High-precision radiocarbon accelerator mass spectrometry (AMS) measurements of a new high-altitude stone-pine tree-ring chronology from the European Alps were performed for a 500-yr stretch in the second half of the 4th millennium BC. A 14C calibration curve with a typical 1-σ uncertainty of about 20 14C yr was achieved. Although the general agreement of our data set with INTCAL98 is very good (confirming once more that INTCAL98 is also proper for calibration of samples of extraordinary sites), we found small deviations of 17 ± 5 14C yr, indicating possible seasonal effects of the delayed growing season at high altitude.

Actinide isotopes are present in environmental samples at ultra-trace levels (236U concentration is quoted to be on the order of pg/kg or fg/kg). Their detection requires the resolution of mass spectrometry (MS) techniques, but only accelerator mass spectrometry (AMS) has the sensitivity required. In order to perform the isotopic ratio measurements of actinides, such as 236U/238U, an upgrade of the Center for Isotopic Research on Cultural and Environmental Heritage accelerator (CIRCE) in Caserta, Italy, has been performed. The system was originally equipped for radiocarbon AMS measurements. The main difficulty of AMS measurement of 236U is the intense neighboring beam of 238U. Although most of the 238U ions are suppressed by means of magnetic and electrostatic elements, a small fraction of this intense beam can interfere with the rare isotopes. This paper reports the preliminary results of the 236U/238U isotopic ratio measurement limit (<5.6 x 10–11), aimed also to better understand the origin of background ions. For this purpose, a large 16-strip silicon detector providing spatial resolution has been used. In addition, calculations to assess the performance of the system obtained by adding a high-resolution time of flight-energy (TOF-E) detector are discussed.

The carbonate hydrochemistry of groundwater from the Hvinningdal aquifer (Denmark) was studied by radiocarbon (accelerator mass spectrometry (AMS)) and δ13C measurements as a preliminary step towards 14C groundwater dating. The 14C concentrations varied between 30 and 100 percent modern carbon (pMC) in apparent contradiction with tritium (3H) data, which in most cases indicate a post-bomb date. The dilution of 14C can be explained as being due to the combined effect of dissolution of old soil carbonate and oxidation of old organic carbon. The last effect proved to be essential. To calculate this correction the dissolved oxygen concentration was used together with the δ13C values. The combined corrections bring the 14C concentrations up to post-bomb levels in better agreement with the 3H data.

Radiocarbon activity of dissolved inorganic carbon has been measured in the northwestern Black Sea. Both continental shelf and open-sea profiles show that surface waters are in equilibrium with the atmosphere. The observed distribution of 14C activity shows a weak contribution of the deep 14C-depleted CO2 to the photic zone. Such a distribution of 14C within the water column is unable to explain the aging of sedimentary organic matter and reservoir ages greater than 500 yr. A contribution of production by chemoautotrophic bacteria feeding on 14C-depleted methane at the boundary of the oxic and anoxic zones is a realistic hypothesis. Also, a contribution to sedimentary organic carbon estimated at <15% of the photosynthetic primary production could explain 14C reservoir ages greater than 1300 yr.

The debate over the dating of the Santorini (Thera) volcanic eruption has seen sustained efforts to criticize or challenge the radiocarbon dating of this time horizon. We consider some of the relevant areas of possible movement in the 14C dating—and, in particular, any plausible mechanisms to support as late (most recent) a date as possible. First, we report and analyze data investigating the scale of apparent possible 14C offsets (growing season related) in the Aegean-Anatolia-east Mediterranean region (excluding the southern Levant and especially pre-modern, pre-dam Egypt, which is a distinct case), and find no evidence for more than very small possible offsets from several cases. This topic is thus not an explanation for current differences in dating in the Aegean and at best provides only a few years of latitude. Second, we consider some aspects of the accuracy and precision of 14C dating with respect to the Santorini case. While the existing data appear robust, we nonetheless speculate that examination of the frequency distribution of the 14C data on short-lived samples from the volcanic destruction level at Akrotiri on Santorini (Thera) may indicate that the average value of the overall data sets is not necessarily the most appropriate 14C age to use for dating this time horizon. We note the recent paper of Soter (2011), which suggests that in such a volcanic context some (small) age increment may be possible from diffuse CO2 emissions (the effect is hypothetical at this stage and has not been observed in the field), and that "if short-lived samples from the same stratigraphic horizon yield a wide range of 14C ages, the lower values may be the least altered by old CO2." In this context, it might be argued that a substantive “low” grouping of 14C ages observable within the overall 14C data sets on short-lived samples from the Thera volcanic destruction level centered about 3326–3328 BP is perhaps more representative of the contemporary atmospheric 14C age (without any volcanic CO2 contamination). This is a subjective argument (since, in statistical terms, the existing studies using the weighted average remain valid) that looks to support as late a date as reasonable from the 14C data. The impact of employing this revised 14C age is discussed. In general, a late 17th century BC date range is found (to remain) to be most likely even if such a late-dating strategy is followed—a late 17th century BC date range is thus a robust finding from the 14C evidence even allowing for various possible variation factors. However, the possibility of a mid-16th century BC date (within ∼1593–1530 cal BC) is increased when compared against previous analyses if the Santorini data are considered in isolation.

