A newly developed compact AMS, LEA (Low Energy Accelerator), is tested and compared with a state-of-the-art AMS system MICADAS (Mini Carbon Dating System), which has a precision performance of better than 1‰ for modern 14C. The main difference between these two systems is the acceleration voltage, which has been reduced from 200 kV with the MICADAS system to 50 kV with the LEA system. In order to execute the final performance tests, exactly same samples (2 sets consisting of 7 standards, 4 blanks, 26 wood samples) are measured on both systems successively. The results show that the LEA system is fully operational, and the performance is entirely comparable with that of the MICADAS system.

The article presents results of measurements of radiocarbon (14C) concentration in sub-annual dendrochronologically dated tree rings of English oak (Quercus robur L.) from Grabie village near Kraków (southern Poland). Samples of early wood (EW) and late wood (LW) spanning the years 664–658 BCE. α-cellulose was extracted from each sample and their radiocarbon content was measured at the ATOMKI laboratory in Debrecen, Hungary. The EW and LW data confirm a prolonged increase in Δ14C values around 665–663 as was observed by Park et al. (2017), Rakowski et al. (2019), or Sakurai et al. (2020). In addition, we found that this event may consist of two relatively small events, as was proposed by Sakurai et al. (2020). Based on obtained in this and previous study data we estimate that the occurrence of the two events were between 665 and 664 BCE (Rakowski et al. 2019), and in late spring of 663 BCE (May–June, before beginning of LW formation).

We present an alternative radiocarbon (14C) age-depth model using IntCal20 to calibrate new accelerator mass spectrometry (AMS) data applied to a Lake Baikal sediment core (VER99G12) in southern Siberia. 14C dating showed that the core extends to 31 ka. To take into account uncertainties in 14C age and sedimentation depth in the core, a new age-depth modeling routine, undatable, was used in this study. Undatable revealed that significant changes in sedimentation rate correspond to global climate events, either warm or cold, which periods are likely close to the timing of the occurrence of the Meltwater pulses (MWP) at 19 and 14 ka, and the Last glacial Maximum (LGM) at 21–20 ka. Since the Selenga River accounts for 50% of the total river inflow to Lake Baikal, we interpret that these changes in sedimentation rate could be signals of significant changes in Selenga River discharge to the lake, which is expected to be affected by global climate change. Based on pollen analysis, it is highly probable that the sudden influx of the Selenga River to Lake Baikal, particularly at 19 ka, was due to the thawing of permafrost water through the Selenga River, which had developed in the region. Total organic carbon content and mean grain size increases concurrent with sedimentation rate, suggesting river inflow increased available nutrients for biological activity. Our results indicate that hydrological changes corresponding to MWP events can be observed in continental areas of the Northern Hemisphere.

Dissolved inorganic carbon (DIC) in ocean water is a major sink of fossil fuel derived CO2. Carbon isotopes in DIC serve as tracers for oceanic water masses, biogeochemical processes, and air-sea gas exchange. We present a timeseries of surface DIC δ13C and Δ14C values from 2011 to 2022 from Newport Beach, California. This is a continuation of previous timeseries (Hinger et al. 2010; Santos et al. 2011) that together provide an 18-year record. These data show that DIC Δ14C values have declined by 42‰ and that DIC δ13C values have declined by 0.4‰ since 2004. By 2020, DIC Δ14C values were within analytical error of nearby clean atmospheric CO2 Δ14C values. These long-term trends are likely the result of significant fossil fuel derived CO2 in surface DIC from air-sea gas exchange. Seasonally, Δ14C values varied by 3.4‰ between 2011 and 2022, where seasonal δ13C values varied by 0.7‰. The seasonal variation in Δ14C values is likely driven by variations in upwelling, surface eddies, and mixed layer depth. The variation in δ13C values appears to be driven by isotopic fractionation from marine primary producers. The DIC δ13C and Δ14C values record the influence of the drought that began in 2012, and a major upwelling event in 2016.

