bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiocarbon Age of the Laacher See Tephra: 11,230 ± 40 BP
Authors: Hajdas Irena , Ivy-Ochs Susan D. , Bonani Georges , Loiter André F. , Zolitschka Bernd , Schlüchter Christian
Published: July 2016

The Laacher Sec Tephra (LST) layer provides a unique and invaluable time marker in European sediments with increasing importance because it occurs just before the onset of the Younger Dryas (YD) cold event. As the YD begins ca. 200 calendar years after the LST was deposited, accurate determination of the radiocarbon age of this ash layer will lead to a more accurate age assignment for the beginning of the YD. On the basis of 12 terrestrial plant macrofossil 14C ages derived from sediments from Soppensee, Holzmaar and Schlakenmehrener Maar, we found an age of at least 11,230 ± 40 bp for the LST event. This is ca. 200 yr older than the often reported age of 11,000 ± 50 bp (van den Bogaard and Schmincke 1985).
Studies on Selected Proteins of Bone in Archaeology
Authors: Sobel Harry , Berger Rainer
Published: July 2016

With the advent of AMS radiocarbon dating of very small samples, a much greater opportunity now exists for research into specialized materials. Investigations of the proteins of bone and teeth for archaeological purposes suggest that much more information might be obtained by appropriate study of individual proteins in these tissues. Although present research seems limited to14C dating, racemization and dietary selection, conditions of the environment during preservation and some of the physiological events during life are likely to be discernible through further studies.
Radiocarbon Variations from Tasmanian Conifers: Results from Three Early Holocene Logs
Authors: Barbetti Mike , Bird Trevor , Dolezal George , Taylor Gillian , Francey Roger , Cook Edward , Peterson Mike
Published: July 2016

Dendrochronological studies are being carried out on two conifer species in the Stanley River area of western Tasmania. The chronology for Huon pine (Lagarostrobos franklinii), with living trees up to 1400 yr old, extends back to 571 bc. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 yr old. Apart from living or recently felled trees, sections have been taken from 350 subfossil logs preserved in floodplain sediments. They range in age from >38 ka to modern, with good coverage for the periods 9–3.5 ka and from 2.5 ka to the present. We report here on 14C measurements of decadal samples from three early Holocene logs, between 10 and 9 ka bp, providing short (ca. 300-yr) records of atmospheric 14C variations when plotted against ring numbers. The southern hemisphere data from Tasmania can be compared and wiggle-matched with published 14C calibration curves from German oak and pine. One set of measurements covers the period, ca. 9280–8990 cal bp, overlapping the link between the Hohenheim “Main 9” and middle Holocene master oak chronologies. The other sets of measurements from Tasmania coincide; they span the period, ca. 9840–9480 cal bp, overlapping the end of the German Preboreal pine and the beginning of the oak chronologies. Our measurements confirm that this part of the calibration curve is a gently sloping 14C-age plateau (ca. 8900–8700 bp, between 10,000 and 9500 cal bp), and suggest interhemispheric 14C differences close to zero.
Concentration of Radiocarbon and Its Chemical Forms in Gaseous Effluents, Environmental Air, Nuclear Waste and Primary Water of a Pressurized Water Reactor Power Plant in Hungary
Authors: Veres Mihály , Hertelendi Ede , Uchrin György , Csaba Eszter , Barnabás István , Ormai Péter , Volent Gábor , Futó István
Published: July 2016

We measured airborne releases of 14C from the Paks Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP). Two continuous stack samplers collect 14C in 14CO2 and 14CnHm chemical forms. 14C activities were measured using two techniques; environmental air samples of lower activities were analyzed by proportional counting, stack samples were measured by liquid scintillation counting. 14C concentration of air in the stack varies between 80 and 200 Bqm−3. The average normalized yearly discharge rates for 1988–1993 were 0.74 TBqGW−1ey−1 for hydrocarbons and 0.06 TBqGW−1ey−1 for CO2. The discharge rate from Paks Nuclear Power Plant is about four times higher than the mean discharge value of a typical Western European PWR NPP. The higher 14C production may be apportioned to the higher level of nitrogen impurities in the primary coolant. Monitoring the long-term average excess from the NPP gave D14C = 3.5‰ for CO2 and D14C = 20‰ for hydrocarbons. We determined 14C activity concentration in the primary coolant to be ca. 4 kBq liter−1. The 14C activity concentrations of spent mixed bed ion exchange resins vary between 1.2 and 5.3 MBqkg−1 dry weight.
A Survey of Environmental14C Levels in Hong Kong
Authors: Leung P. L. , Stokes M. J. , Qiu S.H. , Cai L. Z.
Published: July 2016

As an industrialized city, Hong Kong annually consumes a large amount of fossil fuel. In addition, the Daya Bay Nuclear Power Plant in Shenzhen, Guangdong Province, has just begun operation 20 km from Hong Kong. These factors suggest that it may be appropriate and significant to examine the variation of atmospheric14C levels in Hong Kong. We have collected and tested a variety of samples from different parts of Hong Kong: terrestrial annual grasses, marine plants and atmospheric CO2. We measured their14C activity and compared it with that of cassia oil samples from Guangxi Province, China. The values obtained indicate that environmental14C levels in the Hong Kong region agree with those found in Guangxi, both of which are significantly higher than the levels predicted by Povinec, Chudý and Šivo (1986).
The14C Content of Modern Vegetation Samples from the Flanks of the Katla Volcano, Southern Iceland
Authors: Shore J. S. , Cook G. T. , Dugmore A. J.
Published: July 2016

