Accurate radiocarbon ages were obtained from terrestrial moss from two drill holes in Tern Lake deposits, Antarctica, using liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The results show that the lake deposits have been accumulating since the end of the last glacial epoch ca. 12,600 cal BP at the rate of 0.13–1.1 mm a-1. We discuss the validity of 14C ages of Antarctic lake deposits, with respect to the latitude effect of 14C productivity, the reservoir effect, the environment effect and the hard-water effect.

The distribution of bomb-produced 14C in the ocean provides a powerful constraint for circulation models of upper ocean mixing. We report 14C measurements from an east-west section of the main thermocline at 24°N latitude in the subtropical North Atlantic Ocean in summer 1992, and one profile from the Gulf of Mexico in 1993. Observed gradients reflect the transient invasion of bomb 14C into the thermocline via mixing along isopycnals from the poleward outcrop, with progressively more sluggish mixing at greater depths. A slight deepening of the profile is observed over the 20-yr period since the GEOSECS survey at one location where the comparison is possible.

Radiocarbon (14C) dating has been widely used to determine the age of deposits, but there have been frequent reports of inconsistencies in age among different dating materials. In this study, we performed radiocarbon dating on a total of 33 samples from 8-m-long sediment cores recovered from the wetland of the Muljangori volcanic cone on Jeju Island, South Korea. Ten pairs of humic acid (HA) and plant fragments (PF) samples, and three pairs of HA and humin samples, from the same depths were compared in terms of age. The PF were consistently younger than the HA. Interestingly, the age difference between HA and PF samples showed a long-term change during the past 8000 years. To test whether there was an association between this long-term age difference and climate change, we compared with the carbon/nitrogen (C/N) ratios and total organic carbon isotope (δ13CTOC) values of the sediments, as indicators of the relative abundance of terrestrial and aquatic plants; these parameters showed similar long-term trends. This suggests that the increasing (decreasing) trend in age difference was influenced by long-term dry (wet) climate change.

The paper “The effects of possible contamination on the radiocarbon dates of the Dead Sea Scrolls I: castor oil” by Rasmussen et al. (2001) is discussed. Detailed analysis of the extant dates of the Dead Sea Scrolls suggests that the pretreatment of the samples was adequate. Errors and omissions in the paper are discussed and the implications of the experiment of Rasmussen et al. (2001) are questioned.

The following date list presents results obtained during 1975-1977. The facilities at Glasgow have been further developed and include a gas counting system utilizing CO2 as counting material and two liquid scintillation counting laboratories based on synthesis of benzene. The results presented here were obtained using the liquid scintillation system only. Sample pretreatment varied according to individual sample type, whether wood or charcoal. The majority of samples were of preserved wood. After manual removal of gross contamination, samples of wood were finely chopped and digested in boiling, 2M KOH solution. The dehumified wood was then separated by filtration, thoroughly washed with distilled water and dilute hydrochloric acid, and then bleached in a solution of NaClO2/HCl at 80°C for 48 hours. Pure, white wood cellulose was obtained by filtration and washed with a large volume of distilled water. The cellulose, typically 40% by weight of the original material, was then dried overnight in an oven at 80°C. Samples of charcoal were closely examined for non-contemporaneous contamination and then subjected to successive treatments with hot, dilute (1M) KOH and HCL, respectively. The remaining charcoal was then dried overnight at 80°C.

This series reports some of the measurements made since publication of the previous list (R, 1979, v 21, p 48–94). Acetylene proportional gas counting methods essentially remain as described in Saskatchewan II (R, 1960, v 2, p 73). Bone dating is now carried out on soluble collagen extract (Longin, 1971). The laboratory is associated with the National Museum of Canada to provide radiocarbon dating service for Canadian archaeologists but commercial services are also available to others.

In autumn of 2016, the National 1MV Accelerator Mass Spectrometry (AMS) Laboratory at The Scientific and Technological Research Council of Türkiye (TÜBİTAK), Marmara Research Center (MRC), Türkiye (Turkey), started to offer radiocarbon (14C) analysis service internationally. In this article, the process from sample acceptance to reporting and the primary procedures implemented and applied for 14C analysis at the TÜBİTAK AMS Radiocarbon Dating Laboratory are described. The service provided by the laboratory includes sample evaluation for 14C analysis, sample preparation, graphite production, AMS measurement, data supervision, calendar date calculations, and consultancy. For commercial testing and analysis, a one-page official report which shows the 14C age and uncertainty is provided for each sample. In addition to a dedicated wet chemistry laboratory to process samples before measurement with AMS, there are two systems for the conversion of CO2 to elemental carbon process; an automated graphitization system (AGE III) and a manual graphitization system based on a glass high vacuum line. A 1MV UAMS NEC Pelletron system installed in the laboratory is used for natural level 14C samples needed to be analyzed for archeological, geological, geographical, and environmental and forensic science applications. In addition to commercial 14C testing and analysis activities, national and international research projects can be developed or contributed to within the scope of project management or partnership.

