bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experiment to Refute the Likelihood of Cellulose Carboxylation
Authors: Hedges R. E. M. , Ramsey Christopher Bronk , Van Klinken G.-J.
Published: July 2016

To test the hypothesis that cellulose in linen can be carboxylated at high temperatures in the presence of CO2, water and silver, we heated two aliquots of cellulose extracted from old wood in glass ampoules, adding Ag powder to one to test its potential action as a catalyst for the carboxylation reaction. AMS measurement of the heated aliquots showed no statistically significant difference in 14C content from the “uncarboxylated” cellulose. We conclude that carboxylation is not a systematic source of error in the dating of cellulose-containing materials such as the linen in the Shroud of Turin.
Estimation of Gas Purity in a CO2-Filled Proportional Counter by Rise-Time Analysis
Authors: Michczyński Adam , Pazdur Anna
Published: July 2016

Since 1994, a new data-acquisition system with rise-time (RT) based background reduction has been in operation at the Gliwice Radiocarbon Laboratory. During long-term stability tests, we observed large shifts in the RT spectra obtained during various measurement series. These shifts caused important changes in the count rate measured with RT reduction. As a result, we have ascertained that the shifts are the consequence of variable concentration of electronegative impurities. A correction method was considered, using average RT of pulses obtained in coincidence with the muon events, so-called ARTL (average rise time of L pulses), for estimation of the RT of the spectrum's shift. However, radiocarbon dates calculated based on count rates with RT discrimination, which were corrected using this method, are not more precise than traditional 14C dates. Nevertheless, the value of the average coincidence pulse RT is a good indication of sample gas purity.
Development of New Beta-Counting Programs Operating Under a Windows® NT Workstation
Authors: Omoto Kunio
Published: July 2016

β-counting software programs were developed and installed in new PCs for operation under a Windows® NT workstation. The new software programs allow us to simultaneously control several β-counting systems, either remotely or from within the laboratory. This setup is much less expensive than our previous arrangement, which required a separate PC for each counter.
Radiometric 14C Dating: New Background Analysis, Basis of Improved Systems
Authors: Theodórsson Pall
Published: July 2016

A recent broad study of the background of all types of low-level beta and gamma detectors has now made it possible to analyze its components more reliably and with greater detail. This general analysis is developed further here for gas proportional and liquid scintillation counters used in radiocarbon dating. The background of gas counters, which is dominated by secondary cosmic gamma radiation, is now well understood and can be described quantitatively. The background of liquid counters is less well understood and can only be described semiquantitatively, its analysis resting partly on estimates. Methods to reduce the background of both types of systems are described and their effectiveness discussed. This analysis may help in evaluating the quality of existing systems as well as in designing better ones.
Comparison of Vanadium Oxide Catalysts for Synthesis of Benzene: Benzene Purity, Yields and Reconditioning Methods
Authors: Enerson T. B. , Haas Herbert , Zarrabi Kaveh , Titus R. L.
Published: July 2016

This study compares vanadium oxide catalysts from three different sources: Noakes (N), Harshaw Chemical (H) and Kh. Arslanov at the St. Petersburg State University, Russia (R). The catalysts are used to convert acetylene to benzene in the last step of benzene synthesis. The organic purity of benzene in all three catalysts is high; 99.91–99.93% for (N) and (H) and 99.87% for (R). The benzene yields range from 90.0 to 94.3%. (N) averaged 92.6%, (H) averaged 91.1% and (R) averaged 92.0%. A conversion residue in the catalysts was analyzed for δ13C and found to be isotopically lighter relative to acetylene by −2.2% for (N) and (H) and −3.9% for (R). Benzene yields were studied on different reconditioning methods applied to all catalysts: heating to 400° in air averaged 92.3%; the same temperature with a half and half mixture of O2 and Ar averaged 91.9%, adding a half and half mixture of H2 and Ar at 200° to the end of this treatment averaged 91.8%. Based on this research, the obvious difference seen between the catalysts is in their trace by-products.
Contamination and Fractionation Effects in AMS-Measured 14C/12C and 13C/12C Ratios of Small Samples
Authors: Alderliesten Cees , Van Der Borg Klaas , De Jong Arie F. M.
Published: July 2016

In AMS measurements on small (m 400 μg) carbon samples, an m-dependence has been noted for the 14C/12C and 13C/12C ratios that is due to the combined effect of contamination and fractionation. A simple formalism is presented to describe the phenomena and to correct measurements on unknowns for their effect.
14C Database and Geographic Information System for Western Siberia
Authors: Orlova Lyobov A. , Kuzmin Yaroslav V. , Zolnikov Ivan D.
Published: July 2016

We illustrate here the combined use of geographic information system (GIS) technology and a radiocarbon database for analysis of the environmental components and ancient sites in Western Siberia during the period 10–45 ka bp. In total, 230 14C dates from 75 Late Pleistocene outcrops and Paleolithic sites were used to generate paleolandscape maps and to establish the features of the spatiotemporal distribution of Paleolithic sites.
Two Decades of Environmental Isotope Records in Croatia: Reconstruction of the Past and Prediction of Future Levels
Authors: Krajcar-Bronić Ines , Horvatinčić Nada , Obelić Bogomil
Published: July 2016

