ALBERT

Description: 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.

Description: Δ14C values of leaves of deciduous trees provide a means to map the regional-scale fossil fuel ratio in the atmosphere. We collected a batch of ginkgo (Ginkgo biloba Linnaeus, a deciduous tree) leaf samples from across Korea in the month of July in both 2010 and 2011 to obtain the regional distribution of Δ14C. The Δ14C values of the samples were measured using accelerator mass spectrometry (AMS) at the Korea Institute of Geoscience and Mineral Resources (KIGAM). The average of the Δ14C values from clean air sites in Korea in 2011 measured slightly lower than the average of Δ14C values in 2010. Distribution maps of Δ14C of 2011 and 2010 in Korea were made based on a series of Δ14C values of ginkgo leaf samples from Korea using the Geostatistical and Spatial analyst tools in ESRI's ArcMap software. The distribution maps of Δ14C showed that Δ14C values in the western part of Korea are lower than those in the eastern part of Korea. This is because the western part of Korea is densely populated and contains many industrial complexes, and also because westerly winds from China, containing CO2 from fossil fuel use, blow into Korea. We compared the distribution maps of 2010 and 2011 and tried to find traces of the Fukushima power plant accident in Japan.

Description: Recent fieldwork by the Industries of Angkor Project (INDAP) has identified the first extensive evidence of iron production within an Angkorian Khmer (9th to 15th centuries AD) center at Preah Khan of Kompong Svay (Preah Khan) in Preah Vihear province, Cambodia. This immense 22-km2 temple complex appears to be an outpost of Khmer settlement situated in close proximity to Phnom Dek (“Iron Mountain”), the richest known source of iron oxide in Cambodia. Combined with the fact that Preah Khan's temple architecture dates between the late 10th to early 13th centuries, the period that the Khmer greatly expanded their territorial influence, our primary hypothesis is that this complex was established to gain access to and monitor production of iron for the capital of Angkor. The vast number and size of these iron slag concentrations, some up to 5 m in height by 35 m in length, precludes the use of traditional excavation and dating methods. Instead, this paper employs 14C dating of “in-slag” charcoal from surface slag cakes to produce a spatial chronology of late or “terminal” industrial activities. The results indicate that metallurgy was “last” practiced at various locations within Preah Khan in the mid-13th to late 17th centuries, with 3 distinct clusters between the late 13th and late 15th centuries. Based on this initial survey of surface collections, it appears that iron production at Preah Khan occurred after the final phase of masonry construction. More significantly, this work provides the first robust set of dates for late Angkorian and Middle period industrial activities in Cambodia.

Description: Extraneous carbon (Cex) added during chemical processing and isolation of black carbon (BC) in environmental matrices was quantified to assess its impact on compound specific radiocarbon analysis (CSRA). Extraneous carbon is added during the multiple steps of BC extraction, such as incomplete removal of solvents, and carbon bleed from the gas chromatographic and cation columns. We use 2 methods to evaluate the size and Δ14C values of Cex in BC in ocean sediments that require additional pretreatment using a cation column with the benzene polycarboxylic acid (BPCA) method. First, the direct method evaluates the size and Δ14C value of Cex directly from the process blank, generated by processing initially empty vials through the entire method identically to the treatment of a sample. Second, the indirect method quantifies Cex as the difference between processed and unprocessed (bulk) Δ14C values in a variety of modern and 14C-free or “dead” BC standards. Considering a suite of hypothetical marine sedimentary samples of various sizes and Δ14C values and BC Ring Trial standards, we compare both methods of corrections and find agreement between samples that are 〉50 μg C. Because Cex can profoundly influence the measured Δ14C value of compound specific samples, we strongly advocate the use of multiple types of process standards that match the sample size to assess Cex and investigate corrections throughout extensive sample processing.

Description: We report and compare the results of long-term observations (1998–2006) of monthly mean soil CO2 fluxes and their carbon isotope composition, carried out at 3 sites with contrasting characteristics: 1) a grassland site located in the urban area of Krakow, southern Poland, which was exposed to anthropogenic impact for more than a century; 2) a mixed forest site; and 3) cultivated agricultural field site. A closed-chamber, dynamic sampling system was used to collect monthly cumulative samples of soil-respired CO2. The CO2 collected at the mixed forest site was enriched in 14C with respect to European free-atmosphere continental 14CO2 background (high-altitude station Jungfraujoch in Swiss Alps) by approximately 40%, while the urban site revealed 14C depletion by ∼30% against the same reference. The Δ14C values observed at the agricultural site were lying in between, clustering along the regional reference atmospheric Δ14CO2 trend curve. The Δ14C values of soil-respired CO2 at the urban site turned out to be indistinguishable from the Δ14CO2 values in the local atmosphere. For the estimation of mean turnover time of soil carbon for each of the monitored sites, we used a multicompartment model (MCM) accounting for input of carbon to the soil profile via deposition of fresh organic matter, as well as 3 different sources of CO2 in the soil profile: 1) root respiration; 2) “fast”; and 3) “slow” pools of soil carbon. The estimated mean turnover time of carbon in the “fast” carbon pool was ∼14 yr for both urban grassland and mixed forest sites, and ∼22 yr for the cultivated agricultural field. From the observed differences in Δ14C values of the measured fluxes of soil-respired CO2, we conclude that 14C content of the biogenic component in the local atmospheric CO2 is site-specific and may differ significantly from the regional atmospheric background Δ14CO2 value. Therefore, the assumption widely used in 14C-based assessments of the fossil-fuel contribution local atmospheric CO2 load, stating that 14C concentration in the biogenic CO2 component is equal to that of regional atmospheric reference value, needs to be carefully evaluated on a case-by-case basis.

Description: We studied the chronology and periodization of the Pit-Grave (Yamnaya) culture at the Volga and Ural interfluve. Establishing the chronology of the Pit-Grave culture by archaeological methods is difficult due to the lack of artifacts in the burials. Therefore, we excavated 3 kurgan groups in the Orenburg region of Russia during the last decade. Eighteen kurgans of the Pit-Grave culture were studied using archaeological and paleopedological methods and radiocarbon dating. The funeral complexes studied were divided into 3 stages. A variety of carbon-containing materials from the same complexes were dated by different laboratories to increase the accuracy of the obtained dates. In addition, from the excavations of the last years some monuments of the Repino stage, the earliest period of the Pit-Grave culture, were dated using ceramics. Together with archaeological and paleopedological data, 14C dating helped to clarify and, in general, to confirm the 3-stage periodization of the Pit-Grave culture in the Volga-Ural interfluve: the early (Repino) stage, 4000–3300 BC; the advanced (classical) stage, 3300–2600 BC, which is divided into substages A and B at 3300–2900 and 2900–2600 BC, respectively; and the late (Poltavkinsky) stage, 2600–2300 BC.

Description: We discuss a radiocarbon study of sediment samples collected from Nanfu terrace in western Taiwan. From these, we extracted humic acids (HA) and humin from the very fine and coarse grain-size fractions using a standard acid-alkali-acid pretreatment. The humin extracts were combusted at 400 and 1100 °C by stepped-combustion, to yield a low-temperature (LT) carbon component and a high-temperature (HT) carbon component. We compare the ages of the LT and HT humin fractions to the HA fractions, in samples collected at 2 depths within the Nanfu terrace. As in previous stepped-combustion studies on sediments, we find that the HA ages are the youngest on average, and overlap the LT ages, and that the carbon contained in the HT fraction is always distinctly older than the LT and HA ages. To better understand the relationship between 14C age and combustion temperature, we conducted an incremental stepped-combustion experiment with one of the samples (1E) using 50 °C steps that ranged from 300 to 1100 °C. The 14C results of the stepped-combustion products show a clear division between 2 isotopically identifiable carbon constituents, from carbon released below 400 °C and carbon released above 550 °C. By comparing the δ13C and 14C results, we find evidence for a third carbon isotopic component in the humin that is released when combusted at ∼500 °C.

Description: A number of electronic systems are used on the ANTARES accelerator at ANSTO to implement its fast cycling accelerator mass spectrometry (AMS) capability. The fast cycling system was originally installed and commissioned in 1993 and has recently been updated. This paper describes the more significant of the electronic systems, such as the controller (“sequencer”), the high-voltage power supply (“bouncer”), the fast electrostatic beam chopper, and those used for measurement of the pulsed ion beam current. The sequencer, a programmable 15-bit digital pulse generator, generates the timing and sequencing of the control signals for bouncing voltage selection, beam chopping, Faraday cup current measurement, and rare isotope event measurement. The new sequencer is implemented using a National Instruments FPGA (field programmable gate array) card, programmed using LabVIEW 2010. This device has the benefits of host CPU-independent operation, simple interfacing (PCI), a small footprint, off-the-shelf availability at modest cost, and ease of functionality upgrade. The sequencer provides 15 synchronous digital signals, whose “on” and “off” transitions can be independently specified, in both number and time, with a time resolution of between 0.5 and 128 μs, and with the total duration between repetitions adjustable between 65.5 ms and 8.4 s per cycle. It is hosted by a generic PC because of the low-cost and ubiquity of these. The stand-alone FPGA-based approach ensures that the sequencer determinism is unaffected by processes executing in the host CPU.

Description: Establishing precise age-depth relationships of high-alpine ice cores is essential in order to deduce conclusive paleoclimatic information from these archives. Radiocarbon dating of carbonaceous aerosol particles incorporated in such glaciers is a promising tool to gain absolute ages, especially from the deepest parts where conventional methods are commonly inapplicable. In this study, we present a new validation for a published 14C dating method for ice cores. Previously 14C-dated horizons of organic material from the Juvfonne ice patch in central southern Norway (61.676°N, 8.354°E) were used as reference dates for adjacent ice layers, which were 14C dated based on their particulate organic carbon (POC) fraction. Multiple measurements were carried out on 3 sampling locations within the ice patch featuring modern to multimillennial ice. The ages obtained from the analyzed samples were in agreement with the given age estimates. In addition to previous validation work, this independent verification gives further confidence that the investigated method provides the actual age of the ice.