Samples of living terrestrial plants comprising a moss (Calliergon sp.), Carex spp. and Alchemilla spp. were collected from the surface of the mire at Engimýri in Mýrdalur, southern Iceland, 10 km from the crater rim of the central complex of the Katla volcano. This area is 16 km from the fissures active in ad 1918 and was directly affected by the tephra fall. Although there is no hot-spring or fumerole activity in the area, sufficient volcanic activity during the weeks preceding sample collection produced a strong sulphurous odor in the streams. As part of a large-scale dating program, we analyzed the modern vegetation to determine whether anomalies caused by the uptake of “old” volcanic CO2 were apparent. The results showed 14C values for the Calliergon sp., Carex spp. and Alchemilla spp. of 113.2 ± 0.6 pMC, 113.03 ± 0.52 pMC and 113.10 ± 0.6 pMC, respectively. The δ13CPDB values were −28.7‰, −28.0‰ and −27.0‰, respectively. Similar vegetation, i.e., terrestrial plants from a marsh environment in southern Scotland, were also analyzed as a comparison and gave 14C values of 113.16 ± 0.55 and 112.98 ± 0.59 pMC. The implication is that Icelandic vegetation at Engimýri is not affected by “old” carbon from volcanic emissions and dates obtained for this Icelandic peat are acceptable and directly comparable with Scottish peat.
Estimating Flow and Recharge Rates of Groundwater in Western Taiwan Using Radiocarbon and Tritium
Authors: Liu Tsung-Kwei
Published: July 2016

The Choushuichi alluvial-fan delta is the largest groundwater system in Taiwan. The coastal area of this fan delta has recently suffered severe land subsidence and sea-water intrusion due to overpumping of groundwater. To study the hydrogeological character of proper water-resource management, an intensive program of geological and water monitoring through well drilling and sampling has been undertaken. At present, radiocarbon dating and/or tritium analysis for samples from >70 boreholes has been completed. The clearly defined position of “bomb-tritium front” allows the groundwater flow and recharge rates of the confined aquifer to be calculated with confidence at <10 m yr−1 and 9.0 × 108 m3 yr−1, respectively. The flow velocities of the confined aquifer have also accelerated remarkably due to much pumping during the last decades.
A Method for Quantifying Deep-Sea Carbonate Dissolution Using14C Dating
Authors: Van Kreveld S.A. , Ganssen G. M. , Van Hinte J.E. , Melkert M. M. , Troelstra S. R. , Van Der Borg K. , De Jong A.
Published: July 2016

We quantified the rate of carbonate dissolution with increasing water depth by taking the difference in the carbonate mass accumulation rate of deep (3393–4375 m) core top sediments from the shallowest one (3208 m), which we assumed was unaffected by dissolution. This method depends on high quality14C dates that we calibrated to calendar years for calculating sedimentation rates. Our results show low (ranging from 0 to 0.3 g cm−2ka−1) and high (ranging from 1.5 to 1.7 g cm−2ka−1) carbonate dissolution rates, above and below 4000 m, respectively. Therefore, we interpret the sudden increase in the carbonate dissolution rate at 4000-m water depth to mark the lysocline.
Solar Flare Particle Effects and Seasonal Radiocarbon Variations in Tree Rings of the Northern and Southern Hemispheres
Authors: Bartolomei Paolo , Cecchini Stefano , Cini Stefano , Galli Menotti , Gaimpieri Roberto , Mongardi Cinzia , Nanni Teresa , Salomoni Agostino
Published: July 2016

Measurements of ∆14C and δ13C, separately in early wood and late wood of two Mediterranean pine species, with a nearly year-long growth season, were made to better define possible solar flare particle effects. The measurements were made for suitable periods around the years of big flares (e.g., 1942, 1946, 1989) in Pinus pinea of the Adriatic area and Pinus halepensis from South Australia. We found that the 14C concentration is consistently greater in early wood than in late wood of the same growth ring and considerably higher in the Australian samples than in the European samples. The data so far reveal no evidence of solar-flare effect.
The Antares AMS Centre: A Status Report
Authors: Tuniz Claudio , Fink David , Hotchkis Michael , Jacobsen Geraldine , Lawson Ewan , Smith Andrew , Hua Quan , Drewer Peter , Lee Peter , Levchenko Vladimir , Bird Roger , Boldeman John , Barbetti Mike , Taylor Gillian , Head John
Published: July 2016

The ANTARES accelerator mass spectrometry facility at Lucas Heights Research Laboratory is operational and AMS measurements of 14C, 26Al and 36Cl are being carried out routinely. Measurement of 129I recently commenced and capabilities for other long-lived radioisotopes such as 10Be are being established. The overall aim of the facility is to develop advanced programs in Quaternary science, global climate change, biomedicine and nuclear safeguards.
Improvements in Procedural Blanks at NOSAMS: Reflections of Improvements in Sample Preparation and Accelerator Operation
Authors: McNichol A.P. , Gagnon A. R. , Osborne E. A. , Hutton D. L. , Von Reden K.F. , Schneider R. J.
Published: July 2016