A two-decade-long record of environmental isotopes (2H, 3H, 14C, 18O) in Croatia is presented and the data are statistically analyzed. The atmospheric 14C activity for the period before the actual measurements started is reconstructed by measuring tree rings from the clean-air sites, and the past tritium activity in precipitation is estimated by the correlation of our data with the Vienna station record. The long-term 3H record helped to determine a locally contaminated sampling site, and new clean sites are put into operation. The 14C data were fitted by an analytical function and the prediction of future levels is given assuming that the rate of the 14C releases remains constant. From the long-term stable isotope data record, the local meteoric water line and the temperature gradient of δ18O in precipitation are determined.
14C Levels in the Vicinity of Two Swedish Nuclear Power Plants and at Two “Clean-Air” Sites in Southernmost Sweden
Authors: Stenström Kristina , Skog Göran , Thornberg Charlotte , Erlandsson Bengt , Hellborg Ragnar , Mattsson Sören , Persson Per
Published: July 2016

14C is one of the radionuclides that are produced to different degrees by neutron-induced reactions in all types of nuclear reactors. Part of the 14C created is continuously released into the surrounding environment during normal operation as airborne effluents in various chemical forms (such as CO2, CO and hydrocarbons) through the ventilation system of the plant. Because of the biological importance of carbon and the long half-life of 14C, it is of interest to measure the releases and their incorporation into living material. We report here on the 14C activity concentrations in annual tree rings and the air around two Swedish nuclear power plants, as well as the background 14C activity levels from two reference sites in southern Sweden from 1973–1996. We used both accelerator mass spectrometry (AMS) and decay counting in the investigation.
A New 14C Calibration Data Set for the Last Deglaciation Based on Marine Varves
Authors: Hughen Konrad A. , Overpeck Jonathan T. , Lehman Scott J. , Kashgarian Michaele , Southon John R. , Peterson Larry C.
Published: July 2016

Varved sediments of the tropical Cariaco Basin provide a new 14C calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10–14.5 cal ka bp). Independent evaluations of the Cariaco Basin calendar and 14C chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to 14C age agreement with terrestrial 14C dates, even during large climatic changes. These assessments indicate that the Cariaco Basin 14C reservoir age remained stable throughout the Younger Dryas and late Allerød climatic events and that the varve and 14C chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of 14C change not seen in the coral records. 14C plateaus can be identified at 9.6, 11.4, and 11.7 14C ka bp, in addition to a large, sloping “plateau” during the Younger Dryas (∼10 to 11 14C ka bp). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global climate changes of the last deglaciation.
America's Oldest Basketry
Authors: Berger Rainer , Bendat Millie , Parker Andrea
Published: July 2016

We have determined the earliest calibrated dates on three types of basketry from the Great Basin of western North America. The oldest twined basketry dates to 10,380–10,918 cal bp, reed duck decoys to 2355–2773 cal bp, and wooden sandals of sagebrush bark or twined tule to 9247–10,375 cal bp and 9242–9836 cal bp, respectively.
Dating a Chalcolithic Burial Cave in Peqi'in, Upper Galilee, Israel
Authors: Segal Dror , Carmi Israel , Gal Zvi , Smithline Howard , Shalem Dina
Published: July 2016

In May 1995 an impressive karstic cave possessing dozens of burials dating to the main phase of the Chalcolithic Period (ca. 4500–3500 bce) was discovered in Peqi'in in the high hills of Galilee in northern Israel. It was subsequently excavated over the course of the following months. The large amount of unique ceramic ossuaries and the variety of burial offerings shed light, for the first time, on this critical societal development period in a region where its remains have rarely been found. Although the major significance of the cave is as a mortuary center, it was also utilized in a domestic capacity some centuries previously, during the generally less familiar Early Chalcolithic Period. We present here the dating of 22 14C samples collected from these separate phases of cave use. Their interpretation should aid in understanding of the absolute dating of the Chalcolithic Period and its relation to the period preceding its inception.
Chronology of the Burial Finds from Scythian Monuments in Southern Siberia and Central Asia
Authors: Sementsov A. A. , Zaitseva G. I. , Görsdorf J. , Nagler A. , Parzinger H. , Bokovenko N. A. , Chugunov K. V. , Lebedeva L. M.
Published: July 2016

We present here new radiocarbon dates for the different barrows (burial mounds) of the nomadic tribes of the Scythian period in the Khakassia and Tuva regions (Central Asia). The time scale of these barrows is compared with the elite barrows of the Sayan-Altai. In agreement with archaeological evidence, some barrows in Khakassia are chronologically close in time to the Arzhan barrow. The first 14C dates produced for the barrows from the Tuva region belong to a later Scythian period, compared with the elite Arzhan barrow. We determined the final stage of the barrow construction, but to establish the starting time, more dates are necessary (both by dendrochronology and 14C).
Radiometric Dating of Young and Old Calcrete
Authors: Geyh Mebus A. , Eitel Bernhard
Published: July 2016

To obtain a better understanding of the relationship between calcrete genesis and the results of different absolute dating methods, thermoluminescence (TL), radiocarbon (14C) and uranium/thorium (U/Th) were applied to coeval sample; take from a very young calcrete profile in Namibia. The methodically different ages reflect the characteristics of the applied dating methods, the genetics of calcrete and different events of calcrete genesis. The conventional 14C ages and the TL dates cover the last 50 ka, while the corresponding U/Th dates of coeval samples are many times larger, Uranium-series dates are not related to the deposition of the host material or to its cementation if the ages are smaller than ca. 120 ka. The TL clock is set to zero during eolian transport and the corresponding radiometric ages of the quartz and feldspar grains date the time of their deposition. The 14C ages of the cement correspond, on the other hand, to a time shortly after the onset of the cementation and long before its termination. In the case of very old calcrete, the mixture of young and old cement results in ambiguous ages if they cannot be confirmed by an independent technique.
The 14C Age of Palsas in Northern Eurasia
Authors: Vasil'Chuk Yurij K. , Vasil'Chuk Alla C.
Published: July 2016