CH4 and CO2 emissions from geologic sources, which are devoid of radiocarbon (14C), dilute the atmospheric 14C/C ratio. Observations of 14C/C can be used to estimate fossil fuel-derived CH4 and CO2. However, the atmospheric 14C/C ratio is perturbed by emissions of 14C from nuclear power plants (NPPs) and fuel reprocessing sites, which may affect such 14C/C-based estimation if they are not correctly quantified. We calculate NPP 14C emissions for CO2 and CH4 from 1972–2016 using standard emission factors (14C emitted per unit of power produced) and analyze trends in global and regional emissions. We use available observations of 14C emissions and power generation in Europe to assess emission factors for different reactor types, as well as potential differences related to the age or manufacturer of the NPPs. Globally, nuclear 14C emissions increase until 2005 and then decrease, mostly because of the closure of gas-cooled reactors in the United Kindom and the shutdown of light water reactors after the Fukushima nuclear accident in March 2011. Observed emission factors in Europe show strong variability, spanning values from 0.003 to 2.521 TBq/GWa for PWR and from 0.007 to 1.732 TBq/GWa for BWR reactors, suggesting more information and more sophisticated models are needed to improve estimates of 14C emissions.

The updated chronology of the earliest pottery-containing complexes in Siberia and the Russian Far East is presented herein. The appearance of pottery (i.e. the process of Neolithization) in this vast region of Eurasia is discussed based on a model that represents a simple approximation of calendar ages between key sites as isolines. No clear spatiotemporal patterns for the origin and spread of pottery in northern Asia can be observed because pottery-making (unlike agriculture) could have emerged in different parts of the Old World at various times. Before modeling of pottery dispersal is conducted, careful evaluation of typology and technology of ceramics and stone artifacts should be done, in order to avoid the confusing situation when the results of modeling contradict the basic archaeological information.

The radiocarbon dates reported in this list are almost all based on collagen measurements from human archaeologic bone material. This collagen was isolated according to the methods developed by Berger, Horney and Libby (1964), Ho, Marcus and Berger (1969), Longin (1971) and Protsch (1973). All samples were counted as CO2 gas at close to 1 atm in a 7.5L proportional counter with three energy channels. The 14C dates reported are calculated with the Libby half-life of 5568 ± 30 years as required by convention. 13C measurements were used to normalize to −25‰ in the standard manner. The biospheric standard is 95% the count rate of NBS oxalic acid for radiocarbon laboratories. Background is based on CO2 obtained from marble. The accuracy of counter operation is checked against historically dated wood from the funerary boat of Sesostris III, 1872−8 +4 bc (Hayes, 1962). The 14C ages are not tree-ring calibrated.

Since the early 1950s, the Sellafield nuclear fuel reprocessing plant in Northwest England has released radiocarbon into the Irish Sea in a mainly inorganic form as part of its authorized liquid effluent discharge. In contrast to the trend in which the activities of most radionuclides in the Sellafield liquid effluent have decreased substantially, 14C discharges have increased since 1994–95. This has largely been due to a policy change favoring marine discharges over atmospheric discharges. 14C is radiologically important due to its long half life, mobility in the environment, and propensity for entering the food chain. Current models for radionuclide dispersal in the Irish Sea are based on a reversible equilibrium distribution coefficient (kd), an approach which has been shown to be inadequate for 14C. Development of predictive models for the fate of Sellafield-derived 14C requires a thorough understanding of the biogeochemical fluxes between different carbon reservoirs and the processes controlling the net flux of 14C out of the Irish Sea, through the North Channel. In this study, both an empirical and a halving time approach indicate that close to 100% of the 14C that is discharged from Sellafield is dispersed beyond the Irish Sea on a time-scale of months in the form of DIC, with little transfer to the PIC, POC, and DOC fractions, indicating that the “dilute and disperse” mechanism is operating satisfactorily. This is consistent with previous research that indicated little transfer of 14C to Irish Sea sediments. While significant 14C enhancements have been observed in the biota of the Irish Sea, this observation is not necessarily in conflict with either of the above as the total biomass has to be taken into account in any calculations of 14C retention within the Irish Sea.

