In 1989 and 1991, wood charcoal samples were excavated at a Predynastic settlement in Upper Egypt, Halfiah Gibli (HG). A second site, Semaineh (SH), was also investigated, but as the ceramics there were mostly from the Old Kingdom, excavations were concentrated at HG. Wood charcoal was obtained in undisturbed contexts, in association with Nagada culture potsherds and lithics, ranging in date from about 3700 BC to 3200/3100 BC. These new radiocarbon dates provide more data for the relative phases of the Nagada culture, formulated mainly from ceramic seriation.

Measurements have continued with the same proportional counter system, the same procedure in sample pretreatment, methane preparation and measurement, and the same age calculation using a half-life of 5568 ± 30 yr as described previously (R., 1970, v. 12, p. 298–318).

Direct accelerator mass spectrometry (AMS) dating is crucial for a correct integration of plant remains in the (pre)history of crops, particularly for those that do not belong to the Neolithic package and are known to arrive in Europe much later. This paper reviews one of the earliest records of rye from Romania. The grains were discovered in the tell settlement of Cunești, which belongs to the Gumelnița communities (ca. 4600–3900 BC). In 1954, due to Danube flooding, a large portion of the south part of the tell collapsed, and between the burnt dwelling visible in the resulting profile, a large number of sherds from three typical Gumelnița pots were identified. According to the excavation’s author, rye grains were found in association with those sherds, and it was assumed that a batch was stored in these Eneolithic vessels. Consequently, the rye was published as belonging to the Gumelnița period. Our reanalysis led to two radiocarbon (14C) dates, from two different laboratories, which indicate that the Cunești rye is not prehistoric but dates to the medieval period. To correct this error concerning this rye batch and the implications for European archaeology, we decided to republish these grains in an updated chronological framework. In addition, we performed stable isotope analyses on the charred grains, confirming they were cultivated on dry land, as well as a 3D morphometric investigation. Our research brings new and original data on rye cultures from the medieval period in southeastern Europe.

The following radiocarbon dates are a partial list of samples measured since Sept 1977. The chemical and counting procedures are the same as indicated previously (R, 1978, v 20, p 134-138).

A fully automatic continuous-flow gas injection interface was built to couple an elemental analyzer with a MICADAS accelerator mass spectrometer (AMS) as a low-cost option that does not require an absorber trap for CO2 injection. The complication of the variable ion current during gas injection can be overcome by understanding and controlling the mass flow-dependent ionization yield. The time-varying CO2 concentrations and carbon mass flows are estimated with a mathematical model in order to investigate their relationship with the abundant isotope (12C–) signal. This model is based on a complete CO2 diffusion equation and instantaneous mass flow. It shows a good agreement between model calculations and the measurements. A reversible suppression of the formation of ions occurs, if the carbon mass flow exceeds 2.0–2.3 µg C/min. This result repeats for different injection capillaries and for different carrier volumetric flow rates.

In-situ cosmogenic 10Be (and 26Al) concentrations in alluvial sediments provide a spatially averaged signal of the erosion rate of the catchment area. Catchmentwide erosion rates reflect the production rate of the entire basin, and their calculation requires knowledge of the complete production rate model. Available calculators determine production rates on a pixel-based approach and achieve computational efficiency by relying on a scaling method that ignores geomagnetic field strength variations. Here we introduce a new python-based tool that determines erosion rates based on the hypsometry of the catchment. The method relies on the fact that production rates are much more sensitive to changes in elevation than latitude. Our tool has two main advantages: (1) computation time is short (<30 seconds) and independent of the scaling method; there is no need to neglect magnetic field variations, and (2) because production rate scaling is performed by a widely used online calculator, the results are fully comparable to exposure ages or point-based erosion rates determined with the same calculator; future updates to production rate scaling are immediately effective for catchmentwide erosion rate calculation. We demonstrate in two case studies that (1) for similar scaling methods, our calculator reproduces pixel-based results within a few percent, and (2) erosion rates determined with different scaling methods may differ by >20%, differences can vary systematically with erosion rate, and using a time-constant scaling method may result in a bias in the interpretation of catchmentwide erosion rates.