Known as lead white, lead carbonates were used as white pigment or cosmetics from the 4th century BC to the 20th century AD. Lead white was produced by the corrosion of metallic lead by vinegar and horse manure up to the 19th c. In order to document the incorporation of carbon in the corrosion mechanism, lead carbonates were produced in the laboratory under monitored experimental conditions using materials with different isotope signatures in 14C and 13C. Six experimental setups were defined combining vinegar, acetic acid, horse manure and fossil CO2 gas. The corrosion products were characterized by X-ray diffraction. 14C content and δ13C values of the initial reactants and the final products were measured by accelerator and isotopic ratio mass spectrometry (AMS and IRSM). The reaction between lead and vinegar or acetic acid resulted in lead acetates with a carbon isotopic signature close to that of the corrosive reagent. In the presence of CO2, the carbonatation reaction occurred and the cerussite produced had a predominant 14C signature of the carbon dioxide source. These experiments demonstrate that the CO2 produced by horse manure fermentation is incorporated into the corrosion products, allowing the absolute dating of lead white by the radiocarbon method.

Over the course of one year (2021), we monitored the carbon isotope composition of atmospheric CO2 at three locations in Croatia: the Adriatic port city of Rijeka (Cfa climate) and at two rural sites: Gornje Jelenje (Cfb climate) in the vicinity of a main road and clean-air site Parg (Dfb climate). Carbon isotope composition at all sites shows seasonal variation, ranging from –41.3 to 25.2‰ for Δ14C and from –13.1 to –11.3‰ for δ13C. Rijeka systematically has the lowest and Parg the highest Δ14C, and δ13C at the sites are not statistically different one from another. The Δ14C of leaves of deciduous trees reflect the trend of atmospheric Δ14C. Based on the assumption that the investigated area is under the influence of two main sources of CO2: fossil and natural (sea exchange, biosphere, and undisturbed – clean air atmospheric component) the approximate share of fossil CO2 in total atmospheric CO2 has been estimated for Rijeka (2.1 ± 1.3%) and Gornje Jelenje (1.0 ± 0.9%). Comparison of our results with the data from European CO2 sampling stations indicates strong influence of CO2 from sea and biosphere. Backward trajectories indicate a possibility of Δ14CCO2 contribution from distant EU nuclear power plants, but movement of air masses should be considered in more detail to confirm this.

Archaeological dung pellets are time capsules of ancient herbivore diets and gut flora, informing on past agropastoral activity, ecology, and animal health. Improving multi-proxy approaches is key to maximizing this finite archaeological resource. Through experiments with standard pretreatments used in radiocarbon (14C) dating, we address a fundamental problem in maximal multi-proxy analysis: How to chronometrically date individual caprine pellets while conserving as much as possible for additional analyses? We applied acid-alkali-acid (AAA) or acid-only pretreatments to 37 samples of ancient and recent sheep/goat dung pellets from sites in the Negev desert, Israel, measuring weight-loss due to pretreatment. Shavings of outer surfaces and remaining inner pellets of four pairs were dated and compared. We found that (i) sample-specific factors affect pretreatment survivability, including preservation quality and initial sample size; (ii) given sufficient start weight, AAA can be used to pretreat sheep/goat coprolites; (iii) 100 mg appeared a desirable minimum sample weight before pretreatment; and (iv) shavings of coprolites’ outer surface produced 14C dates equivalent to dates obtained from inner coprolites. Whereas standard coprolite analysis protocols discard shavings removed from outer surfaces to avoid contamination, our findings indicate their efficacy for 14C dating. This offers an important addition to workflows for multi-proxy coprolite analysis.

We compare radiocarbon (14C) ages of coexisting planktonic foraminifera species from sediment cores VM12-107 and KNR166-2-26JPC from the Equatorial Atlantic Ocean for three time periods (Holocene, Heinrich Stadial 1, last glacial maximum). We find a maximum inter-species difference of 1200 14C yr. On average, the 14C ages deviate by ∼300 yr between Globigerinoides ruber and other species. In most cases, this exceeds the analytical uncertainty range of the measurements and thus renders the choice of species for generating age models as important as sample weight. While modern stratified water-column profiles imply an increase in 14C ages with water depth, we observe an expected parallel increase of 14C ages and δ18O only at VM12-107. The mismatch between 14C ages and δ18O at KNR166-2-26JPC likely results from the effects of bioturbation and the hydrographic setting. The largest difference in 14C ages between mixed-layer versus thermocline-calcifying planktonic foraminifera are observed during Heinrich Stadial 1 despite a decrease in upper-ocean stratification at that time. This difference is likely the result of inconsistent increases in 14C reservoir ages during times of reduced overturning circulation masking the potential of 14C ages of coexisting planktonic foraminifera to reflect the density stratification of the water column.

