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.

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.

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.

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.

We present 35 AMS 14C dates from 26 horizons on a 30-cm gravity core from Shira Lake in the republic of Khakassia, Central Russia. The chronology of the core is determined by 210Pb/137Cs dating results and interpretation of elemental geochemistry with historic documents, covering deposition since ca. 1870 CE. This study assesses the old carbon influence (OCI) on organic carbon 14C by comparison with the 210Pb/137Cs dates, sources of carbon, and lake conditions interpreted from elemental proxies. These include elemental concentrations in 0.5N HCl leaches and Aqua Regia dissolution fractions, as well as organic C, N and C/N measurements. From these data we establish a succession of the following six zones: I) (1870∼1900 CE) relatively fresh lake with high lake level, low productivity and high surface runoff (wet conditions); II) (1900∼1940 CE) a “white zone” reflected by high carbonate and low magnetic signal formed in a saline, oxidizing and holomictic lake stage; III) (1940∼1963 CE) reduced carbonate with elevated organic C, N, C/N, Mo and magnetic signal, indicating a stratified and anaerobic lake; IV) (1963∼1994 CE) increased salinity and productivity with the highest observed magnetic signal and elevated heavy metal and Mo contents, implying enhanced anoxic conditions and human impact; V) (1994∼2003 CE) high C/N, organic and carbonate contents suggesting meromictic and anaerobic lake conditions; VI) (2003∼2020 CE) decreased carbonate content with increased organic C and N, and heavy metals showing a deteriorating lake environment under human impact.

A 350 14C yr discrepancy was found between dates on postcranial remains and mandibular teeth on what was thought to be the same individual from the Early Neolithic cemetery of Shamanka II, Lake Baikal. Stable nitrogen isotope results suggested a major shift in diet between childhood (when the teeth formed) and adulthood (represented by the postcrania), which could have resulted in different 14C ages through a freshwater reservoir effect. Subsequent additional dating on the mandible and postcranial elements, however, indicated that the mandible actually belonged to a different individual. More subtle reservoir effects can be seen on the sequentially forming teeth and mandible. The practice by prehistoric hunter-gatherers of Lake Baikal of re-opening graves and removing cranial elements has long been known, but this is the first evidence for the inclusion of a mandible from a separate individual, though whether it was intentional or incidental is uncertain. As well as providing new insights into mid-Holocene mortuary practices in the region, our findings raise a cautionary note for the examination of disturbed graves.

The study analyses in situ CO2 mole fraction, 14CO2, and fossil based excess CO2 mole fraction (Cfoss) data at Hegyhátsál (HUN) rural monitoring station (Central Europe) supplemented by passive monitoring of 14C content of tree-rings. Through the observed period (2014–2020) we focused on revealing trends in atmospheric CO2 and 14C levels, particularly during the year of the first COVID lockdown, in comparison to the preceding five years. In addition, monthly integrated samples of atmospheric CO2 and tree-rings from the six years were subjected to 14C analysis. The passive tree-ring measurements focuses on two major urban areas (Budapest and Debrecen) in Hungary, along with the rural monitoring site. Results show a steady increase in CO2 levels at HUN between 2014 and 2020. The calculated fossil based excess CO2 concentrations for the initial year of COVID are in good agreement with the previous five-year averages both at 115 m and 10 m elevations. These results also show seasonal variations of CO2 mole fractions, peaking in winter and decreasing in summer. Tree-ring results from Debrecen show a good alignment with the results of the atmospheric monitoring station, and it does not show a significant fossil contribution in the urban background area during the vegetation periods. Tree-ring results from Budapest show a stronger fossil contribution compared to the Debrecen ones. Our atmospheric CO2 results do not show a large decrease in fossil CO2 atmospheric contribution during the first lockdown. We found that the use of this passive CO2 monitoring technique can provide a valuable tool for investigating such differences.

Western Zhou Dynasty (ca. 1046–771 BC) was established soon after conquering the Shang Dynasty (ca. 1600–1046 BC) and brought about the earliest enfeoffment system in Chinese history. Yan was one of the vassal states of the same clan as Zhou. According to historical records, the capital of Yan state was located near Yan mountain, which is now known as the Liulihe site in the Fangshan District, Beijing. This study carries out the high-precision dating of two newly discovered Western Zhou Dynasty noble tombs at the Liulihe site. The man in tomb M1902 participated in the groundbreaking ceremony of Yan’s capital according to inscriptions on the bronze vessel found in this tomb. Samples of different materials, especially different parts of human skeletons from the tombs, were selected to form a sample series in chronological order. Wiggle-matching models were established in OxCal program based on the growth and development time of different teeth and bones of human skeletons. More accurate ages were acquired for the death of the individuals. The results indicate that the most probable distribution range of the death date of the individual in M1902 is about 1045–1010 BC. The radiocarbon dates of M1902 give important chronological information about the founding of Yan state, and they are very close to those of the year in which King Wu of Zhou conquered the Shang Dynasty.

A new model for the interpretation of radiocarbon (14C) dates of Holocene marine shells is presented. For the Netherlands, the size of reservoir effect is difficult to assess, as these shells often lived in an environment of mixed marine- and river waters. Both stable isotopes 13C and 18O of the shell carbonate give insight in the environmental conditions the shells lived in. River water occurs in two main categories, distinguished by 18O: the Rhine which is dominant, and other rivers. This leads to two estuary mixing lines between the North Sea and rivers. The stable isotopes of the shell carbonate are also indicative for additional processes, such as uptake of secondary carbonate from the soil by shells, and exchange of C isotopes between atmosphere and water. Extensions of the main model deal with special cases such as pools of stagnant water and lakes. The model leads to an assessment of the recent 14C activities of the system the shells lived in, called 14aSYS. The measured 14C activities relative to these 14aSYS values determine the 14C age of the shells and include the reservoir effect. This way we circumvent normalizing to δ13C = –25‰, i.e. the terrestrial timescale and the subsequent correction for reservoir effects. The model is applied to a large legacy dataset of marine shells from the Netherlands, obtained during the last 7 decades. It contains 1116 14C dated shells; for the majority of these, the 3 isotopes 13C, 14C and 18O are measured.

Accelerator mass spectrometry (AMS) is a worldwide recognized method for radiocarbon (14C) dating. The advantageous aspects of this method include the variety of materials and the small sample size (1 mg of carbon) that can be measured. However, these pose several challenges in the laboratory, such as developing appropriate chemical pretreatment methods. In the summer of 2022, the Radiocarbon and Mass Spectrometry Laboratory in Gliwice, Poland, launched the MICADAS accelerator spectrometer. The report on background and reference materials measurement results for the period from September 2022 to July 2024 is presented in this publication. Quality assurance and quality control processes are extremely important to guarantee the high quality of the results obtained in the laboratory. Hence, our Radiocarbon and Mass Spectrometry Laboratory in Gliwice took part in the Glasgow International Radiocarbon Inter-Comparison (GIRI) program. The radiocarbon ages for wood, bone, humic acid, and barley mash samples were determined and compared with reported values. The resulting data confirmed that our Laboratory is capable of dating samples across a spectrum of materials and ages ranging from contemporary to the limits of the radiocarbon method, achieving precision on par with that of other laboratories.