Wiggle-match dating of tree-ring sequences is particularly promising for achieving high-resolution dating across periods with reversals and plateaus in the calibration curve, such as the entire post-Columbian period of North American history. Here we describe a modified procedure for wiggle-match dating that facilitates precise dating of wooden museum objects while minimizing damage due to destructive sampling. We present two case studies, a dugout canoe and wooden trough, both expected to date to the 18th–19th century. (1) Tree rings were counted and sampled for dating from exposed, rough cross-sections in the wood, with no or minimal surface preparation, to preserve these fragile objects; (2) dating focused on the innermost and outermost portions of the sequences; and (3) due to the crude counting and sampling procedures, the wiggle-match was approximated using a simple ordered Sequence, with gaps defined as Intervals. In both cases, the outermost rings were dated with precision of 30 years or better, demonstrating the potential of wiggle-match dating for post-European Contact canoes and other similar objects.

We present a broad and detailed study of the background components of a liquid scintillation (LS) detector, using a simple laboratory-built system, ICELS. It was specifically designed for radiocarbon dating and is compact and easily transportable (total weight 35 kg). Its flexible LS detector unit has a dome-shaped vial with 3 mL benzene to which 45 mg butyl-PBD is added. The vial sits on the top of a vertical 28-mm-diameter phototube. The gamma radiation, to which the benzene is exposed under varying conditions, was measured by replacing the vial with a 38-mm-diameter Nal crystal. The pulse-height spectra of the 14C LS background and the Nal gamma background were measured in a surface laboratory and in a deep underground counting room with: 1) a lead shield of varying thickness; 2) lead of normal and low 210Pb concentration; 3) phototubes of 2 different types; and 4) varying benzene volume. The beta emission from the face of the tubes was measured with a low-level Geiger counter.

There are two units with RBMK-1500 type reactors at the Ignalina Nuclear Power Plant (Ignalina NPP) in Lithuania where graphite was used as a neutron moderator and reflector. These reactors are now being decommissioned, and Lithuania has to find a solution for safe irradiated graphite disposal. It cannot be disposed of in a near surface repository due to large amounts of 14C (radiocarbon, carbon-14); thus, a deep geological repository (DGR) is analyzed as an option. This study had the aim to evaluate 14C migration from the RBMK-1500 irradiated graphite disposed of in a potential DGR in crystalline rocks taking into account the outcomes of the research performed under the collaborative European project CAST (CArbon-14 Source Term) and to identify the potential to reduce the conservatism in the assumptions that was introduced in the lack of data and led in the overestimated 14C migration. The information gathered during the CAST project was used to model 14C transport in the near field by the water pathway and to perform uncertainty analysis. The study demonstrated that more realistic assumptions could reduce the estimated 14C flux from the near field by approximately one order of magnitude in comparison with the previous estimations based on very conservative assumptions.

Twelve lacustrine sediment samples from a relict lake in the Kalla Glacier valley were co-dated using AMS radiocarbon (14C) and infrared stimulated luminescence (IRSL) dating methods. In general, the radiocarbon ages of bulk organic matter were older by a minimum of 1500 years compared to (age depth) modeled luminescence ages after fading corrections. This is observed for the first time in the lake sediments of High Himalayan Crystalline zone. A combination of lipid n-alkane data, Raman spectra and geochemical proxies suggested that this was due to ancient organic carbon (OCancient) that is a mixture of pre-aged (OCpre-aged) and petrogenic (OCpetro) organic carbon within older glacial moraine debris that served as sediment source to the lake. Raman spectra suggest the presence of moderate to highly graphitized OCpetro in all the profile samples. The OCpetro contributed 0.064 ± 0.032% to the sediment and the lake stored 2.5 ± 0.7 Gg OCpetro at variable rates during the last 16 kyr, with the mean burial flux 160 kg OCpetro yr−1. This study implies (1) employing another independent dating method in addition to radiocarbon method using bulk sediment organic matter, if the carbon content is low, to observe any discrepancy, and (2) a need to investigate on the fate of OCpetro as many such small lakes become relict in this region.

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 C13/C12 ratios were measured.

An attempt is presented to establish an absolute chronology of early Slavonic habitation in the region of the mouth of the Odra River up to the Baltic and to find associations with a series of stave boats and dugouts of different levels of technology and navigation. The methodology of the research project is presented and some conclusions of a general nature are drawn from the results already obtained.

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.

An ancient pottery workshop belonging to the Han Dynasty was excavated in Caoxie village, Hepu County. Caoxie village is an important archaeological site in Hepu County, Beihai City, in south China's Guangxi Zhuang Autonomous Region. It is believed that Hepu County was the oldest departure point on the ancient maritime trading route during the Han Dynasty (206 BC to AD 220) due to the ideal natural geographical conditions and the existence of a large number of Han tombs. Radiocarbon measurements on wood and charcoal samples from the Caoxie village site were performed at the Peking University AMS facility (PKU-AMS), Beijing, and the Centre for Isotopic Research for Cultural and Environmental Heritage (CIRCE) at Naples Second University, Italy. Calibrated ages were obtained with code CALIB 5 (Stuiver and Reimer 1993). The results of these measurements are presented and the related chronology is discussed.

