bluuebunny/crossref_metadata_2025 huggingface dataset:
Dating the Volcanic Eruption at Thera
Authors: Bronk Ramsey Christopher , Manning Sturt W , Galimberti Mariagrazia
Published: July 2016

The eruption of the volcano at Thera (Santorini) in the Aegean Sea undoubtedly had a profound influence on the civilizations of the surrounding region. The date of the eruption has been a subject of much controversy because it must be linked into the established and intricate archaeological phasings of both the prehistoric Aegean and the wider east Mediterranean. Radiocarbon dating of material from the volcanic destruction layer itself can provide some evidence for the date of the eruption, but because of the shape of the calibration curve for the relevant period, the value of such dates relies on there being no biases in the data sets. However, by dating the material from phases earlier and later than the eruption, some of the problems of the calibration data set can be circumvented and the chronology for the region can be resolved with more certainty.

In this paper, we draw together the evidence we have accumulated so far, including new data on the destruction layer itself and for the preceding cultural horizon at Thera, and from associated layers at Miletos in western Turkey. Using Bayesian models to synthesize the data and to identify outliers, we conclude from the most reliable 14C evidence (and using the INTCAL98 calibration data set) that the eruption of Thera occurred between 1663 and 1599 BC.
A Novel Approach for Developing High-Resolution Sub-Fossil Peat Chronologies with 14C Dating
Authors: Donders T H , Wagner F , van der Borg K , de Jong A F M , Visscher H
Published: July 2016

Sub-fossil sections from a Florida wetland were accelerator mass spectrometry (AMS) dated and the sedimentological conditions were determined. 14C data were calibrated using a combined wiggle-match and 14C bomb-pulse approach. Repeatable results were obtained providing accurate peat chronologies for the last 130 calendar yr. Assessment of the different errors involved led to age models with 3–5 yr precision. This allows direct calibration of paleoenvironmental proxies with meteorological data. The time frame in which 14C dating is commonly applied can possibly be extended to include the 20th century.
Source Apportionment of Aerosols by 14C Measurements in Different Carbonaceous Particle Fractions
Authors: Szidat S , Jenk T M , Gäggeler H W , Synal H-A , Fisseha R , Baltensperger U , Kalberer M , Samburova V , Wacker L , Saurer M , Schwikowski M , Hajdas I
Published: July 2016

Radiocarbon enables a distinction between contemporary and fossil carbon, which can be used for the apportionment of biogenic and anthropogenic sources in environmental studies. In order to apply this approach to carbonaceous atmospheric aerosols, it is necessary to adapt pretreatment procedures to the requirements of 14C measurements. In this work, we followed an approach in which total carbon (TC) is subdivided into fractions of different chemical and physical properties. 14C data of ambient aerosols from Zürich (Switzerland) are presented for the 2 sub-fractions of TC, organic carbon (OC) and elemental carbon (EC). Furthermore, OC is separated into water-insoluble OC (WINSOC) and water-soluble OC (WSOC). Results demonstrate the importance to differentiate between these fractions for 14C-deduced source apportionment, as the contributions can range between both extremes, nearly exclusively biogenic and anthropogenic.
Superconducting Mini-Cyclotrons as AMS Instruments
Authors: Subotic K M , Milinkovic L S , Zupancic M T , Novkovic D N , Stojanovic M S
Published: July 2016

We have studied the limitations of conventional mass spectrometry and have examined accelerator based methods which could help circumvent these limitations. In particular, cyclotron-based accelerator mass spectrometric (AMS) techniques are discussed with an emphasis on evaluating performances of superconducting mini-cyclotrons designed for use as AMS instruments. We discussed the design of superconducting mini-cyclotrons dedicated to radioisotope dating research.
The Use of Radiocarbon Measurements in Atmospheric Studies
Authors: Manning M R , Lowe D C , Melhuish W H , Sparks R J , Wallace Gavin , Brenninkmeijer C A M , McGill R C
Published: July 2016

14C measured in trace gases in clean air helps to determine the sources of such gases, their long-range transport in the atmosphere, and their exchange with other carbon cycle reservoirs. In order to separate sources, transport and exchange, it is necessary to interpret measurements using models of these processes. We present atmospheric 14CO2 measurements made in New Zealand since 1954 and at various Pacific Ocean sites for shorter periods. We analyze these for latitudinal and seasonal variation, the latter being consistent with a seasonally varying exchange rate between the stratosphere and troposphere. The observed seasonal cycle does not agree with that predicted by a zonally averaged global circulation model. We discuss recent accelerator mass spectrometry measurements of atmospheric 14CH4 and the problems involved in determining the fossil fuel methane source. Current data imply a fossil carbon contribution of ca 25%, and the major sources of uncertainty in this number are the uncertainty in the nuclear power source of 14CH4, and in the measured value for δ14C in atmospheric methane.
Some Radiocarbon Dates for Tufas of the Craven District of Yorkshire
Authors: Pentecost Allan , Thorpe P M , Harkness D D , Lord T C
Published: July 2016

