied widely in terms of sample type and preparation, but all have had as their primary goal the investigation of the comparability of results produced under possibly quite different laboratory protocols. As techniques have been developed and new labs formed, the reference materials created as a result of the intercomparisons have presented an opportunity for checking procedures and results. Users have been reassured by the existence of regular comparisons as one sign of the concern that laboratories have to ensure highest quality results, but also confused about how to make use of the results from past exercises in the interpretation of sets of dates from many laboratories. The laboratories have also learned valuable lessons from participation in such studies. These have included identification of systematic offsets and additional sources of variation and in studies which have used realistic samples requiring pretreatment, chemical synthesis and counting, it has been possible to identify the stage at which such problems have arisen and to quantify the relative contributions to the overall variation. In this paper, we will briefly review the comparisons so far, draw some conclusions from their findings, and make proposals for the future organization of intercomparisons.
Secular Variation of Δ14C During the Medieval Solar Maximum: A Progress Report
Authors: Damon P. E. , Eastoe C. J. , Hughes M. K. , Kalin R. M. , Long A. , Peristykh A. N.
Published: July 2016

The Earth is within the Contemporaneous Solar Maximum (CSM), analogous to the Medieval Solar Maximum (MSM). If this analogy is valid, solar activity will continue to increase well into the 21st century. We have completed 75 single-ring and 10 double-ring measurements from ad 1065 to ad 1150 to obtain information about solar activity during this postulated analog to solar activity during the MSM. δ14C decreases steadily during the period ad 1065 to ad 1150 but with cyclical oscillations around the decreasing trend. These oscillations can be successfully modeled by four cycles. These four frequencies are 1/52 yr-1, 1/22 yr-1, 1/11 yr-1, and 1/5.5 yr, i.e., the 4th harmonic of the Suess cycle, the Hale and Schwabe cycles and the 2nd harmonic of the Schwabe cycle.
14C Measurements at PWR-Type Nuclear Power Plants in Three Middle European Countries
Authors: Uchrin György , Hertelendi Ede , Volent Gábor , Slavik Ondrej , Morávek Jozef , Kobal Ivan , Vokal Barbara
Published: July 2016

Regular 14C sampling of discharged air began in 1988 at Paks Nuclear Power Plant (NPP), Hungary, and in 1991 at NPPs in Krsko, Slovenia and Bohunice, Slovakia. Monitoring of 14C discharges is carried out at all NPPs with similar differential samplers continuously collecting 14C in the form of 14CO2 and 14CnHm. The main results of airborne discharge monitoring are as follows: 14C activity concentration varied roughly within a factor of two around their mean values, 125 Bq m-3 and 90 Bq m-3 for Paks and for Krsko NPP, respectively. The pattern of discharge for Bohunice NPP is slightly different from that at the other two stations. At Bohunice, there has been a continuous increase in the discharge rate at power unit V1, starting with 70 Bq m-3 in 1991 and reaching a value of 190 Bq m-3 in 1995. The values for power unit V2 are 50 Bq m-3 and 82 Bq m-3. The average normalized yearly discharge rates are 0.887 (TBqGWe-1yr-1) for Paks, 0.815 (V1) and 0.500 (V2) for Bohunice, and 0.219 for Krsko. Most of the discharged 14C is in hydrocarbon form, 95% for Paks and Bohunice V2, but the CO2 fraction may reach 25% or 43% at Bohunice V1 and Krsko, respectively. At Bohunice V1, not only the discharge rate increased but the 14CO2 ratio to the total changed from 30% to 13%. The local radiological impact is estimated to be 1.5 μSv a-1 for Paks, 1.7 μSv a-1 for Bohunice, and 0.12 μSv a-1 for Krsko. The 14C excess in the environment has been measured at Paks NPP since 1989. Based on the monitoring data, the long-term average 14C excess from the Paks NPP was D14C=50% for hydrocarbons. Tree-ring analysis has shown a slight excess around Krsko NPP: D14C is equal to 199.9% for a tree at 1 km from the NPP compared with a “reference” one for which D14C was equal to 111.6% (in 1994).
The Behavior of Sellafield-Derived 14C in the Northeast Irish Sea
Authors: Wolstenholme Anne , Cook G. T. , MacKenzie A. B. , Naysmith Philip , Meadows P. S. , McDonald Paul
Published: July 2016

