bluuebunny/crossref_metadata_2025 huggingface dataset:
Stable Carbon Isotope Measurements on Hair from Wild Animals from Altiplanic Environments of Jujuy, Argentina
Authors: Panarello Héctor O , Fernández C Jorge
Published: July 2016

The use of stable carbon isotopes as dietary tracers is an application that is widening its scope within the fields of ecology and paleoecology. Although hair is potentially one of the most favorable animal tissues for isotopic measurement for dietary studies, this tissue is rarely included in research works. This may be due to the fact that many aspects related to hair tissue are not fully understood, especially in the case of wild animals whose diets consist of plants with contrasting 13C/12C ratios, their abundance depending on seasonality. The present isotopic study of hair from animals inhabiting the Andes in northwestern Argentina, at heights ranging from 3500 to about 5000 m above sea level (asl) shows that 1) δ13C values measured on hair from herbivores with a mixed and isotopically contrasting diet, and from their carnivorous predators, differ in their respective trophic levels, 2) in primary consumers, different types of hair from the same individual have different δ13C values, whereas hair values are homogeneous in carnivores, and 3) some types of hair from rodents, such as whiskers, show δ13C values similar to those of less metabolically active tissues such as bone collagen.
Investigation of a Chinese Ink Rubbing by 14C AMS Analysis
Authors: Yuan Hong-Chien , Kutschera Walter , Lin Tze-Yue , Steier Peter , Vockenhuber Christof , Maria Wild Eva
Published: July 2016

The date of a Chinese ink rubbing was determined using radiocarbon accelerator mass spectrometry (AMS) to be in the range from AD 1480 to AD 1670 (95.4% confidence limit). Together with a scanning electron miscroscope (SEM) analysis of the ink and a comparative study of the Chinese characters, it was determined that the ink rubbing must have been performed before Emperor Kang Hsi (AD 1662–1722), who ruled at the beginning of the Chin Dynasty. On the other hand, the stone stele, from which the ink rubbing was produced, was carved in AD 531, which is consistent with an analysis of some erased characters. Such analysis seems to be useful to help clarify possible forgeries of these art objects.
Radiocarbon Dating of Individual Fatty Acids as a Tool for Refining Antarctic Margin Sediment Chronologies
Authors: Ohkouchi Naohiko , Eglinton Timothy I , Hayes John M
Published: July 2016

We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C14, C16, and C18) fatty acids isolated from Ross Sea surface sediments. The corresponding14C ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular14C variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular14C chronology suggests that the accumulation rate of relict organic matter has not changed during the last 50014C yr. The focus of this study is to determine the validity of compound-specific14C analysis as a technique for reconstructing chronologies of Antarctic margin sediments.
El Mirón Cave and the 14C Chronology of Cantabrian Spain
Authors: Guy Straus Lawrence , González Morales Manuel
Published: July 2016

Excavations since 1996 in the large El Mirón Cave in the Cantabrian Cordillera of northern Spain have revealed a cultural sequence of late Mousterian, early Upper Paleolithic, Solutrean, Magdalenian, Azilian, Mesolithic, Neolithic, Chalcolithic, Bronze Age, and Medieval occupations. These components have been dated by 51 generally coherent radiocarbon determinations, all run by the Geochron labs, in association with the Lawrence Livermore labs for AMS. This series is one of the largest for a single prehistoric site in Iberia or even Europe. The series is consistent with the record from Cantabrian Spain and provides new detail on the age of the Middle–Upper Paleolithic transition, on the various phases of the Magdalenian culture, on the appearance of the Neolithic in the Atlantic zone of Spain, and on the origins of the socioeconomic complexity in the metal ages. The stratigraphic relationship of 14C-dated levels to a roof-fall block and adjacent cave walls (both with engravings) provides rare terminus post and ante quem ages for execution of the rupestral art in El Mirón during the early to mid Magdalenian. The 14C record has also been instrumental in revealing the existence of depositional hiati during the early Holocene.
Bomb Radiocarbon in Tree Rings from Northern New South Wales, Australia: Implications for Dendrochronology, Atmospheric Transport, and Air-Sea Exchange of CO2
Authors: Hua Quan , Barbetti Mike , Zoppi Ugo , Chapman David M , Thomson Bruce
Published: July 2016

We have analyzed by radiocarbon 27 consecutive single rings, starting from AD 1952, of a preliminarily cross-dated section (DFR 021) of Pinus radiata, which grew in Armidale, northern New South Wales, Australia. The bomb 14C results suggested the possibility of 2 false rings, and, consequently, 2 misidentified rings in the preliminary count for this section. This possibility was supported by a better ring-width correlation between the revised DFR 021 count and other Pinus radiata chronologies in the study region. This indicated that bomb 14C is a useful tool to complement the standard techniques of dendrochronology in tree species where annual rings are not always clearly defined.
Freshwater Reservoir Effect in14C Dates of Food Residue on Pottery
Authors: Fischer Anders , Heinemeier Jan
Published: July 2016

