This study carried out accelerator mass spectrometry radiocarbon (AMS 14C) measurement of Japanese tree rings dating from the middle to early modern eras to investigate calibration curve fine structure. Tree-ring ages were determined by dendrochronology or δ18O chronology for Japanese trees. 14C ages from the 15th century to the middle of the 17th century followed the IntCal13 calibration curve within measurement error. Different patterns of fluctuations during the latter half of the 17th century to the early the 18th century were observed in different tree samples. In the 19th century, patterns of 14C ages of different samples appeared similar but did not exactly match each other.

The Kuju volcanic group, located in central Kyushu, Japan, consists of small stratovolcanoes and lava domes. To refine the eruptive history of the group, we conducted accelerator mass spectrometry (AMS) radiocarbon dating of charcoal fragments from three pyroclastic-flow (PF) deposits on the southern slope. The obtained 14C dates are consistent with the geomorphology, stratigraphy, and thermoluminescence (TL) ages. The Handa PF deposits, which are products of the largest eruption of the group, were dated to ~53.5 ka BP. The Shirani and Muro PF deposits, which are block-and-ash flows, were dated to 44 to >50 cal ka BP and 35–39 cal ka BP, respectively. These ages can be correlated with TL ages for lava domes. This study demonstrates that the lava domes and associated PF deposits formed after the Handa eruption.

After decades of collaborative experience between archaeologists and radiocarbon scientists, with the aim at producing radiocarbon dates capable of answering the most various research questions, it is now widely recognized that an accurate sampling strategy is the cornerstone of a solid 14C-based chronology. In this paper, we discuss the sampling criteria required to obtain good quality 14C data within a challenging archaeological context like the Bronze Age site of Erimi Laonin tou Porakou (Limassol, Cyprus). Following a dedicated sampling strategy, in the productive complex of the settlement, charcoal samples were collected from secure contexts according to stratigraphic examination of excavated strata and analysis of associated features and material culture. Micromorphology was also applied for a more accurate interpretation of individual deposits and reconstruction of depositional and post-depositional processes. In the necropolis, bone samples were selected among the fragmentary and commingled human remains through evaluation of the preservation state and the minimum number of individuals (MNI). A discrepancy between the charcoal and the bone 14C determinations was encountered, probably due to old wood issues. The 14C dates were analyzed using a Bayesian model that incorporates the archaeological information, and a preliminary 14C-based chronology was defined for this site.

Insoluble bone collagen is one of the most common materials used for high-resolution radiocarbon (14C) dating. Unfortunately, in some bones, poor preservation of the insoluble collagen excludes the possibility of dating. During the burial of the bone the collagen sometimes degrades into peptides. These peptides are soluble in the acid used to dissolve the bone mineral. It is known that under appropriate conditions, collagen has the ability to self-assemble. Here we exploit this capability and present a method for reassembling the soluble collagen peptides in archaeological bones and dating them. We treated the acid fraction generated during the demineralization of the bone by desalting and neutralizing the solution by dialysis. During the dialysis, the soluble collagen peptides reassemble and precipitate in the dialysis bag. We used FTIR spectroscopy to determine that the precipitated material is indeed collagen. The 14C dates obtained from the reassembled collagen were compared to the dates of “standard” insoluble collagen, extracted in parallel from the same bone. Although there are some divergences of the dates, 3 out of 10 samples could have been dated only by the reassembled collagen. This shows that collagen peptides reassembly can be a valuable tool for dating bones with little or no insoluble collagen.

This article reports on the performance of a continuous-flow interface for CO2 gas feeding into the ion source of a 200-kV accelerator mass spectrometer (AMS) in splitless mode. Distinct CO2 fractions and subfractions produced by a commercial Sunset OC/EC (organic carbon/elemental carbon) analyzer from ambient atmospheric aerosols filters are injected into the source and then analyzed by their 14C/12C ratio in real time. New features are revealed from organic aerosol subfractions, which thermally desorb close to each other and are only visible by real-time analysis. An optimized setup for this purpose is presented for the measurement of CO2 amounts from 3 to 45 μg C. Efficiencies of 4.5–8.0% for the formation of C- ions from CO2 are obtained for sample masses of 5–10 μg C and carbon mass flow rates below 2 µg min–1. However, this ionization efficiency is substantially suppressed at high carbon mass flow rates. The potential of this method for a refined apportionment of aerosol sources is demonstrated with ambient filter samples.