We discuss results of 14C dating peat of palsa of different regions of Northern Eurasia. We apply these dates to determine the age of active palsa growth during different periods of the Holocene in permafrost zone.
14C Dating of Modern Marine and Estuarine Shellfish
Authors: Hogg A. G. , Higham T. F. G. , Dahm J.
Published: July 2016

We measured the 14C content of 36 living marine molluscs from Tairua Harbour and the rocky coast on the Coromandel Peninsula of New Zealand. We identified species suitable for radiocarbon dating and show that the open marine intertidal zone is enriched in 14C compared to the open marine subtidal zone or estuary. We also found a uniform 14C distribution in the Tairua Harbour, by analyzing samples of the estuarine bivalve Austrovenus stutchbwyi collected up to 5 km from the harbor entrance.
Chronology of Vegetation and Paleoclimatic Stages of Northwestern Russia During the Late Glacial and Holocene
Authors: Arslanov Kh A , Saveljeva L A , Gey N A , Klimanov V A , Chernov S B , Chernova G M , Kuzmin G F , Tertychnaya T V , Subetto D A , Denisenkov V P
Published: July 2016

We have studied 6 reference sections of bog and lake sediments in the Leningrad and Novgorod provinces to develop a geochronological scale for vegetational and paleoclimatic changes in northwestern Russia during the Late Glacial and Holocene. Every 10-cm layer along the peat and gyttja sections (4–8.5 m thick) was investigated palynologically and the great majority of them were radiocarbon dated. Using the data obtained, standard palynological diagrams were plotted and vegetation history reconstructed. The palynozones indicated on the diagrams were related to the climatic periods and subperiods (phases) of the Blytt-Sernander scheme. On the basis of 230 14C dates obtained, we derived the geochronology of climatic periods and phases, as well as the chronology for the appearance and areal distribution of forest-forming tree species. The uppermost peat layers were dated by using the “bomb effect”. We compared the stages of Holocene vegetation and paleoclimatic changes discovered for the Leningrad and Novgorod provinces with the those obtained for Karelia, which we had studied earlier using the same methodology.
Oceanic Radiocarbon Between Antarctica and South Africa Along Woce Section 16 at 30°E
Authors: Leboucher Viviane , Orr James , Jean-Baptiste Philippe , Arnold Maurice , Monfray Patrick , Tisnerat-Laborde Nadine , Poisson Alain , Duplessy Jean-Claude
Published: July 2016

Accelerator mass spectrometry (AMS) radiocarbon measurements were made on 120 samples collected between Antarctica and South Africa along 30°E during the WOCE-France CIVA1 campaign in February 1993. Our principal objective was to complement the Southern Ocean's sparse existing data set in order to improve the 14C benchmark used for validating ocean carbon-cycle models, which disagree considerably in this region. Measured 14C is consistent with the θ-S characteristics of CIVA1. Antarctic Intermediate Water (AAIW) forming north of the Polar Front (PF) is rich in 14C, whereas surface waters south of the PF are depleted in 14C. A distinct old 14C signal was found for the contribution of the Pacific Deep Water (PDW) to the return flow of Circumpolar Deep Waters (CDW). Comparison to previous measurements shows a 14C decrease in surface waters, consistent with northward displacement of surface waters, replacement by old deep waters upwelled at the Antarctic Divergence, and atmospheric decline in 14C. Conversely, an increase was found in deeper layers, in the AAIW. Large uncertainties, associated with previous methods for separating natural and bomb 14C when in the Southern Ocean south of 45°S, motivated us to develop a new approach that relies on a simple mixing model and on chlorofluorocarbon (CFC) measurements also taken during CIVA1. This approach leads to inventories for CIVA1 that are equal to or higher than those calculated with previous methods. Differences between old and new methods are especially high south of approximately 55°S, where bomb 14C inventories are relatively modest.
Use of Three Isotopes to Calibrate Human Bone Radiocarbon Determinations from Kainapirina (SAC), Watom Island, Papua New Guinea
Authors: Petchey Fiona , Green Roger
Published: July 2016

In archaeological dating, the greatest confidence is usually placed upon radiocarbon results of material that can be directly related to a defined archaeological event. Human bone should fulfill this requirement, but bone dates obtained from Pacific sites are often perceived as problematic due to the incorporation of 14C from a range of different reservoirs into the collagen via diet. In this paper, we present new human bone gelatin results for 2 burials from the SAC archaeological site on Watom Island, Papua New Guinea, and investigate the success of calibrating these determinations using dietary corrections obtained from δ34S, δ15N, and δ13C isotopes.
University of Texas at Austin Radiocarbon Dates XV
Authors: Valastro S , Davis E Mott , Varela Alejandra G , Lisk Susan V
Published: July 2016

This list begins a program of publishing our large backlog of unpublished dates. The dates listed here are not a specific block of dates but simply those ready for publication. In many cases we have received comments from submitters, to whom we are grateful. Where no comment is included, none was received.
Radiocarbon Dates from an Upland Site of the Kona Field System, Hawai'I Island, Hawaii
Authors: Kawachi C T
Published: July 2016

