Radiocarbon is the main international journal of record for research articles and date lists relevant to 14C and other radioisotopes and techniques used in archaeological, geophysical, oceanographic, and related dating.

This archive provides access to Radiocarbon Volumes 1-54 (1959-2012).

As of 2016, Radiocarbon is published by Cambridge University Press. The journal is published quarterly. Radiocarbon also publishes conference proceedings and monographs on topics related to fields of interest. Visit Cambridge Online for new Radiocarbon content and to submit manuscripts.

ISSN: 0033-8222


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  • ZAGRADA—The New Zagreb Radiocarbon Database

    Porter, Antun; Obelić, Bogomil; Krajcar Bronić, Ines (Department of Geosciences, The University of Arizona, 2010-01-01)
    After introducing the liquid scintillation counting (LSC) method and graphite target preparation for accelerator mass spectrometry (AMS) measurements in the Zagreb Radiocarbon Laboratory, the existing database software designed only for gas proportional counting (GPC) (using a DOS operating system) could not satisfy the requirements for parallel conduction of several techniques. This has been enabled recently by the development of the new relational database ZAGRADA, which--using SQL scripts and constraints defined by primary and foreign keys--enforces high data integrity and provides better performances in data filtering and sorting. The structural scheme of this database conceptually comprises 4 basic modules with data on the samples, chemical pretreatment and preparation, measurements and data on the final results. A user-friendly graphical user interface has been designed to perform various actions and data manipulation to the database. The implementation of a new database for 14C samples has significant contribution to scientific research performed in the Radiocarbon and Tritium Laboratory and to quality assurance and quality control, and will enable better and easier communication with customers.
  • Variability of Dissolved Inorganic Radiocarbon at a Surface Site in the Northeast Pacific Ocean

    Druffel, Ellen R. M.; Beaupré, Steven; Griffin, Sheila; Hwang, Jeomshik (Department of Geosciences, The University of Arizona, 2010-01-01)
    We report radiocarbon measurements of dissolved inorganic carbon (DIC) in surface water samples collected daily during 12 cruises to Station M in the northeast Pacific off central California. Individual surface ∆14C values ranged from 22 to 70 over 10 yr. Variability of average cruise values is highest during winter likely due to increased mixing. A general decrease of ∆14C values was observed at a rate of about 3 per year between 1994 and 2004, about half of that in atmospheric CO2 during this period (Levin and Kromer 2004). The ∆14C results ranged from 2-18 during individual cruises and were often significantly larger than the total uncertainty for individual measurements (3.9). This indicates that a single ∆14C result from a surface site is not sufficient to capture the true variability of ∆14C in the surface ocean.
  • Wiggle-Match Dating of Wooden Samples from Iron Age Sites in Northern Italy

    Quarta, G.; Pezzo, M. I.; Marconi, S.; Tecchiati, U.; D'Elia, M.; Calcagnile, L. (Department of Geosciences, The University of Arizona, 2010-01-01)
    Archaeological excavations carried out at the sites of Laion/Lajen (Bolzano/Bozen) and Stufles-Oberegger (Bressanone/Brixen) in northern Italy uncovered well-preserved wooden samples in cultural layers archaeologically dated to the Iron Age. From the 2 sites, different wooden samples were recovered that were well preserved enough to allow clear identification of the tree species and of the ring structure. Among the different wooden samples, 2 were selected for radiocarbon analyses: from Laion/Lajen, a beam with an unbroken sequence of 158 rings; from Stufles-Oberegger, a combusted trunk with a sequence of 217 rings. Both samples were identified as Larix decidua species. From each sequence, single rings were selected and submitted for accelerator mass spectrometry (AMS) 14C dating analysis at CEDAD. Conventional 14C ages were then calibrated to calendar ages using the IntCal04 atmospheric data set, while the statistical constraints resulting from the defined ring sequence were used to develop a wiggle-matching approach by making use of the Bayesian analysis functions available in OxCal. The obtained results are an important contribution in refining the chronology of the studied sites.
  • Turnover Rate of Soil Organic Matter and Origin of Soil 14CO2 in Deep Soil from a Subtropical Forest in Dinghushan Biosphere Reserve, South China