14C dates of relict tufa deposits at Gordale indicated a Subboreal age when the carbonate age was corrected with empirical bedrock dilution factors ‘q’ of 0.79 or 0.85. Estimates of ‘apparent age,’ based on extrapolated δ13C values were about twice those obtained with q, and the 1σ error was large. The δ13C values of tufa samples were not correlated with carbonate age and were close to −10. Application of q values in this district requires caution as they appear to be site-specific. We recommend that wherever possible, levels of 13C and 14C are measured in the associated tufa-depositing water, and an empirical dilution factor employed.
Accelerator Mass Spectrometric Radiocarbon Measurements on Foraminifera Shells from Deep-Sea Cores
Authors: Broecker Wallace S , Klas Mieczyslawa , Clark Elizabeth , Trumbore Susan , Bonani Georges , Wölfli Willy , Ivy Susan
Published: July 2016

Radiocarbon ages determined by the AMS method on hand-picked foraminifera shells are reported. The results allow estimates of the ventilation rate of the deep Atlantic and Pacific Oceans during glacial time. They also extend our knowledge of the chronology of events associated with the transition from full glacial conditions ca 15,000 years ago to full interglacial conditions ca 8000 years ago. This and the previous lists (Broecker et al 1988c) contain all the results obtained as part of this program through the fall of 1989.
Late Quaternary Pteropod Preservation in Eastern North Atlantic Sediments in Relation to Changing Climate
Authors: Ganssen G. M. , Troelstra S. R. , van der Borg Klaas , de Jong A. M. F.
Published: July 2016

AMS 14C measurements on pteropod shells from eastern North Atlantic deep-sea cores reveal distinct periods of aragonite preservation during the last 16,000 years. Most preservation spikes coincide with documented periods of climatic change on a scale of 2 × 101 to 2 × 103 years.
Cuello: Resolving the Chronology Through Direct Dating of Conserved and Low-Collagen Bone by AMS1
Authors: Law I. A. , Housley R. A. , Hammond Norman , Hedges R. E. M.
Published: July 2016

It is well known that14C dating of fossil bone with seriously depleted protein levels, or bone that has been consolidated with preservatives, can produce erroneous results. In the tropics, warm and moist soil conditions lead to constant reworking of organic matter and add to the danger of bone contamination. Because of this,14C dating of preservative-impregnated bone from such areas has rarely been successful. We report here a set of AMS dates on both unconsolidated animal bone and polyvinyl acetate/polyvinyl alcohol (PVA/PV-OH) impregnated human burials from the Maya site of Cuello, Belize. The steps needed to purify the samples are described, together with details on the use of qualitative infra-red (IR) spectra as a means of assessing sample purity.
High-Resolution AMS 14C Dating of Post-Bomb Peat Archives of Atmospheric Pollutants
Authors: Goodsite Michael E , Rom Werner , Heinemeier Jan , Lange Todd , Ooi Suat , Appleby Peter G , Shotyk William , van der Knaap W O , Lohse Christian , Hansen Torben S
Published: July 2016

Peat deposits in Greenland and Denmark were investigated to show that high-resolution dating of these archives of atmospheric deposition can be provided for the last 50 years by radiocarbon dating using the atmospheric bomb pulse. 14C was determined in macrofossils from sequential one cm slices using accelerator mass spectrometry (AMS). Values were calibrated with a general-purpose curve derived from annually averaged atmospheric 14CO2 values in the northernmost northern hemisphere (NNH, 30°–90°N). We present a thorough review of 14C bomb-pulse data from the NNH including our own measurements made in tree rings and seeds from Arizona as well as other previously published data. We show that our general-purpose calibration curve is valid for the whole NNH producing accurate dates within 1–2 years. In consequence, 14C AMS can precisely date individual points in recent peat deposits within the range of the bomb-pulse (from the mid-1950s on). Comparing the 14C AMS results with the customary dating method for recent peat profiles by 210Pb, we show that the use of 137Cs to validate and correct 210Pb dates proves to be more problematic than previously supposed.

As a unique example of our technique, we show how this chronometer can be applied to identify temporal changes in Hg concentrations from Danish and Greenland peat cores.
Environmental and Climatic Change as Recorded in Geological Sediments from the Arid to Semi-Arid Zone of China
Authors: Zhou Weijian , Zhengkun Wu , Jull A J T , Burr G , Donahue D D , Baosheng Li , Head J
Published: July 2016

Stratigraphic investigations together with climatic proxy data measurements and reliable radiocarbon dating show a history of fluctuations of dry and wet environmental conditions in the arid to semi-arid zone of northern China since the late Pleistocene. Based on these data, we are able to reconstruct shifts of the desert margin in two period extremes, the last glacial maximum (21–15 ka) and the Holocene Optimum (9–5 ka). We have compared the present desert margin with that for the two extremes. The results indicate that a southward shift of the present margin of about 3 degrees in latitude might be caused by anthropogenic impact. Hence the influence of human activity must be taken into consideration for sustainable development and environment protection. Future research will be to find a two-way feedback existing between climate and anthropogenic impacts.
Bomb Radiocarbon Dating of Animal Tissues and Hair
Authors: Geyh Mebus A
Published: July 2016

Initially, radiocarbon dating by bomb14C was used to check vintages of wine and whisky and to estimate the turnover times of carbon in various biological tissues. However, this technique has never been widely used for routine dating, although it has a wide field of application in geriatric medicine and forensic investigations. Fifteen years' experience in this field has shown the potential and limits of this technique. Taking into account the decisive biological factors, such as growth and aging, a complicated picture is obtained. Recent human bones cannot be dated with a constant precision. Despite an incomplete understanding of the process of incorporation of14C into human bones, the present dating technique is still more precise than most estimates by geriatric experts, for conventional14C dating follows that14C dates of bone collagen represent the years of the termination of puberty rather than those of death.