Radiocarbon dates of food residue on pottery from northern European inland areas seem to be influenced significantly by the freshwater reservoir effect (“hardwater” effect) stemming from fish and mollusks cooked in the pots. Bones of freshwater fish from Stone Age åmose, Denmark, are demonstrated to be 100 to 50014C yr older than their archaeological context. Likewise, food residues on cooking pots, seemingly used for the preparation of freshwater fish, are shown to have14C age excesses of up to 300 yr. It is probable that age excesses of similar or even larger magnitude are involved in food residue dates from other periods and regions. Since this effect cannot, so far, be quantified and corrected for,14C dating of food residue, which may potentially include material from freshwater ecosystems, should be treated with reserve.
14C Ages of a Varved Last Glacial Maximum Section Off Pakistan
Authors: von Rad Ulrich , Sarnthein Michael , Grootes Pieter M , Doose-Rolinski Heidi , Erbacher Jochen
Published: July 2016

In a core off Pakistan, we obtained 38 14C analyses by accelerator mass spectrometry (AMS) from a 4.4-m-thick, expanded, annually-laminated Last Glacial Maximum (LGM) section, bracketed by bioturbated intervals ascribed to the Heinrich-1 (H1) and Heinrich-2 (H2) equivalent events (52 14C analyses between 24–15 kyr BP). A floating varve age scale, anchored to the oxygen isotope record of the layer-counted GISP2 ice core at the H2/LGM boundary, results in an annually dated record for the LGM from 23,450–17,900 cal BP. The floating varve scale of the LGM provides us with a tentative calibration of local marine AMS 14C age dates to calendar years.
AMS Dating of Pollen Concentrates—A Methodological Study of Late Quaternary Sediments from South Westland, New Zealand
Authors: Vandergoes Marcus J , Prior Christine A
Published: July 2016

A simple method for preparing pollen concentrates for14C AMS dating is applied to organic and inorganic deposits from a peat bog in south Westland, New Zealand, from which preliminary AMS dating indicated age inversions and severe younger carbon contamination problems. The AMS ages of the pollen concentrates provided consistently older age estimates for each sample than ages derived from their respective organic residue or combined pollen and organic residue fractions. It is likely that the younger age estimates of the organic residue fractions result from the incorporation of younger plant material into the sample and possible contamination from younger humic acids percolating through the site.
Characterizing the Error in the Estimated Age-Depth Relationship
Authors: Solow Andrew R
Published: July 2016

It is common practice to estimate the age of undated material extracted from a sediment core from radiocarbon or other radiometric dates of samples taken above and below the extracted material. This paper presents a simple expression for the variance of this estimated age. This variance accounts for both 14C dating error and error due to bioturbation.
The Tropospheric 14CO2 Level in Mid-Latitudes of the Northern Hemisphere (1959–2003)
Authors: Levin Ingeborg , Kromer Bernd
Published: July 2016

A comprehensive tropospheric 14CO2 data set of quasi-continuous observations covering the time span from 1959 to 2003 is presented. Samples were collected at 3 European mountain sites at height levels of 1205 m (Schauinsland), 1800 m (Vermunt), and 3450 m asl (Jungfraujoch), and analyzed in the Heidelberg Radiocarbon Laboratory. The data set from Jungfraujoch (1986–2003) is considered to represent the free tropospheric background level at mid-latitudes of the Northern Hemisphere, as it compares well with recent (yet unpublished) measurements made at the marine baseline station Mace Head (west coast of Ireland). The Vermunt and Schauinsland records are significantly influenced by regional European fossil fuel CO2 emissions. The respective Δ14CO2 depletions, on an annual mean basis, are, however, only 5 less than at Jungfraujoch. Vermunt and Schauinsland both represent the mean continental European troposphere.
AMS Dating on the Shell Bar Section from Qaidam Basin, Ne Tibetan Plateau, China
Authors: Zhang H C , Fan H F , Chang F Q , Zhang W X , Lei G L , Yang M S , Lei Y B , Yang L Q
Published: July 2016

Radiocarbon dating by accelerator mass spectrometry (AMS) of the shell bar section of Qaidam Basin, NE Tibetan Plateau, shows that this section was formed between ~39.7 and ~17.5 14C kyr BP and represented the highest paleolake development period since the Late Pleistocene. It was difficult to obtain reliable dates due to the low organic carbon content, which was formed mainly by authochtonous algae-bacteria (Zhang et al. 2007a). In order to improve the dating, 14C ages of both the alkali residual and acid-soluble components of the organic carbon were measured to check the consistency of the dating results. Total organic carbon (TOC) content and stable carbon isotopes (δ13Corg) might also be used as critical references for checking the reliability of dates. For example, in our study of the shell bar section from Qaidam Basin, we found that when the TOC content was higher than 0.15% and/or δ13Corg was lower than −23, the AMS dates were reliable. AMS dating of fossil shells demonstrated that they could provide valuable age information. The ages given by fossil shells are comparable to those of bulk carbonate from a similar sampling site, and are about 15~18 kyr older than the ages given by organic matter. Due to the U/Th dating requirements and open nature of the system, we concluded that U/Th dating results are unreliable and that this technique is unsuitable for dating halite deposits from Qaidam Basin.
Marine Reservoir Corrections: St. Helena, South Atlantic Ocean
Authors: Lewis Colin A , Reimer Paula J , Reimer Ron W
Published: July 2016

We present the first marine reservoir age and δR determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and δR determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman's button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815-1835.
Radiocarbon and the Old World Archaeology: Shaping a Chronological Framework
Authors: Kuzmin Yaroslav V
Published: July 2016