The North Sea is considered a unique heritage site that yielded a huge amount of zoological and archaeological data. More than 200 palaeozoological and archaeological fossil bone samples from the North Sea bed are dated by 14C. About 2/3 of these dated bones are Pleistocene in age; the majority of the bones are from extinct species (in particular woolly mammoth); about 1/3 of the sample date to the Holocene. The presented dataset is important in its kind, but interpretation is limited because of a lack of context of the finds. The stable isotopes (13C, 15N) of the dated samples provide additional information on palaeoenvironmental conditions and dietary habits in the past. We present primarily a Groningen list of data; a few fossils dated in other laboratories are included for completeness.

The Laboratoire des Sciences du Climat et de l’Environnement (LSCE) has operated a radiocarbon dating laboratory for almost 70 years. It has evolved from a traditional ß-decay counting to an accelerator mass spectrometry facility. In 2015, the LSCE received a major upgrade with the installation of a MICADAS. This evolution required adjustments in sample preparation to match the new capability to date samples as small as a few tens of µgC. We summarize here the sample cleaning procedures and the chemical purification or extraction treatment that we apply to the samples. We also report values of blank and reference materials of different matrices that match the large diversity of samples handled at LSCE.

This paper integrates the first rock art directly dated with radiocarbon (14C) in Southeast Asia with the archaeological activity in the area and with stylistically similar rock art in the region. Peñablanca is a hotspot of archaeological research that includes the oldest dates for human remains in the Philippines. The caves in Peñablanca with known rock art were revisited and only 37.6% of the original recorded figures were found; the others are likely lost to agents of deterioration. A sample was collected from an anthropomorph and accelerator mass spectrometry (AMS) dated to 3570–3460 cal BP. The date corresponds to archaeological activity in the area and provides a more holistic view of the people inhabiting the Peñablanca caves at that time. A systematic review was used to find similar black anthropomorph motifs in Southeast Asia to identify potential connections across the region and provide a possible chronological association.

We report here dates on archaeologic and geologic samples. The samples were counted as methane in gas proportional counters. The techniques used have been described earlier (R, 1971, v 13, p 442–449). Dates are expressed in years BP, taking AD 1950 as the reference year. Modern standard was NBS oxalic acid. Quoted errors are based on counting statistics alone and are equivalent to ±1 standard deviation for samples younger than 10,000 years and ± 2 standard deviations for older samples. Descriptions and references regarding the samples have been supplied by the submitters of the samples.

In coastal and island archaeology, carbonate mollusk shells are often among the most abundant materials available for radiocarbon (14C) dating. The marsh periwinkle (Littorina irrorata) is one of these such species, ubiquitously found along the Atlantic and Gulf coasts of the United States in both modern and archaeological contexts. This paper presents a novel approach to dating estuarine mollusks where rather than attempting to characterize the size and variability of reservoir effects to “correct” shell carbonate dates, we describe a compound-specific approach that isolates conchiolin, the organic matter bound with the shell matrix of the L. irrorata. Conchiolin typically constitutes <5% of shell weight. In L. irrorata, it is derived from the snail’s terrestrial diet and is thus not strongly influenced by marine, hardwater, or other carbon reservoir effects. We compare the carbon isotopes (δ13C and Δ14C) of L. irrorata shell carbonate, conchiolin, and bulk soft tissue from six modern, live-collected specimens from Apalachicola Bay, Florida, with samples that represent possible sources of carbon within their environment including surface sediments, marsh plant tissues, and dissolved inorganic carbon (DIC) in water. Ultimately, this paper demonstrates that samples obtained from wet chemical oxidation of L. irrorata conchiolin produces accurate 14C dates.

Measurements of ∆14C and δ13C, separately in early wood and late wood of two Mediterranean pine species, with a nearly year-long growth season, were made to better define possible solar flare particle effects. The measurements were made for suitable periods around the years of big flares (e.g., 1942, 1946, 1989) in Pinus pinea of the Adriatic area and Pinus halepensis from South Australia. We found that the 14C concentration is consistently greater in early wood than in late wood of the same growth ring and considerably higher in the Australian samples than in the European samples. The data so far reveal no evidence of solar-flare effect.

In the 19th and early 20th centuries, many museums acquired Egyptian coffins containing mummies from private donors who bought them from dealers in Egypt. Owing to the unknown context of such acquisitions, it cannot be assumed that the mummified individual inside the coffin is the same person named on it. Radiocarbon dating is a key diagnostic test, within the framework of a multidisciplinary study, to help resolve this question. The dating of an adult mummy in the Nicholson Museum at the University of Sydney was therefore checked using 14C dating. For over 150 yr, mummy NM R28.2 was identified as Padiashaikhet as per his coffin, dated to the 25th Dynasty, about 725–700 BC. 14C results from samples of linen wrappings revealed that the mummy was an unknown individual from the Roman period, cal AD 68–129. The mummification technique can now be understood within its correct historical context.