Another application is the identification of furs of illegally hunted animals on the “Red List of threatened species” of the World Conservation Union (IUCN). For court cases, the year the animals were killed must be precisely determined. Due to the long and variable turnover time of more than one year of leather hair is the best dating material for animals.
In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes
Authors: Lal D , Jull A J T
Published: July 2016

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.
In-Situ Radiocarbon Production by Neutrons and Muons in an Antarctic Blue Ice Field at Scharffenbergbotnen: A Status Report
Authors: van der Borg K , van der Kemp W J M , Alderliesten C , de Jong A F M , Lamers R A N , Oerlemans J , Thomassen M , van de Wal R S W
Published: July 2016

In the radiocarbon accelerator mass spectrometry (14C AMS) analysis of gases obtained in a dry extraction from a 52–m Antarctic ice core, we observed 14CO2 and 14CO concentrations decreasing with depth. The concentrations are explained in terms of in-situ production by neutrons and captured muons in ablating ice. The ratio of the 14CO2 concentration to that of 14CO has been found to be constant at 1.9 ± 0.3. The ablation rates obtained of 42 ± 18 cm.yr−1 and 40 ± 13 cm.yr−1 for the neutron and muon components, respectively, are about three times higher than observed from stake readings. The discrepancy may point to an incomplete extraction of the dry extraction method. Using the constant ratio in 14CO2 and 14CO concentrations we correct for the in-situ component in the trapped 14CO2 and deduce an age of 10,300 ± 900 BP for the ice core.
Radiocarbon in Seawater at Radioactive Waste Dumping Sites in the Northeast Atlantic and Northwest Pacific
Authors: Povinec P P , Jull A J T , Burr G S
Published: July 2016

Radiocarbon has been an important constituent of radioactive wastes dumped in the open ocean and marginal seas as well as wastes released from nuclear reprocessing plants. Therefore, in some regions these sources could have a greater impact on 14C concentration in seawater than global fallout. The high analytical sensitivity of 14C measurement by accelerator mass spectrometry (AMS) allows even tracer amounts of 14C to be found in seawater at radioactive waste dumping sites and their comparison with the global distribution of this radionuclide. Data on measurements of 14C in samples taken at former dumping sites in the northeast Atlantic and northwest Pacific Oceans and in the open ocean are discussed and compared with other anthropogenic radionuclides, namely 3H. Small increases in 14C concentrations observed in some bottom and surface seawater samples collected at the Northwest Pacific Ocean dumping sites require further 14C analyses before final conclusions can be made on possible leakages from dumped radioactive wastes.
The Late Quaternary Sedimentary Record of Reykjanes Ridge, North Atlantic
Authors: Prins M A , Troelstra S R , Kruk R W , van der Borg K , de Jong A F M , Weltje G J
Published: July 2016

Variability in surface and deep ocean circulation in the North Atlantic is inferred from grain-size characteristics and the composition of terrigenous sediments from a deep-sea core taken on Reykjanes Ridge, south of Iceland. End-member modeling of grain size data shows that deep-ocean circulation in this area decreased significantly during periods of maximum iceberg discharge. The episodes of reduced circulation correlate with the cold and abrupt warming phases of the Dansgaard-Oeschger cycles as recognized in the Greenland ice cores.
Dating of Ancient Icons from Kiev Art Collections
Authors: Kovalyukh N , van der Plicht J , Possnert G , Skripkin V , Chlenova L
Published: July 2016

Icon painting in the Ukraine is rooted in the Byzantine culture, after the conversion to the Christian religion. During the medieval epoch, Kiev became the artistic center for highly skilled icon painters. The icons were painted on wooden boards, specially made for this purpose. Historic dating of some even well-known icons is uncertain or not precise. Here we present for the first time radiocarbon dates for selected icons. Both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) dating methods were applied, allowing intercomparison.
New Radiocarbon Dates of the North Asian Steppe Zone and its Consequences for the Chronology
Authors: Görsdorf Jochen , Parzinger Hermann , Nagler Anatoli
Published: July 2016

The chronological problems of the Steppe zone have been under intensive investigation during the last years but no generally accepted chronological system existed up to now. We present new radiocarbon dates of samples from several excavation sites. The dates allow a comparison of the Bronze Age development in the Siberian Steppe Zone with other neighboring regions.
Radiocarbon Chronology of the Earliest Neolithic Sites in East Asia
Authors: Kuzmin Yaroslav V , Keally Charles T
Published: July 2016