The following samples were excavated in July 1985 in an upland (elev 609.6m) prehistoric agricultural site in the Kona Field System on the west coast of Hawai'i Island.
University of Michigan Radiocarbon Dates IV
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of radiocarbon dates obtained since the time of the preparation of Michigan list III.∗ The description of the essential features of our method of measurement as given in the introduction to list III applies to this list. The modern standards used were obtained from hardwood logs, and were of various ages from 75 to 150 years by ring count. These standards were sufficiently old so that no correction for the recent dilution of the atmospheric C14is believed to be necessary in the dates reported here. The ages of carbonate sample are also calculated from modern wood as a reference standard, without any correction for isotope fractionation.
Dublin Radiocarbon Dates I
Authors: McAulay I. R. , Watts W. A.
Published: July 2016

A C14-dating installation was operated in the Physics Department, Trinity College, Dublin, from early 1958 until early 1960, by I. R. McAulay. Construction and testing of the apparatus had occupied 15 months previous to this. Material for dating was selected and pretreated by W. A. Watts, who also collected and submitted the samples and carried out pollen analyses except where the contrary is stated in the text. The project was a short-term one with two main aims; to obtain a few key archaeologic dates, particularly in the Neolithic, to help orientate chronologic discussion; and to test the validity of the pollen zonation for the post-Atlantic of Mitchell (1956).
British Museum Natural Radiocarbon Measurements III
Authors: Barker Harold , Mackey John
Published: July 2016

The third series of radiocarbon measurements made at the British Museum Research Laboratory is reported in the following list. Equipment and method used are as described previously (British Museum I) and, as in previous lists, the error terms are not based solely on counting statistics, but are widened to include contributions of ±80 years for possible isotopic fractionation effects and ±100 years for the de Vries effect. Ages are calculated on a half-life of 5568 ± 30 years. NBS oxalic acid is now used as a reference standard in place of 100-yr-old oak. The latter gave an age-corrected value almost exactly 95% of the oxalic-acid activity and thus no corrections are required to our previous date lists to bring them into line with the new standard.
Isotopes, Inc. Radiocarbon Measurements I
Authors: Walton Alan , Trautman Milton A. , Friend James P.
Published: July 2016

Radiocarbon analyses have been performed at Isotopes, Inc. since 1957 using proportional-counting techniques. Carbon dioxide is employed as the counting gas at pressures up to two atmospheres. The counter presently in service is electrolytic copper and has an active volume of just under two liters. It is shielded by one in. of mercury, a ring of 23 G-M counters operated in anti-coincidence with the sample counter, 4 in. of paraffin wax, and 18 in. of hot-rolled steel. A background of 9.2 counts/min has been attained with this arrangement.
WOCE Pacific Ocean Radiocarbon Program
Authors: Key Robert M.
Published: July 2016

Fieldwork for the World Ocean Circulation Experiment (WOCE) radiocarbon program was recently completed. Ca. 9000 samples were collected for analysis using both conventional β-counting techniques and the newer AMS technique. The mean uncertainty for the β analyses is 3‰; for AMS analyses, ca. 4.5‰.
Toward an Absolute Chronology at ELK Lake, Minnesota
Authors: Aardsma Gerald E.
Published: July 2016

Radiocarbon measurements on organic carbon from the varved cores of Elk Lake, Minnesota suggest that the varve count may underestimate calendar years by 18% for the most recent 3800 varve years.
Radiocarbon Levels in the Iceland Sea from 25–53 kyr and their Link to the Earth's Magnetic Field Intensity
Authors: Voelker Antje H L , Grootes Pieter M , Nadeau Marie-Josee , Sarnthein Michael
Published: July 2016

By correlating the climate records and radiocarbon ages of the planktonic foraminifera N. pachyderma(s) of deep-sea core PS2644 from the Iceland Sea with the annual-layer chronology of the GISP2 ice core, we obtained 80 marine 14C calibration points for the interval 11.4-53.3 ka cal BP. Between 27 and 54 ka cal BP the continuous record of 14C/cal age differences reveals three intervals of highly increased 14C concentrations coincident with low values of paleomagnetic field intensity, two of which are attributed to the geomagnetic Mono Lake and Laschamp excursions (33.5-34.5 ka cal BP with maximum 550 marine δ14C, and 40.3-41.7 ka cal BP with maximum 1215 marine δ14C, respectively). A third maximum (marine δ14C: 755) is observed around 38 ka cal BP and attributed to the geomagnetic intensity minimum following the Laschamp excursion. During all three events the A14C values increase rapidly with maximum values occurring at the end of the respective geomagnetic intensity minimum. During the Mono Lake Event, however, our A14C values seem to underestimate the atmospheric level, if compared to the 36Cl flux measured in the GRIP ice core (Wagner et al. 2000) and other records. As this excursion coincides with a meltwater event in core PS2644, the underestimation is probably caused by an increased planktonic reservoir age. The same effect also occurs from 38.5 to 40 ka cal BP when the meltwater lid of Heinrich Event 4 affected the planktonic record.
Radiocarbon Age Offsets in Different-Sized Carbonate Components of Deep-Sea Sediments
Authors: Thomson John , Cook G. T. , Anderson Robert , MacKenzie A. B. , Harkness D. D. , McCave I.N.
Published: July 2016