Radiocarbon is an important constituent of the low level, liquid, radioactive effluent discharged from the Sellafield nuclear fuel reprocessing plant in northwest England, but despite the fact that it gives the highest collective dose commitment of all the nuclides in the waste, its behavior in the Irish Sea is poorly defined. There is therefore a clear requirement for an improved understanding of 14C behavior in the Irish Sea, to assist with dose evaluation modeling and definition of the mixing and accumulation characteristics of the sediment in this area. In this context, results are presented here for a temporal study of 14C activities in four geochemical fractions of seawater and in a sediment core from the vicinity of the Sellafield effluent outfall. Clear 14C enrichments in the dissolved inorganic carbon (DIC) and particulate organic carbon (POC) components of seawater were observed, with temporal trends in activity that were related to variations in the Sellafield discharge. Smaller, but nevertheless detectable, enrichments were also observed for particulate inorganic carbon (PIC) and dissolved organic carbon (DOC) in the seawater. The distribution of 137Cs and 241Am revealed that the sediment core could be classified into three zones in which the intensity of mixing decreased discontinuously with depth. Bulk carbonate 14C analyses of the core demonstrated the presence of glacial or pre-glacial carbonate in the system, but failed to show any evidence of contaminant 14C input or provide information on sediment accumulation processes. In contrast, analysis of bulk organic matter from the sediment provided clear evidence of the recent perturbation of a well mixed system by input of younger material, consistent with the recent input of contaminant 14C from Sellafield and possibly weapons testing fallout.
Calibration of the 14C Time Scale Beyond 22,000 BP
Authors: Geyh Mebus A. , Schlüchter Christian
Published: July 2016

The conventional 14C time scale between 11,500 and 22,000 sidereal years has been calibrated by TIMS U/Th dates for corals. Only a few studies have been made for the time beyond this range. Obtaining samples suitable for numerical dating or estimating the reservoir correction of the 14C dates has been difficult, but we do not have these problems with TIMS U/Th dating of interstadial and interglacial lignite, because reservoir corrections are unnecessary.
A Tree-Ring and 14C Chronology of the Key Sayan-Altai Monuments
Authors: Zaitseva G. I. , Vasiliev S. S. , Marsadolov L. S. , Van Der Plicht J. , Sementsov A. A. , Dergachev V. A. , Lebedeva L. M.
Published: July 2016

We present a radiocarbon chronology of key Sayan-Altai monuments from the Scythian period, based on a statistical analysis of dates produced in the 1980s and now supplemented with new dates. These new 14C dates were produced for samples from the Tuekta-1 barrows (burial mounds) and were measured both in St. Petersburg and Groningen. These tree-ring samples were fitted to the calibration curve. Chronologies were established for the Arzhan, Tuekta-1 and Pazyryk-5 barrows. The time of the construction of the Arzhan and Pazyryk-5 barrows is the 9th and late 5th–4th centuries bc, respectively, and agrees with archaeology. According to new data obtained, the time of the Tuekta-1 barrow construction is some years older than has been accepted thus far by archaeologists.
The Early History of Moscow: 14C Dates from Red Square
Authors: Alexandrovskiy Alexander L. , Van Der Plicht Johannes , Krenke Nikolay , Chichagova Olga , Kovaliukh Nikolai , Sulerzhitsky Leopold D.
Published: July 2016

For the first time, a series of 14C dates has been obtained for samples from the archaeological excavations in Red Square, the historical center of Moscow. The remains of burned dwellings from the bottom of the cultural layer were dated as well as dispersed charcoal from the underlying plough soil. The results correspond to a 200-yr time interval and prove that arable activity at the site began as early as the late 11th century ad. The field belonged to Moscow itself or to rural settlements nearby. The oldest dwelling was built ca. the late 12th–early 13th century ad.
Problems with Radiometric “Time”: Dating the Initial Human Colonization of Sahul
Authors: Webb R. Esmée
Published: July 2016

