By constraining organic carbon (OC) turnover times and ages, radiocarbon (14C) analysis has become a crucial tool to study the global carbon cycle. However, commonly used “bulk” measurements yield average turnover times, masking age variability within complex OC mixtures. One method to unravel intra-sample age distributions is ramped oxidation, in which OC is oxidized with the aid of oxygen at increasing temperatures. The resulting CO2 is collected over prescribed temperature ranges (thermal fractions) and analyzed for 14C content by accelerator mass spectrometry (AMS). However, all ramped oxidation instruments developed to date are operated in an “offline” configuration and require several manual preparation steps, hindering sample throughput and reproducibility. Here we describe a compact, online ramped oxidation (ORO) setup, where CO2 fractions are directly collected and transferred for 14C content measurement using an AMS equipped with a gas ion source. Our setup comprises two modules: (i) an ORO unit containing two sequential furnaces, the first of which holds the sample and is ramped from room temperature to ∼900°C, the second of which is maintained at 900°C and holds catalysts (copper oxide and silver) to ensure complete oxidation of evolved products to CO2; and (ii) a dual-trap interface (DTI) collection unit containing two parallel molecular sieve traps, which alternately collect CO2 from a given fraction and handle its direct injection into the AMS. Initial results for well-characterized samples indicate that 14C content uncertainties and blank background values are like those obtained during routine gas measurements at ETH, demonstrating the utility of the ORO-DTI setup.

To investigate the environmental history of the Tisza River (Hungary), we applied 14C and OSL dating methods for five parallel, neighboring cores from the flood plain area (Jászság Basin). Four major sedimentary layers were identified: meadow soil on the top (S1); silty-clay (S2); clayey-silt (S3) section; and fine sand (S4). 14C and OSL data were integrated into a synthetic age-depth model using the BACON software package. Formation of the S1 layer (depth: 0–1.0 m) falls in the Holocene, up to 10 kyrs cal BP, with moderate sedimentation rate (100 yr/cm aAR). The S2 layer (1.0–8.0 m depth) represent the entire Last Glacial to Upper Pleniglacial period (19–27 kyrs cal BP), with a much faster sedimentation (20 yr/cm aAr). The S3 section (8.0–17.0 m) represents a longer period (27–45 kyrs cal BP) with similar sedimentation rate (19 yr/cm aAr) as S2. These clayey silt layers fall into the Late Pleistocene/Middle Pleniglacial period, a period of nearly 18 kyrs of sedimentation resulting ∼9 m thick sediment. Our study delivered some new and important details about the surface evolution of the investigated Tiszasüly area. A missing part of about 10 kyrs period (between 10–19 kyrs cal BP) was revealed in the investigated synthetic cores.

The Cunene region of southern Angola, especially the area around Xangongo, hosts a large number of African baobabs, including several superlative specimens. Our research reports the investigation of the three biggest specimens from Xangongo Grove, named XG-1 (11 stems; circumference 26.34 m), XG-2 (5 stems; 22.70 m) and XG-3 (9 stems; 27.73 m), and of the largest baobab from Xangongo town, named XT-1 (7 stems; 21.02 m). Several wood samples were collected from these four baobabs mainly as cores from trunks and/or primary branches and then radiocarbon-dated by AMS. The two oldest samples were extracted from two primary branches of baobab XG-1. These have practically identical radiocarbon dates of 1822 ± 19 BP and 1822 ± 10 BP, which correspond to identical calibrated ages of 1785 ± 15 and 1785 ± 10 calendar years. The calculated age of baobab XG-1 is 2100 ± 50 years. Thus, XG-1, which is called by the locals “The biggest baobab of Africa”, becomes the oldest living African baobab with accurate dating results. The results indicate ages of 1100 years for baobab XG-2, 850 years for baobab XG-3 and 550 years for baobab XT-1.

We report a set of radiocarbon dating of prehistoric settlements located on the paleolake Baruun Khuree shores in the Gobi-Altai area, southern Mongolia. The obtained series of 11 AMS 14C measurements on charcoal and other charred plant macro-remains can be associated with one of the earliest episodes of the Holocene highly mobile desert-adapted hunter-gatherers activities from the Gobi desert (ca. 11,250–10,500 cal BP). Exploiting a wide range of environments, including dune fields, they are characterized by pottery usage and microblade core technology with wedge-shaped cores as well as osteological materials. These preliminary results are part of a project analyzing the nature of long-lasting prehistoric occupation around Tsakhiurtyn Hundi (Eng. Flint Valley)—one of the most extensive early prehistoric sites of Central Asia owing its name to the presence of abundant flint outcrops, lithic workshops and their innumerable flint artifacts.

