In two forensic cases, radiocarbon (14C) bomb-pulse datings of human bones have been performed and analyzed using detailed models to correct for collagen-carbon turnover rates and reservoir effects. The modeled corrections are discussed and the resulting 14C ages compared to later information on actual time of birth and death of the individuals. Simple time lag corrections of bone dates are found to be inadequate, whereas modeling based on age dependent turnover rates and bomb-pulse levels through life combined with substantial reservoir age corrections can explain the observed 14C results.

The lack of radiocarbon measurements of funerary contexts is a major shortcoming of the Late Bronze Age and Early Iron Age of the Eastern Carpathian Basin, especially in the Banat region. The present batch of samples tries to address these drawbacks, by detailing sampling strategies, employed pre-treatment and by providing a robust and coherent dataset of radiocarbon measurements. Implications of the new radiocarbon dates is discussed from a supra-regional perspective, while keeping aspects of typo-chronology, circulation of goods, and social nuances of employment of Bronze Age bronzes in the forefront. Ten burials were selected from four Banatian burial grounds according to the occurrence of metal finds in the funerary inventories. Beyond establishing a broad frame of absolute chronology for these sites of interment, the radiocarbon data provide reliable arguments for the precise attribution of metal discoveries. In addition, the data allow us to challenge some previously stated chronological assignments.

During the last two decades the radiocarbon (14C) dating of hydroxyapatite archaeological cremated bones has become standard practice. Various pretreatment procedures exist among different laboratories of which some include fixation of SO2 using “Sulfix” prior to CO2 reduction. Recently it was reported that the use of Sulfix may cause the resulting 14C age to be too old. Here we report on the use Sulfix at the Aarhus AMS Centre. Further, we report on an experiment designed to test alternatives for the use of Sulfix as a purification agent.

A laboratory intercomparison project was carried out on 20 annually resolved late-wood samples from the Danish oak record. The project included the following three laboratories: (1) the University of Arizona AMS Laboratory, University of Arizona, USA (AA); (2) HEKAL AMS Laboratory, MTA Atomki, Hungary (DeA); and (3) Aarhus AMS Centre (AARAMS), Aarhus University, Denmark (AAR). The large majority of individual data points (96%) lie within ±2σ of the weighted mean. Further assessment of the accuracy associated with the individual laboratories showed good agreement, indicating that consistent and reliable 14C measurements well in agreement with each other are produced at the three laboratories. However, the quoted analytical uncertainties appear to be underestimated when compared to the observed variance of differences from the geometric mean of the samples. This study provides a general quality check of the single-year tree-ring 14C measurements that are included in the new calibration curve.

The Nekselø Wickerwork provides an unusually solid estimate on the marine reservoir age in the Holocene. The basis for this result is a 5200-year-old fish weir, built of hazel wood with a brief biological age of its own. Oysters settled on this construction. They had lived only for a short number of years when the fence capsized and was covered in mud and the mollusks suffocated. Based on the difference in radiocarbon (14C) age between accelerator mass spectrometry (AMS) samples of oyster shells and wood, respectively, the marine reservoir age for this site is estimated to 273 ± 18 14C years. Re-evaluations of previously produced data from geological and archaeological sites of Holocene date in the Danish archipelago indicate marine reservoir ages in the same order as that of the Wickerwork. Consequently, we recommend the use of the new value, rather than the ca. 400 14C years hitherto favored, when correcting for the dietary induced reservoir effect in radiocarbon dates of humans and animals from the Late Mesolithic and Early Neolithic periods of this region.

Dating lime mortar samples using the radiocarbon (14C) method can be difficult. This is because the contamination is similar to the primary dating material (CaCO3) and consequently difficult to remove. Mortar can also have late-in-formation pyrogenic carbonate from interactions with the environment after the initial hardening phase, such as recrystallization, fire damage or delayed hardening. When 14C dating a system of primary dating material, contamination and late-in-formation pyrogenic carbonate, one approach is multi-fraction dating with conclusiveness criteria. If a sample has sufficient contamination or late-in-formation pyrogenic carbonate, the criteria evaluate the result inconclusive. To improve inconclusive results from such samples, this study investigates sample preparation by thermal decomposition. Here samples that were inconclusively dated by the authors’ traditional method, sequential dissolution with 85% phosphoric acid, are investigated further. This study finds that CO2 thermally decomposed at low temperatures contains some late-in-formation pyrogenic carbonate. By rejecting CO2 decomposed at low temperatures, Kastelholm castle and Kimito church in Finland are conclusively and accurately dated. Furthermore, a preheating method removes some late-in-formation carbonate, but not enough for a conclusive result. Finally, thermal decomposition finds difficulty in discerning binder carbonate from limestone and marble contamination.