During the four years the Sample Preparation Laboratory (SPL) at the National Ocean Sciences Accelerator Mass Spectrometer (NOSAMS) Facilty has been in operation we have accumulated much data from which we can assess our progress. We evaluate our procedural blanks here and describe modifications in our procedures that have improved our analyses of older samples. In the SPL, we convert three distinct types of samples—seawater, CaCO3 and organic carbon—to CO2 prior to preparing graphite for the accelerator and have distinct procedural blanks for each procedure. Dissolved inorganic carbon (∑CO2) is extracted from acidified seawater samples by sparging with a nitrogen carrier gas. We routinely analyze “line blanks” by processing CO2 from a 14C-dead source through the entire stripping procedure. Our hydrolysis blank, IAEA C-1, is prepared by acidifying in vacuo with 100% H3PO4 at 60° overnight, identical to our sample preparation. We use a dead graphite, NBS-21, or a commercially available carbon powder for our organic combustion blank; organic samples are combusted at 850° for 5 h using CuO to provide the oxidant. Analysis of our water stripping data suggests that one step in the procedure contributes the major portion of the line blank. At present, the contribution from the line blank has no effect on our seawater analyses (fraction modern (fm) between 0.7 and 1.2). Our hydrolysis blanks can have an fm value as low as 0.0006, but are more routinely between 0.0020 and 0.0025. The fm of our best organic combustion blanks is higher than those routinely achieved in other laboratories and we are currently altering our methods to reduce it.
Improvements and Applications of AMS Radiocarbon Measurement at Peking University
Authors: Guo Zhiyu , Liu Kexin , Li Kun , Wang Jianjun , Li Bin , Lu Xiangyang , Chen Chia-Erh , Chen Tiemei , Yuan Sixun , Gao Shijun
Published: July 2016

AMS radiocarbon measurements were started at Peking University in 1992 with a modified HICONEX 834 ion source. Some archaeological samples were measured at a sensitivity of 10−14 with ca. 1.7% precision for modern samples. We have made many improvements in our first two years of operation: a high-intensity Cs sputtering ion source was installed; the graphite sample preparation technique was investigated; and the system stability has been improved. The blank sample background is currently ca. 0.006 MC and a precision within 1% can be reached for modern samples. Geological, archaeological, environmental and biomedical samples can be measured routinely. We present some typical applications.
Changes of Subtropical North Pacific Radiocarbon and Correlation with Climate Variability
Authors: Druffel Ellen R M , Griffin S , Guilderson T P , Kashgarian M , Southon J , Schrag D P
Published: July 2016

We show that high-precision radiocarbon (Δ14C) measurements from annual bands of a Hawaiian surface coral decreased by 7‰ from AD 1893 to 1952. This decrease is coincident with the Suess Effect, which is mostly due to the dilution of natural levels of 14C by 14C-free fossil fuel CO2. This decrease is equal to that expected in surface waters of the subtropical gyres, and indicates that the surface waters of the North Pacific were in steady state with respect to long term mixing of CO2 during the past century. Correlation between Δ14C and North Pacific gyre sea surface temperatures indicates that vertical mixing local to Hawaii and the North Pacific gyre as a whole is the likely physical mechanism to result in variable Δ14C. Prior to 1920, this correlation starts to break down; this may be related to the non-correlation between biennial Δ14C values in corals from the southwest Pacific and El Niño events observed during this period as well.
Development of a Robust 14C Chronology for Lynch's Crater (North Queensland, Australia) Using Different Pretreatment Strategies
Authors: Turney C S M , Bird M I , Fifield L K , Kershaw A P , Cresswell R G , Santos G M , di Tada M L , Hausladen P A , Youping Z
Published: July 2016

Lynch's Crater in northeastern Australia provides a long, continuous record of environmental change within the Late Quaternary. Here, we present newly determined radiocarbon ages, using acid-base-acid stepped combustion (ABA-SC) and acid-base-wet oxidation stepped combustion (ABOX-SC) pretreatment strategies. The new results largely confirm the original untreated radiocarbon results for the uppermost 9 m of sediments, (ca. 35 ka BP). Below this depth, results from both pretreatment methods are in stratigraphic agreement and extend the dating of the record from 38 ka BP to about 48 ka BP, although an apparent increased sedimentation rate below 12 m is questionable. The scarcity of “charcoal” in several of the samples raises questions regarding the application of ABOX-SC to lake or swamp sediments, with evidence for contributions from younger, chemically resistant bacterial carbon along with fine “charcoal” in some samples. However, the extent to which this phenomenon is significant to the final age estimate appears to be sample specific, and is probably dependent upon the length of the wet oxidation step in the pretreatment.
Least-Squares Fitting Smooth Curves to Decadal Radiocarbon Calibration Data from AD 1145 to AD 1945
Authors: Knox F B , McFadgen B G
Published: July 2016

Smoothed curves are least-squares fitted to three sets of decadal radiocarbon calibration data from New Zealand and British Isles (AD 1725–1935) and western North America (AD 1145–1945). The curves are compared with each other and with a curve previously calculated from New Zealand data (AD 1335–1745). The smoothing procedure results in reduced standard deviations of the curves, but at the expense of time resolution. The comparison shows a variable 14C offset between the northern and southern hemispheres of 0–70 years (Southern Hemisphere older), and a Northern Hemisphere longitudinal variation of −20 to +60 years (British Isles generally older than western North America).
Radiocarbon Dates from the Ice-Free Corridor
Authors: Arnold Thomas G
Published: July 2016