The radiocarbon age of the earliest pottery from Russian Far East—Gromatukha and Osipovka cultures—is between around 13,300 BP and around 10,400 BP. This shows that the Amur River basin was one of the centers of origin of pottery in East Asia, at the end of the Pleistocene. Today, there are three areas within East Asia with pottery-associated 14C dates between around 14,000 BP and 13,000 BP—southern China, the Japanese Isles, and Russian Far East.
Radiocarbon Sample Preparation at the Circe AMS Laboratory in Caserta, Italy
Authors: Passariello Isabella , Marzaioli Fabio , Lubritto Carmine , Rubino Mauro , D'Onofrio Antonio , De Cesare Nicola , Borriello Gianluca , Casa Giovanni , Palmieri Antonio , Rogalla Detlef , Sabbarese Carlo , Terrasi Filippo
Published: July 2016

A system with several lines for the preparation of graphite targets for radiocarbon analysis has been built at the new accelerator mass spectrometry (AMS) facility in Caserta, Italy. Special attention has been paid in the design to the reduction of background contamination during sample preparation. Here, we describe the main characteristics of these preparation lines. Results of tests performed to measure 14C background levels and isotope fractionation in several blank samples with the Caserta AMS system are presented and discussed.
Radiocarbon Wiggle-Matching of Japanese Historical Materials with a Possible Systematic Age Offset
Authors: Imamura Mineo , Ozaki Hiromasa , Mitsutani Takumi , Niu Etsuko , Itoh Shigeru
Published: July 2016

Progress in radiocarbon accelerator mass spectrometry (AMS) techniques enables much more access to wiggle-matching techniques for high-precision 14C dating with relatively low costs than before. Recently, we have applied wiggle-matching for a number of wood samples where dendrochronology is difficult because of various limitations imposed for dendro-dating. In most cases, wiggle-matching gave rather unambiguous calendar ages, but we found that in some cases the calibrated date was very sensitive to a systematic error of the 14C date. Here, we present a wooden artifact from the Ujishigai archaeological site as a case where the highest wiggle-matched date did not agree with the date given by dendrochronology. An age with lower probability agreed with the tree-ring age of AD 389, which marked the beginning of the production of Sue ware (unglazed stoneware) in Japan. We show that systematic errors must be carefully taken into account while interpreting 14C wiggle-matching results, whether they are due to instrumental errors (statistical) or due to a regional offset from the IntCal04 (Reimer et al. 2004) calibration curve.
Re-Evaluation of the Late Bronze Age and Early Iron Age Chronology of the Western Belgian Urnfields Based on 14C Dating of Cremated Bones
Authors: De Mulder Guy , van Strydonck Mark , Boudin Mathieu , Leclercq Walter , Paridaens Nicolas , Warmenbol Eugène
Published: July 2016

The urnfields in western Belgium have been studied since the second half of the 20th century. Most of these studies, as well as the excavations themselves, date from before the last quarter of the 20th century, except for the urnfields at Velzeke and Blicquy, which were excavated recently. The chronology of these cemeteries was largely based on typochronological studies of pottery. Other funeral gifts, like bronze objects in the graves, are rather exceptional. The typochronology was worked out in a comparison with the framework of neighboring regions and central Europe. There was a need, then, for a chronology based on absolute dates. This was only possible by radiocarbon dating of the cremated bones. Tests on duplicate samples, like cremated bone in context with charcoal or 2 depositions of cremated bones within 1 urn, have shown that the results are reproducible and that there is no discrepancy between the charcoal and the cremated bone dates.

The results of the 14C dating project on the cremated bones of the 2 urnfields at Velzeke and the one at Blicquy are promising. The interpretation of the occupational history of both sites at Velzeke can be revised, and the currently accepted ceramic sequence for this period needs reworking. In addition, the chronological framework of the Late Bronze Age and Early Iron Age is open for discussion. It seems plausible that the urnfield phenomenon starts earlier in western Belgium than previously expected. These dates can also contribute to the discussion about the transition from the Late Bronze Age to the Early Iron Age.
Radiocarbon Dating in Late-Roman and Medieval Contexts: An Archaeological Excavation in the Center of Florence, Italy
Authors: Fedi M E , Arnoldus-Huyzendveld A , Cartocci A , Manetti M , Taccetti F
Published: July 2016

A series of samples for radiocarbon dating were collected in 2005 from the Biblioteca Magliabechiana archaeological excavation area in the center of Florence, Italy, in a project directed by the Dipartimento di Archeologia e Storia delle Arti of the University of Siena, in cooperation with the Soprintendenza per i Beni Architettonici e per il Paesaggio per le province di Firenze e Prato. This area is located near the Uffizi Galleries, close to the Roman town, the Arno River and one of its former tributaries. The area is peculiar for the Florentine urban context because it was free from urban development until the 12th century AD. The exposed stratigraphy showed the presence of several layers composed of natural sediments, partly the result of historical floods. Here, we report a series of 14C measurements on charcoal and seed samples collected on this excavation. 14C dating has been performed in the LABEC laboratory in Florence, on the accelerator mass spectrometry (AMS) beam line of the AMS-IBA 3MV Tandetron accelerator. We also had the opportunity to compare the 14C dates obtained with several series of samples previously collected in nearby archaeological areas. Results were consistent with the data obtained previously and, moreover, offer interesting new aspects to the interpretation of the archaeological findings.
Charcoal Production During the Norse and Early Medieval Periods in Eyjafjallahreppur, Southern Iceland
Authors: Church M J , Dugmore A J , Mairs K A , Millard A R , Cook G T , Sveinbjarnardóttir G , Ascough P A , Roucoux K H
Published: July 2016

