Although initial studies in the 1960's established the feasibility of applying the radiocarbon technique directly to ceramics, subsequent analyses have revealed this category of materials to be more complex than previously believed. Consideration of the points at which various types of organic carbon are introduced into ceramic materials by natural or human agencies allows more effective screening of potential sherd samples. It also suggest ways to overcome some of the limiting factors involved in dating ceramics.

The following list covers the samples measured at the Uppsala radiocarbon laboratory during 1959.

The “bomb” radiocarbon spike induced by atmospheric nuclear detonations has been reconstructed at a latitude of 40°N by measuring the 14C content in annual rings of a living pine (Pinus pinea) at the Accelerator Mass Spectrometry facility of the University of Lecce. We report how the samples were taken, selected, prepared for analysis, and measured. The results are in good agreement with other data sets available for the Northern Hemisphere temperate regions, showing that a curve for the calibration of 14C dates, valid for the whole Northern Hemisphere, can be established for the second half of the 20th century.

Analysis of biological proxies in lake sediment and geochemical analysis of soil profiles reveal natural vegetation dynamics, with climate inferences, since the late Pleistocene in a fragment of the pristine lowland Atlantic Forest of southeastern Brazil. Carbon isotopes from soil organic matter and 14C ages from the humin fraction indicate the dominance of C3 plants since ∼17,000 cal BP. Palynological analysis of a sediment core indicates the presence of Atlantic Forest vegetation since 7700 cal BP. Changes in the relative abundance of tree ferns and palms suggest the predominance of a humid period from ∼7000–4000 cal BP and establishment of the modern seasonal climate at ∼4000 cal BP. Data indicate maintenance of the regional forest coverage since the late Pleistocene, corroborating previous suggestions that this region was a forest refuge during less humid periods of the late Pleistocene and Holocene. Some plant taxa with currently divided distributions between Amazonia and the Atlantic Forest colonized the region since at least 7500 cal BP, indicating an earlier connection between Amazonia and Atlantic Forest.

The following list shows the age measurements carried out at Saclay by the Service d'Electronique Physique, using the C14 method.

The apparatus employed was completed and calibrated in 1956 and the first tests were performed during the same year. The counting unit is a 1.2 L stainless steel proportional counter and the filling gas is pure CO2 at 74 cm Hg pressure. The shield consists of 20 cm of lead, 10 cm of iron, a coincidence ring and 2 cm of bismuth. The background is 4.86 ± 0.05 counts/min. (Error is ± σ, the duration of each counting being 24 hours.) Final purification is performed by adsorption of CO2 on alumina at low temperature, followed by desorption at room temperature; this has proved particularly effective and gives a very good filling gas. Technique was described in detail previously by the authors (Perquis, Delibrias, and David, 1956; Delibrias and Perquis, 1958).

As a modern carbon standard we first used wood taken from the 1930 to 1945 rings of a large Douglas fir; this standard gave a net count of 6.02 counts/min. This activity, taking into account a 2% Suess-effect for this wood, was found to be 95% of the activity of the NBS oxalic-acid standard, measured in the same counter.

The NBS standard has been adopted by this laboratory since January 1961, and values given here are calculated from this new standard.

Measurements listed are dates obtained from 1956 through 1962. No reports are given here from other types of measurements carried out at Saclay, such as: (1) C14 content of wild plants growing in the vicinity of nuclear reactors; (2) measurement of C14 in blood proteins of workers of the radioactive-tracers industry; (3) Spallation cross-sections for C14 production in oxygen and iron by high energy protons; (4) C14 content of meteorites.

We have developed a software utility, “DateLab”, for conventional radiocarbon age (CRA) calibration and Bayesian analysis of CRAs. The current version has a smaller range of applicability than other similar utilities such as Bcal, Oxcal, and Mexcal. However, it enables analysis of some common types of CRA datesets. The main advantages of DateLab are its high quality sampling algorithm, the possibility of carrying out model comparison and hypothesis testing in a straightforward way, and the unbiased character of the summary statistics on which the analysis depends.