The Ice-Free Corridor has been hypothesized as the main migration route into the Americas since the 1930s. Radiocarbon dates have been used by archaeology, geology, and palynology to date the corridor. A total of 56414C dates ranging between 20,000 and 8000 BP from the corridor area were gleaned from the published literature. After assessing these dates for suitability, 255 were plotted over four time periods. The results indicate that the corridor was not feasible as an early human migration route until after 11,000 B P, or after the appearance of Clovis south of the continental glaciers.
Radiocarbon Age Offsets Between Living Organisms from the Marine and Continental Reservoir in Coastal Localities of Patagonia (Argentina)
Authors: Cordero Roberto R , Panarello Héctor , Lanzelotti Sonia , Dubois Cristian M Favier
Published: July 2016

The radiocarbon of the local reservoir effect (RE) was observed in many sectors along the Argentinean Patagonic coast. Results show variations in the 14C offsets and differences between marine and continental species growing within the same locality, ranging from about 80–1100 yr BP. It is postulated that such variations are mainly due to local factors, including the coast morphology and the contribution of continental waters. The relevance of these kinds of studies for the interpretation of age in archaeological samples is highlighted in this paper.
14C Absolute Chronology of Pyramid III and the Dynastic Model at Pachacamac, Peru
Authors: Michczyński Adam , Eeckhout Peter , Pazdur Anna
Published: July 2016

Pachacamac, covering an area of about 600 hectares (ha) near the Pacific shore, is one of the largest and most important archaeological sites in Peru. Most of the monumental adobe-made buildings of the later pre-Inca period (or Late Intermediate Period, about 10th–15th century AD) are so-called pyramids with ramps (the role of the ramps has been interpreted in different ways). Precise dating of the pyramids appears as a crucial step in defining the functions of Pachacamac in pre-Inca times. In this paper, we present the results obtained from 3 field campaigns at Pyramid III, one of the biggest buildings of the site. A total of 24 radiocarbon datasets from 4 different laboratories will help us to place the various steps of development of Pyramid III on a timescale, defined on the basis of the excavations. More absolute dates are available from another pyramid with ramps, which allow us to make comparisons and propose a new model of interpretation for the Pachacamac site during the Late Intermediate Period (LIP).
A New Chronology for Pololu Valley, Hawai'i Island: Occupational History and Agricultural Development
Authors: Field Julie S , Graves Michael W
Published: July 2016

A reanalysis of the chronology of Pololu Valley, located in the district of Kohala on Hawai'i Island, is presented using standard radiocarbon and accelerator mass spectrometry (AMS) dating. Using curated materials from the 1970s, Pololu is reassessed and found to have the earliest coastal occupations in this part of Hawai'i, beginning about AD 1300. Occupations at the dunes and in the valley interior are investigated, as are dryland and wetland field agricultural systems. These data provide a refined model for expansion and intensification of agricultural production in the 15th–17th centuries, and link this remote valley to demographic and sociopolitical trends that were occurring in the rest of Hawai'i.
Radiocarbon Dating History: Early Days, Questions, and Problems Met
Authors: Olsson Ingrid U
Published: July 2016

W F Libby's new dating method from the 1940s, based on experience in physics and chemistry, opened possibilities to check and revise chronologies built on other principles than radioactive decay. Libby's method initially implied collaboration with archaeologists to demonstrate that it worked but also with physicists to improve the technique to measure low β–activities. Chemists, geophysicists, botanists, physiologists, statisticians, and other researchers have contributed to a prosperous interdisciplinary development. Some pitfalls were not recognized from the beginning, although issues such as contamination problems were foreseen by Libby. Pretreatment of samples was discussed very early by de Vries and collaborators, among others. This subject has not yet been abandoned. Closely related to pretreatment is the choice of fraction to be dated and chemicals to be used, especially for accelerator mass spectrometry (AMS) measurements. Calibration against tree rings and comparison with dates obtained using other methods as well as intercomparison projects are partly history but still very actual. The impact by man and climate is also studied since the early days of the method. Also, the carbon cycle has been of great interest. The tools for measurements and statistical analysis have been improved during these first 3 or 4 decades, allowing interpretations not possible earlier. δ13C determinations are mostly very important and useful, but sometimes they have been misleading in discussions of the origin of carbon, especially for human tissues—the metabolism was not yet fully understood. The history and development of the method can only be illustrated by selected examples in a survey like this.
New Radiocarbon Dates and a Review of the Chronology of Prehistoric Populations from the Minusinsk Basin, Southern Siberia, Russia
Authors: Svyatko Svetlana V , Mallory James P , Murphy Eileen M , Polyakov Andrey V , Reimer Paula J , Schulting Rick J
Published: July 2016

The results are presented of a new program of radiocarbon dating undertaken on 88 human skeletons. The individuals derived from Eneolithic to Early Iron Age sites—Afanasievo, Okunevo, Andronovo (Fedorovo), Karasuk, and Tagar cultures—in the Minusinsk Basin of Southern Siberia. All the new dates have been acquired from human bone, which is in contrast to some of the previous dates for this region obtained from wood and thus possibly unreliable due to old-wood effects or re-use of the timber. The new data are compared with the existing14C chronology for the region, thereby enabling a clearer understanding to be gained concerning the chronology of these cultures and their place within the prehistory of the Eurasian steppes.
A Random Walk Through Time
Authors: Stuiver Minze
Published: July 2016

