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.

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.

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.

This study presents the initial results of carbon-14 dating after performing sample preparation and graphite production processes at the Federal University of Bahia (UFBA) in an intercomparison with the same processes performed at the Radiocarbon Laboratory of the Fluminense Federal University (LAC-UFF). Both laboratories are located in Brazil. The accelerator mass spectrometry (AMS) system at LAC-UFF was used for radiocarbon measurements. To verify any possible contamination sources during sample preparation, we initially performed swipe tests at UFBA, which were subsequently processed and the graphite samples were produced at LAC-UFF. After UFBA, several reference materials (IAEA-C1, -C2, -C6, -C9, and OXII standards) were prepared and converted into graphite. In addition, the sample material was first partially prepared at UFF and UFBA and then analyzed with the AMS system at LAC-UFF. Subsamples were prepared for additional measurements of the δ13C composition with an elemental analyzer coupled to an isotope ratio mass spectrometer (EA–IRMS) in LFNA-UFBA to study the isotopic fractionation and yield of the graphitization reaction. The obtained values closely aligned with the reference values, demonstrating reproducibility and quality and indicating minimal contamination during chemical and graphitization processes. In the future, samples from different matrices will be prepared at UFBA for application in paleoenvironmental and archaeological studies.

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.

Although radiocarbon-accelerator mass spectrometry (14C-AMS) is an important tool for the establishment of soil chronology, its application is challenging due to the complex nature of soil samples. In the present study, chemical extraction methodologies were tested to obtain the most representative age of Amazonian soil deposition by 14C-AMS. We performed acid hydrolysis with different numbers of extractions, as well as treatments combining acid and bases and quartered and non-quartered samples. The ages of the soil organic matter (SOM) fractions were compared to the ages of naturally buried charcoal samples at similar depths. The results showed that the age of the non-hydrolyzable inert fraction of soil was closer to the age of charcoal and older than the ages of humin. It was also observed that the quartering process can influence the results, since the dating of the humin fraction showed variability in the results. Our results are important to provide information about the most suitable method for the 14C-AMS dating of soil samples for paleoenvironment reconstruction studies.

With the development of radiocarbon dating methods in the last decade, the Andean archaeological community has successfully leaned into the problem of the chronology of the expansion of the Inca State. While this chronology was based on ethnohistorical accounts (Rowe 1945), it has been possible to verify its foundations precisely in the last decade. The results from the Maucallacta region are part of these discussions and are intended to add new data from the Inca province of Kuntisuyu, which was neglected in this debate until now. The project encompasses archaeological investigations near the snow-covered volcano Coropuna, frequently mentioned by chroniclers of the 16th and 17th centuries as an oracle worshiped since pre-Inca times. This includes a large complex known as Maucallacta-Pampacolca, located approximately 170 km northwest of Arequipa in the southern highlands of Peru, within the District of Pampacolca, Province of Castilla, Department of Arequipa (LS; 3750 m asl). Due to its location, it holds a unique relationship with the Coropuna landscape. The site is a vast administrative center featuring over three hundred stone buildings, tombs, and ceremonial structures. Among them, the most important is the large ceremonial platform with ushnu and the dumps deposited beneath it. The analysis of ceramics and animal bones, combined with stratigraphic analysis and the results of new calibrations and interpretations of radiocarbon dates, provides a comprehensive picture of the formation and use of ceremonial dumps at the site, making them one of the most thoroughly examined collections in this regard.

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.

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.

Radiocarbon (14C) dating of soil samples by accelerator mass spectrometry (AMS) has been proven useful for studying carbon (C) cycling in terrestrial ecosystems. However, this application has two primary difficulties in sample preparation: inhibition of graphite formation due to sulfur (S)-containing impurities and contamination of samples with modern C (MC). Herein, we evaluated these effects using three sample preparation methods (silver foil, silver wire, and Sulfix) by conducting AMS-14C measurements of a 14C-dead charred wood and S-rich soil samples. The preparation methods were all successful in graphite formation and AMS-14C measurement for soil samples with an organic S content <6.9 wt%. The methods showed different percent modern carbon (pMC) values from 0.16% to 0.64% for the 14C-dead sample. The results also revealed that across different methods, MC contamination can be significantly reduced by applying two-step procedure (combustion and subsequent reaction to remove S-containing impurities) during sample preparation. The three methods had a negligible influence on determining the 14C age for samples that were at least younger than 12,000 yr BP. As the 14C ages of the soil samples are typically younger than 12,000 yr BP, any method explored in this study can be employed for 14C dating with sufficient accuracy for application to C cycle studies.

The ubiquitous marine radiocarbon reservoir effect (MRE) constrains the construction of reliable chronologies for marine sediments and the further comparison of paleoclimate records. Different reference values were suggested from various archives. However, it remains unclear how climate and MREs interact. Here we studied two pre-bomb corals from the Hainan Island and Xisha Island in the northern South China Sea (SCS), to examine the relationship between MRE and regional climate change. We find that the MRE from east of Hainan Island is mainly modulated by the Southern Asian Summer Monsoon-induced precipitation (with 11.4% contributed to seawater), rather than wind induced upwelling. In contrast, in the relatively open seawater of Xisha Island, the MRE is dominated by the East Asian Winter Monsoon, with relatively more negative (lower) ΔR values associated with high wind speeds, implying horizontal transport of seawater. The average SCS ΔR value relative to the Marine20 curve is –161±39 14C years. Our finding highlights the essential role of monsoon in regulating the MRE in the northern SCS, in particularly the tight bond between east Asian winter monsoon and regional MRE.

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.

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.

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.

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.

In this paper we present new AMS radiocarbon dates from the Bronze Age cemetery of Tiszafüred-Majoroshalom excavated between 1961 and 1972. The cemetery provides crucial information on the cultural development and chronology of the Bronze Age Otomani-Füzesabony and the Tumulus cultures of Eastern Central Europe, in addition to the transition between the Middle and Late Bronze Age (approx. 1500 BC) in the Great Hungarian Plain.

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.

This brief review describes the discovery of cosmic rays by Victor Hess from the Vienna Radium Institute and the later contribution of Marietta Blau through her observation of “disintegration stars” in photographic emulsion plates exposed to cosmic-ray bombardment. Marietta Blau, a nearly forgotten cosmic-ray pioneer from the Vienna Radium Institute, developed the nuclear emulsion technique for studying nuclear reactions, eventually discovering the disintegration of nuclei through high-energy cosmic rays. Blau survived the Holocaust by escaping to Mexico City from 1939 to 1944. Starting in 1948 at Columbia University, later as a staff member of Brookhaven National Laboratory and then University of Miami, she performed fundamental and original research with nuclear emulsions exposed to 3-GeV protons at the Brookhaven Cosmotron and to 6-GeV protons at the Berkeley Bevatron. Blau returned to Vienna in 1960, where at the Radium Institute a classical β-decay counting facility for radiocarbon dating had been installed, which was finally superseded by the Vienna Environmental Research Accelerator (VERA), a modern versatile accelerator mass spectrometry facility.