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

We present two new millennium-long tree-ring oxygen isotope chronologies for central and northern Japan, based on 9693 annually resolved measurements of tree-ring oxygen isotopes from 39 unearthed samples consisting mainly of Japanese cedar (Cryptomeria japonica). These chronologies were developed through cross-dating of tree-ring widths and δ18O data from multiple samples covering the periods 2349–1009 BCE (1341 yr) and 1412–466 BCE (947 yr) for central and northern Japan, respectively. In combination with our published chronology for central Japan, the tree-ring δ18O dataset currently available covers the past 4354 yr (2349 BCE to 2005 CE), which represents the longest annually resolved tree-ring δ18O dataset for Asia. Furthermore, the high-resolution temporal record of 14C contents independently developed by Sakurai et al. (2020) was reproduced by our 14C measurements of earlywood and latewood in annual rings for the period 667–660 BCE.

A Bayesian model for accelerator mass spectrometry (AMS) data analysis is presented. Instrumental drift is modeled with a continuous autoregressive (CAR) process, and measurement uncertainties are taken to be Gaussian. All samples have a parameter describing their true value. The model adapts itself to different instrumental parameters based on the data, and yields the most probable true values for the unknown samples. The model is able to use the information in the measurements more efficiently. First, all measurements tell something about the overall instrument performance and possible drift. The overall machine uncertainty can be used to obtain realistic uncertainties even when the number of measurements per sample is small. Second, even the measurements of the unknown samples can be used to estimate the variations in the standard level, provided that the samples have been measured more than once. Third, the uncertainty of the standard level is known to be smaller nearer a standard. Fourth, even though individual measurements follow a Gaussian distribution, the end result may not.

For simulated data, the new Bayesian method gives more accurate results and more realistic uncertainties than the conventional mean-based (MB) method. In some cases, the latter gives unrealistically small uncertainties. This can be due to the non-Gaussian nature of the final result, which results from combining few samples from a Gaussian distribution without knowing the underlying variance and from the normalization with an uncertain standard level. In addition, in some cases the standard error of the mean does not represent well the true error due to correlations within the measurements resulting from, for example, a changing trend. While the conventional method fails in these cases, the CAR model gives representative uncertainties.

The Danube region in Central Europe was one of the areas where several cultures appeared before moving further or being defeated during the Migration Period in the middle of the first millennium AD. The Lombards, who crossed the Danube in 505 AD, settled in the “Tullnerfeld” where the Maria Ponsee graveyard was excavated in 1965–1972. From the historical evidence about the temporal and spatial migration of the Lombards, it was concluded that the graveyard was in use between 505 and 568 AD by three groups of migrants. We processed and dated a new set of 23 bones, found in the Maria Ponsee site. The determined 14C dates fit well in the expected time interval, though discrimination between the grave groups could not be obtained. The dates were added to the chronological sequence, recording the Migration Period in Central Europe. The sequence lead to a good correlation of the modelled and historical data (Amodel = 87.6%). The results show differentiations of the respective tribes in the pre-Lombardic period. However, transitions between the Lombard phases were rather ambiguous, indicating that the Lombards set up new settlements while only partially abandoning the already inhabited ones before 546 AD.

In the journal Radiocarbon, Hall et al. (2005:383) claim that 35-CS-9, located in Bandon Ocean Wayside State Park on the southern Oregon coast, is one of the few Oregon coast sites “that includes sediments and artifacts dating to the early Holocene and possibly to the late Pleistocene.” Their claim for an early Holocene or late Pleistocene human occupation rests on a single radiocarbon date of 11,000 ± 140 BP (12,710–12,680 cal BP) taken from charcoal found at least 20 cm below the nearest artifact. Although Hall et al. compile various kinds of geoarchaeological evidence to support this claim, their case is not convincing. While we applaud aspects of their analyses, the inferences they have drawn are not substantiated by the evidence they present. We agree that 35-CS-9 is a significant site but believe claims for the antiquity of its human use have been exaggerated.

Yedoma sediments with thick syngenetic ice wedges have been studied on the Yamal Peninsula, northwestern Siberia. The accumulation of yedoma strata occurred under alternating subaqueous-subaerial conditions, and three tiers of ice wedge were formed mainly on subaerial stages. The ice wedges and enclosing sediments were dated, revealing that the ice wedges were formed between 29 and 18 cal ka BP, while the enclosing sediments are generally older, possibly due to contamination with ancient material (especially in the central part of the yedoma). However, the termination of yedoma complex formation was dated not later than 13.5 cal ka BP. Stable oxygen-isotope data for the ice wedges indicate more severe winter climate conditions during 25–21 cal ka BP, when mean January air temperatures were at least 10°C lower that modern ones, favoring syngenetic ice wedge growth. Yedoma accumulation in the western part of northern Siberia does not support the existence here of an ice sheet during the LGM.