    Ding, P.; Shen, C. D.; Wang, N.; Yi, W. X.; Ding, X. F.; Fu, D. P.; Liu, K. X.; Zhou, L. P. (Department of Geosciences, The University of Arizona, 2010-01-01)
    This paper examines the carbon isotopes (13C, 14C) of soil organic carbon (SOC) and soil CO2 from an evergreen broadleaf forest in southern China during the rainy season. The distribution of SOC 13C, and SOC content with depth, exhibits a regular decomposition of SOC compartments with different turnover rates. Labile carbon is the main component in the topsoil (0-12 cm) and has a turnover rate between 0.1 and 0.01 yr-1. In the middle section (12-35 cm), SOC was mainly comprised of mediate carbon with turnover rates ranging between 0.01 and 0.025. Below 35 cm depth (underlayer section), the SOC turnover rate is slower than 0.001 yr-1, indicating that passive carbon is the main component of SOC in this section. The total production of humus-derived CO2 is 123.84 g C m-2 yr-1, from which 88% originated in the topsoil. The middle and underlayer sections contribute only 10% and 2% to the total humus-derived CO2 production, respectively. Soil CO2 13C varies from -24.7 to -24.0, showing a slight isotopic depth gradient. Similar to soil CO2 13C, ∆14C values, which range from 100.0 to 107.2, are obviously higher than that of atmospheric CO2 (60-70) and SOC in the middle and underlayer section, suggesting that soil CO2 in the profile most likely originates mainly from SOC decomposition in the topsoil. A model of soil CO2 ∆14C indicates that the humus-derived CO2 from the topsoil contributes about 65-78% to soil CO2 in each soil gas sampling layer. In addition, the humus-derived CO2 contributes ~81% on average to total soil CO2 in the profile, in good agreement with the field observation. The distribution and origin of soil 14CO2 imply that soil CO2 will be an important source of atmospheric 14CO2 well into the future.
  • Update on the Performance of the SUERC In Situ Cosmogenic 14C Extraction Line

    Fulöp, R. H.; Naysmith, P.; Cook, G. T.; Fabel, D.; Xu, S.; Bishop, P. (Department of Geosciences, The University of Arizona, 2010-01-01)
    In this paper, we describe improvements to the in situ cosmogenic radiocarbon extraction system at SUERC made since 2004, highlighting the factors that potentially control the reduction of analytical variability. We also present new results on system blanks and of measurements of in situ 14C in shielded quartz and a surface quartz sample used at the University of Arizona as an in situ 14C standard (PP-4). The SUERC in situ 14C extraction system was built in 2001 and is based on a combustion technique following the design of the extraction system at the University of Arizona. Our preliminary results suggest that the continuous running of the extraction system and the monitoring of gas collecting time and of the temperature of the cryogenic traps used in the gas cleaning steps are key to maintaining low and stable system blanks. Our latest average system blank is 2.02 +/- 0.23 x 105 14C atoms. This is consistent with those recently published by the University of Arizona and ETH in situ 14C labs. Measurements of in situ 14C concentrations in sample PP-4 yield an average of 3.82 +/- 0.23 x 105 atoms g-1 quartz, again consistent with published values.
  • Upland Olive Domestication in the Chalcolithic Period: New 14C Determinations from el-Khawarij (Ajlun), Jordan

    Lovell, J. L.; Meadows, J.; Jacobsen, G. E. (Department of Geosciences, The University of Arizona, 2010-01-01)
    New radiocarbon results on olive stones from el-Khawarij date olive cultivation at this site, in the Jordanian highlands, to the last 2 centuries of the 5th millennium cal BC. This period also sees the emergence of olive cultivation at Teleilat Ghassul, by the Dead Sea. The 10 new AMS dates were deliberately obtained from carbonized olive stones in order to date the exploitation of olives at el-Khawarij, a late prehistoric settlement believed to have been reliant on olive production. The results reveal a much longer span of occupation than hitherto suspected, including 2 dates that may fall later than 3900 cal BC (particularly OZI221, 3950-3530 cal BC). These later dates are in line with dates from other upland sites in the region, and may strengthen suggestions that Chalcolithic settlement persisted for longer in better watered upland areas (Lovell 2002). Further, an early date from a sample in a rock-cut installation in Area A suggests a much earlier date for occupation at the site, implying that upland olive exploitation may have commenced before 4700-4450 cal BC.
  • Using car4ams, the Bayesian AMS Data Analysis Code

