New radiocarbon (14C) dates we obtained in our radiocarbon laboratory equipped with a liquid scintillation counter using BGO (Bi4Ge3012) tubes. The electronic stability of the counter gave a background below 0.2 cpm. Our 14C dates agree well with the interpretations done for the samples. Most of the results in these analyses were obtained on shell samples, charcoal samples, and tree leaves. Calibration of the dates with the appropriate software (Calib 7.0.4) allows better interpretation of the results and their importance in the studied regions. In this paper, we present 14C results from archaeological and environmental sites in Senegal, Mali, and Togo and report the results in our second laboratory date list.

This paper presents new results of radiocarbon (14C) ages from archaeological sites in northern Igboland. The study was designed to shed more light on early human occupation and activities in the study area based on sediments from cave and iron-smelting sites. The approach consisted of ethnographic, archaeological, palynological, and slag analyses; these were complemented with 14C dates. The technology adopted as well as the paleoenvironmental conditions that prevailed during the period of human settlement in both sites was revealed. These data, complemented by 14C dates, highlight the human behavioral and subsistence patterns within the region and are comparable to those from similar sites in southeastern Nigeria.

Tombs and cairns present a dating challenge when the human remains are unstratified, incomplete and dispersed. By considering the distribution of time intervals between deaths as a possible a priori condition of multiple burials of select groups, a Bayesian model is suggested that may constrain the uncertainty date range of the group. The method may also address the wide uncertainties seen in radiocarbon calibration on a calibration curve plateau. The mathematical justification for the choice of Log Normal intervals, between death events, is first presented, followed by worked examples that compare the treatment of groups of 22 dates using Phase then Sequence with interval gaps. Finally, scenarios of potential Select Groups are examined, to demonstrate the efficacy of this alternative heuristic model to current model treatments.

Current scholarship suggests that Neo-Eneolithic systems of settlement and subsistence in Eastern Europe were defined by short-to-medium range migration, while sparsely populated land in peripheral regions allowed for the continual colonization of new territories. We address the Eastern Tripolye Culture (ETC), a sub-group of the Cucuteni-Tripolye cultural complex that flourished ca. 4300–2950 BC by expanding into the forest-steppe ecozone of Central Ukraine. While a general lack of multi-layer sites complicates regional chronology, we resolve several longstanding questions in Ukrainian archaeological discourse by combining traditional relative chronologies of ceramic types with high-precision AMS dating of material from key sites. We offer a revision of the chronology of Tripolye BI and BI-II, which, rather than consisting of distinct “early” and “late” temporal periods, instead constitute a single period characterized by stylistic diversity in material culture. With an absolute chronology established, we then analyze the space-time distribution of sites, revealing a southwest-to-northeast migratory vector across Central Ukraine characterized by punctuated episodes of “leapfrog” colonization. The establishment of this vector by the ETC presages larger-scale population movements by the Western Tripolye Culture (WTC), which led to the establishment of the giant-settlement phenomenon during the first part of the 4th millennium BC.

The paper presents radiocarbon (14C) dates of samples collected from the Bronze Age cultural strata (VI–II) excavated within Sector P, Tell Arbid, Khabur Triangle, northern Mesopotamia. These strata contain objects (remains of a caravanserai, pits, graves, pottery kilns, and multi-phase houses) representing the periods of Early Jezirah 4-5, and Old Jezirah I-II. 14C dating of these strata was especially important because of a clearly visible period of abandonment of the area at the onset of 2nd millennium BC, recorded on all Khabur Triangle sites studied so far, and because of the questionable reliability of the chronology derived from scarce historical sources. Of the 29 samples of cereal grains, 9 appeared to contain residual material, while Bayesian-analyzed 14C ages of the remaining 20 allowed us to say that, at the turn of the 3rd millennium BC, Tell Arbid was abandoned later than other sites in the area, and that it was occupied over a distinctly longer period during the early 2nd millennium.

Measurements have continued with the same proportional counter system, pretreatment procedure, methane preparation and measurement, and calculation, as described previously (R, 1970, v 12, p 298-318). Uncertainties quoted are single standard deviations originating from standard, sample, background counting rates and half-life. No 13C/12C ratios were measured.

The results presented in this date list are from the same sampling program previously reported (R, 1978, v 20, p 436–440). Each sample reported herein was geologic in origin and, in most instances, represents a single shell date.