Edward Smith Deevey, Jr died on November 29, 1988, following a heart attack. He was Graduate Research Curator of Paleoecology at the Florida Museum of Natural History, University of Florida, Gainesville. As a reflection of his expertise in many academic disciplines, Ed held Graduate Research Professorships in four University of Florida departments: zoology, botany, geology and Latin American studies.

It has been shown that contamination from humic acids, chitin, fungal products, etc., contributing young carbon, and from bitumen and carbonate, contributing old carbon, may not be completely removed from wood and char samples by the usual hydrochloric acid and sodium hydroxide pretreatments of the samples. A procedure is offered for the isolation of a pure chemical substance from such samples, cellulose from wood and uncombined carbon from char, that must represent the original material. Cellulose is prepared by boiling the resin-free sample in 1.25% H2SO4 and 1.25% NaOH, adding Schweitzer's reagent, filtering, and precipitating from the filtrate by acidification. Uncombined carbon is separated from char samples as the flocculant precipitate remaining after boiling in 70% HNO3, followed by settling overnight from a large volume of 6M HNO3. A simple procedure for the chemical examination of char samples is also offered for the estimation of the amounts of bitumen, carbonate, combined, and uncombined carbon in char.

This list contains the results of 14C determinations obtained at the laboratory in 1984. Our laboratory measures 14C activity in the form of methane with a proportional counter built by Heidelberg University and an electronic unit built by Berthold, Benelux Analytical Instruments. The sample counting time is 4000 minutes with printouts at 100 minute intervals. Sample error is reported as one standard deviation. δ13C for mortar is measured by the University of Lyon Laboratory, δ13C was not measured or estimated for other samples.

Detonation of the first fission bomb at White Sands, New Mexico, on July 16, 1945, produced a tremendous neutron flux capable of creating tritium and radiocarbon byproducts. We sampled a 115-year-old pinyon (Pinus edulis) 10km east of the Trinity test site to determine 14C evidence of this event. The most likely mechanism for this enrichment in the 1945 tree ring would be fixation of 14CO2 produced at the blast site and carried with the fallout cloud over the pinyon site. Analysis of cellulose of the 1944 and 1945 rings shows δ13C values of −19.9 and −19.5, respectively, and 14C activity (fraction of modern uncorrected for δ13C) as 0.991 ± .005 and 0.991 ± .006, respectively. It is likely that the duration and/or concentration of the 14CO2 exposure was not sufficient to increase 14C activity expected for that year.

We performed pollen analysis and accelerator mass spectrometry (AMS) radiocarbon dating on cored sediments (KS0412-3) from Kashibaru Marsh, located in the western part of the Sefuri Mountains in northern Kyushu, southwestern Japan, to investigate environmental change around the marsh. Sediment accumulation began in this marsh around cal AD 1200 and continued with an estimated average sedimentation rate of about 4 mm/yr. Human rice cultivation at this location began around cal AD 1300 and was abandoned due to the deposition of a thick sand layer at around cal AD 1400. Since this event, the area has been maintained as a “natural” marsh.

The archaeological site of Tlatoani at Tlayacapan is located in the Mexican Highlands, in the present-day state of Morelos. The site is an extant settlement located at the top of the Tepoztlan mountain range, and has been occupied since the Late Preclassic period (AD 150–500). At the height of its occupation in the Epiclassic and Early Postclassic periods (AD 600–1150), Tlayacapan was situated on the top of the hill. The radiocarbon investigations reported herein revealed some further distinct findings, although no clear absolute chronology was demonstrated. A dog skull was found inside the oldest foundation stage, and dated between cal AD 646 and 765, the middle of the Epiclassic period. Human remains found in the first grave belonged to three individuals. A male skeleton was dated to AD 1158–1227. Fragments of an incomplete skeleton of a child and an incomplete skeleton of a second male were placed on top of the first male skeleton and were dated in the range AD 1030–1156. A fourth skeleton found nearby in the second grave gave a similar date of AD 1164–1253. These burials were in accordance with the Middle America cosmovisional system, where bodies were buried beneath the household space. It is evident from the 14C dates of the skeletons that the burial sites beneath the household space had been reused by exhuming and reburying skeletons that had been previously buried there. A comparison of dates on fractions of collagen and bioapatite of the same bones was possible. Two of the samples were in good agreement between these fractions, whereas the other three samples are close but just outside the 2σ range.