Description: Radiocarbon dating of carbonates is of increasing importance for archaeology and climate research. Like most samples, these usually require pretreatment to remove surface contamination. We studied several pretreatment techniques using snails and shells of different stages of preservation and sensitivity to dissolution during the acid step of the pretreatment. We find that simple acid treatment leads to reliable results, and is applicable especially to very fragile specimens. We also compare conversion of calcite using an elemental analyzer (EA) to the conventional acid dissolution technique.

Description: A simple way to upgrade the Peking University 500kV NEC radiocarbon facility (CAMS) for 10Be measurements is presented. In a first phase, a silicon nitride foil as passive boron degrader was mounted in front of the electrostatic deflector near the focal plane of 10Be. The Si detector at the end of the beam line was replaced with a high-resolution ΔE-Eres gas ionization chamber. In addition, a Faraday cup for the measurement of 9Be1+ was installed. Tests with this arrangement showed promising results: a 10Be/9Be background level of 3.4 × 10–14 and an overall transmission for 10Be of 2.2% were obtained. Measurements of standards showed very good stability and reproducibility. In the next step, it is planned to add a second magnet to reduce the background and to partly compensate losses due to energy and angular straggling in the degrader foil by the energy and angular refocusing effect of a magnetic sector field. With this final arrangement, a performance with 10Be/9Be background levels at 10−15 and 10Be overall transmission of 6–7% can be expected. The design proposed in this paper has the advantage that the modifications can be realized in a rather inexpensive way and that the measurement performance for 14C will not be affected.

Description: Radiocarbon measurements on bulk subaqueous sediments typically provide ages significantly older than actual time of deposition. This is generally caused by the presence of reworked organic compounds, which are depleted in 14C. To explore this issue of age heterogeneity, we collected 4 organic-rich samples from varying depths in a lake sediment core at the Gemündener Maar (Eifel, Germany), a lake of volcanic origin. We divided each sample into 5 standard grain-size fractions: gravel, sand, silt, clay, and 1 fraction smaller than 0.45 μm. These were cleaned separately using a standard acid-alkali-acid treatment. The highly organic gravel-size fraction provided the youngest 14C ages of all grain-size fractions and seems to be associated most closely with the time of deposition. By contrast, the silt and clay fractions show significantly older ages. If the investigated limnic sediment layer does not contain any identifiable terrestrial macrofossils, extracting and measuring coarser grain-size fractions instead of measuring bulk sediment samples will provide a better approximation of the time of sedimentation.

Description: A new 250kV single stage AMS accelerator (SSAMS) was installed at the Center for Applied Isotope Studies, University of Georgia. The accelerator is intended to be used primarily for radiocarbon measurements of natural and biobased samples, while all other samples such as marine, geological, atmospheric and archaeological samples are measured on the decade-old 500kV compact tandem accelerator (CAMS). The new AMS system is equipped with a 134-cathode MC-SNICS ion source. In this article, we show the results of the tests carried out on standards and blanks and compare the performance of the new machine with that of the CAMS unit. We have also compared the stable isotope data from AMS measurements to the conventional isotope ratio mass spectrometers (IRMS) data.

Description: Radiocarbon decay is rarely used to assess the residence time of modern groundwater due to the low resolution of its long half-life in comparison to the expected range of ages. Nonetheless, the modern 14C peak induced by the nuclear bomb tests traces efficiently the impacts of recent human activities on groundwater recharge, as well as for tritium. A simple lumped parameter model (LPM) was implemented in order to assess the interest of 14C and 3H nuclear peaks in a highly anthropized aquifer system of southeastern Spain under intense agricultural development. It required i) to assess a correction factor for modern 14C activities and ii) to reconstruct the 3H recharge input function, affected by irrigation. In such a complex hydrogeological context, an exponential model did not provide satisfying results for all samples. A better solution was reached by taking into account the qualitative recent variation of the recharge rates into a combined exponential flow and piston flow model. Apart from presenting an uncommon approach for 14C dating of modern groundwater, this study highlights the need of considering not only the variation of the tracer but also the variability of recharge rates in LPMs.

Description: The question of whether the rise in CO2 levels observed during the industrial era has influenced the rates of tree biomass growth represents one of the main unsolved questions in the field of climate change science. In this framework, the African tropical forest represents one of the most important carbon (C) sinks, but detailed knowledge of its response to elevated CO2 is still lacking, especially regarding tree growth rate estimations. A major limitation to determining growth rates in the African tropical region is that many trees lack seasonality in cambial activity determining annual growth rings. In this study, several species of trees characterizing the African tropical forest have been investigated to estimate their biomass growth rate by means of a procedure based on 14C and growth models. A total of 71 subsamples were analyzed for a Entandrophragma cylindricum (sapele) tree, and 38 and 25 wood subsamples for Erythrophleum suaveolens (tali) and Triplochiton scleroxylon (ayous) trees, respectively, using radiocarbon measurements at the Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE). All measured modern samples were in agreement with the Southern Hemisphere (SH) 14C bomb-spike curve. Observed preliminary results indicate a decrease in the growth rate of the sapele tree (∼350 yr old) in the industrial period compared to the pre-industrial era. Growth rates for trees of the other 2 species were higher than sapele, with ayous being the fastest-growing species.

Description: Tephra from the Cape Riva (Y-2) eruption of Santorini has been found across the eastern Mediterranean. It presents an important link between marine and terrestrial records. A Poisson process (P Sequence) age-depth prior, with model averaging, is used to model individual previously published radiocarbon sequences, cross-linked with an exponential phase model parameter to obtain a robust age. Multiple sequences and 14C determinations from 3 eastern Mediterranean data sets (Seymour et al. 2004; Margari et al. 2009; Müller et al. 2011; Roeser et al. 2012) are used in the model. The modeled age of the Y-2 tephra produced within this study is 22,329–21,088 cal BP at 95.4% probability.

Description: Compound specific radiocarbon measurements can be made instantaneously using a gas chromatograph (GC) combustion system coupled to a 14C AMS system fitted with a gas ion source. Samples below 10 μg C can be analyzed but the precision is reduced to 5–10% because of lower source efficiency. We modified our GC for CH4 and CO2 analysis and injected samples multiple times to sum data and increase precision. We attained a maximum precision of 0.6% for modern CO2 from 25 injections of 27 μg C and a background of ≃0.5% (40 kyr) for ancient methane. The 14C content of dissolved CO2 and CH4 in water samples collected at a deep-sea hydrothermal vent and a serpentine mud volcano was measured and the results for the vent sample are consistent with previously published data. Further experiments are required to determine a calibration and correction procedure to maximize accuracy.

Description: The archaeological site of Zaballa is a Medieval rural site located in the province of álava (Basque Country, northern Iberia). The site has been excavated during a rescue archaeology project, over an area of about 4.5 ha, where human occupation has been documented ranging from the 6th to 15th century. The archaeological operations have shown the transformation of the village, in diachronic terms, by unearthing the structure of production areas (agricultural lands, storage areas, and craft activities), the shape of domestic spaces, and the Saint Tirso monastery, with its adjacent cemetery. Much of the evidence and features related to a peasant community are small and disturbed by recent agricultural activities, and are therefore difficult to be interpreted in social terms. Studying dietary patterns has helped to fill this gap by providing a protein-rich diet of the elitist population and by highlighting the existence of hierarchies separating the inhabitants of Zaballa. In this paper, we discuss the reconstruction of the chronological sequence of the site inhabitation, with a multidisciplinary approach. The archaeological evidences and the critical use of radiocarbon dating have been integrated with stable isotope analysis on human remains found in the cemetery of the church of San Tirso, resulting in a first attempt to find evidence of the social structure of the rural community of Zaballa.

Description: Radiocarbon dating of plant remains is often difficult due to the complete dissolution of the samples in the alkaline step of the ABA pretreatment. At the VERA laboratory, this problem was encountered frequently when numerous Bronze and Early Iron Age samples from the eastern Mediterranean were dated in the course of the special research program SCIEM2000 and in other collaborations with archaeologists focused on that area and time period. For these samples, only a 14C age determination of the humic acid fraction was possible. Humic acids from archaeological samples are always assessed as a second-choice material for 14C dating. It is assumed that the 14C ages may be affected by the presence of humic acids originating from other (younger) organic material, e.g. from soil horizons located above a sample. Therefore, when humic acids are dated a verification of the dates is crucial. To address this basic requirement, we started some time ago to date both fractions of charred seeds, wood, and charcoal samples whenever available, i.e. the residue after the ABA treatment and the humic acids extracted from the samples in the alkaline step. The results of this comparison showed that for the investigated eastern Mediterranean archaeological sites, 50 (out of 52) humic acid dates were in agreement with the 14C dates of the respective ABA-treated samples. Statistical analysis of the age differences leads to the conclusion that the extracted humic acids originated from the samples themselves or from contemporaneous material and were not appreciably contaminated by extraneous material of different age.

Description: Time-series radiocarbon measurements have substantial ability to constrain the size and residence time of the soil C pools commonly represented in ecosystem models. 14C remains unique in its ability to constrain the size and turnover rate of the large stabilized soil C pool with roughly decadal residence times. The Judgeford soil, near Wellington, New Zealand, provides a detailed 11-point 14C time series enabling observation of the incorporation and loss of bomb 14C in surface soil from 1959–2002. Calculations of the flow of C through the plant-soil system can be improved further by combining the known constraints of net primary productivity (NPP) and 14C-derived C turnover. We show the Biome-BGC model provides good estimates of NPP for the Judgeford site and estimates NPP from 1956–2010. Synthesis of NPP and 14C data allows parameters associated with the rapid turnover “active” soil C pool to be estimated. This step is important because it demonstrates that NPP and 14C can provide full data-based constraint of pool sizes and turnover rates for the 3 pools of soil C used in nearly all ecosystem and global C-cycle models.