We compared accelerator mass spectrometry (AMS) 14C ages of large (>150 μm) pelagic foraminifera with radiometric bulk carbonate 14C ages in two northeastern Atlantic cores. The foraminiferal ages are consistently older than those of the bulk sediment (by + 0.76 ka in Core 11881 and by + 1.1 ka in Core 11886), whereas corresponding fine (<5 μm) fraction ages are similar to those of the bulk sediment carbonate. We calculated near-identical sediment accumulation rates from both the foraminiferal and bulk sediment age/depth relations (3.0 cm ka−1 in Core 11881 and 5.9 cm ka−1 in Core 11886). Consideration of various factors that might produce such offsets leads us to believe that they are not artifacts, but were most probably caused by differential bioturbation of the different size-fractions in the sediment surface mixed layer. The importance of this finding is that many paleoceanographic records, such as the oxygen isotope record, also derive from analyses of large foraminifera, so that these records must be offset in time from the bulk of the sediments that they characterize.
Paleoclimatic Implications of Radiocarbon Dating Of Speleothems from the Cracow-Wieluń Upland, Southern Poland
Authors: Pazdur Anna , Pazdur Mieczysław F. , Pawlyta Jacek , Górny Andrzej , Olszewski Michał
Published: July 2016

We report preliminary results of a long-term systematic study intended to gather paleoclimatic records from precisely dated speleothems. The research project is limited to speleothems deposited in caves of the Cracow-Wieluń Upland, the largest and best-explored karst region in Poland, covering ca. 2900 km2 with >1000 caves. Speleothem samples were selected from collections of the Geological Museum of the Academy of Mining and Metallurgy in Cracow. Radiocarbon dates of these samples from ca. 45–20 ka bp almost exactly coincide with age range of the Interplenivistulian. A break in speleothem formation between ca. 20 and 10 ka bp may be interpreted as a result of serious climatic deterioration associated with the maximum extent of the last glaciation. We observed differences among 14C, U/Th and AAR dating results. Changes of δ13C and δ18O in speleothems that grew between ca. 30 and 20 ka bp may be interpreted as changes of paleoclimatic conditions.
A Comparative Study of Monsoonal and Non-Monsoonal Himalayan Lakes, India
Authors: Kusumgar Sheela , Agrawal D. P. , Deshpande R. D. , Ramesh Rengaswamy , Sharma Chhemendra , Yadava M. G.
Published: July 2016

Sedimentological, mineral magnetic and carbon isotopic studies on cores from Mansar Lake in the Jammu area provide paleomonsoonal history dating back to 580 bc. From ca. 580 bc to ad 300, the region experienced precipitation similar to the present, whereas from ad 300 to 1400, the monsoon was relatively subdued. A small excursion ca. ad 1100 suggests an effect of medieval warming. Studies in the Kumaon region did not provide a proper precipitation record, as anthropogenic activity interfered with sedimentation. Manasbal Lake in Kashmir gave an inversion of 14C chronology due to younger paleosols in the drainage basin. Further, the episodic nature of sedimentation in Manasbal Lake hampered the reconstruction of precipitation history in the area.
Precision Calendar-Year Dating of the Elm Decline in a Sphagnum-Peat Bog in Southern Sweden
Authors: Skog Göran , Regnéll Joachim
Published: July 2016

The cause of the mid-Holocene elm decline in northwestern Europe and its relation to the contemporaneous transition from Mesolithic to Neolithic economy are still unclear, partly owing to the lack of a precise, calibrated chronology. Matching of a sequence of 14C dates to the calibration curve in combination with accurate 14C dating allows high-precision dating of paleoecological events. We have completed high-resolution dating of a Sphagnum-peat sequence from Ageröds Mosse in southernmost Sweden. The basis for selecting 14C samples was pollen analysis at 1 cm intervals. Nine 14C dates, covering an interval of ca. 500 calendar years around the elm decline, showed that this event occurred in Ageröds Mosse within a few decades ca. 3770 bc.
Berlin 14C Dates of Archaeological Sites in Vietnam
Authors: Görsdorf Jochen , Viet Nguyen
Published: July 2016

In 1968, H. Quitta, J. Herrmann, G. Kohl and P. H. Thong initiated cooperation between the Archaeological Institute in Hanoi and the Radiocarbon Dating Laboratory in Berlin. Since 1969, the Berlin 14C laboratory has measured 215 14C dates from 65 archaeological sites in Vietnam. As a result, important problems in Vietnamese archaeology have been recognized and partially solved with the aid of a secure chronological framework.
Direct Radiocarbon Dating of Pottery: Selective Heat Treatment to Retrieve Smoke-Derived Carbon
Authors: Delqué Količ Emmanuelle
Published: July 2016

I attempted to separate smoke-derived carbon from carbon derived from clay by variable-temperature burning. First, using liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS), I dated experimental potsherds containing these two sources of carbon. I used the same techniques to date archaeological samples. The results on archaeological sherds confirm the difficulty of establishing a standard procedure for pottery dating. Nevertheless, reliable dates on smoke-blackened potsherds are potentially obtainable with AMS dating of thin lamellas in the sherd surface following adequate NaOH treatment.
Chemical Composition and Sample Preparation of Archaeological Wood for Radiocarbon Dating
Authors: Zaitseva G. I.
Published: July 2016