Sudden annual rises in radiocarbon concentration have proven to be valuable assets for achieving exact-year calibration of radiocarbon measurements. These extremely precise calibrations have usually been obtained through the use of classical χ2 tests in conjunction with a local calibration curve of single-year resolution encompassing a rapid change in radiocarbon levels. As the latest Northern Hemisphere calibration curve, IntCal20, exhibits single-year resolution over the last 5000 years, in this study we investigate the possibility of performing calibration of radiocarbon dates using the classical χ2 test and achieving high-precision dating more extensively, examining scenarios without the aid of such abrupt changes in radiocarbon concentration. In order to perform a broad analysis, we simulated 171 sets of radiocarbon measurements over the last two millennia, with different set lengths and sample spacings, and tested the effectiveness of the χ2 test compared to the most commonly used Bayesian wiggle-matching technique for temporally ordered sequences of samples such as tree-rings sequences, the OxCal D_Sequence. The D_Sequence always produces a date range, albeit in certain cases very narrow; the χ2 test proves to be a viable alternative to Bayesian wiggle-matching, as it achieves calibrations of comparable precision, providing also a highest-likelihood estimate within the uncertainty range.

Ocean radiocarbon (14C) is a proxy for air-sea exchange, vertical and horizontal mixing, and water mass identification. Here, we present five pre- to post-bomb coral Δ14C records from West Flower Garden Bank and Santiaguillo reefs in the Gulf of Mexico, Boca de Medio, and Isla Tortuga near the Cariaco Basin north of Venezuela. To assess basin-wide Δ14C variability, we compiled the Atlantic Ocean reef-building surface coral Δ14C records (24 corals and 28 data sets in total) with these new records. Cumulatively, the Δ14C records, on their independent age models, reveal the onset of post-bomb Δ14C trends in 1958 ±1 to 2 years. A general decrease in maximum Δ14C values occurs with decreasing latitude reflecting the balance between air-sea gas exchange and surface water residence time, vertical mixing, and horizontal advection. A slightly larger atmospheric imprint in the northern sites and relatively greater vertical mixing and/or advection of low-14C waters influence the southern Caribbean and eastern Atlantic sites. The eastern Atlantic sites, due to upwelling, have the lowest post-bomb Δ14C values. Equatorial currents from the eastern Atlantic transport low Δ14C water towards the western South Atlantic and southern Caribbean sites. Decadal Δ14C averages for the pre-bomb interval (1750–1949) for the low latitude western Atlantic are relatively constant within analytical (3–5‰) and chronological uncertainties (∼1–2 years) due to mixing and air-sea exchange. The compiled Δ14C records provide updated regional marine Δ14C values for marine reservoir corrections.

Highly precise and reproducible radiocarbon (14C) measurements are regularly performed at the Heidelberg Institute for Environmental Physics, Heidelberg, Germany, in collaboration with the radiocarbon laboratory of the Curt-Engelhorn-Center Archaeometry in Mannheim, Germany. Here, we report an update of the technical details, focusing on the analysis of cold-water corals (CWC), and present an improved long-term blank value with a mean of (0.190 ± 0.064) pMC (n = 138) and excellent reproducibility of the IAEA-C2 standard with a mean of (41.15 ± 0.16) pMC (n = 75), consistent with its certified consensus value. Furthermore, 33 duplicates of the CWC 14C measurements agree within 2σ, 85% even within the 1σ range. This provides excellent conditions for accurate 14C measurements. As an application example, we present combined 230Th/U and 14C ages of a coral-bearing sediment core from the upper Mauritanian slope. The resulting ventilation age record confirms decreasing ventilation between 30 and 25 kyr BP, most likely reflecting a northward propagation of a water mass originating from the south. During the LGM, we confirm a previously hypothesized southward displacement of the Cap Verde Frontal Zone. With the onset of the deglaciation, our record documents again an advance of a southern-sourced water mass into the subtropical North Atlantic. During the Bølling-Allerød warm period, strong ventilation fluctuations possibly indicate temporal influence of southern-sourced water.