Description: Δ14Catm has been estimated as 420 ± 80% (IntCal09) during the Last Glacial Maximum (LGM) compared to preindustrial times (0%), but mechanisms explaining this difference are not yet resolved. Δ14Catm is a function of both cosmogenic production in the high atmosphere and of carbon cycling and partitioning in the Earth system. 10Be-based reconstructions show a contribution of the cosmogenic production term of only 200 ± 200% in the LGM. The remaining 220% have thus to be explained by changes in the carbon cycle. Recently, Bouttes et al. (2010, 2011) proposed to explain most of the difference in pCO2atm and Δ13C between glacial and interglacial times as a result of brine-induced ocean stratification in the Southern Ocean. This mechanism involves the formation of very saline water masses that contribute to high carbon storage in the deep ocean. During glacial times, the sinking of brines is enhanced and more carbon is stored in the deep ocean, lowering pCO2atm. Moreover, the sinking of brines induces increased stratification in the Southern Ocean, which keeps the deep ocean well isolated from the surface. Such an isolated ocean reservoir would be characterized by a low Δ14C signature. Evidence of such 14C-depleted deep waters during the LGM has recently been found in the Southern Ocean (Skinner et al. 2010). The degassing of this carbon with low Δ14C would then reduce Δ14Catm throughout the deglaciation. We have further developed the CLIMBER-2 model to include a cosmogenic production of 14C as well as an interactive atmospheric 14C reservoir. We investigate the role of both the sinking of brine and cosmogenic production, alongside iron fertilization mechanisms, to explain changes in Δ14Catm during the last deglaciation. In our simulations, not only is the sinking of brine mechanism consistent with past Δ14C data, but it also explains most of the differences in pCO2atm and Δ14Catm between the LGM and preindustrial times. Finally, this study represents the first time to our knowledge that a model experiment explains glacial-interglacial differences in pCO2atm, Δ13C, and Δ14C together with a coherent LGM climate.

Description: Due to its possible role in solid/water carbon isotope exchange, the effect of salinity on radiocarbon dating of groundwater was examined by batch interaction of alluvial sediment and calcite powder with freshwater (Cl–= 100 mg L–1) and Dead Sea (DS) brine (Cl–= 225 g L–1). These 2 water types were spiked with H13CO3–tracer and kept under constant agitation for about 1 yr. Several bottles were respiked twice with the tracer. The uptake of the13C by calcite was monitored through repeated isotopic measurements of the aqueous solutions, and the effect on14C groundwater dating was evaluated using a simple transport reaction model. The results indicate that the kinetics of water/calcite isotope exchange start with a very fast initial step followed by a slower one, which was used here to simulate the long-term water/solid exchange in “real” aquifers. The exchange model that best fits the data was homogeneous recrystallization that formed just a very thin layer of newly formed calcite. The estimated recrystallization rates for calcite powder/solution interaction were much smaller for the DS brine than for freshwater: 3 x 10–5to 7 x 10–6and 9 x 10–4to 7 x 10–5mol m2yr–1, respectively. The13C experimental data imply a very small effect of the brine/calcite isotope exchange on the14C age estimate for the brines within the DS coastal aquifer. However, when calcite recrystallization reaches ∼1% of the solid, the14C groundwater dating estimates will show aging by ∼10%.

Description: Due to its possible role in solid/water carbon isotope exchange, the effect of salinity on radiocarbon dating of groundwater was examined by batch interaction of alluvial sediment and calcite powder with freshwater (Cl– = 100 mg L–1) and Dead Sea (DS) brine (Cl– = 225 g L–1). These 2 water types were spiked with H13CO3– tracer and kept under constant agitation for about 1 yr. Several bottles were respiked twice with the tracer. The uptake of the 13C by calcite was monitored through repeated isotopic measurements of the aqueous solutions, and the effect on 14C groundwater dating was evaluated using a simple transport reaction model. The results indicate that the kinetics of water/calcite isotope exchange start with a very fast initial step followed by a slower one, which was used here to simulate the long-term water/solid exchange in “real” aquifers. The exchange model that best fits the data was homogeneous recrystallization that formed just a very thin layer of newly formed calcite. The estimated recrystallization rates for calcite powder/solution interaction were much smaller for the DS brine than for freshwater: 3 × 10–5 to 7 × 10–6 and 9 × 10–4 to 7 × 10–5 mol m2 yr–1, respectively. The 13C experimental data imply a very small effect of the brine/calcite isotope exchange on the 14C age estimate for the brines within the DS coastal aquifer. However, when calcite recrystallization reaches ∼1% of the solid, the 14C groundwater dating estimates will show aging by ∼10%.

Description: To investigate the radiocarbon concentration of atmospheric CO2 over the past few millennia in Japan, we measured the 14C age of annual rings from 3 Japanese trees with calendar dates ranging from ∼2000 yr old to present, and we compared the tree-ring 14C age with the corresponding 14C age from IntCal09. In some instances, the 14C ages of the annual rings of Japanese trees are not consistent with the IntCal09 data sets. Often, the 14C ages of tree rings are older than those from IntCal09, but younger than those from the SHCal04 data sets. The average shifts in the Nagoya 14C age from IntCal09 data sets and 1σ errors were determined to be +26 ± 36, +24 ± 30, +16 ± 22, +5 ± 21, and +14 ± 22 14C yr for the intervals AD 72– 382, 589–1072, 1413–1615, 1617–1739, and 1790–1860, respectively. The Japanese Archipelago is situated near the boundary of the Intertropical Convergence Zone in summer, and the 14C concentration of atmospheric CO2 over Japan can be influenced by air masses of the Southern Hemisphere with lower 14C concentrations during periods of higher solar activity and heightened East Asian summer monsoons. Our results suggest that the Japanese Archipelago is located in a critical zone where it is difficult to calibrate the 14C age of tree-ring samples using existing calibration data sets. It should be noted that calibration of the 14C dates of Japanese samples with IntCal09 may induce additional systematic shifts of calibrated ages toward older ages by about 30 yr compared with the sample optimum calendar ages.

Description: Rice paddies are highly important agricultural soils in view of their relevance as major staple food provider in the world and their key role in the global carbon cycle, caused by special management practices. A soil chronosequence, consisting of paddy and upland soils, developed on reclaimed estuarine sediments in the Province of Zhejiang, China, was sampled to investigate the influence of duration of agricultural use (50 to 2000 yr) on soil composition. The uniform composition of the parent material provides the unique opportunity to compare the effects of different land management practices (paddy and non-paddy) on soil carbon dynamics and the origin of organic carbon (OC) in top- and subsoils, using 14C measurements by accelerator mass spectrometry (AMS). The total soil organic carbon (TOC) was split into chemically defined pools of different mobility, namely the acid- and water-soluble fulvic acids (FA), the alkali-soluble humic acids (HA), and insoluble humin fraction. The more mobile HA and FA fractions contain significantly more 14C than the corresponding TOC and humin, indicating a downward transport of OC in the subsoil. Plant roots with 14C concentrations up to 128% of the modern standard, found far below the plough pan, reveal plant roots and root exudates as other direct sources of subsoil OC in paddy soils.

Description: Currently, there is significant ongoing research into the temporal and spatial variability of marine radiocarbon reservoir effects (MREs) through quantification of ΔR values. In turn, MRE studies often use large changes in ΔR values as proxies for changes in ocean circulation. ΔR values are published in a variety of formats with variations in how the errors on these values are calculated, making it difficult to identify trends or to compare values, unless the method of calculating the ΔR is explicitly described or all of the data are made available in the publication. This paper demonstrates the large range in ΔR values (+34 to −122) that can be obtained from a single, secure archaeological context when using the multiple paired sample approach, despite the fact that the terrestrial entities were of statistically indistinguishable 14C ages, as were the marine samples. This demonstrates the inherent variability in the ΔR calculations themselves and we propose that, together with calculation of mean ΔR, the distribution of ΔR values should be displayed, e.g. as histograms in order to illustrate the full data range. This spread is only apparent when employing a multiple paired sample approach as the uncertainty derived on a single pair of samples, taking account only of the errors on the individual 14C ages, will never truly represent the overall variability in ΔR that results from the intrinsic variability in the population of 14C ages in samples that might have been used. Consequently, ΔR values and the associated uncertainty calculated from single pairs should be treated with some caution. We propose that, where possible, when using paired archaeological samples, that a multiple paired approach should be employed as it will test the context security of the material used in the ΔR calculations. When summarizing the values by the weighted average, we also propose that the standard error for predicted values should be employed as this will fully encompass the uncertainty of a future ΔR calculation, using different samples for a similar time and location. Finally, we encourage future publishing of ΔR values using the histogram format, making all of the data available. This will help ensure that ΔR values are comparable across the literature and should provide a framework for standardization of publication methods.

Description: Increasingly, the uses of data arc becoming more and more sophisticated as the archaeological and chronological questions being asked become more complex. Statistical models and tools for inference arc a routine part of an archaeological investigation encouraged through the availability of software, and with each release of that software, additional functionality is being added. This comes with enormous benefit but also at a cost—the dreaded black box. Therefore, this article, as the first in a series of short articles, will attempt to cover some of the things one needs to know to make the most of the power of the statistical revolution, while avoiding the pitfalls.

Description: The radiocarbon dating laboratory at KIK-IRPA in Brussels was founded in the 1960s. From the beginning, dates were reported at more or less regular intervals in the journal Radiocarbon (Schreurs 1968) as did most of the other 14C laboratories.

Description: Conventional radiocarbon calculations correct for isotopic fractionation using an assumed value of 2.0 for the fractionation of 14C relative to 13C. In other words, isotopic discrimination in physical and chemical processes is assumed to cause relative shifts in 14C/12C ratios that are exactly double those of 13C/12C. This paper analyzes a 1984 experiment that produced a value for the fractionation ratio in photosynthesis of 2.3, which is used to this day by some researchers in the fields of hydrology and speleothem geochemistry. While the value of 2.3 is almost certainly incorrect, theoretical work suggests that the true value may indeed deviate from 2.0, which would have significant implications for 14C calculations.

Description: We present the water column profiles (surface to 2000 m depth) for dissolved inorganic radiocarbon (14CDIC) from 2 stations in the Kuroshio region including the Kuroshio large meander (LM) of 2004–2005. Surprisingly, the Δ14CDIC value varied up to 125‰ in the intermediate layer, especially near 600 m depth. In addition, the Δ14CDIC value was approximately − 150‰ at 200 m depth at the northern station of Kuroshio in August 2005. This value is ∼100‰ less than other Δ14CDIC values for the same depth. In comparison, the Δ14CDIC water column profiles for the southern station of Kuroshio and GEOSECS station 224 decrease down to 600 m depth and were similar below 600 m depth. Our results suggest that strong upwelling associated with the Kuroshio LM has a powerful influence on the Δ14CDIC water column profiles in the study region.