Until recently, the only chronometric technique applied to Sahulian archaeological sites was14C dating; the ages obtained rarely exceeded 40,000 bp. Belief that the region was first colonized around that time has recently been shaken by luminescence dates from several archaeological sites in northern Australia that suggest people arrived between 60,000 and 55,000 bp. The ensuing debate over their validity revealed that some participants misunderstood luminescence dating and the temporal limitations of14C dating, illustrated here through a discussion of thetempoandmodeof Sahulian colonization. Radiometric techniques cannot distinguish between the models proposed because they are unable to resolve temporal issues that occur within their limits of error.
Minimal Extension Phases of Unteraarglacier (Swiss Alps) During the Holocene Based on 14C Analysis of Wood
Authors: Hormes Anne , Schlüchter Christian , Stocker Thomas F.
Published: July 2016

Tree trunks and wood fragments in minerotrophic fen peat that accumulated as the result of a jökulhlaup in the outwash plain of Unteraarglacier were radiocarbon-dated using conventional ß-counting. Different pretreatment methods were tested on two wood samples to determine the reliability of our dates. We dated the wood compounds after extended acid-alkali-acid treatment, as well as extraction of cellulose and lignin. The results of the samples Picea (B-6687) and Pinus cent-bra (B-6699) show insignificant differences of < 1σ.

The 14C dates represent retreat of Unteraarglacier due to warmer and/or drier phases in the Holocene compared to modern climate conditions. The glacier was at least several hundred meters smaller in extent than today ca. 8100–7670 bp, 6175–5780 bp, 4580–4300 bp, 4100–3600 bp and 3380–3200 bp. The 14C dates suggest a ca. 2000-yr cyclicity of tree growth in the area covered by the present Unteraarglacier. The most intense warm and dry period occurred between 4100 bp (probably extending back to 4580 bp) and 3600 bp, with growth of fen peat between 3800 and 3600 bp attributed to wetter conditions.
14C Ages of Tephra Layers from the Holocene Deposits of Kunashir Island (Russian Far East)
Authors: Razjigaeva N. G. , Grebennikova T. A. , Ganzey L. A. , Bazarova V. B. , Mokhova L. M. , Korotky A. M. , Sulerzhitsky L. D.
Published: July 2016

Holocene deposits from the central and southern regions of the Kunashir Island contain tephra from 12 volcanic eruptions (Kn1–12). We studied radiocarbon data, mineralogical composition, and distribution of the tephra layers in different Holocene facies. The main sources of the Holocene tephra samples were the volcanoes of Hokkaido Island. The distribution of ash layers on Kunashir Island allows us to estimate their direction. Ash layers can be reliable markers for age determination of different coastal landforms on open oceanic shores. We propose here a tephrastratigraphical scheme for different Middle-Late Holocene facies.
14C and 18O in Siberian Syngenetic Ice-Wedge Complexes
Authors: Vasil'Chuk Yurij K. , Vasil'Chuk Alla C.
Published: July 2016

We discuss the possibility of dating ice wedges by the radiocarbon method. We show as an example the Seyaha, Kular and Zelyony Mys ice wedge complexes, and investigated various organic materials from permafrost sediments. We show that the reliability of dating 18O variations from ice wedges can be evaluated by comparison of different organic materials from host sediments in the ice wedge cross sections.
Isotopic Analysis and Cycling of Dissolved Inorganic Carbon at Lake Biwa, Central Japan
Authors: Nakamura Toshio , Kojima Sadao , Ohta Tomoko , Oda Hirotaka , Ikeda Akiko , Okuno Mitsuru , Yokota Ki-Ichiro , Mizutani Yoshihiko , Kretschmer Wolfgang
Published: July 2016