Earthworm biospheroids are a useful alternative to radiocarbon (14C) soil dating. In this study, we undertook a series of measurements to test the 14C dating potential/performance of recent earthworm biospheroid granules. A novel sample preparation protocol for 14C in biospheroids was developed and elaborated at Atomki (Institute for Nuclear Research) and tested on IAEA reference materials. 24 natural biospheroid samples were extracted from five different location/environment-eight topsoils (A-horizon soils). Bomb-peak-based, high-resolution 14C dating show very uniform 14C results at 105.6 ± 2.6 pMC (1σ) and none of the biospheroids are older than 30 yr. It also shows that no biospheroid with a 14C bomb-peak as high as that observed in the 1960s and 1990s were observed. The results confirmed that earthworms do indeed consume almost exclusively recent biogenic carbon, not other organic compounds or inorganic carbonates previously bound in the soil. The calendar age of their biospheroids were extremely close to the real (zero) age of the surface. Thus, no “reservoir effect” is seen for these macrofossils. We conclude that a biospheroid-based 14C age determination method may be suitable to measure the burial time as long as earthworm biospheroids can be found in the soil.

Ever since the first discovery of urn burials in eastern Serbia during the 1980s, their dating has been uncertain and based on distant analogies and typological parallels. In this paper, we present radiocarbon dates from five urn cemeteries and three associated settlement sites, showing that the initial dating (Late Bronze Age; 14th–11th BCE) is highly questionable. Instead, radiocarbon dating and modeling presented here connect the urn cemeteries—characterized by a specific grave architecture and associated with settlements that display evidence of copper production—to a period between the 20th and 16th centuries BC. The fact that many of our dates come from cremated bones requires a discussion with regard to the circumstances of carbon exchange during cremation. The absolute dates thus far available for most urn cemeteries from the neighboring regions of the Balkans are all markedly younger (15th–11th century BC) than the data presented here and fall in the frame of the overall expansion of cremation in Europe during the Urnfield period. The new absolute dates from eastern Serbia provide a possibility to change our understanding of the Bronze Age dynamics of the 2nd millennium in the broader area of southeastern Europe and indicate a much earlier acceptance of cremation among certain groups than previously thought.

Radiocarbon (14C) measurements play important roles in dating and tracing applications where the isotopic concentration can differ from 0.1 to 106 pMC (percent modern carbon). A liquid scintillation counter cannot provide enough sensitivity when dealing with low-concentration samples of limited amounts over a reasonable time period. Accelerator mass spectroscopy (AMS) measures low-concentrations well but must first do dilution for high-concentration samples, and suffers from high instrument and maintenance costs. Saturated absorption CAvity Ring-down spectroscopy (SCAR) has now been developed into a practical technique with performances close to AMS but at much lower costs. The dynamic range covers 1–105 pMC, and the measurement uncertainties in the range of 0.4–1 pMC can be achieved within 0.5–2.5 hr of operation time. SCAR measures CO2 gases directly without graphitization in sample preparation. The typical sample consumption is ∼1 mg of carbon mass and the time for sample preparation can be as short as 15 min. Applications of SCAR to Suess-effect evaluation, biogenic-component analysis, ancient- and modern-sample dating, food-fraud detection and medicine-metabolism study have all been demonstrated by employing a close-to-automatic sample preparation system.

Marine aerosols can enter the terrestrial environment via sea spray which is known to affect the stable isotope fingerprint of coastal samples (plants, animals/humans), including δ13C. However, the impact of sea spray on 14C dating of terrestrial organisms at coastal sites has not been investigated so far. Besides a direct effect, sea spray is accompanied by physiological effects, e.g., due to salinity. In an artificial sea spray experiment in the greenhouse, the effect of sea spray on 14C in plant tissue was investigated. Beach grass was sprayed with mineral salt solutions containing only traces of NaCl or with brackish water from the Schlei inlet or the Baltic Sea. These plants should give a 14C signal close to the modern atmospheric 14CO2 composition. However, three treatment groups showed variable radiocarbon concentrations. Plants sprayed with water from the Schlei inlet, Baltic Sea water, or with a mineral salt solution with very high HCO3– concentration are depleted in 14C content relative to contemporary atmospheric composition. While δ13C reflects physiological effects in the plants, caused either by salinity (NaCl) or HCO3– stress, resulting in decreased discrimination against 13C, the uptake of high amounts of 14C (ca. 53–67%) from DIC (dissolved inorganic carbon) partly masks the underlying physiological reactions, as is visible in the radiocarbon signature of the plant tissues. This preliminary study indicates that sea spray effects on plant tissue could potentially influence faunal tissue 14C composition at coastal sites. Further research is required to better understand the observed reservoir effect.

