This article reports on 12 new accelerator mass spectrometry (AMS) dates from the latest phases of the Chalcolithic period occupation (late 5th millennium cal BC) at Teleilat Ghassul, type site for the south Levantine Ghassulian Chalcolithic culture. The new AMS dates from Teleilat Ghassul favor an amendment to a previous suggestion (Bourke et al. 2001), that all significant occupation at the site had ceased by 4000/3900 cal BC. This end-date should now be amended to 3900/3800 cal BC. Follow-up statistical modelling sourced to published 14C data drawn from a wide selection of south Levantine Chalcolithic period sites (Bourke 2001; Burton and Levy 2001) raises the possibility that Chalcolithic period occupation had ceased at virtually all major centers by 3800/3700 cal BC. This, in turn, suggests that the new data bearing on the end-date for occupation at Teleilat Ghassul may reflect a more widespread horizon of abandonment in the southern Levant.

Frequency distributions of more than 300 14C groundwater ages from various regions in northern and southern Sahara reflect the alternating sequence of humid and arid periods in the Sahara during the Holocene and late Pleistocene. A broad frequency maximum between 20,000 and 50,000 years bp indicates a long humid period. During this time span, the northern Sahara received rain from the Western Drift, which is concluded from a west-east decrease of deuterium and oxygen 18 of these groundwaters (continental effect). In the time-slice between 14,000 and 20,000 years bp, groundwater formation was significantly lower due to a cool and (semi-)arid period. In the Holocene, the Saharian climate is characterized by a sequence of dry and wet periods.

The effect of nitrous oxide (N2O) upon the graphitization of small (∼40 μg of carbon) CO2 samples at the ANSTO and University of California, Irvine, radiocarbon laboratories was investigated. Both laboratories produce graphite samples by reduction of CO2 over a heated iron catalyst in the presence of an excess of H2. Although there are significant differences between the methods employed at each laboratory, it was found that N2O has no effect upon the reaction at levels of up to 9.3% by volume of CO2. Further, it was systematically determined that more effective water vapor trapping resulted in faster reaction rates. Using larger amounts of the Fe catalyst generally resulted in higher yields or reaction rates (but not both). The effects of changing the type of Fe catalyst on the final yield and reaction rate were less clear.

We report in this paper on a preliminary analysis of Stages 1 and 2 of the International Collaborative program. We have chosen to concentrate on the internal and external consistencies of the participating laboratories. The two stages so far completed have dealt only with the processes of sample synthesis and counting, and results indicate that the major component of variability lies in the counting process. Outlying laboratories are observed at each stage. A third stage is in progress which will allow an assessment of any further variability due to sample pretreatment. With the inclusion of duplicate samples in each stage, we are able to report that laboratories are remarkably consistent internally, ie, the differences between duplicates generally agree with the laboratory's claimed precision.

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.

One of Hungary's geological and environmental treasures is nestled in the heart of the Great Hungarian Plain. The catchment basin of Lake Kolon was subjected to detailed environmental historical studies starting in 2005. Undisturbed cores taken along transects of the basin were subjected to detailed sedimentological, paleoecological, and geochemical studies. To establish a reliable timeframe of the lacustrine and marshland sedimentary sequence identified, 22 samples were analyzed by accelerator mass spectrometry (AMS) in the radiocarbon laboratories of Poznań and Tucson. With the new results in hand, we had the opportunity to elucidate the geological evolution of the area for the past 25,000 yr. This sequence is highly beneficial, as it is probably the most well-dated profile of the Quaternary from the area studied. The new absolute dates enabled the comparison of local geological evolution of the studied area with those of global climatic changes. As seen from our findings, the geological evolution of the catchment basin was congruent with major climatic events during the Pleistocene and the entire Holocene. However, a very peculiar trajectory was identified for the terminal part of the Pleistocene and the opening of the Holocene regarding the evolution of the landscape, the vegetation, and the fauna of this part of the Great Hungarian Plain.

The present date list describes the first stage of a co-operative study on the validity of dating secondary soil carbonates in arid and semi-arid environments of Australia. Because of the complex nature of the physical and chemical variables in a soil environment, many additional samples are being dated from stratigraphically controlled sites before final evaluation of carbonate reliability is possible.