    Palonen, V.; Tikkanen, P.; Keinonen, K. (Department of Geosciences, The University of Arizona, 2010-01-01)
    The Bayesian CAR (continuous autoregressive) model for accelerator mass spectrometry (AMS) data analysis delivers uncertainties with less scatter and bias. Better detection and estimation of the instrumental error of the AMS machine are also achieved. Presently, the main disadvantage is the several-hour duration of the analysis. The Markov chain Monte Carlo (MCMC) program for CAR model analysis, car4ams, has been made freely available under the GPL license. Included in the package is an R program that analyzes the car4ams output and summarizes the results in graphical and spreadsheet formats. We describe the main properties of the CAR analysis and the use of the 2 parts of the program package for radiocarbon AMS data analysis.
  • Towards On-Line 14C Analysis of Carbonaceous Aerosol Fractions

    Perron, N.; Szidat, S.; Fahrni, S.; Ruff, M.; Wacker, L.; Prévôt, A. H.; Baltensperger, U. (Department of Geosciences, The University of Arizona, 2010-01-01)
    Atmospheric carbonaceous aerosol is traditionally divided into organic carbon (OC) and elemental carbon (EC). Their respective carbon amounts are usually analyzed by means of an OC/EC analyzer and their fossil and non-fossil origins can be determined by radiocarbon analysis, which has proven to be a powerful tool for carbonaceous aerosol source apportionment. Thus far, separation of OC and EC has been performed off-line by manual and time-consuming techniques. We present an on-line system that couples a commercial OC/EC analyzer with the gas ion source of the accelerator mass spectrometer (AMS) MICADAS and its CO2 feeding system. The performance achieved with reference materials and blanks are discussed to demonstrate the potential of this coupling for source apportionment of atmospheric carbonaceous particulate matter.
  • Timing of the Landslide-Dammed Lake Triggered by Earthquake, at Toyama River, Central Japan

    Goto, Akiko S.; Muramatsu, Takeshi; Teraoka, Yoshiji (Department of Geosciences, The University of Arizona, 2010-01-01)
    Huge landslides triggered by strong earthquakes or torrential rains can result in unstable natural dams that pose serious risks to humans. In this study, we attempt to document the age of an ancient earthquake that produced a landslide-dammed lake. A buried forest found in the Toyama River area of the southern Nagano Prefecture, central Japan, provides evidence of this event. The dammed lake formation has been previously estimated to have occurred in AD 714. However, the age of the dam and the way it was formed have never been directly determined. To determine the position and timing of the landslide dam, we analyzed the radiocarbon content of branches and wood fragments from a brecciated deposit. We show that the 14C dating method is suitable for clarifying the timing of burial for a variety of trees, although the method does not produce a narrow age for the event. In addition to the dating, we determined the landslide dam's position and reconstructed the formation of the lake.
  • Tree-Ring Dating and AMS Wiggle-Matching of Wooden Statues at Neunggasa Temple in South Korea

    Park, Won-Kyu; Kim, Yojung; Jeong, Ah-Reum; Kim, Sang-Kyu; Oh, Jung-Ae; Park, Suh-Young; Cho, Sunil; Park, Gyujun; Seo, Jeong-Wook (Department of Geosciences, The University of Arizona, 2010-01-01)
    This paper reports the results of tree-ring dating and accelerator mass spectrometry (AMS) wiggle-matching for wooden Buddhist statues stored at the Eungjindang Hall of Neunggasa Temple, South Korea. Among 23 statues, 10 were successfully dated by tree rings. The cutting date of logs used for the statues was determined as some time between late fall 1684 and early spring 1685 when the bark ring (AD 1684) completed latewood formation. The 95.4% confidence interval of a radiocarbon date (cal AD 1688-1713, 2 ), which was obtained by wiggle-matching 7 samples of a statue, is similar to the dendro-date (AD 1684). A historical document recorded that the statues in the Eungjindang of Neunggasa were dedicated in July 1685. The dendro-date and written record indicate that Eungjindang statues were made within 3-8 months after log cutting. This seems rather short if we consider the period required for natural drying to avoid defects such as cracking and crooking.
  • The Low-Energy Isobar Separator for Anions: Progress Report