The Manych Depression is a relatively narrow elongated depression of tectonic origin, connecting the Caspian and Azov-Black Sea basins. The Caspian Sea repeatedly discharged its waters through this depression into the Black Sea and further into the Mediterranean Sea during the Quaternary period. The last discharge occurred in MIS 2 when the Khvalynian transgression waters exceeded the drainage divide between those two basins. The geochronology of the last flow of Caspian waters into the Black Sea was established recently based on 14C dating of Khvalynian shells, carried out mainly by liquid scintillation counting, and the end of this event was dated to 12.5–12.8 ka cal BP. Recently obtained OSL dates for one of the most complete sections of the Khvalynian deposits of the Manych Depression indicate an older time for the end of the flow. This study aimed to clarify the timing of the Khvalynian transgression discharge by examining two sections containing the Khvalynian mollusk fauna in layers that, according to their stratigraphic and geomorphological position, belong to the final phase of the flow of the Caspian waters. Four 14C AMS dates were obtained from single shells of Didacna ebersini and Hypanis plicata, which agree with the OSL dating results. The results indicate that the last overflow of Caspian waters through the Manych Depression had ceased at around 14.5 ka cal BP.

Grand solar minima are periods spanning from decades to more than a century during which solar activity is unusually low. A cluster of such minima occurred during the last millennium, as evidenced by reductions in the numbers of sunspots observed and coeval increases in cosmogenic isotope production. Prior to the period of instrumental records, natural archives of such isotopes are the only resources available for detecting grand solar minima. Here, we examine the period 433–315 BCE, which saw a sustained increase in the production of the cosmogenic isotope, radiocarbon. Our new time series of radiocarbon data (Δ14C), obtained on cellulose extracted from known-age oak tree rings from Germany, reveal that the rise in production that occurred at this time was commensurate with patterns observed over recent grand solar minima. Our data also enhance, and to a degree challenge, the accuracy of the international atmospheric radiocarbon record over this period.

Pahñu is an archaeological site belonging to the Xajay culture, which inhabited north-central Mesoamerica in 350–1000 AD. Human burials contained in three pairs of contiguous cists were discovered inside a ceremonial structure at Pahñu during excavations conducted between 2019 and 2022. The walls of the cists separated groups of skeletal remains, so the stratigraphic units containing them did not overlap. Stratigraphically speaking, the six groups of remains could have been contemporary and each of the cists could have been used during periods of different durations. Therefore, the analysis of excavation data could not produce a precise temporal sequence of the events that took place in the cists. However, radiocarbon dating by accelerator mass spectrometry (AMS) of representative samples of bones, teeth, and charcoal, allowed us to refine the temporal sequence of their placement in each cist and thus have a better understanding of the funerary practices of the Xajay.

Age estimates from bomb 14C dating conflict with a well-recognized age reading protocol (grinding, polishing and staining in the sagittal plane) for otoliths of European eel (Anguilla anguilla). Proper alignment of calculated hatch years for 14C measurements taken from the earliest otolith growth—among the smallest otolith extractions to date for successful 14C analysis due to the advent of gas-AMS—was not achieved using age estimates from an accepted method. The realignment of otolith 14C values to a tropical bomb 14C reference chronology, which is most applicable to the Sargasso Sea as the natal origin of European eel, led to an increase of the original age estimates by 8 to 32 years. A maximum age of approximately 46 years was determined for the European eel specimen with the most massive otolith, of which mass is a reasonable proxy for age and was instrumental in identifying age estimate discrepancies. By extending the otolith mass-to-age relationships from this study to the most massive otoliths available from archived otoliths of Norway, an increase of up to several decades from the original otolith age estimates was discovered, leading to support for a potential lifespan of 70–100 years in the natural environment.

The chronology of the Bronze Age in the Carpathian basin is largely based on relative chronologies, i.e. stylistic analysis of ceramic (and other) materials. While the number of radiocarbon dates is generally increasing, certain important sites are still poorly dated. One of the largest necropolises from this period, i.e. Mokrin necropolis, which traditionally belongs to Maros culture, is dated only with 6 radiocarbon dates. Here we synthesize the previous 6 radiocarbon dates with 13 new radiocarbon dates, with two goals in mind: 1) to explore the absolute chronology of the site, specifically to determine its chronological limits; and 2) to test hypotheses about the spatio-temporal organization of the site. Our data show that the chronological limits of the necropolis were most probably between 2073 and 1822 BC. Concerning traditional relative chronologies, none of the previous hypotheses about the internal chronological development of the necropolis is supported by data. Our results suggest that all parts of the necropolis were used relatively simultaneously.