During the four years the Sample Preparation Laboratory (SPL) at the National Ocean Sciences Accelerator Mass Spectrometer (NOSAMS) Facilty has been in operation we have accumulated much data from which we can assess our progress. We evaluate our procedural blanks here and describe modifications in our procedures that have improved our analyses of older samples. In the SPL, we convert three distinct types of samples—seawater, CaCO3 and organic carbon—to CO2 prior to preparing graphite for the accelerator and have distinct procedural blanks for each procedure. Dissolved inorganic carbon (∑CO2) is extracted from acidified seawater samples by sparging with a nitrogen carrier gas. We routinely analyze “line blanks” by processing CO2 from a 14C-dead source through the entire stripping procedure. Our hydrolysis blank, IAEA C-1, is prepared by acidifying in vacuo with 100% H3PO4 at 60° overnight, identical to our sample preparation. We use a dead graphite, NBS-21, or a commercially available carbon powder for our organic combustion blank; organic samples are combusted at 850° for 5 h using CuO to provide the oxidant. Analysis of our water stripping data suggests that one step in the procedure contributes the major portion of the line blank. At present, the contribution from the line blank has no effect on our seawater analyses (fraction modern (fm) between 0.7 and 1.2). Our hydrolysis blanks can have an fm value as low as 0.0006, but are more routinely between 0.0020 and 0.0025. The fm of our best organic combustion blanks is higher than those routinely achieved in other laboratories and we are currently altering our methods to reduce it.

We present here the current status of AMS dating of iron artifacts at Nagoya University. We initially developed a “wet” method of carbon collection from iron samples, consisting of a resistance furnace and a “wet” trapping of the evolved CO2 with a saturated Ca(OH)2 solution, in which overall collection efficiency of carbon ranged from 50 to 60%. To improve the carbon-collection efficiency, we more recently constructed a “dry” system, consisting of an induction furnace followed by “dry” separation of the produced CO2 from combustion gases and conversion of the CO2 into a graphite target. We describe here mainly the performance of the “dry” separation system, tested using standard steel samples. We also report previously determined 14C dates on three ancient Oriental artifacts using the earlier “wet” procedure.

A data set of 18 radiocarbon dates from the domestic quarter and the well at Tel Tsaf provide conclusive evidence for the absolute dating of this Middle Chalcolithic site. Bayesian modeling suggests that the site was occupied in the last quarter of the 6th millennium BC and abandoned in the first quarter of the 5th millennium. The absolute dating of Tel Tsaf has further implications for the synchronization of the protohistory of the Levant. The ceramic assemblage of Tel Tsaf included delicately painted ceramic sherds (so-called Tel Tsaf ware), which are distinct from the common plain ware. Comparable motifs have been identified in ceramic assemblages of contemporary Ubaid sites such as Tell Mashnaqa, Tell Zeidan, Tell el-Abr, and Hammam et-Turkan IV in northern Mesopotamia. Tel Tsaf is a rare example of a little researched connection between the Ubaid culture and the Middle Chalcolithic of the southern Levant. The findings of Tel Tsaf expand the southwestern border of the Ubaid sphere of influence and shed new light on long-distance interaction in protohistory.

The use of stable carbon isotopes as dietary tracers is an application that is widening its scope within the fields of ecology and paleoecology. Although hair is potentially one of the most favorable animal tissues for isotopic measurement for dietary studies, this tissue is rarely included in research works. This may be due to the fact that many aspects related to hair tissue are not fully understood, especially in the case of wild animals whose diets consist of plants with contrasting 13C/12C ratios, their abundance depending on seasonality. The present isotopic study of hair from animals inhabiting the Andes in northwestern Argentina, at heights ranging from 3500 to about 5000 m above sea level (asl) shows that 1) δ13C values measured on hair from herbivores with a mixed and isotopically contrasting diet, and from their carnivorous predators, differ in their respective trophic levels, 2) in primary consumers, different types of hair from the same individual have different δ13C values, whereas hair values are homogeneous in carnivores, and 3) some types of hair from rodents, such as whiskers, show δ13C values similar to those of less metabolically active tissues such as bone collagen.