The inception of the radiocarbon dating method in 1949 was immediately supported by many archaeologists. In the following 2 decades, many important archaeological sites in the Old World were dated, marking the beginning of building a reliable chronological framework for prehistoric and early historic cultural complexes worldwide. The author presents an observation of some of the most important results in establishing a chronology for Old World archaeology, based on14C dating performed in the last 50 yr. An extensive bibliography should help scholars to get acquainted with early summaries on archaeological chronologies based on14C data and their evaluation, as well as with some recent examples of the application of14C dating in Old World archaeology.
The Iron Age Around the Mediterranean: A High Chronology Perspective from the Groningen Radiocarbon Database
Authors: van der Plicht Johannes , Bruins Hendrik J , Nijboer Albert J
Published: July 2016

In this paper, we present an overview of radiocarbon dating contributions from Groningen, concerning 9 sites from around the Mediterranean region: Israel, Sinai (Egypt), Jordan, Spain, Tunisia, and Italy. Full date lists of the 9 sites are presented. Our 14C dates are discussed in terms of present actual chronological debates. We show that all our 14C dates coherently support a “high chronology” for the Iron Age in each respective area of the Mediterranean region.
Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals
Authors: Burr G S , Beck J W , Corrège Thierry , Cabioch G , Taylor F W , Donahue D J
Published: July 2016

This paper presents radiocarbon results from modern South Pacific corals from the Marquesas Islands, Vanuatu, Papua New Guinea (PNG), and Easter Island. All of the measurements are from pre-bomb Porites corals that lived during the 1940s and 1950s. The data reflect subannual to multiannual surface ocean 14C variability and allow for precise, unambiguous reservoir age determinations. The results are compared with published values from other coral records throughout the South Pacific, with striking consistency. By comparisons with other published values, we identify 3 South Pacific regions with uniform pre-bomb reservoir ages (1945 to 1955). These are 1) the Central Equatorial South Pacific (361.6 − 8.2 14C yr, 2 σ); 2) the Western Equatorial South Pacific (322.1 − 8.6 14C yr, 2 σ); and 3) the subtropical Pacific (266.8 − 13.8 14C yr, 2 σ).
Dendrochronology and Radiocarbon Dating: The Laboratory of Tree-Ring Research Connection
Authors: Leavitt Steven W , Bannister Bryant
Published: July 2016

The field of dendrochronology had a developmental “head start” of at least several decades relative to the inception of radiocarbon dating in the late 1940s, but that evolution was sufficiently advanced so that unique capabilities of tree-ring science could assure success of the 14C enterprise. The Laboratory of Tree-Ring Research (LTRR) at the University of Arizona played a central role in the cross-pollination of these disciplines by providing the first wood samples of exactly known age for the early testing and establishment of the “Curve of Knowns” by Willard Libby. From the 1950s into the early 1980s, LTRR continued to contribute dated wood samples (bristlecone pine and other wood species) to 14C research and development, including the discovery and characterization of de Vries/Suess “wiggles,” calibration of the 14C timescale, and a variety of tests to understand the natural variability of 14C and to refine sample treatment for maximum accuracy. The long and varied relationship of LTRR with 14C initiatives has continued with LTRR contributions to high-resolution studies through the 1990s and systematic efforts now underway that may eventually extend the bristlecone pine chronology back beyond its beginning 8836 yr ago as of 2009. This relationship has been mutualistic such that a half-century ago the visibility and stature of LTRR and dendrochronology were also elevated through their association with 14C-allied “hard sciences.”
Major Patterns in the Neolithic Chronology of East Asia: Issues of the Origin of Pottery, Agriculture, and Civilization
Authors: Kuzmin Yaroslav V , Timothy Jull J A , Burr G S
Published: July 2016

General chronological frameworks created recently for the Neolithic complexes of China, Japan, Korea, and far eastern Russia allow us to reveal temporal patterns of Neolithization, origin of food production, and the emergence of civilizations. Pottery originated in East Asia, most probably independently in different parts of it, in the terminal Pleistocene, about 14,800–13,300 BP (uncalibrated), and this marks the beginning of the Neolithic. Agriculture in the eastern part of Asia emerged only in the Holocene. The earliest trace of millet cultivation in north China can now be placed at ∼9200 BP, and rice domestication in south China is dated to ∼8000 BP. Pottery in East Asia definitely preceded agriculture. The term “civilization,” which implies the presence of a state level of social organization and written language, has been misused by scholars who assert the existence of a very early “Yangtze River civilization” at about 6400–4200 cal BP. The earliest reliable evidence of writing in China is dated only to about 3900–3000 cal BP, and no “civilization” existed in East Asia prior to this time.
Pre-Bomb Surface Water Radiocarbon of the Gulf of Mexico and Caribbean as Recorded in Hermatypic Corals
Authors: Wagner Amy J , Guilderson Thomas P , Slowey Niall C , Cole Julia E
Published: July 2016

Radiocarbon measurements of hermatypic corals from 4 sites in the Gulf of Mexico (GOM) and Caribbean Sea were made to estimate the marine 14C reservoir age (R) and the marine regional correction (ΔR) for this region. Coral skeletal material from the Flower Garden Banks (northern GOM continental shelf), Veracruz, Mexico, and 2 reefs from the Cariaco Basin, Venezuela, were analyzed. Annual and subannual samples from 1945–1955 were milled and 14C composition was determined. In the Gulf of Mexico, average coral Δ14C is −52.6 ± 0.7‰ and average Δ14C for the Cariaco Basin corals is −53.4 ± 0.8‰. Average values for the marine reservoir age and ΔR are computed with this data and compared with results derived from previous measurements made in the same regions. These values are important in calibrating the 14C ages of carbonate samples from the area.
Radiocarbon and Stable Carbon Analysis of Dissolved Methane and Carbon Dioxide from the Profile of a Raised Peat Bog
Authors: Garnett M H , Hardie S M L , Murray C
Published: July 2016