Radiocarbon measurements in tree rings can be used to estimate atmospheric 14C concentration and thereby used to create a 14C calibration curve. When wood is discovered in construction sites, rivers, buildings, and lake sediments, it is unclear if the wood could fill gaps in the 14C calibration curve or if the wood is of historical interest until the age is determined by dendrochronology or 14C dating. However, dendrochronological dating is subjected to many requirements and 14C dating is costly and time consuming, both of which can be frivolous endeavors if the samples are not in the age range of interest. A simplified 14C dating technique, called Speed Dating, was thus developed. It can be used to quickly obtain 14C ages as wood samples are neither chemically treated nor graphitized. Instead, wood is combusted in an elemental analyzer (EA) and the CO2 produced is carried into an accelerator mass spectrometer (AMS) with a gas ion source. Within a day, 75 samples can be measured with uncertainties between 0.5–2% depending on the age, preservation, and contaminants on the material and Speed Dating costs about one-third of conventional AMS dates.

This article discusses radiocarbon dating results for soils and soil-like systems in the East Antarctic oases, including Schirmacher, Thala Hills, and Larsemann Hills. The organic matter of endolithic and hypolithic systems, soils of wind shelters, and soils under moss-algae vegetation were dated along with micro- and macroprofiles. Organic matter pools formed under extreme climatic conditions and originated not from vascular plants but from cryptogamic organisms, and photoautotrophic microbes have been identified within the oases of the East Antarctica. The organic matter of the most of East Antarctic soils is young and cannot reach a steady state because of the high dynamism in the soil cover due to active erosion. The oldest soil organic matter in East Antarctica was found in the soils formed in wind shelters and endolithic soil-like systems under the protection of consolidated rock surfaces. According to our data, the maximal duration for the formation of organic matter profiles within the oases of East Antarctica is ~500 yr, which is similar to the age determined for High Arctic soils in Eurasia. The absence of older soils, comparable with the Holocene deglaciation, can be due to the extreme conditions resulting in occasional catastrophic events that destroyed the soil organic horizons.

This article focuses on radiocarbon (14C) dating of the organic matter (OM) of natural-anthropogenic objects—the cultural layers (CLs) of archaeological sites. Using examples from three ancient sites located within the European part of Russia, in southern taiga and forest-steppe natural zones, we demonstrate approaches to the interpretation of 14C dating of OM derived from the organomineral material of the CLs studied. We use the term “archaeological humus” as defined as the OM formed within the CL from “anthropogenic matter” (i.e., organic residues that were produced during the past human occupation of the site) without or with negligible contribution of OM inherited from pre-anthropogenic stages of pedogenesis. The archaeological humus is formed within closed or semi-closed systems by the processes of humification and physical stabilization of OM. The use of hierarchical (from macro- to submicro-) morphological investigations at one of the sites (Gnezdovo) combined with 14C dating allowed conclusions to be drawn about the age of formation of different OM components in CLs.

Eastern oyster (Crassostrea virginica) is an ubiquitous estuarine shellfish taxon in eastern North America and one of the most abundant materials available for radiocarbon (14C) dating. We examine spatiotemporal variability in carbon reservoir effects among pre-bomb oysters from Apalachicola Bay, USA, a river-influenced estuary on the northern Gulf of Mexico. Shells were sampled at multiple points along the valve to produce time-series records of 14C variation during the lives of the mollusks. Conventional ages within shells differed by as little as 36 14C yr to as much as 295 14C yr. Reservoir offsets varied sub-regionally within the estuary, increasing from 92±37 yr in the eastern edge of study region to 227±110 yr in the west, reflecting the influence of 14C-depleted dissolved inorganic carbon from the Apalachicola River. Dynamic carbon reservoirs can pose problems for the estimation of ΔR and for building coastal chronologies. Estimating sub-regional ΔR values can be useful for assessing the range of variability in reservoir offsets within an estuary, and for correcting sample ages if the shell origin is known. Greater variability and/or uncertainty in ΔR lead to greater uncertainty in the calibrated age.

New computer-controlled, semi-automatic systems were designed and built for CO2 purification and graphitization at the A.E. Lalonde Accelerator Mass Spectrometry (AMS) Laboratory with consideration for user friendliness and high throughput. The stainless steel vacuum lines are orbitally welded to ensure clean seams with low memory. The insulated graphitization ovens with plug-in electrodes provide a hazard-free environment for operators. The closed-loop cooling system circulating low-viscosity Dynalene at –40°C provides highly efficient water trapping. The LabVIEWTM software features (1) pressure and temperature recording for QA/QC; (2) safety interlocks to preclude operator errors resulting in sample loss, cross-contamination, or damaging a vacuum pump; and (3) automation for leak checking, iron conditioning, and running samples. Results from the first year of routinely measured standards, reference, and background materials are reproducible and within acceptance values. In the first year of operation (commissioned in spring 2014), over 1000 targets (~60% unknowns) were produced. With new tube sealing and CO2 purification lines, and two more graphitization lines now operational, the Lalonde AMS Laboratory is able to provide routine radiocarbon analysis (>200 µg carbon) at a capacity of more than 7000 targets per year. Most importantly, the equipment is safe and intuitive, making it ideal for education and training students to run their own samples.