This paper reports on concentrations and carbon isotopic results of dissolved inorganic carbon (DIC) in water samples collected at four locations and from several depths in Lake Biwa, central Japan, covering every season of the year, starting in the spring of 1995. Depth profiles of DIC concentration and DIC δ13C showed a strong seasonal pattern, as a result of vertical mixing of the lake water in winter and early spring, or lack of mixing in the other seasons. No seasonal change in DIC ∆14C depth profiles was recognizable, mainly owing to the wide scatter of DIC ∆14C. Values typically ranged from 0.47 to 0.65 mmol kg-1 for DIC concentration, and from -4 to -8‰ and from +10 to +80‰ for DIC ∆13C and DIC ∆14C, respectively, for the Lake Biwa water.
INTCAL98 Radiocarbon Age Calibration, 24,000–0 cal BP
Authors: Stuiver Minze , Reimer Paula J. , Bard Edouard , Beck J. Warren , Burr G. S. , Hughen Konrad A. , Kromer Bernd , McCormac Gerry , Van Der Plicht Johannes , Spurk Marco
Published: July 2016

The focus of this paper is the conversion of radiocarbon ages to calibrated (cal) ages for the interval 24,000–0 cal BP (Before Present, 0 cal BP = AD 1950), based upon a sample set of dendrochronologically dated tree rings, uranium-thorium dated corals, and varve-counted marine sediment. The 14C age–cal age information, produced by many laboratories, is converted to Δ14C profiles and calibration curves, for the atmosphere as well as the oceans. We discuss offsets in measured l4C ages and the errors therein, regional 14C age differences, tree–coral 14C age comparisons and the time dependence of marine reservoir ages, and evaluate decadal vs. single-year 14C results. Changes in oceanic deepwater circulation, especially for the 16,000–11,000 cal BP interval, are reflected in the Δ14C values of INTCAL98.
Radiocarbon Dates from Northern Mongolia
Authors: Hall Mark , Batsaikhan Zagd , Honeychurch William
Published: July 2016

Since 1996, the Mongolian-American Expedition to Northern Mongolia has been excavating in the Egiin Gol Valley. The goal of this research has been to examine the competing hypotheses explaining the emergence of pastoral nomadism and the evolution of nomadic complexity. The chronological placement of burials and sites in the survey area has been a key facet of this research. At present, these investigations have generated 10 radiocarbon dates from archaeological contexts. Presented here are the previoulsy unpublished 14C dates and some comments on their significance.
Radiocarbon Dating of “Old” Charcoal Using a Wet Oxidation, Stepped-Combustion Procedure
Authors: Bird M I , Ayliffe L K , Fifield L K , Turney C S M , Cresswell R G , Barrows T T , David B
Published: July 2016

We present results that validate a new wet oxidation, stepped-combustion procedure for dating “old” charcoal samples. An acid–base–wet oxidation (ABOX) pretreatment procedure has been developed that is used in place of the conventional acid-base-acid (ABA) pretreatment. Combustions and graphitizations are performed in a vacuum line that is insulated from the atmosphere by a second backing vacuum to eliminate the risk of atmospheric leakage into the line at any stage of the procedure. Combustions are performed at 3 temperatures (330 °, 630 ° and 850 °) with a graphite target produced from the CO2 evolved during each combustion step. In this way, the removal of any contamination can be monitored, and a high degree of confidence can be placed on the final age. The pretreatment, combustion, graphitization, and measurement blank for the procedure, based on the analysis of a “radiocarbon-dead” graphite, is 0.5 ± 0.5 μg C (1σ, n=14), equivalent to 0.04 ± 0.02 pMC or an “age” of approximately 60 ka for a 1 mg graphite target. Analyses of a “radiocarbon-dead” natural charcoal after ABOX pretreatment and stepped combustion suggest that the total blank (including contamination not removed by pretreatment) may be higher than for graphite, ranging up to 0.10 ± 0.02 pMC. Additional experiments confirm good agreement with accepted values for the international low-14C “New Kauri” standard (0.16–0.25 pMC). They also confirm excellent reproducibility, with 3 separate dates on different aliquots of a charcoal sample from Ngarrabullgan Cave (Queensland, Australia) ranging from 35.2 to 35.5 ka 14C BP. It is also demonstrated that the ABOX pretreatment, in conjunction with the new vacuum line described here, is able to remove contamination not removed by the conventional ABA pretreatment, suggesting that the technique can be used to produce reliable 14C dates on charcoal up to at least 50 ka.
Use of Radiocarbon Dating in Assessing Christian Connections to the Dead Sea Scrolls
Authors: Rodley G A , Thiering B E
Published: July 2016