The chemical composition of wood from archaeological sites differs from that of modern wood. The chemical changes depend on the microenvironment of the surrounding matrix more than the time of preservation. Chemical treatment of decomposed wood results in a great loss of initial material. The degree of wood decomposition should be taken into account in the preparation of samples for 14C dating. The main fraction of archaeological decomposed wood is a degraded lignin, with most cellulose totally decomposed. Nevertheless, decomposed wood can be a reliable material for 14C dating archaeological sites. Loss of material through sample preparation can be reduced by using fairly weak concentrations of chemical reagents without influencing the reliability of the dates.
A Comparison of Marine and Terrestrial Radiocarbon Ages from Northern Chile
Authors: Southon John R. , Oakland Rodman Amy , True Delbert
Published: July 2016

The calibration of radiocarbon dates on marine materials involves a global marine calibration with regional corrections. Data from well-associated marine and terrestrial materials in archaeological artifacts from northern Chile indicated that the calibration is valid for the period ad 200–900 and suggest that coastal upwelling intensities during that period were similar to those of the early 20th century.
Anthropogenic 14C Marine Geochemistry in the Vicinity of a Nuclear Fuel Reprocessing Plant
Authors: Cook G. T. , Begg F. H. , Naysmith Philip , Scott E. M. , McCartney Martin
Published: July 2016

The British Nuclear Fuels plc reprocessing plant at Sellafield in Cumbria, Northwest England, discharges between 1 and 3 TBq of 14C per annum as low-level waste via a pipeline into the Eastern Irish Sea. Our results demonstrate 14C activities in excess of the current ambient level (i.e., ca. 260 Bq kg−1 carbon) in a range of both biotic and abiotic samples with evidence that a significant percentage of the discharges are in the form of dissolved inorganic carbon (DIC). There also appears to be a significant seasonal influence on the uptake of the DIC by the phytoplankton, most likely linked to their bloom periods. Results from different aspects of the research are integrated to provide an opportunity to consider the overall distribution and behavior of 14C in the Eastern Irish Sea. We also discuss the results in terms of existing sediment chronologies and sedimentation rates and consider the possible consequences of phytoplankton blooms on the cycling of the other radionuclides.
Measurements of the Oxalic Acid II/Oxalic Acid I Ratio as a Quality Control Parameter at NOSAMS
Authors: Schneider R. J. , McNichol A.P. , Nadeau M. J. , Von Reden K.F.
Published: July 2016

Precision of AMS single-target measurements is usually based on counting statistics and variance during the data acquisition cycle. Additional longer-term variability may be studied by looking at the variability of the standards from cycle to cycle.
Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating
Authors: Buzinny Michael , Skripkin Vadim
Published: July 2016

We have tested two versions of an 0.8-ml volume Teflon® vial, designed specifically for radiocarbon dating in the microvolume range, using a modern Quantulus 1220™ liquid scintillation (LS) spectrometer. We determined the counting performance of each vial type in conjunction with different designs of copper holder, viz., with and without the incorporation of a “Teflon® light coupler”. We also compared the losses of sample benzene during a typical 28-day counting period. Results show that neither vial design nor the type of vial holder used in the intercomparison had a significant influence on counting performance. We recorded an absolute 14C detection efficiency of 82% against a background count rate of 0.1 cpm, i.e., a “figure of merit (FM) value” = 67,240. This compares favorably with the operational parameters anticipated for microvolume 14C dating by modern LS spectrometry. However, variations in the design of the sealing method used between the vial types was reflected in an apparent approximate tenfold difference in the amount of benzene lost during routine counting. In the better case, the evaporation loss was equivalent to 0.032 mg of benzene per day.
Low-Level Liquid Scintillation Counter Array with Computerized Data Acquisition and Age Calculation Capabilities for 14C Dating
Authors: Noakes J. E. , Spaulding J. D. , Valenta R. J.
Published: July 2016

We describe a two-phase study directed toward background reduction of a manual liquid scintillation counter and the interfacing of electronics for counting to a computer data acquisition system. Counter background reduction is achieved with afterpulse electronics, a high-performance cocktail, an auxiliary detector/guard and a special sample vial holder. The data acquisition system is comprised of an electronic signal processor and sorter for operating up to eight counters simultaneously and interfacing to a computer with software for data storage, acquisitions and age dating calculations. We discuss low-background counter modifications, electronic signal processing and computer software for 14C age dating.
Radiocarbon Age Assessment of a New, Near Background Iaea 14C Quality Assurance Material
Authors: Hogg A. G. , Higham Thomas , Robertson Steve , Beukens Roelf , Kankainen Tuovi , McCormac F.G. , Van Der Plicht Johannes , Stuiver Minze
Published: July 2016

The 14C Quality Assurance Programme coordinated by the IAEA (Rozanski et al. 1992) prepared a set of five new intercomparison materials, including 40–50 ka old subfossil wood excavated from New Zealand peat bogs (IAEA C-4 standard). Statistical analysis of 79 14C measurements made on the wood indicated considerable variation in the results, with a marked skewness toward more modern values. The wide range of results and the possibility of inhomogeneity within the standard prompted the recovery and analysis of replacement material. The new subfossil wood sample is kauri (Agathis australis), at least 50 ka old, excavated from a swamp in Northland. It is in the form of a single plank, 6 m long, weighing 80 kg. It will be forwarded to the IAEA in Vienna for milling and distribution. Subsamples were obtained from both ends of the plank and analyzed by six laboratories. We present here the results of these analyses and compare them with the previous IAEA intercalibration results for the C-4 standard.
Libby and the Interdisciplinary Aspect of Radiocarbon Dating
Authors: de Messières Nicole
Published: July 2016

