Data on radiocarbon (14C), 137Cs, 210Pb, and 241Am levels in an ombrotrophic peat sequence from a montane site on the east coast of Ireland are compared with data from a similar sequence at an Atlantic peatland site on the west coast. The 14C profiles from the west and east coasts show a broadly similar pattern. Levels increase from 100 pMC or less in the deepest horizons examined, to peak values at the west and east coast sites of 117 ± 0.6 pMC and 132 ± 0.7 pMC, respectively (corresponding to maximal fallout from nuclear weapons testing around 1964), thereafter diminishing to levels of 110–113 pMC near the surface. Significantly, peak levels at the east coast site are considerably higher than corresponding levels at the west coast site, though both are lower than reported peak values for continental regions. The possibility of significant 14C enrichment at the east coast site due to past discharges from nuclear installations in the UK seems unlikely. The 210Pbex inventory at the east coast site (6500 Bq m−2) is significantly higher than at the west coast (5300 Bq m−2) and is consistent with the difference in rainfall at the two sites. Finally, 137Cs and 241Am inventories at the east coast site also exceed those at the west coast site by similar proportions (east:west ratio of approximately 1:1.2).

One of the greatest challenges of contemporary archaeology is to synthesize the large amount of radiocarbon and archaeological data into a useful dialogue. For the late Epipaleolithic and the Early Neolithic of the Near East, many 14C ages have been published without precise stratigraphic documentation. Consequently, for archaeological age models we often must use some more elementary approaches, such as probabilistic summation of calibrated ages. The stratigraphy of Körtik Tepe allows us for the first time to study an extended series of 14C ages of the earliest Holocene. In particular, we are able to analyze the data according to stratigraphic position within a well-documented profile. However, because of a plateau in the 14C age calibration curve at the transition from the Younger Dryas to the Early Holocene, dates of this period can be interpreted only if an extended sequence of dates is available. Due to problems remaining in the calibration procedure, the best way to achieve an interpretation is to compare the results of different 14C calibration software. In the present paper, we use the results of the calibration programs OxCal and CalPal. This approach has important implications for future age modeling, in particular for the question of how to date the transition from the Epipaleolithic to the PPNA precisely and accurately.

The process of calibrating radiocarbon determinations onto the calendar scale requires the setting of a specific statistical model for the calibration curve. This model specification will bear fundamental importance for the resulting inference regarding the parameter of interest—namely, in general, the calendar age associated to the sample that has been 14C-dated.

Traditionally, the 14C calibration curve has been modelled simply as the piece-wise linear curve joining the (internationally agreed) high-precision calibration data points; or, less frequently, by proposing spline functions in order to obtain a smoother curve.

We present a model for the 14C calibration curve which, based on specific characteristics of the dating method, yields a piece-wise linear curve, but one which rather than interpolating the data points, smooths them. We show that with this specific model if a piece-wise linear curve is desired, an underlying random walk model is implied as covariance structure (and vice versa). Furthermore, by making use of all the information provided by the calibration data in a comprehensive way, we achieve an improvement over current models by getting more realistic variance values for the calibration curve.

Tree-ring series were collected for radiocarbon analyses from the vicinity of Paks nuclear power plant (NPP) and a background area (Dunaföldvár) for a 10-yr period (2000–2009). Samples of holocellulose were prepared from the wood and converted to graphite for accelerator mass spectrometry (AMS) 14C measurement using the MICADAS at ETH Zürich. The 14C concentration data from these tree rings was compared to the background tree rings for each year. The global decreasing trend of atmospheric 14C activity concentration was observed in the annual tree rings both in the background area and in the area of the NPP. As an average of the past 10 yr, the excess 14C emitted by the pressurized-water reactor (PWR) NPP to the atmosphere shows only a slight systematic excess (∼6′) 14C in the annual rings. The highest 14C excess was 13′ (in 2006); however, years with the same 14C level as the background were quite frequent in the tree-ring series.

Dispilio is the only excavated Neolithic lakeside settlement in Greece. Archaeological research provided evidence that the site was continuously used from the Early Neolithic (∼6000 BC) to the Late Chalcolithic period (∼1200 BC, Mycenaean period). During several archaeological campaigns, a portion of the settlement has been excavated that enabled a sufficient understanding of the architectural layout of homes, the building materials, and the organization of space, while the finds (fragments of pottery, stone and bone tools, anthropomorphic and zoomorphic clay figurines, miniature representations of objects also on clay, animal and fish bones, charred cereal grains, and other fruits) provided information on the everyday lives of the Neolithic inhabitants. A series of charcoal and wood samples, originating mostly from the Middle and Late Neolithic layers of the site, were radiocarbon dated and their dates range from ∼5470 to 4850 BC. The most unexpected of the finds, a wooden tablet from the lake bearing engraved symbols, was 14C dated to 5260 ± 40 BC. In addition, clay tablets and pottery vessels engraved with similar symbols were also unearthed from layers dated to the same period. If this proves to be a primary source of written communication, the history of writing should be reconsidered and Neolithic societies should not be considered “societies without writing.”