Timber procurement and the use of woodlands are key issues in understanding the open landscapes of the Norse and Medieval periods in the North Atlantic islands. This paper outlines evidence for the timing and mechanisms of woodland use and deforestation in an area of southern Iceland, which is tracked through the mapping and analysis of charcoal production pits. Precise dating of the use of these charcoal production pits within a Bayesian framework is demonstrated through the combination of tephrochronology, sediment accumulation rates, and multiple radiocarbon dates on the archaeological charcoal. Two phases of charcoal production and woodland exploitation have been demonstrated, the first within the first 2 centuries of settlement (cal AD 870–1050) and the second phase over 100 yr later (cal AD 1185–1295). The implications for using charcoal as a medium for 14C dating in Iceland and the wider North Atlantic are then explored. Archaeobotanical analysis of the charcoal sampled from the pits has indicated that birch roundwood was the dominant wood used, that the roundwood was stripped from larger shrubs/trees in late spring/early summer, and that certain sizes and ages of roundwood were harvested. Finally, the timing of the charcoal production is placed into the wider debate on deforestation across Iceland during the Norse and early Medieval periods.
Dating the Tavan Tolgoi Site, Mongolia: Burials of the Nobility from Genghis Khan's Era
Authors: Youn M , Kim J C , Kim H K , Tumen D , Navaan D , Erdene M
Published: July 2016

The Tavan Tolgoi (Five Holy Hills) site, located in Ongon sum, Sukhbaatar aimag, in southeastern Mongolia, consists of about 20 burials. During the preliminary 2004 excavations conducted by the Department of Anthropology and Archaeology, National University of Mongolia, 7 graves were unearthed. In grave 1 (2004), the skeleton of a woman 40 yr old, wearing golden rings with the inscription of a Siberian falcon, was found together with other ornamental artifacts. In grave 2 (2004), a man with a gold-gilded saddle and a horse were buried. Adornments strongly indicate that these burials date to the Great Mongol Empire period and may relate to the Golden Horde lineage of Genghis Khan. Initial accelerator mass spectrometry (AMS) radiocarbon dating of wood from a coffin at burial 2004–6 (Table 1) gave an age of 860 ± 60 BP, and the age of a human bone sample from burial 2004–1 was determined as 890 ± 40 BP. Subsequent excavations yielded 13 samples for 14C dating, and 7 of them have been dated thus far. The calibrated dates were in the range of AD 1130–1250, which is in agreement with Genghis Khan's life span. Artifacts strongly suggest that these burials belong to nobility or members of the royal family. Given that such burials are hard to find, the Tavan Tolgoi site is expected to yield important archaeological and historical information. In this paper, the historical importance of the artifacts recovered is discussed in light of 14C dating and the results of additional scientific analyses.
Late Holocene Natural and Human-Induced Environmental Change Reconstructed from Peat Records in Eastern Central China
Authors: Zhao Yan , Hölzer Adam , Yu Zicheng
Published: July 2016

We present a high-resolution multiproxy record (geochemistry, macrofossil, and pollen) from a peatland in the Dajiuhu Basin in eastern central China. The chronology of the 120-cm peat profile was controlled by 6 accelerator mass spectrometry (AMS) 14C dates on plant remains, including 2 post-bomb dates. The age model was based on linear interpolations of calibrated ages. Plant macrofossil results indicate a major transition around 3600 cal BP from Sphagnum section Subsecunda and Drepanocladus sp. to Sphagnum imbricatum dominance, followed by the disappearance of S. imbricatum at 700 cal BP. These changes suggest a general sequence of local environment changes from a wet fen, through a Sphagnum-dominated peatland, to a dry sedge-dominated marsh, which are also reflected by change in peat lithology and composition. The drying trend after 3600 cal BP is in general agreement with the speleothem isotope record from this region and other paleoclimate records from east China, indicating a weakening summer monsoon resulting from a decrease in summer insolation. The shift to a dry environment at 700 cal BP might have been caused by human activities. Appearance of Cerealia pollen at 3600–3200 cal BP suggests the first introduction of crop farming in the region, while its absence at 3200–2000 cal BP could be attributed to abandonment of farmland. The increase of Ti and Si since 1300 cal BP may be related to agricultural activity and landscape erosion. A 2-step increase in Pb concentration at 1600 and 600 cal BP suggests 2 phases of industrial pollution intensity.
Frequency Distribution of Radiocarbon Dates as a Tool for Reconstructing Environmental Changes
Authors: Michczyńska Danuta J , Michczyński Adam , Pazdur Anna
Published: July 2016