Through Bayesian analysis of new radiocarbon dates, this paper demonstrates that the Topará tradition did not emerge until after Paracas monumental sites were ritually closed in the Chincha Valley of the Peruvian south coast. These findings controvert a long-held hypothesis of Topará as a foreign tradition which intruded into the Paracas heartland and initiated the period of transformation known as the Paracas-Nasca transition. We present the first radiocarbon dates from Jahuay, the earliest accepted Topará site. These dates are compared with new analyses of published radiocarbon dates from three other sites associated with this transitional period: a Late Paracas politico-ceremonial site in the Chincha Valley, a Late Paracas settlement in the Palpa Valley in the Río Grande de Nasca Drainage, and an Initial Nasca site in the same valley. This work shows Paracas site closures began earlier than has previously been appreciated and demonstrates that the first appearance of the Topará ceramic style post-dates the onset of Paracas decline in the region’s northern valleys. This analysis represents a successful attempt to develop a radiocarbon-based chronology across a calibration plateau by incorporating stratigraphic data into a Bayesian model.

We constructed a laser ablation (LA) system using a diode laser for the accelerator mass spectrometry radiocarbon (AMS 14C) measurement of organic materials. The system could extract adequate CO2 to analyze small masses (0.1 mg C) at a resolution of 250 µm by a 5.5 W diode laser. The LA system was assessed using standard materials (IAEA-C1, IAEA-C2, IAEA-C3, IAEA-C6, and Ox II) and applied to natural tree ring samples. For the LA sampling of organic samples, which generally results in incomplete combustion, tungsten (VI) oxide was used as an oxidant to achieve complete burning. The results of the measurement of standard materials showed a low 14C background of F14C 0.0085 ± 0.0005 and reasonable reproduction of 14C values. Finally, we applied this system to a single-year analysis of tree-ringed spruce timber in Alaska. It was observed to have a detectable background for the 14C bomb peak.

The timeframes of Holocene anthropogenic dune remobilization in Central Europe remain less studied compared to those of Late Glacial climatically controlled dune formation. The present contribution aims to reinforce existing knowledge on the chronology of Late Glacial–Holocene dune activity and stability, as well as to reveal the scale of human impact on dune remobilization. Accelerator mass spectrometry radiocarbon (AMS 14C) dating and calibration of the results are reported from paleosol horizons buried in inland dune deposits that occur in Central and Eastern Poland. Twenty-three new dates are based on charcoal samples collected at 13 sites. From each of the investigated sites, at least one AD date is obtained, indicating that buried paleosols of such young age are far more widespread in Polish dunes than reflected in previous studies. The widespread preservation of these paleosols under cover of aeolian sand reflects the extent of the anthropogenic dune formation phase that peaked during the Medieval and Early Modern periods.

The quantification of fossil-fuel derived carbon dioxide (CO2ff) emissions is critical for regional carbon budgets. Radiocarbon (14C) is an effective tool to estimate the contribution of CO2ff to the total atmospheric CO2. In the present study, we have determined the spatial distribution of fossil fuel derived CO2 across Delhi using 14C measurements in Peepal tree leaves from April 2016 to March 2017 at city scale. Our analysis results show that the Δ14C values vary between –67.78‰ to 5.61‰ and corresponding CO2ff values are varying from 1.63 ppm to 33.34 ppm. CO2ff values from campus sites vary between 6.99 ppm to 16.38 ppm with an average value of 10.22 ± 3.20 ppm, while CO2ff values vary from 2.41 ppm to 33.34 ppm with an average value of 13.32 ± 9.40 ppm for sites located in the parks. Further, we observed the higher contributions of fossil fuels in the CO2 from northwest Delhi, central Delhi, and some parts of east and southwest Delhi. In the absence of real-time CO2 monitoring, the results of this study provide a potential method for analyzing the contribution of CO2ff values over the urban landscape to total CO2 over the study region.