We present an analysis of radiocarbon dates on Dead Sea Scrolls that have a bearing on the question of the Scroll documents’ relation to Christian origins. We assess details of dating reports, discuss paleographical evidence, and consider the content of the documents. When collated, these findings may be seen as compatible with a view that personalities mentioned in the Scrolls were contemporary with the founders of Christianity.
Determination of 14C in Volcanic Gas By Accelerator Mass Spectrometry
Authors: Yoshikawa Hideki , Nakahara Hiromichi , Imamura Mineo , Kobayashi Kouichi , Nakanishi Takashi
Published: July 2016

Radioactive nuclides such as radiocarbon can be good tracers for investigating the circulation of underground carbon and water. Volcanic gas can be sampled reliably for 14C analysis and prepared for analysis by accelerator mass spectrometry (AMS). In this paper, we establish a method for the measurement of 14C in volcanic gas, and measure the amounts of 14C in various volcanic gases. Samples of fumarolic gas from some Japanese volcanoes were found to contain 0.5 to 4.2 pMC, while those from White Island in New Zealand contained 2.6 pMC. Dissolved gas from Lake Nyos, Cameroon, contained 0.4 to 4.8 pMC. The data indicate a mixing process between surface carbon and deep carbon.
AMS Radiocarbon Dating of the Fengxi Site in Shaanxi, China
Authors: Guo Zhiyu , Liu Kexin , Yuan Sixun , Wu Xiaohong , Li Kun , Lu Xiangyang , Wang Jinxia , Ma Hongji , Gao Shijun , Xu Lianggao
Published: July 2016

The Fengxi site is near the Feng River in Shaanxi Province, China. Feng City was the capital of the vassal state of Zhou, and the Zhou people lived in this area until the end of the Western Zhou. Serial samples of charcoal, bone, and charred millet were collected from the site and dated by accelerator mass spectrometry (AMS). A sequence model with 6 phases of the Western Zhou dynasty was constructed and the 14C ages were calibrated with OxCal v 3.9. The results showed that the site was used from 1170–1070 BC until 825–755 BC, and the Conquest of Shang by King Wu most probably occurred during 1060–1000 BC.
Tartu Radiocarbon Dates II
Authors: Punning J. M. , Ilves E. , Liiva A.
Published: July 2016

The following list includes samples dated between 1956 and 1961. Wood dating from A.D. 1850 ± 10 yr is used as a contemporary reference standard. Background sample is synthesized from anthracite. All radiocarbon dates were calculated with the hall-life of C14 being equal to 5568 ± 30 yr. All dates are calculated from the year 1950.
Tata Institute Radiocarbon Date List V
Authors: Agrawal D. P. , Kusumgar Sheela
Published: July 2016

The C14 dates presented here were obtained by counting methane, using the technique described earlier (Agrawal et al., 1965a). In accordance with the decision of the Sixth Pullman Conference (Internat. Gonf., Pullman, 1965) and the editors’ advice we continue to give dates based on τ 1/2 = 5568 years. For converting dates to A.D./B.C. scale, 1950 has been used as reference year. Ninety-five per cent activity of N.B.S. oxalic acid has been used as modern standard.
The Value of210Pb in Dating Scandinavian Aquatic and Peat Deposits
Authors: El-Daoushy Farid
Published: July 2016