Description: The objective of radiocarbon pretreatment is to eliminate any contaminant carbon from the sample material. Solvent washes and acid-base-acid (ABA) procedures are widely used for this purpose. However, quantitatively analyzing their effectiveness is surprisingly problematic, as it often requires large numbers of 14C measurements or high-precision compositional analysis. The technique presented here involves monitoring the impact of different forms of contamination by measuring their adherence to a non-carbonaceous substrate called Chromosorb®. Firstly, the substrate was used in place of a 14C sample in order to monitor the accrual of carbon contamination during a standard solvent wash and ABA pretreatment. This produced a contamination profile against which modifications to the pretreatment procedure could be compared. Secondly, stocks were prepared of Chromosorb that had been infused with environmental contaminants and with common glues, adhesives, and preservatives. By monitoring the elimination of carbon from these stocks, the effectiveness of different pretreatment procedures could be evaluated and the most problematic of the contaminants for 14C dating could be identified.

Description: Radiocarbon analysis of freshwater dissolved organic carbon (DOC) involves substantial sample pretreatment, including an initial rotary evaporation stage necessary to concentrate large volumes of freshwater sample. This may lead to a health risk from the exposure to pathogens, and there is the additional concern that the warm conditions during the rotary evaporation stage may provide ideal growing conditions for some pathogens. To remove any pathogen risk in water samples, boiling or autoclaving can be undertaken. However, to date, no studies have been undertaken to investigate whether boiling will alter the 14C signature of dissolved organic carbon. Here, we analyze the effect of sterilization on 9 contrasting river water samples. Comparing filtered, filtered and boiled, and filtered and sterilized dissolved organic matter, we observe that both boiling and autoclaving increases the uncertainty associated with the 14C and 13C of DOC, that the 14C and 13C changes are not unidirectional, and that they are not related to original DOC composition. Neither sterilization method is recommended unless essential, in which instance we recommend a 3σ uncertainty on 14C and that the 13C is not considered representative of the original sample.

Description: 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.

Description: 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.

Description: Quantification of the marine radiocarbon reservoir effect (ΔR) is essential in order to calibrate conventional 14C dates from marine shell samples with reliability. ΔR also provides information concerning the intensity of coastal upwelling in marine regions influenced by this phenomenon. 14C ages of closely associated marine samples (mollusk shells) and terrestrial samples (goat bones) from São Vicente Island, Cape Verde Archipelago, permitted the first calculation of the marine 14C reservoir effect in this region. A ΔR weighted mean value of 70 ± 70 14C yr was obtained. This value is in accordance with the previously published oceanographic conditions of the region indicating the existence of a seasonal active upwelling regime.

Description: The Caribbean Archaic Age (about 3000–500 BC) is thought to represent the earliest migration of humans from South America into the Lesser Antilles. However, there is a conspicuous absence of these early sites on islands south of the Guadeloupe Passage. To date, only a single radiocarbon date derived from a Queen conch (Strombus [Eustrombus] gigas) shell at the Heywoods site on Barbados was indicative of an Archaic occupation in the southern Antilles apart from a scattering of poorly reported (and mostly undated) sites. Given a number of issues associated with reliance on a single date to establish a cultural horizon, along with other problems derived from possible carbonate cement contamination and dating marine shells of a longer-lived species such as Queen conch, 2 additional samples were taken from the same unit and context at Heywoods to confirm whether the site is truly representative of an occupation during the Archaic Age. Results from a Queen conch shell adze in Context 7 dated to 2530–2200 BC (2 σ) and overlaps with the only other Archaic date from the site dating to 2320–1750 cal BC, while a juvenile specimen of the same species from Context 8 at 3280–2940 BC (2 σ) indicates that Barbados may have been settled even earlier. This suggests that Heywoods may be the oldest site between Trinidad and Puerto Rico. While further confirmation is required, these new dates have implications for understanding the nature of migratory ventures in the Caribbean, such as whether the “Southward Route” hypothesis—which postulates that earlier migration events from South America during the Ceramic Age (beginning ∼500 BC) initially bypassed the southern Lesser Antilles—also applies to the Archaic, and if other phenomena such as active volcanism may have played a role in structuring settlement patterns. Questions also remain as to why Heywoods does not exhibit the typical lithic Archaic tool kit.

Description: A detailed radiocarbon chronology has been established for the deep-sea core CT85-5 from the Tyrrhenian Sea. This chronology, which is based on the analysis of foraminifera shells, shows a set of reversed 14C ages for sediments deposited during the eruption of the Campanian Ignimbrite (∼40 ka cal BP). The anomalous young 14C ages coincide with elevated concentrations of 10Bc measured in the same core. Although reversals in 14C ages have been previously found in other records at 40 ka cal BP, such extreme changes have not been observed elsewhere. The enhancement in 14C concentration in CT85-5 sediments associated with the Campanian Ignimbrite is equivalent to an apparent age ∼15 ka younger than the age for the sediments deposited shortly before the eruption. Here, we present consistent results of repeated measurements showing no analytical problems that can explain the observed rapid changes in 14C of this particular record.

Description: Twenty-three samples of charred food remains, charcoal, burned animals, and human bones from 14 Lithuanian prehistoric sites were dated by radiocarbon as part of a dating project oriented towards renewing the prehistoric ceramics chronology. The new dates modified the dating of ceramic styles by hundreds to a thousand years. Three Textile Ware sherds were dated to 4230–2920 cal BC—the oldest known dates of Textile Ware pottery in the East Baltic. The organic-tempered pointed-bottomed Narva and Combed-like Wares were dated to 3970–3370 cal BC, while Bay Coast Ware (Haffküstenkultur, Rzucewo), including vessels decorated with cord impressions, were dated to 3940–3540 cal BC, i.e. to a period well preceding the Corded Ware/Battle Axe horizon in Europe. Three dates of Globular Amphorae Ware placed the phenomenon directly beyond the Bay Coast chronology, i.e. in 3450–2920 cal BC. Chamotte-tempered Corded Ware from SE Lithuania was dated to 2840–2570 cal BC. The first absolute dating of coarse ware of the Žalioji type pointed to a period of 760–515 cal BC instead of the previously assumed 2nd millennium cal BC. Cremated human bones from urns found at Paveisininkai, Kernavė, and Naudvaris cemeteries were dated to 790–380 cal BC. Accelerator mass spectrometry (AMS) dates obtained from charred food remains should be treated with a certain caution due to a possible freshwater reservoir effect that has not yet been examined in Lithuania.

Description: A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess stratigraphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, secondary calcification, carbonate dissolution, and differential preservation. In this study, paired 14C dates on dissolution-susceptible Globigerinoides ruber and dissolution-resistant Neogloboquadrina dutertrei are used to evaluate a Gulf of Mexico sediment core. Fourteen of 15 pairs (between 8815 and 12,995 uncorrected 14C yr BP) yield concordant uncorrected 14C ages (mean difference −2 ± 75 yr), attesting to continuous deposition at high accumulation rates (〉35 cm/kyr). For 1 pair, N. dutertrei is nearly 1000 yr younger, which is difficult to explain by any combination of dissolution and bioturbation or downslope transport, given the excellent carbonate preservation and persistent laminations. The concordant ages underscore the utility of paired 14C dates in planktic foraminifera as a means of assessing stratigraphic continuity in deep-sea sediment sequences.

Description: At Tell Sabi Abyad, Syria, we obtained a robust chronology for the 7th to early 6th millennium BC, the Late Neolithic. The chronology was obtained using a large set of radiocarbon dates, analyzed by Bayesian statistics. Cultural changes observed at ~6200 BC are coeval with the 8.2 ka climate event. The inhabitation remained continuous.

Description: Intensified archaeological research in the Caribbean over the past 2 decades has provided a wealth of new information on how and when these islands were settled prehistorically. However, there has been a paucity of research on islands in the southern Lesser Antilles, which would allow for more rigorous testing of migration models and various settlement pattern hypotheses. To address some of these chronological and geographical gaps, we present a corpus of 41 radiocarbon dates from several sites in the Grenadine Island chain. Results to date support a relatively late Ceramic Age settlement of these smaller islands (about AD 400) compared to other nearby, larger islands in the southern Lesser Antilles (about AD 200) as well as the Caribbean as a whole (about 400/500 BC). Intriguing questions also remain as to an apparent, but as yet inadequately tested, pattern where earlier colonization dates are correlated with larger island size.

Description: Radiocarbon dating of degraded wool and silk provides 14C results of questionable reliability. In most cases, degraded wool/silk contains humic substances (HSs). Thus, a nondestructive fluorescence spectroscopy method, using a fiberoptic probe, was developed to monitor the presence of HSs in degraded wool and silk. This method can provide information about the presence of HSs before and after pretreatment and about the 14C age reliability. This study suggests considering with care wool/silk samples 14C dating wherein HSs are detected, because the conventional solvent pretreatment method using a NaOH wash is in most cases not sufficient to remove all humic substance contaminants. As a result, unreliable 14C dates can be provided.

Description: After more than 50 years dedicated to scientific research and to the dissemination of knowledge, Dr Jacques Labeyrie recently passed away at the age of 91. Upon graduating from the Ecole Supérieure de Physique et Chimie Industrielle de la Ville de Paris (1940–43), he became the assistant to Frédéric Joliot-Curie at the Collège de France. With Joliot's recommendation, he was recruited in 1946 to the Commissariat à l'Energie Atomique (CEA), where he stayed until his retirement in 1985. He was named Head of the Section d'Electronique Physique (later known as the Service d'Electronique Physique) of the CEA in 1955, which he managed until 1982.