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

    Kuzmin, Y. V. (Department of Geosciences, The University of Arizona, 2010-01-01)
    Mazar and Bronk Ramsey (2008) recently proposed that the Iron I/IIA transition in the Levant took place during the first half of the 10th century. In the first part of this article, we challenge their method and conclusions. We argue against the inclusion of charcoal in their model, which could lead to an 'old wood effect.' We also argue that in dealing with a transition date, all available data must be taken into consideration. In the second part of the article, we propose Bayesian Model I for the Iron I/IIA transition, which is based on 2 sets of data--for the periods immediately before and after this transition. Our model, along with the other 11 published Bayesian models for this transition that used only short-lived samples, agrees with the Low Chronology system for the Iron Age strata in the Levant and negates all other proposals, including Mazar's Modified Conventional Chronology. The Iron I/IIA transition occurred during the second half of the 10th century. In the third part of the article, we present a new insight on the Iron I/IIA transition. We propose that the late Iron I cities came to an end in a gradual process and interpret this proposal with Bayesian Model II. Mazar and Bronk Ramsey (2008) recently challenged Sharon et al. (2007; also Boaretto et al. 2005) and us (e.g. Finkelstein and Piasetzky 2003, 2007a,b) regarding the date of transition from the Iron I to the Iron IIA in the Levant. While we and Sharon et al. placed this transition in the second half of the 10th century BCE, Mazar and Bronk Ramsey positioned it 'during the first half of the 10th century BCE' and argued that 'the second half of the 10th century BCE should be included in the Iron IIA' (Mazar and Bronk Ramsey 2008:178). We discuss some problems in the methodology of Mazar and Bronk Ramsey that may have influenced their results. In particular, we discuss 1) the exclusion of data; 2) the inclusion of data (charcoal samples); and 3) show that even according to Mazar and Bronk Ramsey, excluding these samples position the late Iron I/IIA transition in the late 10th century. Finally, we present our own 2 Bayesian models for the Iron I/IIA transition.
  • The Passage of the Bomb Radiocarbon Pulse into the Pacific Ocean

    Jenkins, William J.; Elder, Kathryn L.; McNichol, Ann P.; Von Reden, Karl (Department of Geosciences, The University of Arizona, 2010-01-01)
    We report and compare radiocarbon observations made on 2 meridional oceanographic sections along 150 degrees W in the South Pacific in 1991 and 2005. The distributions reflect the progressive penetration of nuclear weapons-produced 14C into the oceanic thermocline. The changes over the 14 yr between occupations are demonstrably large relative to any possible drift in our analytical standardization. The computed difference field based on the gridded data in the upper 1600 m of the section exhibits a significant decrease over time (approaching 40 to 50 in ∆14C) in the upper 200-300 m, consistent with the decadal post-bomb decline in atmospheric 14C levels. A strong positive anomaly (increase with time), centered on the low salinity core of the Antarctic Intermediate Water (AAIW), approaches 50-60‰ in ∆14C, a clear signature of the downstream evolution of the 14C transient in this water mass. We use this observation to estimate the transit time of AAIW from its "source region" in the southeast South Pacific and to compute the effective reservoir age of this water mass. The 2 sections show small but significant changes in the abyssal 14C distributions. Between 1991 and 2005, ∆14C has increased by 9 below 2000 m north of 55 degrees S. This change is accompanied overall by a modest increase in salinity and dissolved oxygen, as well as a slight decrease in dissolved silica. Such changes are indicative of greater ventilation. Calculation of "phosphate star" also indicates that this may be due to a shift from the Southern Ocean toward North Atlantic Deep Water as the ventilation source of the abyssal South Pacific.
  • The Late Paleolithic-Neolithic Transition in Korea: Current Archaeological and Radiocarbon Perspectives

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

    Beverly, R. K.; Beaumont, W.; Tauz, D.; Ormsby, K. M.; von Reden, K. F.; Santos, G. M.; Southon, J. R. (Department of Geosciences, The University of Arizona, 2010-01-01)
    We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2-3 for 1-mg samples (Santos et al. 2007c) are presented.
  • The Effect of Storage on the Radiocarbon, Stable Carbon and Nitrogen Isotopic Signatures and Concentrations of Riverine DOM