We developed and tested a new method to separate CO2 and CH4 from bulk gas samples for radiocarbon and stable-carbon analysis that utilizes a zeolite molecular sieve. To validate the technique, tests were performed using a suite of standard gases, composed of CO2 and CH4 of distinctly different isotopic composition. We employed the method to investigate the carbon isotopic composition of samples of dissolved CO2 and CH4 collected in situ from the near surface to deep layers of an ombrotrophic raised peat bog. Results showed that the age of both the CO2 and CH4 components of the dissolved gases increased with depth from ≃0–300 BP at 0.25 m to ≃4000 BP at 4 m. CH4 was mainly similar or slightly older in age compared to CO2, with the greatest difference in ages occurring at 1 m depth where CH4 was older by 430–615 yr. The δ13C values of CO2 increased with depth from −12.4‰ and −8.0‰ at 0.25 m to +6.9‰ and +8.3‰ at 4 m, whereas the δ13C of CH4 stayed in the range −58.4‰ to −70.6‰. The 14C results from the deepest layers are consistent with a similar source for both gases. 14C ages for the CO2 component were younger compared to CH4, within the shallower depths of the peat bog (≤1 m) and demonstrate the incorporation of acrotelm-derived respired CO2 into the catotelm.
Iron Age Mediterranean Chronology: A Rejoinder
Authors: Fantalkin Alexander , Finkelstein Israel , Piasetzky Eli
Published: July 2016

This article is a rejoinder to a recent paper in this journal by van der Plicht et al. (2009) who use radiocarbon determinations from several sites in Israel, Italy, Spain, and Tunisia to advocate a High Chronology system for the entire Mediterranean Basin. We contend that they reached mistaken conclusions due to problematic selection of sites and data. We argue that a reliable way to provide absolute dates for the Iron Age in the central and western Mediterranean is by employing a combination of well-identified Greek pottery found in well-stratified sites and radiometric results from short-lived samples. For the time being, this combination exists only in the Levant, and provides an anchor for Greek chronology, which supports the Conventional Chronology for the Aegean Basin, which corresponds to the Low Chronology in the Levant.
An Improved Pretreatment Protocol for Radiocarbon Dating Black Pigments in San Rock Art
Authors: Bonneau A , Brock F , Higham T , Pearce D G , Pollard A M
Published: July 2016

The dating of South African rock art using radiocarbon is a considerable challenge and only 1 direct date has so far been obtained, on black pigments from Sonia's Cave Upper, Boontjieskloof. The main problem with direct dating these paintings is the presence of calcium oxalates behind, on, and within the pigment layers. Calcium oxalates are formed through lichen and bacterial action on the rock face. These reactions can sometimes take place over long periods and can incorporate carbon of a younger age into the pigments. This study aims to date black pigments from a rockshelter, RSA TYN2 (Eastern Cape, South Africa), by removing the calcium oxalate contamination. Two different protocols were tried: density separation and acidification. The latter successfully removed calcium oxalates and was therefore applied to 3 black pigment samples from the rockshelter. After acid pretreatment, accelerator mass spectrometry (AMS) dating was undertaken on the remaining residues. Three results were obtained (2072 ± 28 BP, 2100 ± 40 BP, and 2083 ± 32 BP), which constitute the oldest results so far obtained for direct dates on South African rock art. The most likely calibrated date range for the painting at this site is between 2120 and 1890 cal BP. The ages are in close agreement with each other and this consistency suggests that our preparation protocol has successfully removed the majority of the carbon contaminants.
AMS Radiocarbon Dating Problems Between 10 and 8 Ka BP in Lacustrine Deposits from Lake Gun Nur, Northern Mongolia
Authors: Chang F Q , Zhang H C , Ming Q Z , Chen G J , Zhang W X , Shi Z T , Feng Z D
Published: July 2016

Accelerator mass spectrometry (AMS) radiocarbon dating a continuous core from Lake Gun Nur, northern Mongolia, shows a period between 10 and 8 ka BP that could not be dated accurately. Further dating on alkali-insoluble residue and humic acid from the same samples in the Gun Nur core suggest that this AMS 14C date anomaly is neither analytical nor material related. We hypothesize that the 14C anomaly may be derived from increasing production rates of 14C caused by diminished solar activity, a low 14CO2/14CO ratio in the atmosphere, or an unstable 14C flux in the lower atmosphere caused by changing geomagnetic field strength. Our results imply that the 14C data used for 14C age calibration cannot correct the age-depth regression between 8 and 10 ka BP to fit the age-depth model along with other time intervals.
Interlaboratory Variability of Radiocarbon Results Obtained from Blind AMS Analyses on Several Modern Carbon Samples
Authors: Norton Glenn A
Published: July 2016