Description: In the 19th and early 20th centuries, many museums acquired Egyptian coffins containing mummies from private donors who bought them from dealers in Egypt. Owing to the unknown context of such acquisitions, it cannot be assumed that the mummified individual inside the coffin is the same person named on it. Radiocarbon dating is a key diagnostic test, within the framework of a multidisciplinary study, to help resolve this question. The dating of an adult mummy in the Nicholson Museum at the University of Sydney was therefore checked using 14C dating. For over 150 yr, mummy NM R28.2 was identified as Padiashaikhet as per his coffin, dated to the 25th Dynasty, about 725–700 BC. 14C results from samples of linen wrappings revealed that the mummy was an unknown individual from the Roman period, cal AD 68–129. The mummification technique can now be understood within its correct historical context.

Description: This paper presents a set of accelerator mass spectrometry (AMS) radiocarbon dates obtained from various archaeological samples collected from 3 shellmounds—CA-MRN-114, CA-MRN-115, and CA-MRN-328—within China Camp State Park, Marin County, California, USA.

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

Description: The canopies of forests and cultivated fields can retard the ventilation of CO2 respired from the soil. The plants in dense canopies can then acquire a small fraction of their carbon by recycling some of the respired CO2. Furthermore, some plants can assimilate a small fraction of their carbon by uptake of CO2 in the soil via their roots. In tectonically active areas, the diffuse flux of CO2 from geological sources may be comparable to that from normal soil respiration. In such areas, both the canopy and root uptake effects may allow plants to acquire a measurable fraction of their carbon from geological sources. Because this “old” carbon lacks radiocarbon, its assimilation would increase the apparent 14C ages of the plants. These effects may account for some of the discrepancies between archaeological and 14C dates.

Description: Glyptodon sp. fossil remains can be found throughout Brazil. However, little information is available about their chronological distribution. With the intention to contribute to this issue, we present, as far as we know, the first direct radiocarbon date for 1 specimen of this genus found in Brazil. The osteoderm MZSP-PV660 found in Abismo do Fóssil Cave (SP-145), Iporanga, São Paulo, Brazil, was dated by accelerator mass spectrometry at the Beta Analytic Radiocarbon Dating Laboratory. The 14C date obtained was between 20,680 and 21,370 calibrated years before the present. Unfortunately, the scant (and often imprecise or unreliable) chronological data regarding this species and genus in Brazil and elsewhere in South America precludes a robust comparison among the dates available and the one presented here. Nevertheless, our finding supports the existence of this genus in South America at least until the Last Glacial Maximum.

Description: 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.

Description: Before the 17th century, charcoal was regularly used in the production of iron (smelting and forging) and some of this charcoal carbon was incorporated into the iron. Depending on the age of the wood used to produce the charcoal, the age of the carbon incorporated in the iron lattice can reflect the age of manufacture of the iron artifacts. A reliable preparation method allowing for the routine dating of iron artifacts would permit the dating of numerous objects for which now the age can only be estimated. In an earlier work (Hüls et al. 2004), we tested the extraction of carbon from iron samples by closed-tube combustion. The samples were cut in small pieces to ease the release of the carbon from the lattice. During the tests, it became clear that the steel tools used to cut the samples can add contamination at the surface. As modern steel is made using coal, this leads to erroneously old ages. We have tested ways to reduce or eliminate this surface contamination from the sampling tools using iron artifacts of known ages. In order to quantify the contamination, we produced standard test materials from pure iron (99.998% Fe) melted with carbon of known 14C content and prepared samples using different cutting tools. The results of these tests indicate that the proper choice of cutting technique and tool, combined with an additional cleaning of the freshly cut surface, reduces sample contaminations to low levels; measured sample 14C concentrations are close to the 14C content of the charcoal used to produce these standard iron samples.

Description: Radiocarbon and tritium determinations were carried out in 2 adjacent small aquifers in Israel. These aquifers have small storage capacities and good hydraulic properties. Darcy calculations suggest that the aquifers contain young waters, ≃50 yr in age. 14C concentrations in the Pleistocene aquifer are between 23–60 pMC, with the lowest activity related to contamination by petroleum-based fertilizers with no 14C. 14C concentrations in the Judea Group aquifer range from 62 to 95 pMC. An apparent difference of ≃1000 yr is indicated for the average recharge age between the 2 aquifers. The tritium data suggests that the water in both aquifers is quite young. The 1000-yr difference is an artifact of initial isotopic fractionation differences through the unsaturated zone as established elsewhere for these 2 aquifers. When these individual fractionation factors (0.54 for the Pleistocene and 0.62 for the Judea Group) are used, it is revealed that both aquifers contain young water, in agreement with the Darcy calculation, which was recharged at the beginning of the period of thermonuclear atmospheric testing in the early 1960s.

Description: The transitional period known as the Final Neolithic-Early Bronze Age in Greece, falling in terms of absolute dates within the 4th millennium BC, is an obscure and enigmatic period. Few sites in northern Greece or the southern Balkans have produced evidence of 4th millennium BC occupation, and the sites that do are mainly concentrated in the last third of the 4th millennium toward the beginning of the EBA. This paper presents archaeological evidence and radiocarbon dates from a site that covers part of the gap, Aghios Ioannis on Thassos, the northernmost Aegean island. It is a coastal site of seasonal occupation and most probably depended on organized animal husbandry plus hunting and fishing activities. From the first excavations in 1996, there was evidence that the site was occupied during the Final Neolithic to the beginning of the Early Bronze Age. The 14C dates obtained fall towards the end of the 4th millennium if not closer to the middle. The presence of human activity in this last part of the 4th millennium “gap” on Thassos is by itself an interesting discovery that enlarges our knowledge for this obscure period and is of environmental and cultural significance.

Description: We present a method for the extraction of dissolved organic carbon (DOC) from water. The method is adapted from Burr et al. (2001) using the basic steps: 1) sample filtration; 2) acidification to liberate and remove dissolved inorganic carbon (DIC); 3) evaporation of the sample to isolate salts that include trace quantities of carbon; 4) combustion of the salts; and 5) purification of the CO2. Two significant improvements have been made to the earlier method. The first is to use wet oxidation with potassium permanganate to oxidize organics in place of the combustion step and the second is the development of a reduction/oxidation purification procedure to remove sulfur and nitrogen oxides that may form during the oxidation step. Wet oxidation has a practical advantage over the previous method because it proceeds at low temperature (70 °C). The original method required quartz vessels to oxidize the salts at 900 °C. At this temperature, salts in the samples formed gases that interfered with the isolation of CO2 and the quartz vessels degraded with each combustion, affecting their structural integrity. The expensive quartz vessels could only be used for a limited number of samples, whereas Pyrex vessels used for wet oxidation are inexpensive and can be used indefinitely.The blank fraction modern carbon (f) and its mass dependence for the refined technique was determined from repeat analyses of salicylic acid produced from petrochemicals. For samples with a mass m above 0.5 mg, F = 0.0083 ± 0.0011. For samples below 0.5 mg, the blank follows a 1/m dependence as observed for other accelerator mass spectrometry (AMS) 14C measurements (Donahue et al. 1990). The reproducibility of the method is demonstrated using repeat measurements from a variety of samples, including a sample measured with the former high-temperature 900 °C combustion technique. The virtues of the wet oxidation method are that it is economical, produces a low blank, and provides good reproducibility.

Description: Lower Congo rock art is concentrated in a region that stretches from Kinshasa to the Atlantic coast and from northern Angola to southern Congo-Brazzaville. Although Lower Congo rock art was identified as early as the 19th century, it had never been a subject of thorough investigation. Presently inhabited by the Ndibu, one of the Kongo subgroups, the Lovo Massif is situated north of the ancient Kongo Kingdom. With 102 sites (including 16 decorated caves), the massif has the largest concentration of rock art in the entire region. In 2008 and 2010, we were able to collect pigment samples directly on the panels of the newly discovered decorated cave of Tovo. Unlike the Sahara and southern Africa, both extensively prospected, rock art of central Africa is still widely unknown and not dated. Radiocarbon dating of rock art in Africa is a real challenge and only a few direct dates have been obtained thus far. After verifying that the pigment samples were indeed charcoal, we proceeded to 14C date them using accelerator mass spectrometry (AMS). The results indicate dates between cal AD 1480 and 1800, confirming that the occupation of Tovo Cave was contemporaneous with the ancient Kongo Kingdom.

Description: This article presents results from the first 3 rounds of an international intercomparison of measurements of Δ14CO2 in liter-scale samples of whole air by groups using accelerator mass spectrometry (AMS). The ultimate goal of the intercomparison is to allow the merging of Δ14CO2 data from different groups, with the confidence that differences in the data are geophysical gradients and not artifacts of calibration. Eight groups have participated in at least 1 round of the intercomparison, which has so far included 3 rounds of air distribution between 2007 and 2010. The comparison is intended to be ongoing, so that: a) the community obtains a regular assessment of differences between laboratories; and b) individual laboratories can begin to assess the long-term repeatability of their measurements of the same source air. Air used in the intercomparison was compressed into 2 high-pressure cylinders in 2005 and 2006 at Niwot Ridge, Colorado (USA), with one of the tanks “spiked” with fossil CO2, so that the 2 tanks span the range of Δ14CO2 typically encountered when measuring air from both remote background locations and polluted urban ones. Three groups show interlaboratory comparability within l% for ambient level Δ14CO2. For high CO2/low Δ14CO2 air, 4 laboratories showed comparability within 2%. This approaches the goals set out by the World Meteorological Organization (WMO) CO2 Measurements Experts Group in 2005. One important observation is that single-sample precisions typically reported by the AMS community cannot always explain the observed differences within and between laboratories. This emphasizes the need to use long-term repeatability as a metric for measurement precision, especially in the context of long-term atmospheric monitoring.

Description: The ancient Egyptian mummy discovered in the wooden coffin of Ankhpakhered, priest of the god Min, has been studied at CEDAD (Centre for Dating and Diagnostics) at the University of Salento, Italy. The CT scan, performed by the multidisciplinary team of the Mummy Project of Milan, highlighted unusual features of the mummy, suggesting a reuse of the sarcophagus. Furthermore, specimens were taken via endoscopy for accelerator mass spectrometry (AMS) radiocarbon dating and Fourier transform infrared (FTIR) analyses, which have been carried out at CEDAD.