The Holocene Dead Sea and the late Pleistocene Lake Lisan were characterized by varying radiocarbon reservoir ages ranging between 6 and 2 ka in the Dead Sea and between 2 ka and zero in Lake Lisan. These changes reflect the hydrological conditions in the drainage system as well as residence time of 14C in the mixed surface layer of the lake and its lower brine. Long-term isolation of the lower brine led to 14C decay and an increase in the reservoir age. Yet, enhanced runoff input with atmospheric 14C brings the reservoir age down. The highest reservoir age of 6 ka was recorded after the sharp fall of the Dead Sea at ~8.1 ka cal BP. The lower reservoir age of zero was recorded between 36 and 32 ka cal BP, when the Lake Lisan mixed layer was frequently replenished by runoff.

The measurements reported have been carried out during the first half of 1968 in the Isotope Laboratory of the Institute of Geophysics and Planetary Physics as a continuation of the UCLA date lists I through VIII. Samples were analyzed as CO2-gas at close to one atm in a 7.5 L proportional counter with three energy channels described in earlier publication. Radiocarbon ages have been calculated for uniformity on the basis of a 5568 yr half-life in accord with a recommendation by the Sixth International C14 and H3 Dating Conference, June 1965, in Pullman, Washington. The standard for the contemporary biosphere remains as 95% of the count rate of NBS oxalic acid for radiocarbon laboratories. Background determinations have been based on CO2 obtained from marble. The error listed is always at least a one-sigma statistical counting error. In critical cases C13/C12 isotope ratio measurements were made to correct the dates for fractionation. All samples were subjected to accepted NaOH, HCl or other special chemical pretreatments discussed below depending on the individual case to exclude contamination.

This date list includes those series of samples completed in this laboratory as of November, 1965. The B.P. ages are based upon A.D. 1950, and are calculated with a half-life value of 5568 yr. Errors quoted are those derived from measurements of sample, background, and modern-age calibration, and do not include any half-life error. All samples were pretreated with 3N HCl, and some, where noted, received additional pretreatment with 2% NaOH for the removal of possible humic contaminants.

Radiocarbon analysis is an important tool in quantifying soil organic matter (SOM) dynamics within the terrestrial carbon cycle. However, there is increasing appreciation that representing SOM as a single, homogeneous pool with a single, mean 14C concentration is inadequate. We investigate whether the differing patterns in CO2 release during ramped-temperature oxidation reflect organic matter of different ages, and hypothesize that thermally labile SOM (combusting at low temperatures) consists of younger carbon than thermally resistant organic matter. Topsoil samples under contrasting land uses (native vegetation and long-term cultivation) were selected for 14C analysis before and after acid fumigation for the removal of carbonates. Results of bulk 14C analyses showed a significant shift in 14C age from 0.944 Fm under native vegetation to 0.790 Fm under cultivation. Four to 5 “fractions” associated with different CO2-evolution regions were identified by thermal analysis and analyzed for 14C via modifications to NOSAMS' established “programmed temperature pyrolysis system,” in which discrete CO2 fractions evolved during ramped-temperature oxidation were isotopically characterized by a microwave gas ion source (GIS) continuous-flow AMS (CFAMS) system. Results showed that while acid fumigation removed soil carbonates, the treatment also significantly altered the thermograms and inferred SOM composition. While direct attribution of 14C values to individual peaks is somewhat confounded by overlapping temperature ranges for oxidation of unique populations of carbon, in general, thermally stable fractions of SOM appear to be 14C-depleted compared to thermally reactive (low temperature) fractions regardless of pretreatment.

The following list covers some old measurements not included in previous lists and most of the samples measured at the Uppsala C14 laboratory since the last list (R., 1969, v. 11, p. 515–544); samples utilized for determining the increase of the C14/C12 ratio due to explosion of nuclear devices are omitted.