Three samples of modern-day vegetation collected in 2009–2010 and a sample of bioethanol produced in 2010 were analyzed for radiocarbon by 5 different accelerator mass spectrometry (AMS) laboratories in a blind analysis study. The magnitude of any variability in the reported results for percent modern carbon (pMC) was observed. Results indicated that the interlaboratory repeatability on the samples of vegetation was generally very good, varying by no more than ~1 pMC for 2 of the 3 samples. Results for the bioethanol were less consistent, and varied by 5.5 pMC (ranging from 101.9 to 107.4 pMC). Variations in the δ13C values used to correct for isotopic fractionation did not account for the variability observed in the pMC values for this sample. In view of the homogeneity of the bioethanol and its inherent simplicity in composition, this suggests that volatile liquid fuels may be more difficult to prepare for analysis without incurring significant sample processing errors. When viewing all of the results as a whole, the analytical errors (incorporating both instrumental and sample processing errors) appeared to be more random than systematic in nature. Because of analytical uncertainties in pMC measurements, as well as inherent local and regional variations in 14C activity levels known to occur in modern-day biomass, there is not a precise (accurate to 2 decimal places) correction factor for negating the bomb carbon effect that is applicable to all biofuels or other biobased products being analyzed in accordance with ASTM Method D6866. Therefore, a reasonable correction factor (currently set at 0.95) needs to be consistently applied in order to make comparisons of biobased content data from different laboratories more valid. Results from this study indicate that, for samples containing predominantly modern carbon, reporting results to the nearest 0.1 pMC is not warranted.
Radiocarbon, Soil, and Artifact Chronologies for An Early Southern Oregon Coastal Site
Authors: Hall Roberta , Davis Loren G , Willis Samuel , Fillmore Matthew
Published: July 2016

Radiocarbon dates together with geoarchaeological, soil, and lithic analyses are presented to describe archaeological site 35-CS-9 in Bandon Ocean Wayside State Park, Oregon, northwestern USA. One of the few Oregon middle-Holocene coastal sites that includes sediments and artifacts dating to the early Holocene and possibly to the late Pleistocene, it was recorded in 1951 and surface surveyed by archaeologists in 1975, 1986, and 1991, but its depth and antiquity were not tested. In February 2002, we studied the site's stratigraphy and sediments and described 8 strata from the aeolian surface to bedrock at 350 cm depth. Soil samples taken from a cut bank for texture classification, particle size analysis, pH, carbon content, and chemical analysis suggested that the site represented a complete history of Holocene deposits. Excavation of 2 test units in August 2002 uncovered substantial lithic and charcoal remains that confirm a protracted middle-Holocene occupation and suggest that human occupation began in the early Holocene. Charcoal recovered at 235–245 cm dated to 11,000 14C BP, and the deepest lithic artifact was recovered in a level at 215–225 cm. Whether the human occupation was continuous throughout the Holocene, and whether it began in the early Holocene or in the late Pleistocene, can only be determined with further excavations.
Progress in AMS Target Production of Sub-Milligram Samples at the NERC Radiocarbon Laboratory
Authors: Ertunç Tanya , Xu Sheng , Bryant Charlotte L , Maden Colin , Murray Callum , Currie Margaret , Freeman Stewart P H T
Published: July 2016

Recent progress in graphite target production for sub-milligram environmental samples in our facility is presented. We describe an optimized hydrolysis procedure now routinely used for the preparation of CO2 from inorganic samples, a new high-vacuum line dedicated to small sample processing (combining sample distillation and graphitization units), as well as a modified graphitization procedure. Although measurements of graphite targets as small as 35 μg C have been achieved, system background and measurement uncertainties increase significantly below 150 μg C. As target lifetime can become critically short for targets <150 μg C, the facility currently only processes inorganic samples down to 150 μg C. All radiocarbon measurements are made at the Scottish Universities Environmental Research Centre (SUERC) accelerator mass spectrometry (AMS) facility. Sample processing and analysis are labor-intensive, taking approximately 3 times longer than samples ≥ 500 μg C. The technical details of the new system, graphitization yield, fractionation introduced during the process, and the system blank are discussed in detail.
Coastal Upwelling and Radiocarbon—Evidence for Temporal Fluctuations in Ocean Reservoir Effect off Portugal During the Holocene
Authors: Soares António M Monge , Dias João M Alveirinho
Published: July 2016

This paper focuses on the use of the radiocarbon content of marine shells collected along the Portuguese coast as a proxy for the intensity of coastal upwelling off of Portugal. Differences in the 14C ages of closely associated marine mollusk shells and terrestrial material (charcoal or bones) from several Portuguese archaeological contexts seem to be significant throughout the Holocene. ΔR values range from 940 ± 50 to −160 ± 40 14C yr. Five of these values are significantly higher than the modern value (250 ± 25 14C yr), while the remaining values are lower. The modern value was calculated by measuring the 14C content of live-collected, pre-bomb marine mollusk shells. This value is in accordance with an active upwelling of strong intensity that currently occurs off of Portugal. Some primary observations based on data presented here can be made: i) during the Holocene important changes have occurred in the ocean reservoir effect off the Portuguese coast; ii) these fluctuations may be correlated with regional oceanographic changes, namely with changes in the strength of coastal upwelling; and iii) these changes suggest some sort of variability of the climatic factors forcing coastal upwelling off of Portugal.
Time-Dependent Factors Inherent in the Age Equation for Determining Residence Times of Groundwater Using 14C: A Procedure to Compensate for the Past Variability of 14C in Atmospheric Carbon Dioxide, with Application to the Wairau Deep Aquifer, Marlborough, New Zealand
Authors: Taylor Claude B
Published: July 2016