Collagen associated with bone samples is frequently used for radiocarbon (14C) dating of bones recovered from archaeological sites. However, submersion and exposure to moisture favors the degradation of collagen, which leads to difficulty in reliably dating bones from tropical, humid, or previously submerged archaeological sites. In this paper, we characterized the preservation state of a series of bones, through parameters such as %C, %N, C/N ratio, and collagen recovery. We performed 14C analyses of three collagen fractions obtained through the pretreatment steps (total, ultrafiltered, and insoluble collagen) in order to link the preservation state and the reproducibility of 14C values obtained from the three fractions. Collagen ultrafiltration resulted in a decrease of C/N ratio, although collagen yield was reduced. When two or three collagen fractions were obtained, ages were reproducible and consistent with expected values, according to archaeological or hydrogeological criteria. The pretreatment steps were monitored by infrared spectroscopy in order to analyze the collagen fractions at the molecular level. The presence of collagen in the total and insoluble fractions was confirmed. Since many of the Mexican samples had poor ultrafiltered collagen yield (<3%) or nonexistent yield, our results show that if additional contextual information is carefully considered, the remnant collagen in the total and insoluble fraction can be dated, especially from sites where no other datable fraction exists.

The chronology of the Mesolithic, Neolithic, Aeneolithic, and Bronze Age sites in the Trans-Urals (Russia) was studied, and a framework for previously established cultural complexes is suggested based on 153 radiocarbon dates. In this new chronological model, the Mesolithic is dated to ~10,000–6500 cal BC; the Neolithic complexes exist at ~6500–3800 cal BC; the Aeneolithic is dated to ~4300–2800 cal BC; the Early Bronze Age spans ~2500–2100 cal BC; and the Late Bronze Age can be preliminary assigned to ~1600–1100 cal BC.

Archaeological investigations of the age and origins of marine shell beads are important for understanding the emergence and maintenance of long-distance trade networks in prehistory. In this paper we expand upon and re-examine the incremental carbon (14C and δ13C) and oxygen (δ18O) isotope data from two Olivella biplicata shell beads from the LSP-1 Rockshelter, Oregon, USA, to address two common problems in dating marine shell trade goods: (1) the source region is large, adding to uncertainty regarding the appropriate specification of ΔR; and (2) the 14C activity within individual specimens is variable. Although this combination of factors severely limits the dating precision that is possible, we recommend a sampling and calibration approach that accounts for these added sources of uncertainty and minimizes the loss of precision. We recommend (1) sequential sampling in order to quantify the range of variability in 14C within shells; (2) a Bayesian calibration procedure that models the 14C dates as an ontogenetic sequence, in this case constrained by stable isotope sclerochronology; and (3) specifying ΔR in a manner that accounts for the full range of possible reservoir offsets in the source region.

Excavations conducted in 1982–1987 by the Polish archaeological expedition of Jagiellonian University in the Sørkappland and Hornsund fjord regions of Spitsbergen encompassed the three Pomor hunting stations of Bjørnbeinflyene, Palffyodden, and Schönningholmane, and included relics from the landing site on the Tørrflya coast used by the Pomors. The wood recovered during the excavations, originating from wooden dwellings, monumental crosses, and a shipwreck, was subjected to dendrochronological analysis. In total, 26 samples were examined, which allowed for the following chronologies to be developed: SPITS_A3 (larch, 9 samples, 208 yr); SPITS_B1 (pine, 5 samples, 222 yr); and SPITS_C1 (spruce, 2 samples, 142 yr). The dendrochronological dating obtained for the spruce sequence was established as AD 1769–1910. The chronological position of the remaining sequences was established by means of wiggle-matching. The results suggest that the youngest rings of the larch sequence cannot be older than AD 1745, and the youngest rings of the pine sequence date within the period of AD 1697–1805 or 1837–1869. Absolute dates obtained for the wood from the huts from the northern part of Sørkappland are consistent with the chronological framework established based on historical data. Thus, the hypothesis positing pre-Barents chronology of the Russian promysl in the investigated area could not be confirmed.