A celebration is in order: the journal Radiocarbon is now a mature 50 years without drastic changes in its identity. There have been, of course, additions in terms of specific isotopes (it is now an international journal of cosmogenic isotope research), but the 14C content is still very extensive. The triannual offshoots, conference proceedings (started in 1980), and calibration issues (the first in 1986) testify to the strength of the 14C component.
Climatic Signature and Radiocarbon Chronology of Middle and Late Pleniglacial Loess from Eurasia: Comparison with the Marine and Greenland Records
Authors: Haesaerts P , Borziac I , Chekha V P , Chirica V , Damblon F , Drozdov N I , Orlova L A , Pirson S , van der Plicht J
Published: July 2016

Recent investigations devoted to the Eurasian loess formations have provided an integrated high-resolution climatic sequence well radiocarbon dated between 13.4 and 42.5 kyr BP on charcoal and wood remains. Here, we show that the reproducible climatic signature of this loess sequence can be compared by proxy-correlation with the Greenland ice climatic signals, taking into account the distribution of the aeolian components in both records. This correlation allows situating with precision the series of14C dates obtained from loess with regard to the Greenland climatic sequence. In this way, comparing the atmospheric loess-derived14C chronology with the chronologies of the marine sequences becomes possible.
Implications of Radiocarbon Dates from Potter Creek Cave, Shasta County, California, USA
Authors: Feranec Robert S
Published: July 2016

New dates obtained from the bone collagen of mammals from the deposits in Potter Creek Cave, Shasta County, California, USA, show that these fossils were emplaced over the last 30,000 yr. The dates support the assignment of the fauna in the cave to the late Pleistocene and are contemporaneous to the dates obtained from the fauna of Samwel Cave located 5 km to the north. These new dates do not support previous radiocarbon dates suggesting a Holocene extinction of the extinct bovid Euceratherium collinum, and demonstrate that this and other megafauna were not present in the vicinity after the terminal Pleistocene.
The Effects of Possible Contamination on the Radiocarbon Dating of the Dead Sea Scrolls II: Empirical Methods to Remove Castor Oil and Suggestions for Redating
Authors: Lund Rasmussen Kaare , van der Plicht Johannes , Doudna Gregory , Nielsen Frederik , Højrup Peter , Halfdan Stenby Erling , Th Pedersen Carl
Published: July 2016

While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14C dates will be skewed artificially towards modern values. In Rasmussen et al. (2001), it was shown that the standard AAA pretreatment procedure used in the 2 previous studies dating Dead Sea Scroll samples (Bonani et al. 1992; Jull et al. 1995) is not capable of removing castor oil from parchment samples. In the present work, we show that it is unlikely that castor oil reacts with the amino acids of the parchment proteins, a finding which leaves open the possibility of devising a cleaning method that can effectively remove castor oil. We then present 3 different pretreatment protocols designed to effectively remove castor oil from parchment samples. These involve 3 different cleaning techniques: extraction with supercritical CO2, ultrasound cleaning, and Soxhlet extraction—each with their own advantages and disadvantages. Our data show that the protocol involving Soxhlet extraction is the best suited for the purpose of decontaminating the Dead Sea Scrolls, and we recommend that this protocol be used in further attempts to 14C date the Dead Sea Scrolls. If such an attempt is decided on by the proper authorities, we propose a list of Scroll texts, which we suggest be redated in order to validate the 14C dates done earlier by Bonani et al. (1992) and Jull et al. (1995).
A Bayesian Approach to the Estimation of Radiocarbon Calibration Curves: The IntCal09 Methodology
Authors: Heaton T J , Blackwell P G , Buck C E
Published: July 2016

This article presents a new approach to the construction of radiocarbon calibration curves. The Bayesian methodology was developed specifically to facilitate construction of the 2009 updates to the internationally agreed14C calibration curves known as IntCal09 and Marine09. The curve estimation approach taken uses Markov chain Monte Carlo sampling, specifically a Metropolis-within-Gibbs sampler, which offers improved flexibility and reliability over the approaches used in the past. In particular, the method allows accurate modeling of calibration data with14C determinations that arise from material deposited over several consecutive calendar years and that exhibit complex uncertainty structures on their calendar date estimates (arising from methods such as wiggle-matching and varve counting).
Bayesian Evaluation of the Southern Hemisphere Radiocarbon Offset during the Holocene
Authors: Hogg Alan , Bronk Ramsey Christopher , Turney Chris , Palmer Jonathan
Published: July 2016

While an interhemispheric offset in atmospheric radiocarbon levels from AD 1950–950 is now well established, its existence earlier in the Holocene is less clear, with some studies reporting globally uniform 14C levels while others finding Southern Hemisphere samples older by a few decades. In this paper, we present a method for wiggle-matching Southern Hemisphere data sets against Northern Hemisphere curves, using the Bayesian calibration program OxCal 4.1 with the Reservoir Offset function accommodating a potential interhemispheric offset. The accuracy and robustness of this approach is confirmed by wiggle-matching known-calendar age sequences of the Southern Hemisphere calibration curve SHCal04 against the Northern Hemisphere curve IntCal04. We also show that 5 of 9 Holocene Southern Hemisphere data sets are capable of yielding reliable offset information. Those data sets that are accurate and precise show that interhemispheric offset levels in the Early Holocene are similar to modern levels, confirming SHCal04 as the curve of choice for calibrating Southern Hemisphere samples.
Radiocarbon Evidence from the Middle Bronze Age Settlement At Portella (Aeolian Islands, Italy): Chronological and Archaeological Implications
Authors: Alberti Gianmarco
Published: July 2016