Description: The radiocarbon concentrations in plant leaves from different altitudes at 3 sampling locations were measured with the new compact accelerator mass spectrometer (AMS) at Yamagata University to investigate air mixing on a global scale. The sampling locations are Yamagata in the mid-latitudes of the Northern Hemisphere (NH), Kenya in the equatorial region (EQ), and Chacaltaya in the Southern Hemisphere (SH). The 14C concentrations of the plant leaves ranged from 102 to 105 pMC. The 14C concentrations at high altitudes and mountain summits showed similar values of 104.2 ± 0.28, 104.3 ± 0.36, and 104.4 ± 0.23 pMC at the Yamagata, Kenya, and Chacaltaya sites, respectively. These results indicate that air from the free troposphere is well mixed on a global scale. The local Suess effect was calculated using the 14C concentrations of leaves at the land surface and mountain summits. The fractions were estimated as 1.25 ± 0.3% and 0.87 ± 0.44% at Yamagata and Nairobi, respectively. This estimation method is more advantageous than the conventional calculation. The life cycle of the leaves sampled is 1 or 2 yr, and hence the leaves allow us to study the 14C concentrations in the ambient atmosphere during a narrow and specific time period.

Description: Tracing human history in west central Africa suffers from a scarcity of historical data and archaeological remains. In order to provide new insight into this problem, we reviewed 733 radiocarbon dates of archaeological sites from the end of the Late Stone Age, Neolithic Stage, and Early and Late Iron Age in Cameroon, Gabon, Central African Republic, Equatorial Guinea, Republic of Congo, and the western Democratic Republic of Congo. This review provides a spatiotemporal framework of human settlement in the forest biome. Beyond the well-known initial spread of Iron Age populations through central African forests from 2500 cal BP, it depicts the geographical patterns and links with the cultural evolution of the successive phases of human expansion from 5000 to 3000 cal BP and then from 3000 to 1600 cal BP, of the hinterland depopulation from 1350 to 860 cal BP, and of recolonization up to 500 cal BP.

Description: Two independent programs have collected and analyzed atmospheric CO2 samples from Point Barrow, Alaska, for radiocarbon content (Δ14C) over the period 2003–2007. In one program, flask collection, stable isotope analysis, and CO2 extraction are performed by the Scripps Institution of Oceanography's CO2 Program and CO2 is graphitized and measured by accelerator mass spectrometry (AMS) at Lawrence Livermore National Laboratory. In the other program, the University of California, Irvine, performs flask collection, sample preparation, and AMS. Over 22 common sample dates spanning 5 yr, differences in measured Δ14C are consistent with the reported uncertainties and there is no significant bias between the programs.

Description: In Korean Paleolithic archaeology, it is traditionally thought that the Late Paleolithic stone tool industries were in some way derived from the Shuidonggou site in northern China. The latter site has long been considered to be the type site of the eastern Asian Late Paleolithic blade technology. However, recent studies suggest that a number of Korean Late Paleolithic sites probably predate Shuidonggou, some by several thousands of years. Here, we present a series of accelerator mass spectrometry (AMS) dates recently analyzed by the AMS laboratory at Seoul National University and discuss further the possibility that the introduction of blade (and later microblade) technologies into Korea may have originated directly from Mongolia, Siberia, and possibly other areas of northeast China, rather than from Shuidonggou.

Description: Several canoes were excavated from coastal rivers in the Guangxi Zhuang Autonomous Region, southwest China. In order to confirm the age of the canoes, 6 samples were selected for radiocarbon dating from 3 canoes. The mean value of canoe NLJ was 365 ± 35 BP, and 2 samples from canoes MLJ and DFJ were 520 ± 21 and 499 ± 33 BP, respectively. The calendar ages cover a period from AD 1328 to 1641 at the 95% confidence level. These results disagree with previous studies that suggested canoes were only used over 1000 yr ago in China. We discuss the possible reasons for the results being younger than expected.

Description: Luzia woman is considered one of the oldest Paleoindian skeletons found in the Americas. Luzia was found at the Lapa Vermelha IV site (Lagoa Santa, Minas Gerais, Brazil) in 1975 by the archaeologist Annette Laming-Emperaire (1917–1977) who sent to the Gif laboratory charcoals collected in the vicinity of the skeleton for radiocarbon dating. Twenty-nine charcoal samples were dated from different levels of the stratigraphy of the cave (Délibrias et al. 1986). Recently, new charcoal samples were discovered within Laming-Emperaire's correspondence and were subsequently dated by the Saclay AMS laboratory. The new results confirm the age of Luzia; however, the ages correspond to the younger part of the interval: charcoals found near Luzia's skull give an age of 10,030 ± 60 14C yr BP (11,243–11,710 cal BP).

Description: The Bronze Age site of ķivutkalns with its massive amount of archaeological artifacts and human remains is considered the largest bronze-working center in Latvia. The site is a unique combination of cemetery and hillfort believed to be built on top of each other. This work presents new radiocarbon dates on human and animal bone collagen that somewhat challenge this interpretation. Based on analyses using a Bayesian modeling framework, the present data suggest overlapping calendar year distributions for the contexts within the 1st millennium BC. The carbon and nitrogen isotopic ratios indicate mainly terrestrial dietary habits of studied individuals and nuclear family remains buried in one of the graves. The older charcoal data may be subject to the old-wood effect and the results are partly limited by the limited amount of data and the 14C calibration curve plateau of the 1st millennium BC. Therefore, the ultimate conclusions on contemporaneity of the cemetery and hillfort need to wait for further analyses on the massive amounts of bone material.

Description: This study compares age estimates of recent peat deposits in 10 European ombrotrophic (precipitation-fed) bogs produced using the 14C bomb peak, 210Pb, 137Cs, spheroidal carbonaceous particles (SCPs), and pollen. At 3 sites, the results of the different dating methods agree well. In 5 cores, there is a clear discrepancy between the 14C bomb peak and 210Pb age estimates. In the upper layers of the profiles, the age estimates of 14C and 210Pb are in agreement. However, with increasing depth, the difference between the age estimates appears to become progressively greater. The evidence from the sites featured in the study suggests that, provided aboveground plant material (seeds, leaves) is selected for dating, the 14C bomb peak is a reliable dating method, and is not significantly affected by the incorporation of old carbon with low 14C content originating from sources including air pollution deposition or methane produced by peat decomposition. 210Pb age estimates that are too old may be explained by the enrichment of 210Pb activity in the surface layers of peat resulting from a hypothesized mechanism where rapidly infilling hollows, rich in binding sites, may scavenge 210Pb associated with dissolved organic matter passing through the hollow, as part of the surface drainage network. Until further research identifies and resolves the cause of the inaccuracy in 210Pb dating, age estimates of peat samples based only on 210Pb should be used with caution.

Description: We conducted an interlaboratory comparison between our radiocarbon-related research group at Lund University and the established ETH-Zurich facility to test the quality of the results obtained in Lund and to identify sources of potential background differences and scatter. We did find differences between the 2 laboratories in the contributions of chemical preparation, graphitization, and measurements to the overall background. The resulting overall background is, however, almost similar. Multiple measurements on 2 wood samples of known calendar age yield consistent and accurate 14C ages in both laboratories. However, one of our known samples indicates that IntCal09 is ≃38 ± 16 14C BP too young at 7020 calendar yr BP, which is consistent with one of the raw data sets contributing to IntCal09. Overall, our results show that a systematic approach to compare the different steps involved in 14C age determination is a useful exercise to pinpoint targets for improvement of lab routines and assess interlaboratory differences. These effects do not necessarily become apparent when comparing 14C measurements that integrate over the whole process of preparation and measurement of different laboratories.

Description: Carbonaceous particles that comprise organic carbon (OC) and elemental carbon (EC) are of increasing interest in climate research because of their influence on the radiation balance of the Earth. The radiocarbon determination of particulate OC and EC extracted from ice cores provides a powerful tool to reconstruct the long-term natural and anthropogenic emissions of carbonaceous particles. However, this 14C-based source apportionment method has not been applied for the firn section, which is the uppermost part of Alpine glaciers with a typical thickness of up to 50 m. In contrast to glacier ice, firn samples are more easily contaminated through drilling and handling operations. In this study, an alternative decontamination method for firn samples consisting of chiselling off the outer parts instead of rinsing them was developed and verified. The obtained procedural blank of 2.8 ± 0.8 μg C for OC is a factor of 2 higher compared to the rinsing method used for ice, but still relatively low compared to the typical OC concentration in firn samples from Alpine glaciers. The EC blank of 0.3 ± 0.1 μg C is similar for both methods. For separation of OC and EC for subsequent 14C analysis, a thermal-optical method instead of the purely thermal method was applied for the first time to firn and ice samples, resulting in a reduced uncertainty of both the mass and 14C determination. OC and EC concentrations as well as their corresponding fraction of modern for firn and ice samples from Fiescherhorn and Jungfraujoch agree well with published results, validating the new method.

Description: The long-lived radioisotope 59Ni is of interest in various research fields including neutron dosimetry, radioactive waste management, and astrophysics. In order to achieve the sensitivity required for such applications, the technique of accelerator mass spectrometry (AMS) 59Ni measurement has been developed at the AMS facility at China Institute of Atomic Energy (CIAE). Based on the AE-Q3D detection system in the CIAE AMS facility, the interference in 59Ni counting from the isobar 59Co has been reduced by a factor of 8 × 106. A series of laboratory reference samples and a blank sample were measured to check the performance of 59Ni measurement. A detection sensitivity of about 5 × 10−13 (59Ni/Ni) has been obtained.

Description: Preservation of seawater samples was tested for total inorganic carbon (∑CO2), stable carbon isotope (δ13C), and radiocarbon (14C) applications using foil bags and storage by refrigeration and freezing. The aim was to preserve representative samples with minimal storage effects but without using toxic methods such as mercuric chloride poisoning. Hydrolysis of samples to CO2 was based on existing methods. Results of IAEA-C2 standard used with deionized water stored in the foil bags showed complete reaction yields, 14C results within 2σ of the consensus value, and δ13C that were internally consistent, indicating that there were no procedural effects associated with the foil bags. 14C results were statistically indistinguishable across the storage times, for frozen and refrigerated seawater samples from a coastal site, Elie Ness, Fife, UK. The scatter of ∑CO2 concentrations and δ13C was within scatter observed in other studies for lake- and seawater samples preserved by acidification or using mercuric chloride. However, both ∑CO2 and δ13C were less variable for frozen samples compared with refrigerated samples. The foil bags are lighter, safer to transport, and similar in cost to glass bottles and allow sample collection in the field and transfer to the hydrolysis vessel without exposure of the sample to atmosphere. Storage of seawater samples in the foil bags was considered a reliable, alternative method to poisoning for ∑CO2, δ13C, and 14C, and freezing the samples is recommended for storage time beyond a week.