El Japón is a 16th century hamlet site in the marshlands of the southern Basin of Mexico in central Mesoamerica. Radiocarbon (14C) dating and OxCal modeling of human bone collagen (n = 11) identifies a range of burials at El Japón cemetery from 1550–1650 cal. CE. The refined chronology identifies use of this rural settlement well after the onset of colonial government-sponsored relocation of Indigenous people to larger settlements (congregaciones). Historically documented information in this work supports chronological modeling beyond stand-alone calibration. Stable isotopic study of bone samples demonstrates similar sources of dietary protein and carbohydrates. The similarity of carbon sources for bone apatite (bioapatite) and collagen offers security that both bone fractions are viable 14C dating opportunities. Recent extension of this work examines bioapatite 14C dates (n = 5) from the same bone samples when quality parameters are met—atomic carbon-nitrogen ratios of 3.2–3.3 and collagen yield of 10–20%. No significant difference is found between collagen and bioapatite dates of the same individuals (p = 0.17, Mann-Whitney U test). 14C dates from human bone samples in this primarily terrestrial dietary context can be successfully acquired from either collagen or bioapatite fractions.

14CO2 activity in air samples collected at Kakrapar Gujarat Site, India, was measured, and site-specific dilution factor for 14CO2 has been evaluated. 14CO2 activity in air samples was monitored for 72 different sampling events at onsite stack of Nuclear Power Plant (NPP) and at ESL meteorology laboratory (at 1.6 km from NPP stack). 14CO2 activity in air at stack of NPP and at ESL meteorology laboratory was observed to 0.10–0.18 TBq (GWe.year)–1, with mean value 0.12 TBq (GWe.year)–1 and ≤0.04–0.13 Bq m–3, with mean value 0.08 Bq m–3 respectively. The results were correlated with meteorological parameters. Site specific dilution factor for 14CO2 in air was evaluated at 1.6 km and was found to be in the range of 4.6E-05 to 21E-05 s m–3. Inter angle (degree) between plume direction and fixed sampling location and rainfall (mm) are found to be the important influencing parameters for dilution factor of 14CO2 in air.

As there exists a growing demand for chronological research and tracer applications using radiocarbon (14C) analyses of samples smaller than 100 μg C, a compact micro-specific hydrogen graphitization method has been developed at the Xi’an Accelerator Mass Spectrometry (AMS) Center. This article describes the performance of the system and the mass of carbon background produced during ultra-small sample preparation. Furthermore, we discuss the results of contamination corrections and perform 14C analyses on small samples with known age or reference values. The results reveal that our 14C analysis of ultra-small samples of 10–100 μg C can obtain accurate and reliable results, and the micro-scale 14C-AMS analysis technique meets our research objectives for dating and tracer applications.

We have conducted radiocarbon (14C) dating of Japanese tree rings from 1053 to 921 BCE and 41 BCE to 130 CE. Dating was also performed using oxygen isotope dendrochronology to investigate subtle structures of the calibration curve corresponding to the beginning and the end of the Yayoi period in Japan. These two results followed IntCal20, which included the 14C ages of two Japan-sourced trees. The findings suggest that dating of specimens obtained from areas around the Japanese archipelago may be affected by periodic monsoons from the ocean, an effect that needs further examination.

GIRI (Glasgow International Radiocarbon Intercomparison) was designed to meet a number of objectives, including to provide an independent assessment of the analytical quality of the laboratory/measurement and an opportunity for a laboratory to participate and improve (if needed). The principles in the design of GIRI were to provide the following: (a) a series of unrelated individual samples, spanning the dating age range, (b) linked samples to earlier intercomparisons to allow traceability, (c) known age samples, to allow independent accuracy checks, (d) a small number of duplicates, to allow independent estimation of laboratory uncertainty, and (e) two categories of samples—bulk and individual—to support laboratory investigation of variability. All of the GIRI samples are natural (wood, peat, and grain), some are known age, and overall their age spans approx. >40,000 years BP to modern. The complete list of sample materials includes humic acid, whalebone, grain, single ring dendro-dated samples, dendro-dated wood samples spanning a number of rings (e.g., 10 rings), background and near background samples of bone and wood. We present an overview of the results received and preliminary consensus values for the samples supporting a more in-depth evaluation of laboratory performance and variability.