An excavation carried out at the megalithic necropolis of Panoria in 2015 offered an excellent opportunity for dating a widespread variety of polygonal, rectangular, and trapezoidal-shaped tombs with short passages for which, surprisingly, there were previously no known radiocarbon (14C) measurements available. Based on the anthropological remains, a series of 19 14C dates was obtained and modeled in a Bayesian statistical framework. The results stress a long period of use that began in the Late Neolithic (3525–3195 cal BC), reaching the most intensive ritual activity during the Copper Age and ending in the Early Bronze Age (2125–1980 cal BC). Throughout this period, tombs were built at different times and used at different temporal scales and intensities, ranging from a few decades to centuries.

Some examples are given to show that the depth distribution curves of natural 14C and 13C of thin-layer sampled soil profiles can be used for inferring changes in soil organic matter and climate changes. By using a simple exchange model, we can determine whether decomposition products are fixed by clay or transported downward toward the groundwater table. We can also estimate the amount of the Greenhouse gases, CO2 and CH4, produced by the decomposition of the organic matter in terrestrial and paddy soils and emitted from the soil. A change from C3 to C4 plants, which might occur during a predicted temperature rise in some areas, thereby influencing the carbon balance, can be clearly detected by the δ13C depth profiles. A change in organic matter input can also be calculated under certain circumstances.

This study compares age estimates of recent peat deposits in 10 European ombrotrophic (precipitation-fed) bogs produced using the 14C bomb peak, 210Pb, 137Cs, spheroidal carbonaceous particles (SCPs), and pollen. At 3 sites, the results of the different dating methods agree well. In 5 cores, there is a clear discrepancy between the 14C bomb peak and 210Pb age estimates. In the upper layers of the profiles, the age estimates of 14C and 210Pb are in agreement. However, with increasing depth, the difference between the age estimates appears to become progressively greater. The evidence from the sites featured in the study suggests that, provided aboveground plant material (seeds, leaves) is selected for dating, the 14C bomb peak is a reliable dating method, and is not significantly affected by the incorporation of old carbon with low 14C content originating from sources including air pollution deposition or methane produced by peat decomposition. 210Pb age estimates that are too old may be explained by the enrichment of 210Pb activity in the surface layers of peat resulting from a hypothesized mechanism where rapidly infilling hollows, rich in binding sites, may scavenge 210Pb associated with dissolved organic matter passing through the hollow, as part of the surface drainage network. Until further research identifies and resolves the cause of the inaccuracy in 210Pb dating, age estimates of peat samples based only on 210Pb should be used with caution.

Controlled feeding experiments demonstrate that the 14C content of the carbonate fraction of fossil avian eggshell should reliably reflect the 14C activity of feed and contemporary atmospheric CO2 regardless of amounts of 14C depleted scratch injested. Consideration of biochemical pathways and exchange rates across lung membranes leads to the possibility that the carbonate fraction may, in some instances, be slightly 14C depleted. 14C dates on eggshell carbonate should require little or no correction. As with marine shell carbonate, normal soil-forming processes may alter the surficial carbon isotopes in eggshell carbonate. 14C dates on the protein fraction should be even more reliable than those on the carbonate fraction, but only if special precautions or separation techniques exclude non-indigenous carbon from the sample. Original protein contents are likely to be too low for conventional 14C dating techniques.

When human remains are found, apart from helping explain the cause of death and determining the extent of any injuries, forensic pathologists are usually requested to determine the identity of the deceased and how much time has elapsed since his death. In the Czech Republic, the criminal liability for murder is set to a statute of limitations of 20 years. In our pilot study, tissue samples of human remains from two decedents were radiocarbon (14C) dated to estimate the date of death. In agreement with published literature, we have confirmed relatively short carbon turnover time in hair, nail, and bone fat. Therefore these samples are the most appropriate for determining date of death. Other samples, such as teeth (collagen and carbonate form) and collagen isolated from bone samples, which exhibit relatively long carbon turnover time, can be used to reduce ambiguity of dating results and to indicate some interfering influences. Given the possibility of processing multiple sample types, we also propose brief guidelines for comparing and interpreting the results of individual analyses.