We present a new biennial record of radiocarbon (14C) measured in Danish oak. The new record covers the years 1251–1378 CE, thereby spanning the Grand Solar Minimum known as the Wolf Minimum. Two oak samples from every other year were measured at the AMS facility at Aarhus University (Denmark), resulting in an average precision of 1.4‰ for the record. Spectral analysis of the new record revealed two peaks at 27 and 9.1 years, which could indicate the Hale cycle was lengthened and the Schwabe cycle shortened during the Wolf Minimum, but it is also possible that the amplitude of the Schwabe cycle was too small to be accurately identified with the acquired precision of this record. The record was bandpass filtered to investigate the variability of the amplitude in different bands, which showed a dampening of the amplitude during the second half of the Wolf Minimum in bands centered on the Schwabe and the Hale cycle, respectively. A reconstruction of the solar modulation function, Φ, also showed a periodicity of ca. 9 years, and indicated that the Wolf Minimum was preceeded by one cycle of decreased solar activity.

We here present a comparison of methods for the pretreatment of a batch of tree rings for high-precision measurement of radiocarbon at the Aarhus AMS Centre (AARAMS), Aarhus University, Denmark. The aim was to develop an efficient and high-throughput method able to pretreat ca. 50 samples at a time. We tested two methods for extracting α-cellulose from wood to find the most optimal for our use. One method used acetic acid, the other used HCl acid for the delignification. The testing was conducted on background 14C samples, in order to assess the effect of the different pretreatment methods on low-activity samples. Furthermore, the extracted wood and cellulose fractions were analyzed using Fourier transform infrared (FTIR) spectroscopy, which showed a successful extraction of α-cellulose from the samples. Cellulose samples were pretreated at AARAMS, and the graphitization and radiocarbon analysis of these samples were done at both AARAMS and the radiocarbon dating laboratory at Lund University to compare the graphitization and AMS machine performance. No significant offset was found between the two sets of measurements. Based on these tests, the pretreatment of tree rings for high-precision radiocarbon analysis at AARAMS will henceforth use HCI for the delignification.

The lowlands of south-western Iran have been studied archaeologically since the mid nineteenth century. The Neolithic period, however, was mostly investigated in the 1960s and 1970s, when Early Neolithic settlements were reported in the western plains, positing the idea that the rest of the lowland plains had been populated after the Neolithic period. The excavation at Tapeh Mahtaj in 2015, however, has changed this view. This article provides inter-disciplinary results and discusses the nature of the Early Neolithic in the Iranian south-western lowlands, thereby enabling a better understanding of the emergence of early domestication and sedentism in the region specifically and in the Eastern Fertile Crescent.

The concentration of radiocarbon (14C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14C curve and reconstructed changes in CO2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.

Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Annually resolved tree-ring samples of the time period 1625–1510 BCE were analyzed from the German oak tree-ring chronology. Blocks of the same tree rings were previously used to generate IntCal calibration data. The new dataset shows an offset to the calibration data IntCal13 of 24 years and resembles annual data for the same time period derived from tree-ring records in other growth locations. A subset of samples of the period 1625–1585 BCE was additionally measured in three other laboratories (ETH, AAR, AA) for quality control.

When sampling mortars for radiocarbon (14C) dating it is crucial to ensure that the sample has hardened rapidly relative the resolution of the dating method. Soft and porous lime mortars usually fulfill this criterion if the samples are taken from an uncovered surface from less than a few centimeters deep. However, hard, concrete-like mortars may be impermeable for carbon dioxide and even the outermost centimeters may still contain uncarbonated calcium hydroxide. These mortars may harden very slowly and contain carbonate that formed centuries or even millennia after the original building phase, and they can still be alkaline and capture modern 14C, causing younger 14C ages than the actual construction age. Another problem is reactivation of the binder carbonate if it has been partly decarbonated during a fire later on in its history. It will be shown that these young carbonates dissolve rapidly in phosphoric acid and in many cases a reasonable 14C age can be read from 14C profiles in sequential dissolution if the measurements from initially formed carbon dioxide are disregarded. However, if a mortar was made waterproof deliberately by adding crushed or ground tile, as in Roman cocciopesto mortars, it may be very difficult to get a conclusive dating.

Single-year measurements of radiocarbon (14C) in tree rings have led to the discovery of rapid cosmic-ray events as well as longer lasting anomalies, which have given new insights into the Sun’s behavior in the past. Here, we present two new single-year 14C records based on Danish oak that span the periods AD 692–790 and 966–1057, respectively, and consequently include the two rapid cosmic-ray events in AD 775 and 994. The new data are presented along with relevant information on the dendrochronological dating of the wood pieces, implying that these new measurements may contribute towards generating the next international calibration curve. The new data covering the AD 966–1057 period suggest that the increase in atmospheric 14C associated with the cosmic-ray event in AD 994 actually occurred in AD 993, i.e. one year earlier than the year reported in Fogtmann-Schulz et al. (2017) based on oak from southern Denmark. Careful reanalysis of the dendrochronology that underpins the new 14C records based on oak material from southern Denmark reveals that the cosmic-ray event reported in Fogtmann-Schulz et al. (2017) actually took place in AD 993.