Sediment and peat chronologies have been further improved allowing alternative radiometric methods to complement14C dating. Lacustrine and coastal marine sediments as well as peat deposits in various parts in Scandinavia are studied using137Cs,210Pb,14C and other methods primarily to evaluate the210Pb but also to extend the14C chronology. The sampling sites have various sources of input and are characterized by different geochemical, depositional, and post-depositional conditions.
Sample Credentials Necessary for Meaningful High-Precision 14C Dating
Authors: Jope E M
Published: July 2016

Samples presented for high-precision 14C dating must satisfy stringent requirements if the 14C determinations are to yield meaningful sharp calendric dates, such as are now possible with the bidecadal high-precision calibration curve. The total carbon content should come from a confined time range 10–20 years (10–20 tree rings in wood or charcoal) appropriate for the bidecadal calibration curve. For accurate calendric dating the relation of these rings to the outer growth rings must be known. Application of the high-precision calibration curve to some archaeologic examples is discussed. It is now up to archaeologists and geoscientists to use this refined chronometric instrument to fullest advantage.
University of Lund Radiocarbon Dates XIX
Authors: Håkansson Sören
Published: July 2016

Most of the14C measurements reported here were made between October 1984 and October 1985. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36–37; 1976, v 18, p 290; 1980, v 22, p 1045) except that 23 separate GM-counters used as guard counters were replaced by a single iron multiwire ring-counter filled with 90Ar/10CH4to ca 130kPa (ca 1.3atm). Background counts were reduced by ca 12% due to this change. High voltage supply for main detectors was replaced as well.
British Museum Natural Radiocarbon Measurements I
Authors: Barker H. , Mackey C. J.
Published: July 2016

The first series of radiocarbon dating measurements made at the British Museum Research Laboratory are reported in the following list. The report covers a period during which two instances of radioactive contamination occurred to interrupt dating work, and is consequently a short one.
Carbon-14 Dating in Pisa
Authors: Ferrara G. , Reinharz M. , Tongiorgi E.
Published: July 2016

About three years ago a laboratory was set up in Pisa for the study of geologic and paleontologic problems with the help of modern nuclear techniques. The two main items of the first program were the construction of a mass spectrometer for paleotemperature measurements and of a carbon-14 dating apparatus.
Yale Natural Radiocarbon Measurements IV
Authors: Deevey Edward S. , Gralenski L. J. , Hoffren Väinö
Published: July 2016

Dates obtained since our last date list (Yale III∗), and up to the end of 1958, are given here. All are based on duplicate measurements of CO2 in a proportional counter. Grateful acknowledgment is made to the National Science Foundation, which has supported our work through grant no. G-2278. Participation of Väinö Hoffren during 1956–1957 was made possible through an arrangement with the Geological Survey of Finland. The technical assistance of Julius Kovats has been invaluable.
University of Pennsylvania Radiocarbon Dates IV
Authors: Ralph Elizabeth K. , Ackerman Robert E.
Published: July 2016

With one exception, the radiocarbon dates in this list were reported previously by Rainey and Ralph (1959). For discussions of the reliability of the dates, of the materials dated, and of the correspondence of the dates with estimated arctic chronologies, the reader is urged to refer to the original publication. The radiocarbon determinations were made over a period of several years. Those processed before 1956 were dated by the solid-carbon method and are so labeled; others, by the carbon-dioxide method. The age calculations are based on the average of several samples dated archaeologically and by tree-rings, corrected to zero age (Rainey and Ralph, 1959, p. 365). By this means the errors due to atmospheric depletion (Suess effect) and to past changes in radiocarbon concentration (de Vries, 1958; Willis, Tauber, and Münnich, 1960) have been minimized. The b.p. dates are calculated from A.D. 1957 (solid-carbon) and A.D. 1958 (carbon dioxide).
(Abstract) the CO2–CS2 Geiger Counter and its Use in C14 Dating
Authors: Crane H. R.
Published: July 2016

A complete description of the CO2-CS2 Geiger-counter system which is in operation at the University of Michigan Radiocarbon Dating Laboratory is available in mimeograph form, upon request to the author. It includes a report on research into the characteristics of the CO2-CS2 counter, as well as a full set of instructions and diagrams for the building of such a system for use in radiocarbon dating.
Cambridge University Natural Radiocarbon Measurements III
Authors: Godwin H. , Willis E. H.
Published: July 2016