At a time when exchange between scientific and non-scientific disciplines was uncommon, Willard F Libby broke through conventional barriers. Early influences prepared him for a career marked by its interdisciplinary approach, and for a discovery with far-ranging applications to many diverse branches of knowledge.
The 4300-yr 14C Age of Glyptodonts at Luján River (Mercedes, Buenos Aires, Argentina) and Comments on ‘Did the Megafauna Range to 4300 BP in South America’ by Cione et al.
Authors: Rossello Eduardo A , Jahn Bor-ming , Liu Tsung-Kwei , Petrocelli Jorge L
Published: July 2016

The glyptodont (Glyptodontidae Burmeister 1879, in Ameghino 1889), a giant cousin of the armadillo, has long been thought to have disappeared in South America at least 10,000 years ago at the end of the Pleistocene. There are indications that the glyptodont had some interaction with ancient hunter-gatherers peoples (Politis et al. 1987; Politis 1995), but the precise time of its extinction has never been well established. Most recently, a brief mention of 14C dates of 7500 to 6500 BP (Geotimes 1996) for glyptodont remains discovered at La Moderna (Azul Department, Buenos Aires province, Argentina), has aroused excitement because the new younger dates have changed the traditional idea about the survival and extinction of this beast.
Dating the First Australians
Authors: Gillespie Richard
Published: July 2016

The dating of selected archaeological and megafaunal sites from the Australian region is reviewed, with emphasis on recent work at some of the oldest sites. Improved chemical procedures with decreased analytical background for 14C analysis, combined with new luminescence dating methods, has confirmed many of the results processed decades ago and significantly increased the maximum age for some others. The oldest occupation horizons in four different regions reliably dated by defendable multi-method results are in the range 42–48,000 calendar years ago, overlapping with the age range for similarly well-dated undisturbed sites containing the youngest extinct megafauna. There is less secure evidence suggesting some archaeology may be earlier and some megafauna may have survived later than this period.
New Radiocarbon Dates from the Balkans (Dubene-Sarovka): Approach to the Early Bronze Absolute Chronology in Upper Thrace
Authors: Nikolova Lolita , Görsdorf Jochen
Published: July 2016

This paper addresses the absolute chronology of the earlier Yunatsite and Ezero cultures in Upper Thrace (South Bulgaria), from Early Bronze I and the beginning of Early Bronze II. The two newly obtained radiocarbon dates from Early Bronze Dubene-Sarovka (the Upper Stryama Valley) are published and discussed in a detailed stratigraphic and comparative Early Bronze I–Early Bronze II context. Date Bln-5233 (3490–3120 cal BC) is the first14C date from the Upper Maritsa valley from Early Bronze I with well-defined stratigraphic context and values earlier than 3100 BC. This date adds new arguments to the discussion of the14C dates from Yunatsite 15 and Plovdiv–Nebet Tepe, and addresses the question of the comparative chronology of Yunatsite I and Ezero I cultures from the late fourth millennium BC.

The sample of the date Bln-5231 (2870–2620 cal BC) comes from a level on the border between Early Bronze I and Early Bronze II. On one hand, its values preceded the values of the earlier-obtained14C dates from IIB layer and confirmed the stratigraphic sequence at Dubene-Sarovka tell. On the other hand, the calibrated values seem to be later than the vast comparative chronology of the end of the Dubene IIA&Mdash;the beginning of Dubene IIB (ca. 3000 BC). Similar problems occur with dates from Yunatsite and Ezero. The published new dates from Dubene-Sarovka are part of the project on complex elaborating of the Early Bronze absolute chronology in the Balkans, and especially on contextual analysis of the14C dates.
The Antiquity of the Prehistoric Settlement of the Central-South Brazilian Coast
Authors: Lima T A , Macario K D , Anjos R M , Gomes P R S , Coimbra M M , Elmore D
Published: July 2016

We discus here the prehistoric settlement of the central-south Brazilian coast, and, more specifically, 1 old radiocarbon date obtained for a costal shellmound, as well as its implications concerning the chronology attributed to the settlement process. The accelerator mass spectrometry (AMS) technique was used to determine the 14C age of charcoal from a shellmound on the southern coast of Rio de Janeiro. The resulting age was 7860 ± 80 BP, an unexpected result that reinforces 2 similar previously obtained dates for the same region. Brazilian archaeologists, however, have questioned those 2 dates, because they would predate by some 2000 yr the antiquity consensually accepted for the settlement of the central-south Brazilian littoral.
On Correcting 14C Ages of Gastropod Shell Carbonate for Fractionation
Authors: Pigati Jeffrey S
Published: July 2016

Correcting the 14C age of a sample for fractionation is straightforward if the measured carbon was derived entirely from the atmosphere, either directly or through chemical and/or biological reactions that originated with atmospheric carbon. This correction is complicated in the case of gastropods that incorporate carbon from limestone or secondary carbonate (e.g. soil carbonate) during shell formation. The carbon isotopic composition of such gastropod shells is determined by fractionation, as well as mixing of carbon from sources with different isotopic values. Only the component of shell carbonate derived from atmospheric carbon should be corrected for fractionation. In this paper, the author derives a new expression for correcting the measured 14C activity of gastropod shells for fractionation, and describe an iterative approach that allows the corrected 14C activity and the fraction of shell carbonate derived from atmospheric carbon to be determined simultaneously.
High-Precision AMS 14C Results on TIRI/FIRI Turbidite
Authors: Guilderson Thomas P , Southon John R , Brown Thomas A
Published: July 2016