This radiocarbon dating laboratory was established to complement the research activities in the field of archaeology and geology in Korea. The benzene liquid scintillation counting method (Noakes, Kim, and Stipp, 1965; Noakes, Kim, and Akers, 1967) is employed in this laboratory because of its compatibility with other dating methods and future possibility in application of this procedure to the biomedical research field. The chemical process for converting carbon from a sample to benzene used by this laboratory is briefly outlined below.

Atmospheric CO2 samples have been collected by the Trondheim Radiocarbon Laboratory since the 1960s. The remaining material from the measurements has been precipitated as CaCO3 and stored in glass containers. We investigated some of the stored samples to assess whether the material could still be used for remeasurements of atmospheric radiocarbon (14C) content, or if it has been contaminated during the years of storage. We attempted different methods to clean the carbonate and release the CO2 for new measurements. The results indicate that the older samples before 1970 show a significant change in 14C content compared to the original measurements, and that our cleaning methods have only little effect. Later samples from the 1970s, which were archived in glass containers with a different lid, show a lower contamination that, however, still leads to an added uncertainty of several pMC and makes these samples unreliable.

The study of the mechanisms of radiocarbon (14C) release from different types of radioactive waste in final disposal conditions (organic, inorganic species, liquid, or gaseous phase) is an important aspect for the definition of waste acceptance criteria in a repository. The goal of this work is to determine the behavior of activated stainless steel, under standard leaching tests performed at El Cabril laboratory, with the aim of determining the retention capacity of the activated stainless steel, and therefore to assess the treatment and the potential additional barriers necessary for the fulfillment of waste acceptance criteria relevant to the El Cabril surface repository, Spain.

In a recent paper (Hartwig, ms.) I have shown that it is possible to understand and discuss the changing Austausch (i.e., exchange of air parcels between different atmospheric layers) between the stratosphere and troposphere by means of long-term measurement of series of spallation products. It is well known (Friend 1961; Müh et al. 1966; Hartwig et al. 1969) that there is a seasonal pattern in the 7Be concentration of ground-level air with a maximum during May–June. This maximum is caused by enhanced exchange processes between the atmospheric compartments of the stratosphere and troposphere during this interval. Generally, those exchange processes are a consequence of stability and dynamics of the atmospheric compartments, which themselves result from, among other factors, the distribution of the heat sources in those compartments, namely the ground and the ozone layer.

The tuning of plateaus in glacial and deglacial planktic radiocarbon records to pertinent structures in the atmospheric 14C record of Lake Suigetsu results in both a record of surface water reservoir ages and a centennial-scale absolute age model. However, the atmospheric origin of planktic 14C plateaus may be questioned. Alternatively, plateaus may result from short pulses of increased hemipelagic sediment deposition, which challenges the technique of 14C plateau tuning. To test the two rationales for the interval 23–12 cal ka, we calculated hypothetical sedimentation rates for all 14C plateaus identified in five Atlantic sediment cores assuming sediment pulses that either span 10, 100, 200, or 300 yr each. These rates were compared to rates derived by 14C plateau tuning that assumes an atmospheric origin of the plateaus. In each plateau suite, our hypothetical sedimentation rates result in at least one or two cases in extreme values that exceed the rates reported for short-lasting pulses of sediment deposition in contourites by a factor of 50 and therefore appear unrealistic. Moreover, they result in entire suites of plateau structures that incidentally appear closely aligned to the pattern of atmospheric 14C plateau suites rather than to any pulses of climate-controlled sediment discharge.

To study the effect of ultrafiltration on the radiocarbon ages of relatively poorly preserved bones in Japan, we analyzed the 14C dates of high-molecular-weight (HMW) gelatin samples and compared them with those of other extracted organic fractions, unfiltered gelatin samples extracted from NaOH-treated or NaOH-untreated collagen, and XAD-purified hydrolysates of animal fossil bones (∼4600 BP; gelatin yield of 2–4%) from the Awazu underwater archaeological site, Shiga, Japan. NaOH-treated, unfiltered gelatins and XAD-purified hydrolysates showed statistically similar 14C ages to those of HMW gelatins. The 14C ages of the HMW gelatins were the oldest and similar to those of wood collected from the same layer as the bones, and the NaOH-treated, unfiltered gelatins gave 14C ages within the acceptable margins of error; therefore, ultrafiltration was effective for accurate 14C dating, while NaOH-treated gelatin without ultrafiltration was also sufficient to obtain accurate 14C dates on the animal bones. The 14C ages of human skeletons (∼750 BP; gelatin yield of 2–11%) from 5 individuals excavated from an archaeological site in Yuigahama, Kamakura, Japan, showed statistically the same 14C ages as NaOH-treated, unfiltered gelatins and HMW gelatins within the margins of error, although HMW gelatins were likely to give slightly older ages than unfiltered gelatin with a yield of less than ∼3%. These results indicate that unfiltered gelatins extracted from fossil bones of gelatin yield more than ∼3% can produce accurate 14C ages without the need for ultrafiltration. Ten bone fragments from 3 humans showed the same 14C ages for each individual, suggesting that any bone part from an individual can be used to obtain a representative age. The 14C ages of tooth enamels of 2 individuals were 35 and 70 yr older than their bone ages. Death dates obtained from these age gaps agreed with those determined by morphology.