Contaminant carbon (blank carbon) was studied for its impact on the carbon isotope measurements (Δ14C and δ13C) of 3 organic compound classes of oceanic particulate organic matter. Two methods of blank correction and associated uncertainties were studied. First, the carbon blanks were quantified manometrically and the isotope ratios of the blank carbon were measured directly. Second, the isotope ratios of the blank carbon were estimated using the standard dilution method from the difference in Δ14C values between unprocessed and processed standards. The 2 methods agreed within the uncertainties. The standard deviations of numerous Δ14C measurements made on processed standard compounds were comparable to those of real samples. Blank correction using the standard dilution method is much less sensitive to the error in determination of blank carbon mass than is correction using the directly measured mass and Δ14C values of the blank carbon. The standard dilution method is recommended for correcting Δ14C analyses of small samples that involve incorporation of a significant amount of blank carbon.

We measured airborne releases of 14C from the Paks Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP). Two continuous stack samplers collect 14C in 14CO2 and 14CnHm chemical forms. 14C activities were measured using two techniques; environmental air samples of lower activities were analyzed by proportional counting, stack samples were measured by liquid scintillation counting. 14C concentration of air in the stack varies between 80 and 200 Bqm−3. The average normalized yearly discharge rates for 1988–1993 were 0.74 TBqGW−1ey−1 for hydrocarbons and 0.06 TBqGW−1ey−1 for CO2. The discharge rate from Paks Nuclear Power Plant is about four times higher than the mean discharge value of a typical Western European PWR NPP. The higher 14C production may be apportioned to the higher level of nitrogen impurities in the primary coolant. Monitoring the long-term average excess from the NPP gave D14C = 3.5‰ for CO2 and D14C = 20‰ for hydrocarbons. We determined 14C activity concentration in the primary coolant to be ca. 4 kBq liter−1. The 14C activity concentrations of spent mixed bed ion exchange resins vary between 1.2 and 5.3 MBqkg−1 dry weight.

We present results of airborne 14C emission measurements from the Paks PWR nuclear power plant. Long-term release of 14C in the form of carbon dioxide or carbon monoxide and hydrocarbons were simultaneously measured. The results of internal gas-proportional and liquid scintillation counting agree well with theoretical assessments of 14C releases from pressurized water reactors. The mean value of the 14C concentration in discharged air is 130Bqm-3 and the normalized release is equal to 740GBq/GWe · yr. > 95% of 14C released is in the form of hydrocarbons, ca 4% is apportioned to CO2, and <1% to CO. Tree-ring measurements were also made and indicated a minute increase of 14C content in the vicinity of the nuclear power plant.

This compilation of radiometric data from Antarctica contains abstracted information from 400 publications, resulting in nearly 2500 separate entries. Each entry, or “date listing”, gives basic information of the sample site as well as the dating method and the age(s) of the sample analysed. The date list differs from those routinely published in Radiocarbon because we included not only radiocarbon but all dating methods.

The valley of the Baxie River, situated in the western region of the Loess Plateau in central China, contains a loess profile 15 m thick, which can be considered representative of loess-paleosol sequences formed over the last 17 ka. Both thermoluminescence (TL) determinations on fine-grained sediment (4–11 μm) and 14C determinations on various organic fractions of paleosols from the profile have provided an extremely useful chronological framework for these sequences. These sequences indicate a weakened summer monsoon during the last glacial maximum followed by a strengthening of the summer monsoon, beginning ca. 13 ka cal bp. An abrupt change to a weakened summer monsoon regime lasted from ca. 10.9 to 10.2 ka cal bp. The Asian summer monsoon circulation, recording the Holocene optimum, then increased and lasted from ca. 10.2 to 6 ka cal bp. The organic component of samples taken down the profile has δ13C values ranging from −21 to −24‰ with respect to the PDB standard. The more positive δ13C values suggest that the proportion of C4-type plants in river valleys of the Loess Plateau increased as Asian summer monsoon influence weakened, and C3-type vegetation increased as the summer monsoon influence strengthened. Magnetic susceptibility and organic content were low during loess deposition, also reflecting weakening of summer monsoon. Two 14C determinations on the humin fraction of the organic component near the top of the lower paleosol and the base of the upper paleosol complex gave ages of 10.2 and 10.9 ka cal BP, respectively. These ages mark the beginning and termination of a brief event involving increased dust influx under weakened summer monsoon conditions.