The radiocarbon concentration of dissolved inorganic carbon in groundwater is most logically and completely represented as the product of 5 time-variable factors; these are mutually independent, and all must be considered and evaluated to determine a groundwater residence time. In the case of one factor, the 14C/(12C+13C) ratio of atmospheric CO2, its time variability can be side-stepped by assuming it to be constant at the pre-bomb 1950 value, and assigning an apparent half-life in the radioactive decay term. Apparent half-lives are calculated here for 5 separate periods extending back to 24,000 BP, working from the INTCAL98 atmospheric calibration. This approach can be extended further back in time when the necessary atmospheric calibrations are updated with greater certainty. The procedure is applied to the recently-explored Wairau Deep Aquifer, underlying central areas of the coastal Wairau Plain, Marlborough. The evolution of dissolved inorganic carbon concentration for this river-recharged groundwater is apparent from distinct trends in 13C, and is confirmed by hydrochemical modelling. Extension to the 14C concentrations yields minimum/maximum limits for groundwater residence times to 3 wells. In all 3 cases, the maximum is uncertain due to present uncertainty of the apparent half-life applicable before 24,000 BP. Residence times for the 2 wells closest to the recharge area are at least 17,400 yr, while that for a well further down the aquifer is at least 38,500 yr. Recharge, therefore, occurred during the Otiran glaciation, while the present-day near-surface fluvioglacial deposits of the Wairau Plain were accumulating. Drawdown-recovery records over 3 yr indicate a permeable connection to compensating recharge, enabling limited exploitation for vineyard irrigation.
Oceanic Radiocarbon and Tritium On A Transect Between Australia and Bali (Eastern Indian Ocean)
Authors: Leboucher Viviane , Jean-Baptiste Philippe , Fourré Elise , Arnold Maurice , Fieux Michèle
Published: July 2016

Results are presented of radiocarbon and tritium measurements along a transect between the Australian continental shelf and the Indonesian coast of Bali. The stations lie in the easternmost part of the Indian Ocean, close to the sills over which the Indonesian throughflow (ITF) makes its way to the Indian Ocean. The present data, obtained as part of the Java-Australia Dynamics Experiment (JADE) in August 1989, complement the WOCE 14C and tritium data set on both sides of the Indonesian archipelago and give us the opportunity to discuss the origin of the water masses and timescale of the throughflow. Both tracers point to a north equatorial Pacific origin of the waters. The comparison of the tritium inventories in the Pacific North Equatorial Current and along the JADE transect suggests a minimum transit time of the waters across the Indonesian seaways of the order of 5 to 6 yr, corresponding to a throughflow <18 × 106 m3/s.
Interannual 14C Variations During 1977–1998 Recorded in Coral from Daya Bay, South China Sea
Authors: Shen C D , Yi W X , Yu K F , Sun Y M , Yang Y , Zhou B
Published: July 2016

Twenty-two annually banded samples of coral from 1977 to 1998 were collected from Daya Bay, South China Sea, and bomb 14C concentrations were determined. The interannual variation of coral Δ14C is controlled mainly by oceanic factors. In ENSO years, the coastwise upwelling current of the South China Sea has been intensified; hence, the coral Δ14C displays its minimum value. The interannual variation curve of Δ14C in coral bears a relationship with the Southern Oscillation Index (SOI) curves: the correlation coefficient between Δ14C and (SOI)w is 0.43 and the correlation coefficient between Δ14C and (SOI)y is 0.27. The coral Δ14C has no remarkable response to the variation of solar radiation energy. In the past 20 yr or so, the general situation and oceanic thermal structure of the South China Sea are still stable even though interannual variations in atmosphere-sea interaction and upwelling current driven by the tropical energy have occurred.
Radiocarbon Chronology of the Late Pleistocene–Holocene Paleogeographic Events in Lake Baikal Region (Siberia)
Authors: Krivonogov Sergey K , Takahara Hikaru , Kuzmin Yaroslav V , Orlova Lyobov A , Timothy Jull A J , Nakamura Toshio , Miyoshi Norio , Kawamuro Kimiyasu , Bezrukova Elena V
Published: July 2016

New radiocarbon dates obtained from Late Pleistocene and Holocene deposits of the southern, eastern, and northern shores of Lake Baikal in 1995–2001 are presented, and the most important results of paleoenvironmental studies based on C data are discussed. The following paleogeographic events were verified with the help of C dating: 1) first Late Pleistocene glaciation (Early Zyryan); 2) Middle Zyryan interstadial; 3) loess formation during the Late Zyryan (Sartan) deglaciation; 4) warm and cold events in the Late Glacial; and 5) vegetation changes and forest successions during the Late Glacial and Holocene.
Changes in Sediment Accumulation Rate in An Oxbow Lake Following Late 19Th Century Clearing of Land for Agricultural Use: A 210Pb, 137Cs, and 14C Study in Mississippi, USA
Authors: Davidson Gregg R , Carnley Meredith , Lange Todd , Galicki Stanley J , Douglas Andrew
Published: July 2016