Large sets of radiocarbon dates of 1019 peat, 155 speleothem, and 100 tufa samples, as well as dates of 330 fluvial samples, were investigated in order to estimate environmental variability during the last 16,000 calendar years in Poland. All 14C dating was carried out in the Gliwice Radiocarbon Laboratory, and results are stored in the RoS database. Probability density functions (PDFs) were created by summing up (on the calendar timescale) individual age probability distributions of all dates for different types of material and for different regions of Poland. We used an updated version of the Gliwice Radiocarbon Laboratory calibration program GdCALIB. The 14C dates were calibrated using the IntCal04 calibration curve (Reimer et al. 2004), and results were compared with other paleoenvironmental records. The authors conclude that analyzing PDFs of different types of sediments can be helpful in the qualitative reconstruction of the past environment. The PDF for peat samples primarily reflects paleohydrological conditions; the PDFs for speleothem and tufa samples reflect changes in temperature and humidity, while analysis of the PDF created for fluvial data is in a general agreement with the PDFs constructed for peat samples.
Natural Climate Variability During the Holocene
Authors: Dergachev V A , Raspopov O M , Damblon F , Jungner H , Zaitseva G I
Published: July 2016

High-precision radiocarbon age calibration for different terrestrial samples allows us to establish accurate boundaries for many climatic time series. At the same time, the fluctuations of 14C content reflect solar variability. A bispectrum analysis of long-term series of the 14C content deduced from decadal measurements in tree rings demonstrates the existence of amplitude modulation, with a period of main modulation of ∼2400 yr. In 14C time series for the last 11 kyr, major oscillations are distinguished at 8.5–7.8, 5.4–4.7, 2.6–2.2, and 1.1–0.4 cal kyr BP with ∼2400-yr periodicity. High amplitudes in cosmogenic isotope content with a periodicity of about 2400 yr appear synchronous to cooling events documented in Greenland ice cores, to the timing of worldwide Holocene glacier expansion, and to the periods of lake-level changes. This paper focuses on revealing solar forcing on the Earth's climate and about the nature, significance, and impact of sharp Holocene climate variability on human societies and civilizations.
Methods of Separating Soil Carbon Pools Affect the Chemistry and Turnover Time of Isolated Fractions
Authors: Castanha Cristina , Trumbore Susan , Amundson Ronald
Published: July 2016

A variety of physical and chemical techniques are used to fractionate soil organic matter, but detailed comparisons of the different approaches and tests of how separation methods influence the properties of isolated organic matter pools are lacking. In this case study based on A horizon samples of 2 California coniferous forests soils, we 1) evaluate the effects of root removal and ultrasonic dispersion on the properties of the <2 g cm-3 light fraction and 2) compare the properties of fractions obtained by sequential density separations of ultrasonically treated soil with those obtained by density followed by acid/base hydrolysis (Trumbore et al. 1996).

A root-removal effort based on hand-picking visible roots reduced the radiocarbon content and increased the estimated turnover time of the light fraction by roughly 12%. Root-removal protocols that vary between investigators thus can potentially confound variability in carbon cycling for this fraction caused by environmental factors, such as climate. Ultrasonic dispersion did not have a clear effect on the light fraction C and N content or isotopic signature, but led to a decrease in the % C and C/N of the recovered heavy fractions, and losses of 12–19% of the total soil C to the sodium metatungstate density solution.

Sequentially isolated density fractions clearly differed in mineralogy and organic matter chemistry, but natural-abundance 14C analyses indicated that distinct mineral phases did not correspond to unique C-turnover pools. Density fractions containing kaolinite group minerals alone and in combination with hydroxy-interlayered vermiculite were found to harbor both fast and slow cycling carbon. In contrast, severe chemical treatment isolated a carbon pool with the lowest overall 14C content and longest inferred mean turnover time. Overall, our results show that care must be taken when relying on physical (density) separation to isolate soil fractions with different dynamics, as the details of treatment will influence the results.
Radiocarbon Reservoir Ages and Hardwater Effect for the Northeastern Coastal Waters of Argentina
Authors: Gómez Eduardo A , Borel C Marcela , Aguirre Marina L , Martínez Daniel E
Published: July 2016

Accelerator mass spectrometry (AMS) radiocarbon dates were obtained for 18 mollusk shells collected alive along the Buenos Aires province coast, Argentina, over the period AD 1914–1935. Reservoir ages were estimated for all samples on the basis of the tree-ring calibration curve for the Southern Hemisphere (SHCal04, McCormac et al. 2004) and the marine δR values calculated as the difference between the conventional 14C age and the age deduced from the marine, mixed-layer model calculation (Marine04, Hughen et al. 2004). For most coastal locations, a great δR scatter was observed, ranging from 191 to 2482 yr, which is explained by the input of varying content of dissolved carbonate by rivers and groundwater (“hardwater effect”) and indicates a serious limitation for shell-based 14C chronologies. Within the interior of Bahía Blanca estuary, δR values ranged from −40 to 50 ± 46 as a consequence of the local geological particularities of the environment. This suggests that, with some restrictions, the marine calibration curve with standard parameters (δR = 0) could be used at this location.
Comparison of Oceanic Δ14C Data with Those of GEOSECS: Vertical Profiles in 1973 (GEOSECS) and in 1980 at (30° N, 170° E) in the Northwestern Pacific Ocean
Authors: Gamo Toshitaka , Horibe Yoshio , Kobayashi Hiromi
Published: July 2016