Description: A new system for CO2 absorption and liquid scintillation counting (LSC) was designed and developed along with its inherent measurement protocol for radiocarbon analysis in gaseous emissions, fuels, and biobased products. CO2 is chemically trapped as a carbamate in a suitable absorbing solution (3-methoxy-propyl-amine), gravimetrically measured, and analyzed by LSC (using a QuantulusTM 1220) to determine the 14C content. The use of cryogenic traps and a pressure transducer in the system prevents the need for closed-loop recirculation or additional steps to maximize CO2 capture in a short amount of time. The choice of PTFE vials used both for CO2 pretreatment and subsequent LSC analysis provides the opportunity to significantly reduce the background counting down to 40% with respect to the low-40K glass vials. This upgrade resulted in improving the maximum detectable age back to 36,000 yr BP in routine measurements. This method therefore turns out to be flexible enough to be applied for 14C dating as well as to differentiate between modern and fossil carbon.

Description: Guided by simulations using SIMION 8.1, a series of modifications were made to an experimental version of an Isobar Separator for Anions (ISA). The resulting improved version of the ISA provides a means of re-energizing the ions after they are cooled by gas collisions as they pass through the gas-filled radiofrequency quadrupoles (RFQ), and also provides higher transmission efficiencies. Reinvestigation of the separation of CaF3− and KF3− with this refined apparatus resulted in a better balance between isobar suppression and analyte transmission. KF3− was attenuated at eV energies by 4 orders of magnitude while 40% transmission of CaF3− was retained, for a 20keV CaF3− beam of Φ2mm and ±12mr. These results advance the possibility of an efficient small ISA-AMS system for both cosmogenic and medical applications of 41Ca.

Description: The Ansanto Valley (southern Italy) is characterized by vents and boiling mud lakes that emit typical volcanic exhalations (mostly fossil CO2). This fossil dilution spreads over the Ansanto Valley and its impact on local trees is investigated in this study. Six trees at increasing distance from the emitting sources and 2 aliquots of gas were sampled. Dendrochronological analysis was performed on tree cores in order to check the accuracy of the tree-ring sequences; the results indicate no anomalies in the curves of the analyzed trees. δ13C and radiocarbon (14C) analyses were performed on the α-cellulose extracted from some selected tree rings. The main aim of δ13C analysis was to gain information about the origin of CO2 arising from the source; the results support the hypothesis of a carbonatic origin, with respect to a volcanic origin. 14C analysis was performed to evaluate the influence and to quantify the percentage of fossil dilution characterizing the local atmosphere and affecting the trees at different distances from the source during the years. The results show the presence of a strong fossil dilution affecting the trees, increasing toward the sources (from ∼6% at 80 m distance to ∼30% at 20 m from the nearest vent) with quite stable values over the examined period.

Description: Horizontal and vertical variations in the distribution of 14C, δ13C, δ18O, and δ2H in groundwater of Žitný Island (Rye Island) have been studied. Žitný Island, situated in the Danube River Basin, is the largest island in Europe that is formed by interconnected rivers. It is also the largest groundwater reservoir in central Europe (∼1010 m3 of drinking water). The δ2H vs. δ18O plot made from collected groundwater samples showed an agreement with the Global Meteoric Water Line. In the eastern part of the island, it was found that subsurface water profiles (below 10 m water depth) showed enriched δ18O levels, which were probably caused by large evaporation losses and the practice of irrigating the land for agriculture. The core of the subsurface 14C profile represents contemporary groundwater with 14C values 〉80 pMC, indicating that the Danube River during all its water levels feeds most of the groundwater of Žitný Island. However, on the eastern part of the island a small area was found where the δ13C and 14C data (down to ∼30 pMC) helped to identify a groundwater aquifer formed below the Neogene clay sediments. This is the first time that vertical distributions of isotopes in different groundwater horizons have been studied.

Description: Dating sedimentary series spanning the past few tens of thousands of years is often problematic due to the quality of radiocarbon data obtained from organic matter (OM), including bulk OM. This problem recently arose when establishing the chronology of a sediment infill at the Sarliève paleolake (French Massif Central). In the studied section of the cores that covers the Neolithic, Ruppia seeds yielded consistent ages for the lower part (7195 ± 75 to 6050 ± 60 yr BP). A reservoir age of 82 ± 42 14C yr was estimated through the comparison of ages derived from charcoal, Ruppia seeds, and charophyte oogonia sampled on a single level. The upper part of the cores lacks macrofossils and bulk OM dating yields unusable data because of a significant contribution of aged OM derived from the Oligocene substratum in the catchment. We therefore performed dating of lipids extracted from the sediments. The age of the lipids was 2880 ± 30 yr BP near the top of the section, i.e. much younger than the age estimated from previous correlations based on pollen assemblages. These new data call into question previous paleoenvironmental interpretations. The combined dating methodology used for the Neolithic series of Sarliève is a rather uncommon approach that may help to refine chronologies of Holocene sedimentary series.

Description: High radiocarbon sample throughput is an increasingly important requirement of accelerator mass spectrometry (AMS) systems, which in turn requires high source output. To accomplish this, HVE AMS systems use a model SO-110B ion source, which can run at outputs of more than 200 μA 12C. It is known that high source output may compromise precision. To quantify this effect, we have tested an HVE 1MV AMS system for the influence of medium (100 μA) and high (200 μA) source outputs on the precision. These early measurements indicate for a 200 μA 12C source output, equivalent to a ≃1 kHz 14C count rate for Ox II samples, a 13C/12C precision of 1% and a 14C/12C precision of 3% can be obtained.

Description: Radiocarbon-based accelerator mass spectrometry (AMS) facilities at Uppsala University include a measurement center for archaeological applications and a separate entity dedicated to life science research. This paper addresses the latter, with the intention of giving a brief description of the biomedical activities at our laboratory, as well as presenting new data. The ultra-small sample preparation method, which can be used down to a few μg C samples, is outlined and complemented with new results. Furthermore, it is shown that the average secondary ion current performance for small samples can be improved by increasing the distance between the cathode surface and the pressed graphite surface. Finally, data is presented for a new application: Amyloidoses are a group of diseases where the conformational changes in specific proteins' structure lead to the formation of extracellular deposits that spread and increase in mass and eventually may lead to total organ failure and death. The formation timeframe is unknown and yet it is an important clue for the elucidation of the mechanism. We present results on bomb-peak dating of 4 different types of purified amyloid proteins from human postmortem heart and spleen samples. The data indicates that the average measured age of the carbon originating from the systemic amyloid types studied here correspond to a few years before the death of the subject. This suggests that a major part of the fibril formation takes place during the last few years before death, rather than as an accumulation of amyloid deposits over decades.

Description: Dendrochronological studies are limited in tropical regions because not many tree species form annual growth rings. This work reports an evaluation of the dendrochronological potential of tropical ash (Fraxinus uhdei) and its use as a bioindicator of fossil CO2 concentration in urban areas by means of radiocarbon analysis on growth rings. We analyzed a cross-section of a tree that grew during the period 1932–2007 in San Luis Potosí, one of the most industrialized cities in Mexico. The Δ14C values obtained follow the same variation pattern as the calibration curve of the Northern Hemisphere (NH) zone 2 (Hua and Barbetti 2004), with the peak centered in 1964, but they are lower by up to 124′. The high correlation coefficient (r = 0.990, p 〈 0.001) between the variation patterns indicates that this species does form annual growth rings, and the lower values can be attributed to the 14C dilution caused by fossil CO2 emissions. The magnitude of the Suess effect varied between −6.9% and −0.5%, equivalent to fossil CO2 concentrations ranging between 21.9 and 1.5 ppmv. The Suess effect and fossil CO2 values have significant variations with no apparent monotone increasing trend, suggesting that the CO2 emissions during the studied period have diverse sources. It is concluded that F. uhdei has potential for dendrochronological studies in tropical areas because its growth rings are formed annually and, furthermore, it can be used as a bioindicator of atmospheric 14C variations and fossil CO2 concentration in urban areas.

Description: Dating of the amino acid hydroxyproline from bone collagen has been shown to produce accurate and reliable radiocarbon dates. This article presents further application of the method demonstrating it can be used to obtain dates for both low-collagen and contaminated bones, extending the capability of 14C dating archaeological bone from conventional limits imposed by alternative pretreatment methods. The method therefore has the potential for significantly benefiting the accelerator mass spectrometry (AMS) dating community in the 14C dating of archaeological bone.

Description: Reconstructions arc presented of past growth rates of 10 Acacia tortilis trees, 5 growing at an arid site (Gebeit, Sudan) and 5 at a hyperarid site (Wadi Nuqrus, Egypt). The reconstructions were made using a free-shape age-depth model based on a series of 14C dates obtained on samples taken along the wood cores retrieved from the trunks of the trees (78 dates in total). In spite of the large difference in annual precipitation between the 2 sites, the range of ages of the trees (60–350 yr) and the variability in their growth rates are quite similar across both sites, whereas within-site growth rates are quite different even for closely spaced individuals. However, the pattern of growth rates of Acacias from the hyperarid Wadi Nuqrus indicates 2 periods of different aridity (the less arid AD 1650–1780 and more arid AD 1780–1930), while at Gebeit no such pattern has been detected.