Sediment cores were collected from 2 sites in the forested fringe of an oxbow lake surrounded by land that was converted from forest to agricultural use in the late 19th century. The 2 sampling areas were selected to represent areas of high (West site) and low (East site) current sediment accumulation rates, based on distance from a perennially discharging stream. Modern (post settlement and land clearing) sediment accumulation rates were calculated using 210Pb and 137Cs on bulk sediment samples from 2 cores from each site. Two additional cores were collected from each site for radiocarbon analysis of twig cellulose with the assumption that most twigs in the sediment within the forested fringe fell from overhead and are contemporaneous with the sediment. Only the West site, however, yielded sufficient identifiable twig material for analysis. Modern sediment accumulation rates based on 210Pb and 137Cs fall between 0.2–0.4 cm/yr at the East site, and 0.7–1.3 cm/yr at the West site (nearest the stream inlet), with approximate agreement between the 210Pb and 137Cs methods. Modern sediment accumulation rate based on bomb-pulse 14C activity of twigs from cores from the West site is approximately 1.0 cm/yr, in agreement with the 210Pb and 137Cs results. Historic sediment accumulation rates were estimated at the West site using twigs from deeper intervals with pre-bomb 14C activity. Sediment covering approximately 1000 yr of pre-settlement sediment accumulation exhibited evidence of minor bioturbation or in-washing of reworked material, but with a clearly lower accumulation rate of less than 0.1 cm/yr.
On the Erosive Trail of A 14Th and 15Th Century Hurricane in Connecticut (Usa) Salt Marshes
Authors: VAN de Plassche O , Wright A J , VAN der Borg K , de Jong F A M
Published: July 2016

This paper examines if an erosive hiatus found in the peat stratigraphy and marsh-accumulation record from northwest Hammock River Marsh (HRM), Connecticut (CT) can be attributed to a 14th or a 15th century hurricane, each documented by a radiocarbon-dated overwash fan in Succotash Marsh (SM) (Rhode Island) about 90 km to the east. Given that (i) the best estimate age range for the 15th century overwash deposit in SM (1400–1440 cal AD, 2 σ) overlaps entirely with that for first plant growth after erosion at HRM (1390–1450 cal AD, 2 σ), while the best estimate age range for the 14th century overwash deposit (1290–1410 cal AD, 2 σ) overlaps just 10 yr, and (ii) interpretation of the available stratigraphic and sedimentary evidence from HRM suggests that a high-energy event offers the simplest explanation for the observed marsh erosion, we conclude that a plausible link exists between the 15th century hurricane and the marsh erosion in HRM. The best estimate age range for the 14th century hurricane appears to overlap for 91% with the age range for the first plant growth (1290–1400 cal AD, 2 σ) following marsh erosion in East River Marsh (CT), located about 12 km west of HRM. These results imply that erosive boundaries in salt-marsh peat deposits have potential as markers of past hurricane activity.
Near-Zero Δ14C Values at 32 kyr cal BP Observed in the High-Resolution 14C Record from U-Th Dated Sediment of Lake Lisan
Authors: van der Borg K , Stein M , de Jong A F M , Waldmann N , Goldstein S L
Published: July 2016

A high-resolution atmospheric radiocarbon record has been obtained for the interval of 17–36 kyr from U/Th-dated aragonite sediment of Lake Lisan. Reservoir age corrections were applied with reservoir ages of 200, 1250, and 2000 yr, which correlate with the different water levels of the lake. The present 14C record for Lake Lisan shows near resemblance with that of Lake Suigetsu: both converge to the value of Δ14C ∼0‰ at 32 kyr cal BP. Both also show significant differences compared to other reported high-resolution 14C records (e.g. Iceland Sea, Cariaco basin, and Bahamas speleothem). This inconsistency should be addressed by re-assessment of the basic assumptions behind the determination of calendar ages of the various records.
Isotopes, Inc. Radiocarbon Measurements II
Authors: Trautman Milton A. , Walton Alan
Published: July 2016

The following list presents the dates obtained on a fraction of the total number of measurements made during the year 1961. Those results which do not appear are withheld pending additional information or at the request of our clients.
Miami Natural Radiocarbon Measurements I
Authors: Östlund H. Göte , Bowman Albert L. , Rusnak Gene A.
Published: July 2016

The construction of the dating apparatus started in the summer of 1960 and was completed one year later. The laboratory is located on the bottom floor of a three-story concrete-block building which has two thin concrete floors on concrete beams above the shield. The building is underlain by carbonate mud and coral rock. The geographic location is 25° 43.9′ N Lat, 80° 09.8′ W Long and only a few feet above sealevel. We use a proportional-counting tube with an active volume of 1 L, and a total sample volume of 1.30 L, filled with purified CO2to a pressure of 225 cm Hg (3 atm) at 25°C. The tube is made of copper with brass ends and quartz insulators. The shielding consists of 20 cm of iron, 10 cm of paraffin with boric acid, 2.5 cm of selected lead (Östlund, 1961), and cosmic ray guard counters. The room is air-conditioned but no additional precautions have been taken to exclude outdoor dust.
Texas Bio-Nuclear Radiocarbon Measurements I
Authors: Chandler John B. , Kinningham Russell , Massey Don S.
Published: July 2016

Texas Bio-Nuclear is a proprietary establishment engaged in offering C14 dating by the liquid-scintillation method as a service to those institutions and individuals who have a need for such a service. The Laboratory began actual dating operations in December 1961. The first few months were devoted to processing check samples in order to establish the reliability of the system. The dates listed below are not inclusive of all our dating, since the dates we furnish our clients are their property and the publishing of this information is their decision.
New Zealand Natural Radiocarbon Measurements I-V
Authors: Grant-Taylor T. L. , Rafter T. A.
Published: July 2016