This paper deals with radiocarbon determinations from the Middle Bronze Age site of Portella on the island of Salina (Aeolian Archipelago, Italy). The available14C evidence is taken into account, in a simple Bayesian model, in order to explore the issue of the absolute chronology of both the settlement and the stage of the local cultural sequence to which Portella belongs. A high date is proposed for the start of the Aeolian (and Sicilian) Middle Bronze Age: 1556–1422 cal BC (95.4% confidence), with a a most likely (modal) date of about 1450 cal BC. Further, the analysis suggests that the Portella phase is likely to have been a very short one, with a span of 0–65 yr (68.2%) or 0–131 yr (95.4%). The archaeological implications are explored. The relation of these results to the evidence of ceramic phasing is also considered. Since Aegean datable ceramic imports are documented in Aeolian/Sicilian Middle Bronze Age contexts, the connection between Portella's chronology and the absolute dating of one of the Aegean phases (namely, Late Helladic IIIA1) is also investigated.
Chronological Distribution of Brazilian Glyptodon SP. Remains: A Direct 14C Date for a Specimen from Iporanga, São Paulo, Brazil
Authors: Hubbe Alex , Vasconcelos André G , Vilaboim Luciano , Karmann Ivo , Neves Walter
Published: July 2016

Glyptodon sp. fossil remains can be found throughout Brazil. However, little information is available about their chronological distribution. With the intention to contribute to this issue, we present, as far as we know, the first direct radiocarbon date for 1 specimen of this genus found in Brazil. The osteoderm MZSP-PV660 found in Abismo do Fóssil Cave (SP-145), Iporanga, São Paulo, Brazil, was dated by accelerator mass spectrometry at the Beta Analytic Radiocarbon Dating Laboratory. The 14C date obtained was between 20,680 and 21,370 calibrated years before the present. Unfortunately, the scant (and often imprecise or unreliable) chronological data regarding this species and genus in Brazil and elsewhere in South America precludes a robust comparison among the dates available and the one presented here. Nevertheless, our finding supports the existence of this genus in South America at least until the Last Glacial Maximum.
Radiocarbon-Dated Paleoenvironmental Changes on a Lake and Peat Sediment Sequence from the Central Great Hungarian Plain (Central Europe) During the Last 25,000 Years
Authors: Sümegi Pál , Molnár Mihály , Jakab Gusztáv , Persaits Gergo , Majkut Péter , Páll Dávid G , Gulyás Sándor , Timothy Jull A J , Törcsik Tünde
Published: July 2016

One of Hungary's geological and environmental treasures is nestled in the heart of the Great Hungarian Plain. The catchment basin of Lake Kolon was subjected to detailed environmental historical studies starting in 2005. Undisturbed cores taken along transects of the basin were subjected to detailed sedimentological, paleoecological, and geochemical studies. To establish a reliable timeframe of the lacustrine and marshland sedimentary sequence identified, 22 samples were analyzed by accelerator mass spectrometry (AMS) in the radiocarbon laboratories of Poznań and Tucson. With the new results in hand, we had the opportunity to elucidate the geological evolution of the area for the past 25,000 yr. This sequence is highly beneficial, as it is probably the most well-dated profile of the Quaternary from the area studied. The new absolute dates enabled the comparison of local geological evolution of the studied area with those of global climatic changes. As seen from our findings, the geological evolution of the catchment basin was congruent with major climatic events during the Pleistocene and the entire Holocene. However, a very peculiar trajectory was identified for the terminal part of the Pleistocene and the opening of the Holocene regarding the evolution of the landscape, the vegetation, and the fauna of this part of the Great Hungarian Plain.
Iron Age Mediterranean Chronology: A Reply
Authors: Bruins Hendrik J , Nijboer Albert J , van der Plicht Johannes
Published: July 2016

This article is a reply to the preceding rejoinder by Fantalkin et al., which they wrote in response to our article concerning radiocarbon dates of Iron Age sites in the Mediterranean region measured at Groningen (van der Plicht et al. 2009). We do not agree with much of their criticism. Our reply is presented in detail with new viewpoints and evaluations concerning a number of sites in the Levant, including Tel Dan, Megiddo Stratum VIA (= K/4), Horvat Haluqim, Tell el-Qudeirat, Khirbet en-Nahas, Tel Rehov, as well as sites in the central and western Mediterranean region, particularly Carthage and Huelva. Our main conclusions are that14C dating supports an Iron Age High Chronology for the above sites, though more14C dating is required, particularly in Greece and the central and western Mediterranean region, to substantiate and refine the current state of knowledge. We prefer detailed investigations per individual site, evaluating both14C dates and site stratigraphy, rather than the wholesale averaging of strata over many sites, which may lead to oversimplification and erroneous results, also on stratigraphic grounds. Contrary to Fantalkin et al. (2011), we emphasize the importance of14C dating as an independent methodology—chronostratigraphy—to evaluate site stratigraphy. The14C dates of Megiddo Stratum VIA (=K/4) clearly indicate field-stratigraphic problems at this site.
New 14C Determinations from Lake Suigetsu, Japan: 12,000 to 0 Cal BP
Authors: Staff Richard A , Bronk Ramsey Christopher , Bryant Charlotte L , Brock Fiona , Payne Rebecca L , Schlolaut Gordon , Marshall Michael H , Brauer Achim , Lamb Henry F , Tarasov Pavel , Yokoyama Yusuke , Haraguchi Tsuyoshi , Gotanda Katsuya , Yonenobu Hitoshi , Nakagawa Takeshi ,   Suigetsu 2006 Project Members
Published: July 2016

Calibration is a fundamental stage of the radiocarbon (14C) dating process if one is to derive meaningful calendar ages from samples' 14C measurements. For the first time, the IntCal09 calibration curve (Reimer et al. 2009) provided an internationally ratified calibration data set across almost the complete range (0 to 50,000 cal BP) of the 14C timescale. However, only the last 12,550 cal yr of this record are composed of terrestrial data, leaving approximately three quarters of the 14C timescale necessarily calibrated via less secure, marine records (incorporating assumptions pertaining to the temporally variable “marine reservoir effect”). The predominantly annually laminated (varved) sediment profile of Lake Suigetsu, central Japan, offers an ideal opportunity to derive an extended terrestrial record of atmospheric 14C across the entire range of the method, through pairing of 14C measurements of terrestrial plant macrofossil samples (extracted from the sediment) with the independent chronology provided through counting of its annual laminations.