In recent times, forensic science has increasingly relied on methods that use stable and radioactive isotope analysis to identify human remains. The use of 14C-AMS dating of dental enamel and dentine of an individual allows the estimation of the year of birth, while that of stable isotopes of carbon and oxygen can provide information on their geographical origin. Isotopic analysis of a tissue complements existing identification techniques, enhancing the capacity to refine, exclude, and affirm investigative approaches directed towards individual identification.

The primary aim of this exploratory study is to amalgamate diverse isotopic methodologies conducive to the prompt and accurate identification of a deceased individual. In this manuscript, we elucidate the application of a rapid processing technique for whole molars from individuals with documented ages, employed to ascertain age through 14C-AMS dating. Furthermore, an investigation was undertaken to assess the capacity of carbon and oxygen-stable isotopes in distinguishing regional disparities. To achieve this, we conducted a comparative analysis of tooth samples sourced from individuals residing in three cities within the Mexican Republic: Mexico City in the central region, Oaxaca City in the southern region, and Tepic Nayarit on the western Pacific coast. The age of dental piece formation, as estimated through 14C-AMS, exhibited a precise correlation with the actual age. By means of the stable isotope outcomes, the data disclosed substantial disparities in 13C and 18O abundances among teeth from individuals residing in the three cities.

Despite the continuous reporting of radiometric chronology of lithic assemblages in the Korean peninsula, systematic evaluation of reliable radiocarbon (14C) dates and discussion on the lithic technological variability have not been adequately presented. This paper attempts to address the issue reviewing the available data on the Early Upper Paleolithic (EUP) of Korea, with a focus on 14C chronology and lithic technology. Also, these recent advances in Paleolithic studies in Korea provide interesting aspects of the transition to Upper Paleolithic (UP) technology in East Asia. The transition to the UP is characterized by two key developments: the emergence of blade technology and tanged points, and the use of quality raw material that had been previously disregarded. Reliable 14C dates published recently indicate that this transition began around 43,000–40,000 cal BP. We propose that the emergence of the UP tradition on the Korean peninsula can be explained by focusing on the mobility, regional exchange networks and population dynamics of hunter-gatherers rather than the continuing resort to the simple unidirectional dispersal.

Radiocarbon (14C) measurements on dissolved inorganic carbon (DIC) are a powerful tool to trace water masses and carbon cycling in the ocean. Existing methodologies to determine the 14C content of seawater DIC requires large volumes of sample (usually >100 mL) and specialized graphitization techniques to achieve the accuracy and precision needed for meaningful data interpretation. The advancement of the CO2 gas ionization accelerator mass spectrometry (AMS) technique today allows routine 14C measurements on small samples (<100 µgC) and may thus permit reducing the sample volumes needed to determine 14C content of seawater DIC to ∼2 mL. The proposed method utilizes the carbonate handling system (CHS), gas interface system (GIS) and MICADAS AMS, and provides good accuracy but reduced precision compared to established methods. Good accuracy is shown by comparing results for a marine in-house DIC standard and a DIC seawater profile from Antarctica between the proposed CHS-GIS-MICADAS approach and reference measurements conducted on the same material at established laboratories (ETH and NOSAMS). Further, two sedimentary porewater profiles from a fjord system in Svalbard are presented. Despite good agreement, the precision of the CHS-GIS-MICADAS approach is reduced, potentially limiting possible interpretations on seawater DIC. Nonetheless, the reduction of sample volumes proves particularly helpful to analyze porewater DIC from sediment cores, where sample material is notoriously limited, reduces the required amounts of toxic HgCl2 and simplifies expedition logistics.

This paper presents the radiocarbon context of the megalithic monument El Amarejo 1, situated in the corridor of Almansa in the southern region of La Meseta in Spain. The monument was constructed using small and medium-sized masonry, comprising a short corridor and two separate chambers in which burials were carried out. The results of the 14C analyses of each of the 11 individuals documented indicate that the monument was in use between approximately 1900 and 1200 cal BC. Bayesian modeling of the radiocarbon dates allows for the proposition of hypotheses regarding the construction, utilisation dynamics, and abandonment of the monument. The combination of these new data with the analysis of the 14C dating of other burials from the Bronze Age of La Mancha reveals a complex and heterogeneous panorama. The evidence presented and analyzed in this paper suggests that burial practices associated with fortified settlements and their domestic areas shared space and time with the construction of megalithic monuments located near settlements.