The vertical profile of radiocarbon at (30° N, 170° E) measured in 1980 was compared with the GEOSECS data measured in 1973. 14C was extracted from 200L of sea water, converted to C2H2, and analyzed with a gas proportional counter. Our profile and that of GEOSECS were in good agreement below 700m depth without systematic deviation of Δ14C values between both measurements. On the other hand, a Δ14C increase was observed above 700m depth, reflecting the transient addition, in 6.6 years, of bomb 14C to the intermediate layer from the atmosphere.
Vienna Radium Institute Radiocarbon Dates XVI
Authors: Felber Heinz
Published: July 2016

Measurements have continued with the same proportional counter system, pretreatment procedure, methane preparation and measurement, and calculation, as described previously (R, 1970, v 12, no. 1, p 298–318). Uncertainties quoted are single standard deviations. No 13C/12C ratios were measured. Sample descriptions have been prepared in cooperation with submitters. Some dates have been calibrated using the correction tables of Klein et al (1982) and are reported as “cal” ages in the comment.
University of Wisconsin Radiocarbon Dates XXIV
Authors: Steventon Raymond L , Kutzbach John E
Published: July 2016

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH—NA4P2O7 and dilute H3PO4 before conversion to the counting gas methane; when noted, marls and lake cores are treated with acid only. Very calcareous materials are treated with HCL instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCL for 15 minutes, then dilute NaOH—Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCL, NaOH—Na4P2O7, and then dilute HCL again.
Gif Natural Radiocarbon Measurements XI
Authors: Delibrias Georgette , Guillier Marie-Therese
Published: July 2016

This list is part of a program of publishing our large backlog of unpublished dates. The dates listed here, from 1974 to 1979, include archaeologic samples from various cultures and countries and geologic samples related to sea-level variations, volcanism, and especially the history of paleolakes in Africa.
Radiocarbon Dating of the Amphipolis Bridge in Northern Greece, Maintained and Functioned for 2500 Years
Authors: Maniatis Y , Malamidou D , Koukouli-Chryssanthaki H , Facorellis Y
Published: July 2016

The remains of a wooden construction, recovered in the 1970s at the northwest sector of the walls of the ancient city of Amphipolis (northern Greece), have been recognized as foundation remains of a wooden bridge described by Thucydides in his description of the events that took place at Amphipolis in 424–422 BC, during the Peloponnesian War. Frequent repairs in the Roman, Byzantine, and even Ottoman periods are very probable. In the last 10 yr, conservation has been done to enhance this unique monument. This work involves systematic investigation with radiocarbon dating of all the verified or suspected phases of this wooden bridge. The dating results reveal the beginning of construction most probably in the Archaic period and confirm beyond a doubt that the major construction phase took place in Classical times. Successive phases, related to repairs rather than to major reconstructions, have been detected during the Hellenistic, Roman, Early Christian, and Byzantine periods as well as the Ottoman era. The combined archaeometric and archaeological evidence leads to the remarkable conclusion that this bridge was functioning for about 2500 yr.
Carbon Isotope Measurements of Surface Seawater from a Time-Series Site Off Southern California
Authors: Hinger Elise N , Santos Guaciara M , Druffel Ellen R M , Griffin Sheila
Published: July 2016

We report carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from a time-series site off the Newport Beach Pier in Orange County, California. These data represent the first time series of Δ14C data for a coastal southern California site. From a suite of samples collected daily from 16 October to 11 November 2004, Δ14C values averaged 32.1 ± 4.4‰. Freshwater input from the Santa Ana River to our site caused Δ14C and δ13C values to decrease. Since this initial set of measurements, a time-series site has been maintained from November 2004 to the present. Surface seawater has been collected bimonthly and analyzed for Δ14C, δ13C, salinity, and ΣCO2 concentrations. Water samples from the Santa Ana River were collected during the wet season. California sea mussels and barnacle shells, ranging from 4 to 6 months old, were also collected and analyzed. Results from May 2005 to January 2008 show no long-term changes in δ13C DIC values. Δ14C DIC values over the 2005–2006 period averaged 33.7‰; high Δ14C values were observed sporadically (every 6–7 months), suggesting the presence of open water eddies at our site. Finally, in 2007, a stronger upwelling signal was apparent as indicated by correlations between Δ14C, salinity, and the Bakun index, suggesting that the Δ14C record is an indicator of upwelling in the Southern California Bight.
A New 1MV AMS Facility at KIGAM
Authors: Hong Wan , Park Jung Hun , Sung Ki Suk , Woo Hyung Joo , Kim Jun Kon , Choi Han Woo , Kim Gi Dong
Published: July 2016