This paper presents new data (182 14C determinations) from the upper (largely non-varved) 15 m of the Lake Suigetsu (SG06) sediment strata. These measurements provide evidence of excellent coherence between the Suigetsu 14C data and the IntCal09 calibration curve across the last ~12,000 cal yr (i.e. the portion of IntCal based entirely on terrestrial data). Such agreement demonstrates that terrestrial plant material picked from the Lake Suigetsu sediment provides a reliable archive of atmospheric 14C, and therefore supports the site as being capable of providing a high-resolution extension to the “wholly terrestrial” (i.e. non-reservoir-corrected) calibration curve beyond its present 12,550 cal BP limit.
Application of the Triple-Photomultiplier Liquid Spectrometer Hidex 300 Sl in Radiocarbon Dating
Authors: Krapiec Marek , Walanus Adam
Published: July 2016

The Hidex 300 SL is a liquid scintillation analyzer with an automatic sample changer and a triple-photomultiplier tube detection assembly that registers triple- as well as double-coincidence spectra. In the triple mode, the background in the 14C window is 13.7 cpm (14C standard 30.8 cpm; =154.3 cpm/5.01), so the factor of merit equals 8.7. The triple-to-double coincidence ratio (TDCR) allows for determining the 14C counting efficiency, the quench level, and quench correction. However, in the case of very low-activity samples, which is the case even for modern 14C samples, the TDCR is not the best method for the correction of benzene impurities. We propose using the position (channel) of the right slope of the sample (14C) logarithmic pulse-height spectrum. In the case of near-background samples, the cosmic muon peak can be used instead. The Monte Carlo modeling of spectra gave the 14C level below which the muon peak is a better quench correction parameter than the position of the 14C spectrum. The spectrometer, with the proposed quench correction method, was tested with wood samples dated dendrochronologically. For 21 samples, there is no systematic bias observed, and the standard deviation of the age differences scaled by the Poisson errors is 1.24 ± 0.15, which means that the counting statistics account for 80% of the total variability (including sample preparation).
Radiocarbon Dating of Alkenones from Marine Sediments: I. Isolation Protocol
Authors: Ohkouchi Naohiko , Xu Li , Reddy Christopher M , Montluçon Daniel , Eglinton Timothy I
Published: July 2016

The chemical and isotopic compositions of long-chain (C36–C39) unsaturated ketones (alkenones), a unique class of algal lipids, encode surface ocean properties useful for paleoceanographic reconstruction. Recently, we have sought to extend the utility of alkenones as oceanic tracers through measurement of their radiocarbon contents. Here, we describe a method for isolation of alkenones from sediments as a compound class based on a sequence of wet chemical techniques. The steps involved, which include silica gel column chromatography, urea adduction, and silver nitrate-silica gel column chromatography, exploit various structural attributes of the alkenones. Amounts of purified alkenones estimated by GC/FID measurements were highly correlated with CO2yields after sample combustion, indicating purities of greater than 90% for samples containing ≥ 100 μg C. The degree of alkenone unsaturation (U37K′) also varied minimally through the procedure. We also describe a high-performance liquid chromatography (HPLC) method to isolate individual alkenones for molecular-level structural and isotopic determination.
Radiocarbon Dating of Alkenones from Marine Sediments: III. Influence of Solvent Extraction Procedures on 14C Measurements of Foraminifera
Authors: Ohkouchi Naohiko , Eglinton Timothy I , Hughen Konrad A , Roosen Ellen , Keigwin Lloyd D
Published: July 2016

As a result of the growing use of multiple geochemical proxies to reconstruct ocean and climate changes in the past, there is an increasing need to establish temporal relationships between proxies derived from the same marine sediment record and ideally from the same core sections. Coupled proxy records of surface ocean properties, such as those based on lipid biomarkers (e.g. alkenone-derived sea surface temperature) and planktonic foraminiferal carbonate (oxygen isotopes), are a key example. Here, we assess whether 2 different solvent extraction procedures used for isolation of molecular biomarkers influence the radiocarbon contents of planktonic foraminiferal carbonate recovered from the corresponding residues of Bermuda Rise and Cariaco Basin sediments. Although minor Δ14C differences were observed between solvent-extracted and unextracted samples, no substantial or systematic offsets were evident. Overall, these data suggest that, in a practical sense, foraminiferal shells from a solvent-extracted residue can be reliably used for 14C dating to determine the age of sediment deposition and to examine age relationships with other sedimentary constituents (e.g. alkenones).
Carbon Dioxide Capture Using a Zeolite Molecular Sieve Sampling System for Isotopic Studies (13C and 14C) of Respiration
Authors: Hardie S M L , Garnett M H , Fallick A E , Rowland A P , Ostle N J
Published: July 2016