Southern Poland is home to numerous large mining and energy industry facilities, which consume relatively great amounts of fossil fuels. Temporal and spatial distribution of CO2 emissions to the atmosphere were estimated on the basis of 13C and 14C isotope measurements in atmospheric CO2 and in α-cellulose from pine tree rings. The Suess effect was evaluated in the atmospheric CO2 from the High Tatra Mountains (Kasprowy Wierch) and the urban area (Kraków), as well as in tree rings from Niepołomice Forest near Kraków. Two different models were used to estimate the emission component recorded in tree ring δ13C on the background of climatic changes.

A high-resolution age model was developed for Kettle Lake, North Dakota, USA, from a series of 53 accelerator mass spectrometry (AMS) radiocarbon ages calibrated with Bayesian statistical methods, which provide a monotonically increasing series of calibrated ages with depth. Evident in the sediment are several slumps, debris flows, or landslides, which are confirmed by 14C dating. Removal of these facies produces a continuous sedimentary sequence for the past 13,000 yr with exception of one ≃260-yr hiatus associated with a 1.5-m-thick slump deposit. All ages except one are on terrestrial macrofossils and charcoal. A test age on aquatic organic detritus shows a hardwater effect of 600 yr at ≃2000 cal BP. Two ages from the same level on herbaceous charcoal and Chenopodium seeds are statistically the same, which further demonstrates the suitability of charcoal from grassland environments for AMS 14C age control. However, 2 specimens of wood charcoal are too old relative to bracketing ages and glacial geologic history. These ages confirm the sedimentary interpretation of redeposition and provide a caution about the longevity of wood charcoal in the environment and its suitability for age control in lacustrine sediments.

The University of Arizona Radiocarbon Laboratory purchased a state-of-the-art LKB Quantulus LSC and placed it into a new underground counting chamber. We have investigated the performance of the Quantulus in this setting comparing different vial types, checking background sources and experimenting with sample size.

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.

Marine radiocarbon (14C) is a widely used tracer of past ocean circulation, but very few high-resolution records have been obtained. Here, we report a time series of carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from the Newport Beach pier in Orange County, within the Southern California Bight, from 2005 to 2010. Surface seawater was collected bimonthly and analyzed for Δ14C, δ13C, and salinity. Results from May 2005 to November 2010 show no long-term changes in δ13C DIC values and no consistent variability that can be attributed to upwelling. Δ14C DIC values have lowered from ∼34‰ to about ∼16‰, an 18‰ decrease from the beginning of this project in 2005, and is consistent with the overall 14C depletion from the atmospheric thermonuclear bomb pulse at the end of the 1950s. Δ14C DIC values, paired with salinity, do appear to be suitable indicators of upwelling strength with periods of upwelling characterized by more saline and lower DIC Δ14C values. However, a similar signal was not observed during the strong upwelling event of 2010. These results were obtained in the Southern California Bight where upwelling is fairly weak and there is a complex occanographic circulation in comparison with the remaining western USA coastline. It is therefore likely that the link between DIC Δ14C, salinity, and upwelling would be even stronger at other sites. These data represent the longest time series of Δ14C data from a coastal Southern California site performed to date.

Mortar as a mixture of binder and aggregate can be reliably dated with radiocarbon if the applied preparation method allows one to eliminate unburnt carbonate fragments, bearing 14C-depleted carbon and causing overestimation of 14C age. To avoid these problems, separation of specific grain-size fractions of mortar and 14C analysis of the CO2 portions collected in different time intervals of the acid-leaching reaction is usually helpful. In the present paper, we demonstrate that the rate of the leaching reaction of mortars with dense carbonate aggregate differs from that of mortars with crumbled limestone and scattered shells (e.g. of foraminifera). Verification of the obtained 14C dates against historical sources shows that for mortars rich in foraminiferous limestone, a reaction rate-based chemical elimination of “dead carbon” may appear impossible.

The measurements presented in this date list were made in the Radiocarbon Dating Laboratory at Teledyne Isotopes during 1969–70. Samples were analyzed by techniques described in R., 1968, v. 10, p. 246. Methods and references to sample pretreatment are provided in R., 1970, v. 12, p. 87. Errors associated with the age determinations are calculated by combining standard deviations from oxalic acid standard, background, and actual sample data. Samples which approach modern or background are reported with at least 2σ limits. Counting time for calculation of errors of background and standard is the same as that used for the sample. The error associated with the De Vries effect and the uncertainty of the half-life are not included.

This article discusses methodological issues related to the radiocarbon dating of Khirbet Qeiyafa, mainly the question of whether the site should be dated solely according to samples retrieved there or dated as part of a regional sequence of stratigraphically based ceramic typology phases. For the latter, we deploy the large number of 14C determinations now available for several sites in the Shephelah, which are located in close proximity to each other, in order to establish a Bayesian model for the absolute chronology of the Iron I–IIA phases in the region. We argue that the information assembled from six neighboring sites in the Shephelah pushes forward the date of Qeiyafa to the 10th century, a date later than the one the excavators estimated based on the more limited 14C information from the site alone.