Radiocarbon (14C) conclusively demonstrates that the very important Yarkon-Tanininm aquifer, named after the two springs where the drainage presumably occurs, is in actuality two distinct aquifers—Upper and Lower. The springs have higher 14C activities than the exploitation wells that surround them (all drilled into the Upper aquifer). The springs are situated at faults that allow the Lower aquifer water to rise due to its higher pieziometric head and drain along with the Upper aquifer. The Lower aquifer water flows rapidly along a path that includes a karstic system. The Upper aquifer flows more slowly, primarily through a system of cracks in the carbonate aquifer. The Upper aquifer groundwater in the Beer-Sheba extension flows northwards at approximately ~4–7 m/yr.

The concentrations of 10Be and 14C and values of δ13C in samples collected during a major dust storm in Beijing on 16–17 April 2006 were studied. The 10Be concentrations ranged from 1.69 × 108 to 2.07 × 108 atom/g, 14C ages for black carbon (BC) ranged from 3001 to 5181 yr BP and for total inorganic carbon (TIC) from 8464 to 9119 yr BP, and δ13C values for BC ranged from -23.15% to -23.80% and for TIC from -5.39% to -5.98%. A comparison of BC content and δ13C value between the dust, surface soil in the dust source region, and aerosols in Beijing indicated that BC in the dust deposited in Beijing is significantly incorporated by aerosol BC during the dust transportation. Based on the 14C ages of BC, the proportion of fossil-fuel-derived BC was 0.35–0.49 of the total. In contrast to BC, the TIC deposited in Beijing can be firmly related to the source area and δ13C was not significantly modified during its transportation. According to the 14C ages of TIC, the proportion of the secondary carbonate in the dust was from 0.63 to 0.70. The results confirm that 14C of TIC is another useful tracer to indicate the source region of dust besides the content and δ13C value of TIC from the arid and semi-arid regions of China.

135Cs with a half-life of T1/2=2.3×106 yr is an important nuclide in studies of the dispersal of nuclear material in the environment. Preliminary measurements using 133Cs as a proxy for the long-lived 135Cs, with accelerator mass spectrometry (AMS) have been developed at the China Institute of Atomic Energy (CIAE). In order to improve the sensitivity of 135Cs AMS measurement, a new conducting material, Fe powder, was used in the experiment. According to the present results, the background level that can be obtained with blanks was 135Ba/Cs~1.83×10–10 with the CIAE-AMS system. These measurements showed that the Fe was an inferior conducting medium because the interference of 135Ba in Fe powder is 10 times higher than that in Ag powder.

Leather has been produced by a variety of methods throughout human history, providing researchers unique insight into multiple facets of social and economic life in the past. Archaeologically recovered leather is often fragile and poorly preserved, leading to the use of various conservation and restoration efforts that may include the application of fats, oils, or waxes. Such additives introduce exogenous carbon to the leather, contaminating the specimen. These contaminants, in addition to those accumulated during interment, must be removed through chemical pretreatment prior to radiocarbon (14C) dating to ensure accurate dating. DirectAMS utilizes organic solvents, acid-base-acid (ABA) and gelatinization for all leather samples. Collagen yield from leather samples is variable due to the method of production and the quality of preservation. However, evaluating the acid-soluble collagen fraction, when available, provides the most accurate 14C dates for leather samples. In instances where gelatinization does not yield sufficient material, the resulting acid-insoluble fraction may be dated. Here we examine the effectiveness of the combined organic solvent and ABA pretreatment with gelatinization for leather samples, as well as the suitability of the acid-insoluble fraction for 14C dating.