Observation of 80 µA/mm2 C– current from a 0.5-mm-diameter sample compared to 20 µA/mm2 from a 1-mm-diameter sample contradicts the long-held surface ionization hypothesis of cesium sputter ion source operation. Resonant ionization occurs in neutral Cs plasma above a sample in a sputtered pit or well. A collision-radiation model of that plasma followed electronic excitation and radiation relaxation up to the Cs(7d) state. The Cs(5d) metastable state dominates plasma in a 1-mm-diameter well, but high electron densities in narrow wells drive a majority to Cs(7d) and higher. Competitive ionization by Al2 dimers from the sample holder reduces Cs(7s,p) states resonant in ionization energy with C–. Al anions from states above Cs(7p) in narrow wells also diminish radiation cascades to the Cs(7s,p), reducing C–. We tested sample wells of non-ionizing Zn to maintain high ionization efficiency for small samples in narrow wells.

Terrestrial gastropods are problematical for radiocarbon (14C) measurement because they tend to incorporate carbon from ancient sources as a result of their dietary behavior. The 14C ecology of the pulmonate land snail, Helix melanostoma in Cyrenaica, northeastern Libya, was investigated as part of a wider study on the potential of using terrestrial mollusk shell for 14C dating of archaeological deposits. H. melanostoma was selected out of the species available in the region as it has the most predictable 14C ecology and also had a ubiquitous presence within the local archaeology. The ecological observations indicate that H. melanostoma has a very homogenous 14C ecology with consistent variations in F14C across sample sites controlled by availability of dietary vegetation. The majority of dated specimens from non-urbanized sample locations have only a small old-carbon effect, weighted mean of 476±48 14C yr, with between ~1% and 9% of dietary F14C from non-organic carbonate sources. Observed instabilities in the 14C ecology can all be attributed to the results of intense human activity not present before the Roman Period. Therefore, H. melanostoma and species with similar ecological behavior are suitable for 14C dating of archaeological and geological deposits with the use of a suitable offset.

14C and U/Th methods were used to date three thin carbonate layers deposited on decorated walls of Nerja Cave (Malaga, southern Spain) in order to constrain the age of the parietal non-figurative marks situated under these carbonate layers. Modern formations were also dated to estimate the detritic contribution for the U/Th method and the dead carbon proportion for 14C dating. We sampled two locations with ocher painting marks. In one case (mark 1), the good agreement between the ages obtained by the two methods suggests that the sample was not subjected to post-deposition alteration and that the results are reliable. In the other case (mark 2), the age discrepancy between the two methods reached 30,000 yr, indicating that geochemical alteration had affected the sample and that one or both results were inaccurate. The ages for mark 1 indicate that this type of non-figurative representation is older than 25,000 cal BP and that it can be associated with the oldest attested Paleolithic occupation of Nerja Cave.

The large number of iron-laden wrecked ships discovered off Saintes-Maries-de-la-Mer (south of France) since the 1990s has enriched our knowledge of both maritime trade in the Mediterranean and the ferrous bars used during antiquity. This exceptional corpus has spawned numerous studies in the fields of archaeology, history, and archaeometallurgy, but, despite a relatively well-documented context, the chronology of wrecks is still to be clarified. Until recently, the chronology of the corpus was mainly supported by the archaeological remains found in the cargo of the wrecks, resulting in a chronological range from the 1st century BC to the 1st century AD. However, the 14C dating of an iron bar from Saintes-Maries-de-la-Mer, older by more than a century from the expected chronological range, has revived discussions about the chronology of all the wrecks. Thanks to the development of a new protocol for dating ferrous alloys, based on an extensive study of the ferrous material, 34 samples of iron extracted from 13 ferrous bars constituting the cargo of seven ships could be 14C dated. The 14C results and the archaeological and historical data were subjected to Bayesian analysis to build a chronological framework for the antique shipwrecks of Saintes-Maries-de-la-Mer. It appears that all these ships could belong to a larger phase than the one deduced from archaeological remains alone. Consequently, this study helps to support a new vision of the trade between the northeastern Mediterranean and western Europe.

Since its invention in the late 1940s, radiocarbon (14C) dating has become an important tool for absolute dating. A prerequisite for the acceptance of this method is consistency between, and compatibility of, 14C dates from different laboratories. To meet these requirements, international laboratory intercomparison studies with different sample materials are frequently performed (e.g. TIRI, FIRI, VIRI and, most recently, SIRI).Intercomparison is especially relevant and difficult for samples close to the dating limit of ~50 kBP, not least for bone samples. A 14C intercomparison study between the Leibniz-Laboratory in Kiel (Germany), the Center for Isotope Research (CIO) in Groningen (the Netherlands), and the Oxford Radiocarbon Accelerator Unit (ORAU, United Kingdom) was performed on three Pleistocene (MIS3) mammal bone samples from the Brick Quarry site Coenen (BQC) in Germany. The comparison of individually prepared and measured bone collagen 14C activities, results from shared collagen measurements, and respective background signatures and correction points to the latter as the main factor responsible for observed differences in final given radiocarbon estimates.