Soils buried under terrace fills have been widely used to date the construction of ancient agrarian terraces. The reliability of the obtained radiocarbon dates entirely depends on the degree of preservation and isolation of the Ab horizons and on the amount of embedded older carbon. To assess these caveats, we analyzed 14 14C dates (11 on charred material and 3 on the bulk organic fraction) obtained from buried soils under Andalusi terrace fills in Ricote, Spain (AD 711–1492). The preservation of Ab horizons was assessed through bulk analyses [particle size distribution (PSD), carbon analyses, magnetic susceptibility (Mag Sus)] and statistics [Welch’s ANOVA, MANOVA (Wilk’s lambda) and effect size tests]. The effects of older carbon were quantified through the systematic dating of Ab horizons within the earliest terrace cluster of Ricote. Our results show that (1) Ab horizons were not disturbed nor mixed with the terrace fills above; (2) the dates determined from the bulk organic fraction were statistically significantly older than those provided by the charred material, probably due to the higher stability of the microcharcoal fraction; and (3) the earliest dates measured on charcoal clustered reliably around cal AD 989–1210, suggesting that the first Andalusi irrigated terraces of Ricote were built between the end of the 10th and the beginning of the 13th centuries AD.

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

Systematic investigations and experience from several application projects on small carbon samples over a number of years have resulted in measuring the radiocarbon content of 10 μg C samples with an overall precision of typically 1%. A substantial reduction of the carbon contamination during graphitization was achieved, resulting in 31±30 ng modern and <100 ng 14C-free carbon. Thus, graphitization is no longer the limiting factor because earlier sample preparation steps usually introduce much larger contamination. The method has been extended to a variety of materials and applied to various projects. Realistic conditions for procedure development can only be achieved in the context of applications on true samples; methods developed are the lyophilization of samples in solution, combustion, ultraviolet oxidation, or carbonate hydrolysis with phosphoric acid, which allows to prepare samples for a wide range of applications. Insights gained from systematic investigations and from real applications are presented.

The Harwell system for measuring milligram size samples using Brookhaven miniature gas counters is fully operative. It comprises 12 counters of different sizes which operate simultaneously within a single NaI crystal (300mm diameter × 300mm long) acting as an anti-coincidence guard counter. Brief details are given of the construction and commissioning of the system, including counter assembly, shield design, electronics, data capture, data analysis, and chemical processing and filling procedures. The performance of the system and an overall view of the fields of application for which the counters have important applications are discussed.

Tree ferns are slow-growing and long-lived components of temperate forests; however, these characteristics make determining size-age and population dynamics through mensuration approaches problematic while dendroecological approaches cannot be used. In this study, we use radiocarbon (14C) dating of Cyathea australis and Dicksonia antarctica to (1) determine their age-to-size relationships, (2) reconstruct the age distribution of tree fern species, and (3) test if predicted ages align with the ages of the co-occurring tree community and observed disturbance history. We used the best age-size models to reconstruct the population structure of tree ferns sampled in five paired rainforest and old-growth eucalypt stands and compared these to the age structure of co-occurring tree species. The species had similar growth allometry; however, C. australis grew four times faster than D. antarctica. The age class structures of tree ferns were congruent with the associated tree species and reflected known fire history and snowfall events in the region. Tree fern abundance increased with increasing time-since-fire and post canopy disturbance. The study demonstrates that 14C dating of tree ferns provides a means of investigating tree fern demographics and the role of disturbance in shaping their population structure in forests of southeast Australia.

This paper discusses the comparative chronology of Upper Paleolithic sites in the Middle Dnieper River basin, based on archaeological and radiocarbon evidence. Three chronological periods of the development of the Upper Paleolithic are distinguished in this area. According to the data obtained, the third period is similar to the European Magdalenian, yet its economies were different. The base of the subsistence economy for Dnieperian hunters was the procurement of mammoth, while reindeer was the most important for the subsistence of European Magdalenian. The abundance of mammoths and the raw material in the form of mammoth tusks made a deep impact on both the economy and material culture of the hunters in the Dnieper River basin. The 14C dates confirm the chronological subdivision.

The reinstallment, operation, and the 14C measurements reported here were made since 1976 in the LATYR, the Radiocarbon Dating Laboratory of the Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata. Sample preparation is preceded by careful visual separation and hand removal of gross impurities. This is followed in all cases (charcoal, wood) with successive washings of the sample with boiling 2% HCl and 1% NaOH solution for removal of carbonates and humic acids. Thereafter, it is washed with distilled water and acidified to pH = 3. Individual variations in the pretreatment are not described in the date list, but they are usually reported directly to the collector together with the data obtained.