Description: Use of coral skeletons to determine growth histories of reefs situated in warm, clear tropical waters is well established. Recently, however, there has been increasing awareness of the significance of reefs occurring in environments that are considered as marginal for coral growth, such as turbid inshore settings characterized by episodes of elevated turbidity, low light penetration, and periodic sediment burial. While these conditions are generally considered as limiting for coral growth, coral reefs in these settings can exhibit high live coral cover and species diversity, and thus can be both ecologically and geologically significant. Turbid-zone reefs are also commonly concentrated along eroding shorelines with many analogues to erosional shorelines developed during the Holocene transgression. A growing number of studies of these previously undocumented reefs reveal that the reef deposits are detrital in nature, comprising a framework dominated by reef rubble and coral clasts and set within a fine-grained terrigenous sediment matrix. In addition to the recognized effects of diagenesis or algal encrustations on the radiocarbon signature of coral samples, episodic high-energy events may rework sediments and can result in age reversals in the same stratigraphic unit. As in other reef settings, the possibility of such reworking can complicate the reconstruction of turbid-zone reef growth chronologies. In order to test the accuracy of dating coral clasts for developing growth histories of these reef deposits, 5 replicate samples from 5 separate coral clasts were taken from 2 sedimentary units in a core collected from Paluma Shoals, an inshore turbid-zone reef located in Halifax Bay, central Great Barrier Reef, Australia. Results show that where care is taken to screen the clasts for skeletal preservation, primary mineralogical structures, and δ13C values indicative of marine carbonate, then reliable 14C dates can be recovered from individual turbid reef coral samples. In addition, the results show that these individual clasts were deposited coevally.

Description: Measurements of the radiocarbon abundance in 5 samples of bis(2–ethylhexyl) phthalate (DEHP) isolated from Stilton cheese were made by accelerator mass spectrometry (AMS) to determine the fraction of carbon originating from contemporary biogenic sources. DEHP is classified as a “priority hazardous substance” by the European Union, a probable human carcinogen by the United States Environmental Protection Agency, and is suspected to be a human endocrine disrupter. Measurement of its 14C abundance in a specific food indicates whether its presence is due to contamination from industrially synthesized DEHP or a naturally inherent component. A method was developed to determine the contemporary carbon fraction of DEHP in a fatty food matrix at concentrations of 0.14 mg/kg. Five 90–μg quantities of DEHP were extracted from 12 kg of Stilton cheese and isolated by silica gel, size exclusion, and high-performance liquid chromatography (HPLC). Masses of samples were determined by gas chromatography mass spectrometry (GC-MS) analyses prior to combustion and manometry afterwards. The purity of DEHP carbon mass in each isolate was determined by multivariate deconvolution of GCMS fragmentation spectra obtained from measurements of standards and isolates, and ranged from 88.0 ± 1.8% to 92.3 ± 1.1% (n = 5, 1σ). Concurrently processed isolation method blanks contained from 0.15 ± 0.04 to 1.52 ± 0.06 μg (n = 3, 1σ) DEHP per sample and significant quantities of pre- and post-chromatographic extraneous carbon contamination. The mean 14C-corrected contemporary carbon fraction of DEHP in the isolates was 0.235 ± 0.073 (1σ; and ± 0.091 at the 95% confidence level), revealing that the majority of DEHP in Stilton cheese results from anthropogenic sources, but with a significant naturally occurring component.

Description: An age-depth model based on radiocarbon dates was produced from a Holocene profile collected from a rich fen situated in the Beskid Sądecki Mountains (the Outer Western Carpathians, southern Poland). The model is compared against the results of palynological and loss on ignition (LOI) analyses supplemented by the identification of organic deposits. Five distinct palynological episodes are detected. These potential palynological age markers are critically compared with the results of age-depth modeling and other dated profiles. The results presented distinctly show that using palynological episodes as age markers for age-depth construction may be highly misleading.

Description: The Indonesian Arc represents the subduction of the Indian-Australian plate beneath Asia. It has been the scene of catastrophic tectonic activity, including the recent 2004 M=9.1 Aceh earthquake and resulting Indian Ocean tsunami. We have dated planktonic forams associated with historic tephras (Tambora, 1815 and Krakatau, 1883) in marine sediment cores to determine radiocarbon reservoir ages for 2 locations along the arc. Our best estimates for 19th century regional reservoir corrections (ΔR) are +90 ± 40 yr for surface-dwelling species and +220 ± 40 yr for mixed planktic assemblages containing some upper thermocline species, but scatter in the data suggests that past surface reservoir ages may have varied by about ±100 yr. We used the results of this study to investigate a proposed very large AD 535 eruption at or near Krakatau. We find no evidence for ash from such an eruption, and although this is negative evidence, we consider it sufficiently strong to rule out any possibility that one took place.

Description: It is important to evaluate each step in radiocarbon analysis to ensure that the whole process is as efficient and accurate as possible. Aerosol filter samples contain a myriad of carbonaceous compounds with varying resistance to oxidation. Complete combustion of the sample is thus of great importance to ensure that the graphitized sample is representative of the original filter sample. We have evaluated sealed tube combustion of μg-sized aerosol samples using different types and amounts of reagents. Successful analysis of aerosol samples as small as 20 μg C was possible following small changes to our standard on-line method. The sealed tube combustion method performs well for standard samples containing 11 μg C.

Description: The Jena Analysis Code (JAC) was developed at the Jena radiocarbon laboratory for the analysis of all 14C accelerator mass spectrometry (AMS) data measured there. The fundamental principles and algorithms of JAC are presented here, along with the equally important checking procedures. JAC places emphasis on the uncertainty due to background subtraction and other contributions to the statistical uncertainty of 14C events.

Description: The assessment of construction sites for the new Visaginas Nuclear Power Plant (Visaginas NPP), including groundwater characterization, took place over the last few years. For a better understanding of the groundwater system, studies on radiocarbon; tritium; stable isotopes of hydrogen, oxygen, and carbon; and helium content were carried out at the location of the new NPP, at the Western and Eastern sites, as well as in the near-surface repository (NSR) site. Two critical depth zones in the Quaternary aquifer system were characterized by different groundwater residence times and having slightly different stable isotope features and helium content. The first shallow interval of the Quaternary multi-aquifer system consists of an unconfined aquifer and semiconfined aquifer. The second depth interval of the system is related to the lower Quaternary confined aquifer. Groundwater residence time in the first flow system was mainly based on tritium data and ranges from 6 to 60 yr. These aquifers are the most important in terms of safety assessment and are considered as a potential radionuclide transfer pathway in safety assessment. Groundwater residence time in the lower Quaternary aquifers based on 14C data varies from modern to several thousand years and in some intervals up to 10,500 yr.

Description: Characteristics of dissolved humic and fulvic acids in river waters were studied during 2003–2005 at 4 sites located in the headwaters and in the upper and lower Tokachi River, including a lowland tributary site. Fulvic acids from the headwaters to downstream areas have similar elemental composition and 13C-NMR spectra. Humic acids have similar characteristics in the Tokachi River system. In contrast, δ13C and Δ14C values exhibit a decreasing trend from the upper to the lower and tributary sites, although the headwater site has heavier δ13C and lower Δ14C values than the upper site. Fulvic acids had similar δ13C values from the upper to lower sites, but 123′ higher in Δ14C than those of humic acids on average. The δ13C and Δ14C values exhibited differences in downward variation for humic and fulvic acids. In the Tokachi River system, these results suggest that differences in transport pathways and residence times of humic and fulvic acids reflect differences in the δ13C and Δ14C values in a single river basin.

Description: The need to address radiological impacts from radiocarbon released to the biosphere has been recognized for some time. In 2011, the Swedish Radiation Safety Authority (SSM) commissioned a study to develop a 14C model of the soil-plant-atmosphere system that would provide them with an independently developed assessment capability. This paper summarizes that study, which comprised a review of contemporary models, the development of a new conceptual model, SSPAM14C, and the application of SSPAM14C to a set of experimental data relating to the atmospheric exposure of cabbages.

Description: The radiocarbon concentration of different atherosclerotic plaque fragments obtained from 20 patients in Portugal, operated in 2000–2001, has been measured in order to define the year of plaque formation. A difference of 1.8–15 yr was observed, with the mean and median both 9 yr, between the bomb-pulse date estimated with the CALIBomb software and the operation date. Stable isotope (δ13C and δ15N) analysis was also performed and provides insight to the diet of the subjects. The wide range of measured stable isotope values could indicate that the subjects' diet varied, including an abundance of marine foodstuffs. It could also mean a different isotope fractionation process for the different plaque fragments (cap, core, interface to media) and a possible difference in tissues in which the various fragments are formed. Analysis of δ13C and δ15N values of each patient separately revealed subjects considered more influenced by marine foodstuffs consumption.

Description: We present the results of a comprehensive study aimed at tracing the evolution of carbon isotopic composition of the TDIC (total dissolved inorganic carbon) reservoir from the unsaturated zone down to the discharge area, in a sandy aquifer near Kraków, southern Poland. A multilevel well penetrating the unsaturated zone in the study area was equipped with horizontally mounted lysimeters with ceramic suction cups to collect samples of pore water and metal probes to collect soil air. Strong seasonal fluctuations were observed of soil pCO2 extending down to the water table, coupled with distinct, well-defined depth profiles of δ13CTDIC reaching approximately −10′ at 8 m depth and almost constant radiocarbon content in the TDIC pool, comparable to 14CO2 levels in the local atmosphere. Simple models (closed/open system) do not account for the observed depth variations of carbon isotopic composition of the TDIC pool. This suggests that the TDIC reservoir of pore waters is evolving under conditions gradually changing from an open towards a closed system. In order to explain 13C and 14C content of dissolved carbonates in groundwater in the recharge area of the studied aquifer, additional sources of carbon in the system are considered, such as organic matter decomposition accompanied by reduction of dissolved nitrates and sulfates. The piston-flow l4C ages of groundwater in the confined part of the studied system were calculated using 2 approaches: 1) the correction model proposed by Fontes and Garnier (1979) was used to calculate groundwater ages, utilizing the chemical and carbon isotopic data available for the sampled wells; and 2) inverse geochemical modeling was performed for selected pairs of wells using NETHPATH code. The calculated 14C ages of groundwater range from approximately 0.6 to 37.5 ka BP. Although both methods appeared to be in a broad agreement, NETHPATH calculations revealed that isotopic exchange processes between TDIC pool and solid carbonates present in relatively small amounts in the aquifer matrix play an important role in controlling the 13C and 14C signatures of the dissolved carbonate species in groundwater and should be taken into account when 14C ages are calculated.