Radiocarbon-dated paleobotanical and palynological samples record complex changes of vegetation and climate in northeastern Russia during the Late Pleistocene and Holocene. Since the Kargin Interval (middle Wisconsin equivalent), which started 50 ka ago, we can distinguish two periods that were colder than the present. The Kirgilyakh was the earliest Karginsk cool period, dating to 45–39 ka BP. The second significant cool period dates to 33–30 ka BP. The boundary between the Kargin Interval and the last Late Pleistocene glaciation (Sartan, late Wisconsin equivalent) dates from 27 ka BP. The sharp change from herbaceous mossy tundra (Sartan) to light-coniferous larch forests (Holocene) in northeastern Russia dates to 12.5 ka ago. The Holocene thermal maximum, linked to the expansion of woody plants into the modern barren-ground tundra, dates from 9.5–8 ka BP.

Dating ice samples from glaciers via radiocarbon is a challenge that requires systematic investigations. This work describes an approach for extraction and accelerator mass spectrometry (AMS) 14C analysis of the particulate organic carbon (POC) fraction in glacier ice samples. Measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples obtained mainly from the non-temperated ablation zone of the Grenzgletscher (Grenz Glacier) system (Monte Rosa Massif, Swiss Alps). The samples were obtained from 2 sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg of ice, yielding between 18 and 307 μg of carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 μg C and originated mainly from the quartz filters and the rinsing liquids used in processing. Minimum sample sizes for successful graphitization of CO2 in our laboratory could be reduced to <10 μg carbon, with a background in the graphitization process of ∼0.5 μg of 40-pMC carbon. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of pMC values. We obtain a mean calibrated age of 2100 BC to AD 900 (95.4% confidence level), which is not significantly different for the 2 sampling sites. Discussions of these results suggest that single 14C dates of glacial POC are presently of limited significance. Future improvements with respect to analytical precision and sample characterization are proposed in order to fully explore the POC dating potential.

14C ages were determined on samples of foraminifera separated from cores from three areas of the tropical Pacific (East Pacific Rise, Oontong Java Plateau, and South China Sea). Analyses were made on four planktonic species and on mixed benthics. The purpose of the multiple analysis on planktonic species is to assess the importance of artifacts resulting from the bioturbation-abundance change couple, from the bioturbation-partial dissolution couple and from redeposition by bottom currents. The goal is to use the benthic-planktonic age difference as a means of establishing changes in deep sea ventilation rate over the past 25,000 years. Results of a part of this work are presented in this paper.

The following is a list of dates obtained since the compilation of List XII. The method is essentially the same as described in that list. Two CO2-CS2 Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) a.d. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In Michigan date lists up to and including VII, we quoted errors at least twice as great as the statistical errors of counting, to take account of other errors in the over-all process.

Specific activities of radiocarbon in annual tree rings corresponding to 1980-2009 are reported for a pine tree located 2 km from the Qinshan Nuclear Power Plant (Qinshan NPP), China. While a negligible enhanced 14C activity due to operation of the Qinshan NPP Plant I is evident, a relative increase (1.8–62.6 Bq/kg C) was observed in the specific activity after operation of the Qinshan NPP Plant II in 2002 and Plant III in 2003. The enhanced values were primarily affected by the 14C discharged from Plant III (CANDU-type reactor), and a good correlation was found between the 14C discharged from Plant III in the growing season and the 14C excess value. The excess 14C activities peaked in 2005 (at 302.0 Bq/kg C, which is 62.6 Bq/kg C above the “clean air” 14C level), and then declined due to the improvement in 14C discharge management of Plant III. In 2009, the 14C-specific activity was near the background level.

The chemical extraction of soil organic carbon (SOC) fractions from soils often does not produce satisfactory results for radiocarbon dating. In this study, a sequential pyrolysis technique was investigated. The soil was pyrolyzed at temperatures of 200, 400, 600, and 800 °C to partition organic carbon into pyrolytic volatile (Py-V) and pyrolytic residue (Py-R) fractions. The preliminary results show that the 14C dates of both fractions become progressively older as the pyrolysis temperature is increased. In addition, the ages of the Py-V fractions are consistently younger than the corresponding Py-R fractions extracted at the same temperature. Experimental results of known-age paleosol samples indicate that the Py-V fractions obtained between 600 and 800 °C yield the most reliable ages. This technique provides a new approach to improve the accuracy of 14C dating of loess-paleosol sequences.