    Gulliver, P.; Waldron, S.; Scott, E. M.; Bryant, C. L. (Department of Geosciences, The University of Arizona, 2010-01-01)
    Chemical preservatives (e.g. mercuric chloride) are routinely added to freshwater samples to prevent biological activity compromising the isotopic signature of dissolved organic matter (DOM) with time. However, alternative preservation methods are needed due to regulations restricting the use of preservatives with potentially adverse environmental and health impacts, rendering such additions unviable. This study investigates whether a non-chemical storage method is sufficient to maintain the radiocarbon and stable carbon and nitrogen signatures of freshwater DOM from a low order river system draining a peaty catchment. Some 50 L of stream water were collected in 1 plastic carbuoy and, within 24 hr, 1-L aliquots were transferred to acid-washed plastic bottles. Five aliquots were analyzed immediately to determine the baseline values for 14C (pMC), 13C (VPDB), 15N (AIR), %C (mg L-1), and %N (mg L-1). Of the remaining subsamples, 20 were frozen and a further 20 refrigerated at 4 C. After 7, 30, 90, and 180 days, 5 frozen and 5 refrigerated aliquots were analyzed in the same manner as the baseline aliquots. Analysis of the results shows that there is no statistically significant interaction between the variables storage method or length of storage for any of the determinants. Storage method has a statistically significant effect on 14C (pMC) and [C] (mg L-1). Length of storage has a statistically significant effect on 13C (VPDB), [C] (mg L-1), and [N] (mg L-1) values. Neither storage method nor length of storage appear to have a statistically significant effect on 15N (AIR) values.
  • The Fifth International Radiocarbon Intercomparison (VIRI): An Assessment of Laboratory Performance in Stage 3

    Scott, E. Marian; Cook, Gordon T.; Naysmith, Philip (Department of Geosciences, The University of Arizona, 2010-01-01)
    Proficiency testing is a widely used, international procedure common within the analytical chemistry community. A proficiency trial (which VIRI is) often follows a standard protocol, including analysis that is typically based on zscores, with one key quantity, p. From a laboratory intercomparison (sometimes called a proficiency trial), we hope to gain an assessment of accuracy (in this case, from dendro-dated samples), laboratory precision (from any duplicate samples), and generally, an overall measure of performance, including measurement variability and hence realistic estimates of uncertainty. In addition, given our stated aim of creating an archive of reference materials, we also gain a determination of consensus values for new reference materials. VIRI samples have been chosen to deliver these objectives and the sample ages included in the different stages, by design, spanned modern to background. With regard to pretreatment, some samples required intensive pretreatment (e.g. bone), while others required none (e.g. cellulose and humic acid). Sample size was not optimized, and indeed some samples were provided solely for accelerator mass spectrometry (AMS) measurement. In this sense, VIRI presented a more challenging exercise than previous intercomparisons, since by its design in stages, one can explore improvements (or deteriorations) over time in laboratory performance. At each stage, more than 50 laboratories have participated, with an increasing demographic shift towards more AMS and fewer radiometric laboratories.
  • The Effects of Rainfall on Carbon Isotopes of POC in the Teshio River, Northern Japan

    Aramaki, T.; Nakamura, Y-H.; Uchida, M.; Shibata, Y. (Department of Geosciences, The University of Arizona, 2010-01-01)
    During a rainfall event in early September 2006, the transport behavior of particulate organic carbon (POC) in a small river (Teshio River, northern Japan) with alluvial plain and forest characteristics was investigated chiefly with carbon isotopes. The radiocarbon (∆14C value) of POC varied widely from -56 at the beginning of the rain event to -10 at peak rainfall. The ∆14C values have a positive correlation with C/N ratios and a negative correlation with 13C values except for the data from when both turbidity and water level were at their maximums due to rainfall. These results indicate that the sources of organic matter in the river come from the surface layer of soil as the water level rises during a rainfall event.
  • The Carbon Origin of Structural Carbonate in Bone Apatite of Cremated Bones

    Van Strydonck, M.; Boudin, M.; Mulder, G. (Department of Geosciences, The University of Arizona, 2010-01-01)
    In order to reveal a possible carbon exchange between carbon dioxide of the fuel and the bone apatite during the cremation process an experiment was set up using fossil fuel. Two setups were constructed, one using natural gas and one using coal. In both experiments, a carbon substitution in the apatite was revealed.
  • The Chronology of Pleistocene Modern Humans in China, Korea, and Japan

    Keates, S. G. (Department of Geosciences, The University of Arizona, 2010-01-01)
    The chronological status of Pleistocene fossils of early modern humans in the People's Republic of China is based almost exclusively on indirect dating of the stratigraphic context and faunal and radiocarbon dating of associated or supposedly associated archaeological specimens. A similar pattern is observed in Korea and Japan. This paper examines the 14C and other dating techniques of early modern humans in East Asia to gain a more complete and up-to-date understanding of their chronology.

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