Canadian deuterium uranium (CANDU) pressurized heavy-water reactors produce 14C by neutron activation of trace quantities of nitrogen in annular gas and reactor components (14N(n,p)14C), and from 17O in the heavy water moderator by (17O(n,α)14C). The radiocarbon produced in the moderator is removed on ion exchange resins incorporated in the water purification systems; however, a much smaller gaseous portion is vented from reactor stacks at activity levels considerably below 1% of permissible derived emission limits. Early measurements of the carbon speciation indicated that >90% of the 14C emitted was in the form of CO2. We conducted surveys of the atmospheric dispersion of 14CO2 at the Chalk River Laboratories and at the Pickering Nuclear Generating Station. We analyzed air, vegetation, soils and tree rings to add to the historical record of 14C emissions at these sites, and to gain an understanding of the relative importance of the various carbon pools that act as sources/sinks within the total 14C budget. Better model parameters than those currently available for calculating the dose to the critical group can be obtained in this manner. Global dose estimates may require the development of techniques for estimating emissions occurring outside the growing season.

Herbivorous and deposit-feeding gastropods are a major component of archaeological shell middens worldwide. They provide a wealth of information about subsistence, economy, environment, and climate, but are generally considered to be less than ideal for radiocarbon dating because they can ingest sediment while they graze, inadvertently consuming terrestrial carbon in the process. However, few studies of 14C activity in herbivores or deposit-feeding gastropods have been conducted into this diverse range of animals that inhabit many environmental niches. Here, we present results investigating 14C variability in shells belonging to the families Strombidae and Potamididae from the Bogi 1 archaeological site, Caution Bay, southern coastal Papua New Guinea (PNG). These shells make up 39.3% of the shell MNI in the excavation units studied and some of these species are the most common taxa of neighboring sites. It would therefore be advantageous to establish if there are any 14C offsets associated with such animals, and identify those that can give reliable calendar ages. Our methodology combines a high-resolution excavation protocol, selection of short-lived samples identified to species level, and a triisotope approach using 14C, δ13C, and δ18O to evaluate the source of variability in shells. Our results indicate that considerable variation exists between different species of Strombidae with some inhabiting muddier environments that act as sinks for limestone-derived sediments with depleted 14C content. The magnitude of variation is, however, overshadowed by that measured in the mudwhelk, Cerithidea largillierti, which has the largest spread in 14C of any shellfish studied so far at Caution Bay. This animal ingests sediment within the estuary that contains 14C derived from both enriched and depleted sources.

The following list covers measurements of bomb-producedC14 in series of cereals and grassescollected on the northern hemisphere from 1956through 1966. Samples were measured in order todetermine the yearly addition of bomb producedC14 at a single locality, and to detectpossible geographic variations in the distributionand uptake of bomb-generated C14 interrestrial plant material during years with greatlyvarying additions of bomb C14.Measurements are given in the ∆ scale (Lamont VIII),i.e. per mil deviations from 0.95 times the activityof the NBS oxalic-acid standard (the naturalC14 level).

This study reports radiocarbon dates of more than 30 samples of charred residues on pottery sherds of the Incipient Jomon period. The ages of Linear-relief (Ryukisenmon) pottery were 15,300–13,700 cal BP, with great differences among the samples. The pitted decoration (Enkomon), Nail-impressed (Tsumegatamon), and pressing and dragging (Oshibikimon) types date to 13,800–12,400 cal BP. For pottery of the same type, differences among sites were large. At the Unokiminami site, the impressed cord mark (Oatsu Jomon) is the main pottery type, including Nail-impressed. The latter shows a slightly older age. Stable isotope and elemental analyses were used to ascertain the origin of charred residues on the pottery. In the data set of Jomon pottery of the oldest type, residues consisting only of cooked nuts were found. However, Jomon people, even from early times, are thought to have cooked mixed plant and animal ingredients, including marine products.