The fifth season of excavations of Oponice Castle in 2020 was located in the lower castle’s courtyard. The research led to discovery of an original clay floor being heavily burned with charred plank and a rectangular stone-brick construction. The construction has collapsed upper part with a fallen low brick arch. The whole area was covered with numerous stove tiles and one clay mold for the production of stove tiles. The construction was identified as a pottery kiln dated to the second half of the 16th until the first half of the 17th century AD by the findings from excavated layer identified to the kiln destruction. Also, written sources mention a large fire in 1645 which destroyed the castle. The aim of this article is to use different methods of dating and refine the chronology of the context through microarchaeology and Bayesian modeling. For these purposes different types of samples were collected. The sampling focused on site formation process determination of pottery kiln use and the way of its destruction. Applying Bayesian analysis improved overall dating, through modeled time interval of the three individual sequences and helped recreated historical events during the period, when the calibration curve fluctuates.

Mesopotamia is often regarded the “cradle of civilization.” The development of water management practices in the region is thought to have played a key role in the emergence of these early civilizations. We present the first direct dating of a palaeo-canal system at the ancient city of Girsu, Mesopotamia (modern Iraq) (occupied between 4800 and 1600 BC). We describe the use of archaeological and radiocarbon (14C) dating techniques to establish the age of this canal system. Our results show considerable differences between shell 14C dates on the one hand and charcoal 14C dates and archaeological evidence on the other. This likely reflects the impact of freshwater reservoir effects from the Tigris and Euphrates Rivers. Although the FRE from rivers is widely acknowledged, its impact on 14C dates in Mesopotamia is rarely discussed and poorly understood. Our results provide a first indication of its variability and magnitude. With the publication of our results we aim to highlight the problem and re-initiate collaborative research efforts in improving 14C dating in this important region.

The Marine20 radiocarbon (14C) age calibration curve, and all earlier marine 14C calibration curves from the IntCal group, must be used extremely cautiously for the calibration of marine 14C samples from polar regions (outside ∼ 40ºS–40ºN) during glacial periods. Calibrating polar 14C marine samples from glacial periods against any Marine calibration curve (Marine20 or any earlier product) using an estimate of ${\rm{\Delta R}}$, the regional 14C depletion adjustment, that has been obtained from samples in the recent (non-glacial) past is likely to lead to bias and overconfidence in the calibrated age. We propose an approach to calibration that aims to address this by accounting for the possibility of additional, localized, glacial 14C depletion in polar oceans. We suggest, for a specific polar location, bounds on the value of ${\rm{\Delta }}{{\rm{R}}_{20}}\left( {\rm{\theta }} \right)$ during a glacial period. The lower bound ${\rm{\Delta R}}_{20}^{{\rm{Hol}}}$ may be based on 14C samples from the recent non-glacial (Holocene) past and corresponds to a low-depletion glacial scenario. The upper bound, ${\rm{\Delta R}}_{20}^{{\rm{GS}}}$, representing a high-depletion scenario is found by increasing ${\rm{\Delta R}}_{20}^{{\rm{Hol}}}$ according to the latitude of the 14C sample to be calibrated. The suggested increases to obtain ${\rm{\Delta R}}_{20}^{{\rm{GS}}}$ are based upon simulations of the Hamburg Large Scale Geostrophic Ocean General Circulation Model (LSG OGCM). Calibrating against the Marine20 curve using the upper and lower ${\rm{\Delta }}{{\rm{R}}_{20}}$ bounds provide estimates of calibrated ages for glacial 14C samples in high- and low-depletion scenarios which should bracket the true calendar age of the sample. In some circumstances, users may be able to determine which depletion scenario is more appropriate using independent paleoclimatic or proxy evidence.