This list comprises dating determinations of the New Zealand Radiocarbon Laboratory.
Bern Radiocarbon Dates IV
Authors: Oeschger H. , Riesen T.
Published: July 2016

This list covers part of the samples measured at the Radiocarbon Dating Laboratory, Physics Department, University of Bern since summer 1962. Two low-level counters, as described by Houtermans and Oeschger (1958), with incorporated anticoincidence are used. Each sample is measured in both counters. The CO2 from the sample is converted to methane by pumping a (CO2 + H2)-mixture at a pressure below 1 atm over a Ru-catalyst at 200°C.
Geological Survey of Canada Radiocarbon Dates IV
Authors: Dyck W. , Fyles J. G. , Blake W.
Published: July 2016

Most of the determinations reported here were obtained with the 2 L counter described in our first date list (GSC I). All age calculations are based on a C14 half-life of 5568 ± 30 yr and 0.95 of the activity of the NBS oxalic-acid standard, and the ages are quoted in years before 1950. The age errors include: counting errors of sample, background, and standard, the error in the half-life of C14, and an error term to account for the average variation of ±1.5% in the C14 concentration during the past 1100 yr. ‘Greater than’ ages are based on the 4 σ criterion (GSC II).
Cambridge University Natural Radiocarbon Measurements VII
Authors: Godwin H. , Willis E. H. , Switsur V. R.
Published: July 2016

The dates and activity measurements given below have been obtained during 1963 and 1964, and have been made with CO2 at 3 atm pressure in a proportional gas-counter as described in previous contributions from this laboratory. We have again concentrated chiefly upon research projects pursued in the University Sub-department of Quaternary Research, but have continued final determinations also in the series of samples of CO2 collected in the lower stratosphere and described in our date list VI.
Radiocarbon Dating in the Soviet Union
Authors: Butomo S. V.
Published: July 2016

This report covers the investigations of the Laboratory of Archeological Technology of the Institute of Archeology of the Academy of Sciences of the U.S.S.R. under the technical direction of Corresponding Academician I. Ye. Starik. This work was begun in 1956, but the bulk of the dates were obtained during 1959–61 by the ethyl-benzol technique. For a control, ethyl-benzol was synthesized from the annual rings of the heartwood of an 80-yr-old larch. Depending on the size of the sample submitted for analysis, from 15–70 ml of ethyl-benzol was used.
University of Saskatchewan Radiocarbon Dates IV
Authors: McCallum K. J. , Wittenberg J.
Published: July 2016

This series reports some of the measurements made since the publication of the previous list. Equipment and methods have been previously described (Saskatchewan II).
Uppsala Radiocarbon Measurements VI
Authors: Olsson Ingrid U. , Karlén Ingvar
Published: July 2016

The following list covers the samples measured since 1962 at the Uppsala C14 laboratory to determine the increase of the C14/C12 ratio due to explosion of nuclear devices.
Institut Royal Du Patrimoine Artistique Radiocarbon Dates VII
Authors: Dauchot-Dehon Michèle , Heylen Jos , Strydonck Mark Van
Published: July 2016

This list contains most of the measurements made during 1979, since our last list (R, 1979, v 21, p 180–185). The laboratory procedures were outlined previously (R, 1968, v 10, p 29–34; R, 1971, v 13, p 29–31). The collagen extraction follows Longin (1970).
Pretoria Radiocarbon Dates II
Authors: Vogel J C , Visser Ebbie
Published: July 2016

This list contains 227 radiocarbon dates pertaining to the western part of southern Africa, between Luanda (9°S) in the north and the Orange R (29°S) in the south.
Cambridge University Natural Radiocarbon Measurements XV
Authors: Switsur V R
Published: July 2016

The dates presented in this paper are concerned with studies of the vegetational history of Western Scotland and are research projects in collaboration with members of staff and research students of the Sub-department of Quaternary Research, Cambridge University. The measurements of radioactivity were carried out between 1975 and 1977 at the University Radiocarbon Research Laboratory at Station Road, Cambridge, using highly purified carbon dioxide as filling gas in proportional counters. The dates are conventional radiocarbon dates calculated using the Libby half-life for the 14C isotope of 5568 years and ad 1950 as the reference year. The associated uncertainties represent one standard deviation and are calculated from a combination of the counting statistics of the samples, standards, and backgrounds together with estimates of population variation, variation of the background rate with changes of barometric pressure, and estimates of other laboratory measurement uncertainties. Thus, the stated uncertainty is considered a fairly reliable estimate of the laboratory uncertainty of the dates. The background samples are prepared from Welsh anthracite and the contemporary standard from NBS oxalic acid. A subsidiary standard is also used which is prepared from the ad 1845 to ad 1855 growth rings of an oak tree which grew near Cambridge, and the activity of this is compared frequently with the NBS standard.
University of Miami Radiocarbon Dates XX
Authors: Crabtree Sharon , Johnson Richard , Stipp J J , Hood Darden
Published: July 2016

The following radiocarbon dates are a partial list of samples measured for a variety of projects and materials since May 1980. Chemical and counting procedures remain the same as indicated in R, v 20, p 274–282.
University of Wisconsin Radiocarbon Dates XVIII
Authors: Bender Margaret M , Baerreis David A , Bryson Reid A , Steventon Raymond L
Published: July 2016

Procedures and equipment 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; marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4.