The aim of this study is to investigate the range, the degree of variability, and a possible time or species dependence of wood and charcoal δ13C values within one small study area. To achieve this, we used δ13C and 14C determinations of more than 400 archaeological samples from a ca. 300 ha area in Denmark, spanning 5000 years and covering several different species. The δ13C values of the wood and charcoal range from −32.8‰ to −21.2‰. We found no time-dependence of wood and charcoal δ13C values, neither in general nor within one species. The mean δ13C of all wood samples is −28.5‰, while the means of individual species range from −30.6‰ to −26.3‰. The mean of all charcoal samples is −25.7‰, with the means of individual species ranging from −28.1‰ to −24.3‰. The wood δ13C values can be used to infer the possible range of plant δ13C values, which otherwise are not available. They imply that a high degree of variability can be expected at the base of the food chain. This is relevant for palaeodietary studies that rely on the measurement of baseline isotope values.

Historical sources reveals that Copenhagen was founded in the late 12th century AD by Bishop Absalon. However, during the excavation for the new metro in central Copenhagen a previously unknown early medieval cemetery was discovered and excavated at the Town Hall Square. Radiocarbon (14C) analysis was conducted on the 9 individuals found in situ, together with 11 individuals from the other early medieval cemetery in Copenhagen, belonging to the St Clemens church. The radiocarbon analysis places the onset of the cemeteries to the early 11th century AD and therefore questions the age of Copenhagen and hence the archaeological and historical perception of the Danish historical record. Here a detailed account of the radiocarbon-based Bayesian model is presented.

The contents of a pit located in the centre of a large communal structure at Asiab in the central Zagros mountains provides rare evidence for ritual food practices during the Early Neolithic (~9660–9300 cal. bc). This pit contained the skulls of at least 19 wild boars carefully placed inside and subsequently sealed. Antler from red deer and the skull of a brown bear were also concealed within the pit. The boars included both male and female animals varying in age and some of the larger canines were deliberately removed. Such a unique collection of remains is unlikely to be the result of day-to-day activities; instead, this represents a group of ritually interred bones. This new evidence strengthens views that activities reinforcing social cohesion were important as human society was approaching a juncture leading towards agricultural subsistence strategies.

Chronic inflammation is associated with disease risk and mortality in the general population. Soluble urokinase plasminogen activator receptor (suPAR) is a stable marker of chronic inflammation, and a higher serum-concentration of suPAR is found in individuals with an unhealthy lifestyle such as smoking. This article investigates the association between suPAR and dietary quality measured with the dietary quality score (DQS). The DQS is an index of the overall quality of an individual’s dietary habits assessed through a self-administered FFQ. Furthermore, this article investigates the association of both suPAR and the DQS with CVD risk and mortality in the general Danish population. We analysed 5347 individuals aged 30–60 years from the Danish Inter99 study cohort. Multiple linear regression analyses showed a linear inverse association between the DQS and suPAR (P=0·0005). Cox regression analyses showed an 18 (95 % CI 9, 26) % increase in the risk of death from any cause with each 1 ng/ml increase in suPAR. We found no significant association between the DQS and the mortality (hazard ratio: 1·16, 95 % CI 0·79, 1·69). All analyses were adjusted for demographics and lifestyle factors. The association between the DQS and suPAR on the one hand and suPAR and mortality on the other supports the argument that low dietary quality may constitute a health risk through its influence on chronic inflammation. Future research should examine whether suPAR is modifiable through changes in dietary habits.

Only a limited number of radiometric dates for the Final Palaeolithic and the first half of the Mesolithic are available from the southeastern Baltic. This paper presents eight new Late Pleistocene/Early Holocene radiocarbon accelerator mass spectrometry (14C AMS) ages of osseous artifacts housed at the Kaliningrad Regional Museum of History and Art. These artifacts include one piece of worked reindeer (Rangifer tarandus) antler, three axes of the so-called Lyngby type, one bone point, one uniserial harpoon, one so-called bâton percé antler shaft, and one slotted bone. All the samples were successfully dated and yielded five Late Pleistocene and three Early Holocene ages, including the hitherto earliest age for human occupation in the Eastern Baltic. The dates include not only a surprisingly early date for a bone point (for this region), but also some dates that contradict expected ages based on traditional typological assessment. Our study significantly adds to the still small number of existing absolutely dated artifacts from the region and proposes new ways of viewing the Final Palaeolithic and Early Mesolithic chronology in the southeastern Baltic.

Substantial amounts of annual radiocarbon (14C) data have recently been produced with the purpose of increasing the time resolution of 14C records used for constructing the calibration curve and for studying the occurrence of abrupt cosmic-ray events. In this study, we investigate if it is possible to resolve sub-annual scale changes in the atmospheric 14C content by measuring radiocarbon in early-wood and late-wood fractions from Danish oak. The tree-ring samples span the period 1954–1970 CE, hereby covering the peak of the bomb pulse. A least squares test comparing the atmospheric 14C content and the new sub-annual 14C record from Danish tree rings reveals that by measuring early-wood and late-wood fractions, it may be possible to resolve sub-annual variations in past atmospheric 14C levels.