A 1MV AMS was installed in KIGAM (Korea Institute of Geoscience and Mineral Resources). After 4 months of installation, the AMS started normal operation from January 2008. This multi-element AMS was developed by HVEE to measure 14C, 10Be, and 26Al. The results of an acceptance test demonstrate that this machine is capable of routine 14C age dating and of measurements of other radioisotopes in terms of accuracy and precision as well as the background level. After installation, an investigation aimed at determining the stable operating conditions was conducted, and background levels were determined to be as low as 10–15 for 14C and 10–14 for 10Be and 26Al.
MICADAS: Routine and High-Precision Radiocarbon Dating
Authors: Wacker L , Bonani G , Friedrich M , Hajdas I , Kromer B , Němec M , Ruff M , Suter M , Synal H-A , Vockenhuber C
Published: July 2016

The prototype mini carbon dating system (MICADAS) at ETH Zurich has been in routine operation for almost 2 yr. Because of its simple and compact layout, setting up a radiocarbon measurement is fast and the system runs very reliably over days or even weeks without retuning. The stability of the instrument is responsible for the good performance in highest-precision measurements where results of single samples can be reproduced within less than 2‰. The measurements are described and the performance of MICADAS is demonstrated on measured data.
Upland Olive Domestication in the Chalcolithic Period: New 14C Determinations from El-Khawarij (Ajlun), Jordan
Authors: Lovell Jaimie L , Meadows John , Jacobsen Geraldine E
Published: July 2016

New radiocarbon results on olive stones from el-Khawarij date olive cultivation at this site, in the Jordanian highlands, to the last 2 centuries of the 5th millennium cal BC. This period also sees the emergence of olive cultivation at Teleilat Ghassul, by the Dead Sea. The 10 new AMS dates were deliberately obtained from carbonized olive stones in order to date the exploitation of olives at el-Khawarij, a late prehistoric settlement believed to have been reliant on olive production. The results reveal a much longer span of occupation than hitherto suspected, including 2 dates that may fall later than 3900 cal BC (particularly OZI221, 3950–3530 cal BC). These later dates are in line with dates from other upland sites in the region, and may strengthen suggestions that Chalcolithic settlement persisted for longer in better watered upland areas (Lovell 2002). Further, an early date from a sample in a rock-cut installation in Area A suggests a much earlier date for occupation at the site, implying that upland olive exploitation may have commenced before 4700–4450 cal BC.
Establishing a Firm Chronological Framework for Neolithic and Early Dynastic Archaeology in the Shangluo Area, Central China
Authors: Zhu Yizhi , Cheng Peng , Yu Shi-Yong , Yu Huagui , Kang Zhihai , Yang Yachang , Jull A J T , Lange T , Zhou Weijian
Published: July 2016

Technological and theoretical advancements in modern radiocarbon chronology make the precise dating of archaeological and geological events possible. Here, we show examples of how these state-of-the-art methods can be used to establish and refine the archaeological cultural chronology for the Shangluo area in the Qinling Mountains of central China. In this study, the Donglongshan and Zijing sites were dated using the high-precision accelerator mass spectrometry (AMS) 14C method. Also, detailed magnetic-susceptibility measurements were conducted at both sites to gain preliminary information about past climate changes. The 14C dates, after being treated with Bayesian statistics, provide a firm constraint on the archaeological chronological framework for this area. Within this framework, the Malan loess-Holocene soil transition can be placed at 10,400–10,090 BC, while the duration of the Yangshao and Longshan cultures was dated to ∼4200–2900 and ∼2900–2100 BC, respectively, revealing an undisrupted history of human occupation in this area until the early dynastic period. Magnetic susceptibility values began to increase in the early Holocene, indicating a progressive amelioration of regional climate. The widespread development of paleosol during the middle Holocene indicates that warm and wet climate conditions prevailed, providing a favorable environmental context within which the Yangshao culture thrived. Magnetic susceptibility values then decreased from ∼2100 BC when the Xia Dynasty started, and loess accumulated again, pointing to cooling and drying climate conditions that may have led to a cultural transition from the Neolithic to the dynastic civilization.
Radiocarbon Dating of Individual Amino Acids from Archaeological Bone Collagen
Authors: McCullagh James S O , Marom Anat , Hedges Robert E M
Published: July 2016

Since the development of accelerator mass spectrometry (AMS) for radiocarbon dating in the late 1970s, its ability to date small samples of bone has been of huge importance in archaeology and Quaternary paleoecology. The conventional approach to sample preparation has been to extract and gelatinize protein, which is then combusted and graphitized for analysis. However, this “bulk protein” can contain a heterogeneous mixture of non-collagenous molecules, including humic acids and other soil components that may be of a different age than the bone and therefore affect the accuracy of its 14C date. Sample pretreatment methods have been an important area of development in recent years but still show inadequacies for the dating of severely contaminated bone. The idea of isolating and dating individual compounds such as single amino acids, to improve dating accuracy, has been discussed in the literature since the 1960s. Hydroxyproline, for example, makes up over 10% of bone collagen but is extremely rare in most other animal proteins, increasing the chances of its presence being endogenous to the individual being dated. Its successful isolation has therefore been considered a potential “gold standard” for dating archaeological bone; however, extracting and suitably purifying single amino acids from bone has proved a challenging task.