Unleached aliquots of TIRI/FIRI turbidite were analyzed by accelerator mass spectronomy (AMS) over a timespan of 18 months. Individual analyses ranged from 18,090–18,245 yr BP with reported errors between 30–50 yr. The weighted average fraction modern (FM) of these 28 measurements is 0.10378 ± 0.00008 (which equates to 18,199 ± 8 yr BP) and the measurements show a 1 standard deviation scatter of 0.00044 (±35 yr). The fractional error of these results indicates reproducibility of individual measurements at the 4 (1σ) level, which is consistent with the quoted counting-statistics-based errors. Laboratories engaged in the determination of 14C results at reasonably high precision should consider taking advantage of the TIRI and FIRI sample materials in the role of process standards. Additional suites of high-precision data are necessary to refine the accuracy of these sample materials.
Radiocarbon Calibration for Japanese Wood Samples
Authors: Sakamoto Minoru , Imamura Mineo , Van der Plicht Johannes , Mitsutani Takumi , Sahara Makoto
Published: July 2016

The radiocarbon content of Japanese cedars was measured by accelerator mass spectrometry for decadal tree-ring samples from the period of 240 BC to AD 900. Conventional gas counting was also used for part of the samples. The data were compared with the INTCAL98 calibration curve (Stuiver et al. 1998). The results indicate that the difference in atmospheric 14C between Japan and North America or Europe is negligible at this period, less than 18 14C yr using an average of 50 yr. However, in the period of about AD 100 to about AD 200, we cannot exclude the possibility of a deviation of the order of 30 to 40 14C yr to the older ages.
Balanced Window Method in 14C Liquid Scintillation Counting
Authors: Theodórsson P , Ingvarsdottir S , Gudjonsson G I
Published: July 2016

The authors present a detailed theoretical and experimental study of the liquid scintillation balanced counting method, widely used in radiocarbon dating, using a simple, laboratory-made system. A fixed counting window becomes a balanced window when the high voltage is set where the 14C count rate rises to a maximum. Using a measured 14C pulse height spectrum, we have calculated the lower and upper limits for 11 balanced windows of varying width and their respective counting efficiencies. Furthermore, we have studied: (1) theoretically and experimentally, the counting efficiency for up to a ±15% shift in pulse height from the balanced setting, (2) the change in pulse height due to temperature variations, (3) the long-time stability of the system, and (4) a method that allows a quick determination of the balance voltage for individual samples, using the Compton spectrum of 133Ba. The standard deviation for thirty 24-hr measuring periods for a 14C standard (190 Bq) was within the expected statistical standard error (0.03%).
AMS Radiocarbon Dating of Bones at LSCE
Authors: Tisnérat-Laborde N , Valladas H , Kaltnecker E , Arnold M
Published: July 2016

In this paper, we explain our routine pretreatment of bone for radiocarbon dating by accelerator mass spectrometry (AMS), based on the specific reaction between amino acids and ninhydrin described by Nelson (1991). The values and uncertainties of the total system background are presented as a function of the carbon sample mass and the reliability of this method is discussed.
Development of an Automated System for Preparation of organic samples
Authors: Hatté Christine , Poupeau Jean-Jacques , Tannau Jean-François , Paterne Martine
Published: July 2016

We constructed an automated system to transform organic samples to CO2, which included several options such as: combustion in 2 steps with collection of the 2 fractions, volatile fraction combustion, and 13C sampling. The process includes organic matter combustion, CO2 drying, quantification of the mass of carbon, CO2 collection in a glass vial, and eventually 13C sampling. The system is computer-controlled and -monitored. The apparent background age of the automated system reaches 0.191 ± 0.011 pMC (2 σ), equivalent to a 14C age of about 51,700 yr BP, and requires only 30 min of handling, instead of the several days needed when using a manual procedure.
Cariaco Basin Calibration Update: Revisions to Calendar and 14C Chronologies for Core Pl07-58Pc
Authors: Hughen Konrad A , Southon John R , Bertrand Chanda J H , Frantz Brian , Zermeño Paula
Published: July 2016

This paper describes the methods used to develop the Cariaco Basin PL07-58PC marine radiocarbon calibration data set. Background measurements are provided for the period when Cariaco samples were run, as well as revisions leading to the most recent version of the floating varve chronology. The floating Cariaco chronology has been anchored to an updated and expanded Preboreal pine tree-ring data set, with better estimates of uncertainty in the wiggle-match. Pending any further changes to the dendrochronology, these results represent the final Cariaco 58PC calibration data set.
Present Status of Radiocarbon Calibration and Comparison Records Based on Polynesian Corals and Iberian Margin Sediments
Authors: Bard Edouard , Ménot-Combes Guillemette , Rostek Frauke
Published: July 2016

In this paper, we present updated information and results of the radiocarbon records based on Polynesian corals and on Iberian Margin planktonic foraminifera. The latter record was first published by Bard et al. (2004a,b), with the subsequent addition of some data by Shackleton et al. (2004). These data sets are compared with the IntCal98 record (Stuiver et al. 1998) and with data sets based on other archives, such as varves of Lake Suigetsu (Kitagawa and van der Plicht 1998, 2000), speleothems from the Bahamas (Beck et al. 2001), and Cariaco sediments (Hughen et al. 2004). Up to 26,000 cal BP, the Iberian Margin data agree within the errors of the other records. By contrast, in the interval between 33,000 and 41,000 cal BP, the Iberian Margin record runs between the Lake Suigetsu and Bahamian speleothem data sets, but it agrees with the few IntCal98 coral data and the Cariaco record.