The analytical facilities at Glasgow have been extended to include gas proportional (CO2 and CH4) and liquid scintillation (C6H6) counting laboratories. The results presented here were obtained during 1972-1974 using the CO2 gas counting system only. In brief, organic samples, after pretreatment as described in the text, are burned in a tube combustion unit and the evolved CO2 absorbed in KOH solution. BaCO3 is precipitated and acid-hydrolyzed in vacuo using H3PO4. Evolved CO2 is purified via adsorption/desorption on CaO and is stored prior to counting. The 2.6L proportional counter is surrounded by a gas-flow Geiger anticoincidence guard and 10cm thick Pb shielding to reduce background count rates to ca 4.9 cpm at 1 atm filling and barometric pressures. A barometric sensitivity in background of −0.01cpm/mbar is observed. Constant gas gain is ensured by monitoring the coincidence meson spectrum and normalizing the detector operating voltage. All sample activities are related to the NBS oxalic acid standard count rate which averages 14.71 cpm at 1 atm filling pressure and 15°C. Mass spectrometric assay of CO2 after counting is performed on a VG Micromass 602B instrument to a precision of 0.05% (±1σ). Since uncertainties quoted on all results represent 1σ counting errors alone, they are related to precision of measurement rather than accuracy. The bulk of data quoted here are connected with a long-term study of the medical aspects of artificial 14C from nuclear weapon tests. These results should therefore be assessed in conjunction with those pub previously (Harkness and Walton, 1972; Farmer et al, 1972).

Dating sediments which have accumulated over the last few hundred years is critical to the calibration of longer-term paleoclimate records with instrumental climate data. We attempted to use wiggle-matched radiocarbon ages to date 2 peat profiles from northern England which have high-resolution records of paleomoisture variability over the last ∼300 yr. A total of 65 14C accelerator mass spectrometry (AMS) measurements were made on 33 macrofossil samples. A number of the age estimates were older than expected and some of the oldest ages occurred in the upper parts of the sequence, which had been dated to the late 19th and early 20th century using other techniques. We suggest that the older 14C ages are the result of contamination by industrial pollution. Based on counts of spheroidal carbonaceous particles (SCPs), the potential aging effect for SCP carbon was calculated and shown to be appreciable for samples from the early 20th century. Ages corrected for this effect were still too old in some cases, which could be a result of fossil CO2 fixation, non-SCP particulate carbon, contamination due to imperfect cleaning of samples, or the “reservoir effect” from fixation of fossil carbon emanating from deeper peat layers. Wiggle matches based on the overall shape of the depth-14C relationship and the 14C minima in the calibration curve could still be identified. These were tested against other age estimates (210Pb, pollen, and SCPs) to provide new age-depth models for the profiles. New approaches are needed to measure the impact of industrially derived carbon on recent sediment ages to provide more secure chronologies over the last few hundred years.

There have been a number of studies that have attempted to estimate the past radiocarbon reservoir effects in Qinghai Lake, China. This article reports on measurements on modern samples collected at the lake in October 2003 and October 2009, which allow us to better understand the systematics of the lake and shed new insights on the processes occurring in the lake. The results indicate that atmospheric exchange of 14C is the main process affecting surface dissolved inorganic carbon (DIC) in the lake, but dissolved organic carbon (DOC) can be explained as a combination of sources. We also conclude that sediment carbon can be explained by a model where input from the surrounding rivers and groundwater are important, in agreement with the model of Yu et al. (2007).

Palynologic and archaeologic studies using 14C dating indicate that elements of farming were introduced even further north than the Arctic Circle during the Neolithic period, ca 4000 BP. A second stage with heavier reliance on farming and with probable establishment of permanent farmsteads is dated to 2000–2500 BP.

In this list, we present 14C ages of archaeological, geological, hydrogeological, botanical and atmospheric samples measured since our previous list (Srdoč et al. 1992). Chemical pretreatment and counting techniques using a methane-filled proportional counter are essentially the same as reported earlier. Sample descriptions are prepared in collaboration with collectors and submitters.