A method for collecting an isotopically representative sample of CO2 from an air stream using a zeolite molecular sieve is described. A robust sampling system was designed and developed for use in the field that includes reusable molecular sieve cartridges, a lightweight pump, and a portable infrared gas analyzer (IRGA). The system was tested using international isotopic standards (13C and 14C). Results showed that CO2 could be trapped and recovered for both δ13C and 14C analysis by isotope ratio mass spectrometry (IRMS) and accelerator mass spectrometry (AMS), respectively, without any contamination, fractionation, or memory effect. The system was primarily designed for use in carbon isotope studies of ecosystem respiration, with potential for use in other applications that require CO2 collection from air.
Seawater Radiocarbon Evolution in the Gulf of Alaska: 2002 Observations
Authors: Guilderson Thomas P , Roark E Brendan , Quay Paul D , Page Sarah R Flood , Moy Christopher
Published: July 2016

Oceanic uptake and transport of bomb radiocarbon as 14CO2 created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic for determining the carbon transfer between the ocean and atmosphere. In addition, the distribution of 14C in the ocean can be used as a tracer of oceanic circulation. Results obtained on samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results in the 1970s during GEOSECS and in the early 1990s during WOCE. The open gyre values are 20–40% lower than those documented in 1991 and 1993 (WOCE), although the general trends as a function of latitude are reproduced. Surface values are still significantly higher than pre-bomb levels (∼ −105% or lower). In the central gyre, we observe Δ14C values that are lower in comparison to GEOSECS (stn 218) and WOCE P16/P17 to a density of ∼26.8 σt. This observation is consistent with the overall decrease in surface Δ14C values and reflects the erosion of the bomb-14C transient. We propose that erosion of the bomb-14C transient is accomplished by entrainment of low-14C water via vertical exchange within the Gulf of Alaska and replenishment of surface and subther-mocline waters with waters derived from the far northwest Pacific.
Marine Radiocarbon Reservoir Ages in Scottish Coastal and Fjordic Waters
Authors: Cage Alix G , Heinemeier Jan , Austin William E N
Published: July 2016

High freshwater inputs into Scottish sea lochs (fjords) combined with the restricted exchange between sea loch basin water and coastal Atlantic water masses are likely to result in reduced regional marine radiocarbon reservoir ages (R[t]) in these environments. To test this hypothesis, historical, museum-archived shells, collected live on known dates prior to AD 1950 from coastal locations in NW Scotland, were14C dated to provide a means of determining R(t) and hence the regional deviation (ΔR) from the modeled global surface ocean reservoir age (R). The sea loch data, when combined with14C dates from the Scottish west coast (Harkness 1983), yield a regional ΔR value of −26 ± 14 yr. The ΔR of sea loch (fjordic) and coastal waters of NW Scotland are statistically different (at a confidence level >95%) from the ΔR value of 17 ± 14 yr reported for UK coastal waters (Reimer 2005; data after Harkness 1983) and are in good agreement with the coastal ΔR value of −33 ± 93 yr reported by Reimer et al. (2002). Therefore, it is recommended that a regional ΔR correction of −26 ± 14 yr should be applied to modern (i.e. pre-bomb but not prehistoric) marine14C dates from the NW coast of Scotland.
Southern Palestinian Chronology: Two Radiocarbon Dates for the Early Bronze Age at Tell El-Hesi (Israel)
Authors: Anderson Roger W
Published: July 2016

Several articles reporting radiocarbon dates of Early Bronze Age (EB) material from excavations in the southern Levant have been published over the last 30 yr. The excavations conducted at Tell el-Hesi have produced material from which 2 additional 14C dates have been extracted to date. The 2 samples confirm the EB dating of Field VI material and suggest EB III settlement at Hesi might be earlier than previously reported based on pottery typology.
Holocene Environmental Changes in Western Hungary
Authors: Szántó Zsuzsanna , Medzihradszky Zsófia
Published: July 2016

We review the reasons for change in paleoecological conditions and their effects on different cultures at the beginning and during the Holocene period in western Hungary using radiocarbon data combined with paleoecological and paleolimnological results. Two sites were investigated in the southern and northern part of the ancient bay of Balaton Lake: Keszthely-Úsztatómajor and Főnyed I. 14C dating of 2 core samples represented a chronology from 11,000 cal BC to 2000 cal BC (10,700 BP to 3700 BP) and from 6200 cal BC to 1200 cal BC (7300 BP to 3000 BP), respectively. A relatively constant inverse sediment accumulation rate was observed in both cases (23 yr/cm and 33 yr/cm, respectively). In the case of Főnyed I, a sharp break was observed in the sedimentation curve around 6000–4800 cal BC (6000 BP). Changes in the vegetation due to human activity were observed in a larger extent only at the end of Late Neolithic, with the most significant changes detected in the landscape coinciding with the presence of Lengyel III culture in the region. The appearance of higher amounts of pollen of cereals at the sites proved the presence of crop cultivation. However, the role of plant cultivation may have been limited for the ancient inhabitants of the Kis-Balaton region due to a limited amount of soil suitable for agriculture and due to the extensive water table. Further changes in vegetation were observed during the Late Copper Age (Baden culture) and the period of Early and Middle Bronze Age, respectively. Signs of forest clearing during the period have not been detected and the increased peak of Fagus indicates climatic change. The low intensity of anthropogenic activity should not be attributed to geographic isolation.