The dates and activity measurements given below have been obtained during the year 1960 (excepting only Q-9 held over from the previous year). They have been made with carbon dioxide at 3 atmospheres pressure in a proportional gas-counter similar to that used for the results given in Radiocarbon Supplement, volumes 1 and 2.
Further Application of Bomb 14C as a Tracer in the Atmosphere and Ocean
Authors: Nydal Reidar , Gislefoss Jorunn S.
Published: July 2016

Bomb 14C from nuclear tests in the atmosphere has proved to be a particularly useful tool in the study of the carbon cycle. We provide here a ca. 30-yr time series of 14C concentrations in the atmosphere between 28°N and 71°N and in the ocean surface between 45°S and 45°N. More recently (since 1990), a north-south profile also has been obtained for 14C in the surface waters of the Atlantic Ocean. The measurements were performed using the conventional technique of beta counting or large samples (4 to 5 liter CO2) in CO2 proportional counters. These data show that the 14C concentration in the atmosphere is leveling off with a time constant of 0.055 yr-1, and is now approaching that of the ocean surface at lower latitudes.

Additional tracer studies have been concerned especially with the penetration of bomb 14C into the deep ocean. The Norwegian and Greenland seas are of interest as a sink for atmospheric CO2 and also a source of water for the deep Atlantic Ocean. During the last five years, several 14C depth profiles have been measured from the Fram Strait (79°N) to south of Iceland (62°N), using the AMS technique available at the University of Arizona AMS Facility. We considered it important to repeat and compare a few of the profiles with those produced by the GEOSECS expedition in 1972 and the TTO expedition in 1981. The profiles show that water descending to the deep Atlantic Ocean is originating mainly from intermediate and surface depths in the Nordic Seas. However, the ventilation rate of the Norwegian Sea deepwater is too slow to be an important component in the transfer of water over the Greenland-Scotland Ridge.
Post-Bomb Radiocarbon Records of Surface Corals from the Tropical Atlantic Ocean
Authors: Druffel Ellen R. M.
Published: July 2016

Δ14C records are reported for post-bomb corals from three sites in the tropical Atlantic Ocean. In corals from 18°S in the Brazil Current, Δ14C values increased from ca. −58% in the early 1950s to +138% by 1974, then decreased to 110‰ by 1982. Shorter records from 8ºS off Brazil and from the Cape Verde Islands (17°N) showed initially higher Δ14C values before 1965 than those at 18ºS, but showed lower rates of increase of Δ14C during the early 1960s. There is general agreement between the coral results and Δ14C of dissolved inorganic carbon (DIC) measured in seawater previously for locations in the tropical Atlantic Ocean. Δ14C values at our tropical ocean sites increased at a slower rate than those observed previously in the temperate North Atlantic (Florida and Bermuda), owing to the latter's proximity to the bomb 14C input source in the northern, hemisphere. Model results show that from 1960–1980 the Cape Verde coral and selected DIG Δ14C values from the North Equatorial Current agree with that calculated for the North Atlantic based on an isopycnal mixing model with a constant water mass renewal rate between surface and subsurface waters. This is in contrast to Δ14C values in Bermuda corals that showed higher post-bomb values than those predicted using a constant water mass renewal rate, hence indicating that ventilation in the western north Atlantic Ocean had decreased by a factor of 3 during the 1960s and 1970s (Druffel 1989).
The 2000 Radiocarbon Varve/Comparison Issue
Authors: van der Plicht Johannes
Published: July 2016

For radiocarbon calibration, the arrow of time is pointing backwards but the entropy does not necessarily decrease in this direction…
AMS Radiocarbon and Varve Chronology from the Annually Laminated Sediment Record of Lake Meerfelder Maar, Germany
Authors: Brauer Achim , Endres Christoph , Zolitschka Bernd , FW Negendank Jörg
Published: July 2016