Radiocarbon dating has had profound implications for archaeological understanding. These have been identified as various “revolutions,” with the latest—Bayesian chronological statistical analyses of large datasets—hailed as a “revolution in understanding.” This paper argues that the full implications of radiocarbon (14C) data and interpretation on archaeological theory have yet to be recognized, and it suggests that responses in Britain to earlier revolutions in archaeological understanding offer salutary lessons for contemporary archaeological practice. This paper draws on the work of David Clarke and Colin Renfrew to emphasize the importance of critical considerations of the relationships between archaeological theory and scientific method, and to emphasize that seemingly neutral aspects of archaeological thought are highly laden interpretatively, and have significant implications for the kinds of archaeology that we write.

The first high-resolution time series of pre- and post-bomb radiocarbon measurements is reported for surface waters in the western Mediterranean Sea. The Δ14C record was obtained from the aragonite skeleton of Cladocora caespitosa using a 50-yr-old corallite collected in the Ligurian Sea in 1998. Laser-ablation ICP measurements of trace elements (Li/Mg and Sr/Ca) show a strong seasonal variability, enabling the chronology of the Δ14C record to be determined at annual timescales. The mean Δ14C of pre-bomb surface water is -56 ± 3%, corresponding to a reservoir age of 262 ± 29 yr. The post-bomb maximum occurs in 1972 with a Δ14C value of 90%, significantly lower than the peak of 150% observed in the North Atlantic. The dilution of the peak-amplitude of Δ14C in western Mediterranean surface waters is attributed to mixing of North Atlantic Central Water inflow with relatively depleted underlying Intermediate Mediterranean and Levantine Intermediate waters. Intensification of this mixing is observed in 1963–1964, consistent with the change in atmospheric circulation from a positive to negative NAO phase (1960–1967). The post-peak Δ14C variability is relatively limited, reflecting mainly local vertical mixing forced by wind stress.

Pottery produced by mobile hunter-gatherer-fisher groups in the northeast European forest zone is among the earliest in Europe. Absolute chronologies, however, are still subject to debate due to a general lack of reliable contextual information. Direct radiocarbon dating of carbonized surface residues (“foodcrusts”) on pots can help to address this problem, as it dates the use of the pottery. If a pot was used to cook fish or other aquatic species, however, carbon in the crust may have been depleted in 14C compared to carbon in terrestrial foods and thus appear older than it really is (i.e. showing a “freshwater reservoir effect,” or FRE). A connected problem, therefore, is the importance of aquatic resources in the subsistence economy, and whether pots were used to process aquatic food. To build better chronologies from foodcrust dates, we need to determine which 14C results are more or less likely to be subject to FRE, i.e. to distinguish crusts derived mainly from aquatic ingredients from those composed mainly of terrestrial foods. Integrating laboratory analyses with relative chronologies based on typology and stratigraphy can help to assess the extent of FRE in foodcrust dates. This article reports new 14C and stable isotope measurements on foodcrusts from six Stone Age sites in central and northern European Russia, and one in southeastern Estonia. Most of these 14C results are not obviously influenced by FRE, but the isotopic data suggest an increasing use of aquatic products over the course of the 6th and 5th millennia cal BC.

This paper summarizes radiocarbon measurements of mainly botanical samples from the Iceman (“Ötzi”) and from his discovery site, an Alpine glacier at the Austrian-Italian border. The results were obtained by accelerator mass spectrometry (AMS) at 3 different laboratories (Vienna, Austria; Uppsala, Sweden; Gif-sur-Yvette, France) between 1992 and 1997. All the dates, except 2, are consistent with the time period 3360–3100 BC, as previously determined from bone and tissue samples from the Iceman himself. The 2 exceptional dates from wooden artifacts suggest that the site of the Iceman was used as a mountain pass for millennia prior to and after the lifetime of “Ötzi”.

For a 2nd sample complex, we studied logs from the beginning of salt mining in the world's oldest salt mines at Hallstatt in Upper Austria. 14C AMS measurements were performed in Vienna on spruce samples found in the prehistoric mines and from a log-house on the surface. Data evaluation included “wiggle matching” of different sets of tree rings. The results suggest that salt mining in the Hallstatt region took place in the 14th–13th century BC, well before the so-called Hallstatt period.

We discuss in some detail the chemical pretreatment of the samples and the data evaluation. We also present a comprehensive survey of 14C dates available in the literature concerning both botanical remains from the vicinity of the Iceman and from the earliest salt mining in Hallstatt.