The Holocene varve chronology of annually laminated sediment sequences from Lake Meerfelder Maar agree for most of the record with dendro-calibrated accelerator mass spectronomy radiocarbon dates from the same site. Only between 9710 and 9950 cal BP does an offset of 240 yr appear between both data sets. At this position, a micro-disturbance in the varve succession has been detected by thin section analyses and was quantified in terms of missing varves. A comparison with the nearby record from Lake Holzmaar, as well providing high resolution AMS14C and varve chronologies, revealed that such gaps (ca. 2% in time for the entire Holocene) are exceptional for these long-varved maar lake records. Moreover, since sections of missing years appear for both profiles at different stratigraphic positions, a combination of both the Meerfelder Maar and Holzmaar records enables us to bridge erroneous zones in varve chronologies. This confirms the high potential of two long-varved records in close vicinity to each other for the elimination of dating errors and for increasing chronological precision at a time resolution that is normally regarded as within the counting errors. Late Glacial varve and14C data beyond the dendro-calibration from Meerfelder Maar and their tentative tele-connections to other high resolution data sets reveal unexplained age discrepancies in the calendar year time scale of about 200 years.
Atmospheric Radiocarbon Calibration Beyond 11,900 cal BP from Lake Suigetsu Laminated Sediments
Authors: Kitagawa Hiroyuki , van der Plicht Johannes
Published: July 2016

This paper presents an updated atmospheric radiocarbon calibration from annually laminated (varved) sediments from Lake Suigetsu (LS), central Japan. As presented earlier, the LS varved sediments can be used to extend the radiocarbon time scale beyond the tree ring calibration range that reaches 11,900 cal BP. We have increased the density of 14C measurements for terrestrial macrofossils from the same core analyzed previously. The combined data set now consists of 333 measurements, and is compared with other calibration data.
Radiocarbon Calibration Beyond the Dendrochronology Range
Authors: Stein Mordechai , Goldstein Steven L , Schramm Alexandra
Published: July 2016

The radiocarbon timescale has been calibrated by dendrochronology back to 11.8 ka cal BP, and extended to 14.8 ka cal BP using laminated marine sediments from the Cariaco Basin. Extension to nearly 23.5 ka cal BP is based on comparison between 14C and U-Th ages of corals. Recently, attempts to further extend the calibration curve to >40 kyr are based on laminated sediments from Lake Suigetsu, Japan, foraminifera in North Atlantic sediments, South African cave deposits, tufa from Spain, and stalagmites from the Bahamas. Here we compare these records with a new comparison curve obtained by 234U-230Th ages of aragonite deposited at Lake Lisan (the last Glacial Dead Sea). This comparison reveals broad agreement for the time interval of 20–32 ka cal BP, but the data diverge over other intervals. All records agree that Δ14C values range between ∼250–450‰ at 20–32 ka cal BP. For ages >32 ka cal BP, the Lake Suigetsu data indicate low Δ14C values of less than 200‰ and small shifts. The other records broadly agree that Δ14C values range between ∼250 and 600‰ at 32–39 ka cal BP. At ∼42 ka cal BP, the North Atlantic calibration shows low Δ14C values, while the corals, Lisan aragonites, and the Spanish tufa indicate a large deviations of 700–900‰. This age is slightly younger than recent estimates of the timing of the Laschamp Geomagnetic Event, and are consistent with increased 14C production during this event.
Subfossil Tree Deposits in the Middle Durance (Southern Alps, France): Environmental Changes from Allerød to Atlantic
Authors: Miramont C , Sivan O , Rosique T , Edouard JL , Jorda M
Published: July 2016

The purpose of this paper is to analyze the numerous holocene subfossil trees (Pinus silvestris) buried in alluvial deposits in the Southern French Alps. These trees lived between the Allerød and Subboreal periods, according to 14C dates. Our dendochronological studies explain the trees' sudden death as due to morphological crisis brought on by climatic oscillations. Tree-ring series could be used to identify the variability of early Holocene atmospheric 14C levels.