The Chalk River Tandem Accelerator Mass Spectrometry System has reached a state of reliable measurement of 14C using 2 to 5mg elemental carbon prepared by Mg reduction of CO2. For two comparisons of a near-modern unknown with the NBS oxalic acid standard we obtain a total error of ∼±4.5%, consisting of a random system error of about ±3.5% combined with the statistical counting error. Measurements have been made on 70 samples in 30 days of running time during the past year. Samples included deep rock carbonates, cosmogenic 14C in meteorites, charcoal from earthquake fault zones, collagen of bone artifacts and fossil beetle-fragments.

A chronological synthesis of prehistoric campsites in alpine and subalpine zones (∼2–3 km asl) at Haleakalā, Maui Island, USA, is based on relative stratigraphy from 24 test excavations, associated artifacts of known or probable time periods, and 12 radiocarbon dates. The results indicate intensive use of the unfavorable high-altitude environment in the range of AD 1400–1600, with very limited use slightly earlier. Numerous campsites were used repeatedly near the Haleakalā crater rim and scattered on the lower western mountain slope. Prior to this time, activity in this inhospitable setting was infrequent and occurred on a small scale.

Radiocarbon measurements mainly on soil samples and soil organic matter fractions are being continued. Sample benzene preparation follows Scharpenseel & Pietig (1969; 1970a). Radioactivity is measured in single screw cap quartz vials using a Packard Tri-Carb 3075 as well as a Berthold Betaszint BF 5000.

Gas chromatographic analysis of the benzene obtained for radiocarbon dating revealed only very low levels (<200 ppm in total) of impurities, most of which were alkylbenzenes. Traces of acetone and phenol were also found. These impurities, at such low levels are thought unlikely to affect counting efficiency.

Micropaleontological and geochemical data were applied to sediments from southeastern Brazil to study the hydrodynamics associated with the Holocene sea level rise. Sediment cores were taken around Vitória Bay, examined for dinoflagellate cysts and subjected to isotopic analysis. The cyst assemblage mainly dominated by autotrophic species most notably O. centrocarpum, L. machaerophorum and T. vancampoae. The influence of the marine transgression and subsequent regression observed during the Holocene along the coast of Brazil could have initially favored the establishment of an oligotrophic and higher energy environment. The inflow of continental water from tributaries combined with a higher inflow of saline water into the estuarine system could have favored the establishment and subsequent deposition of the dinocysts.

We identified human paleodietary changes from inhabitants of the Guanzhong basin since 8000 BP, based on published carbon and nitrogen isotopic measurements on bones, fauna and plant remains. We also directly measured 14C ages, δ13C and δ15N values from bones unearthed at the Zhouyuan site, west of Guanzhong, in order to reconstruct paleodietary changes of the ancient inhabitants. We found that during the Laoguantai period, animal foods were the main source of nourishment with supplementary plant-derived foods. After this period, plant-derived foods became the main food source, with supplementary animal sources. The development of dry farming led to increased consumption of foxtail millet and broomcorn millet. This trend persisted and marked a fundamental shift from hunting, gathering, and fishing to farming and animal domestication. The dietary trends of the ancient inhabitants also show pronounced regional differences through time. The use of domestic animals was proportionally higher in the eastern part of the Guanzhong region, while wild animals were more common in the west.

The paper describes a study undertaken to examine the dispersion pattern of gaseous emissions, as indicated by 14C uptake in natural materials, around the nuclear reprocessing plant at Sellafield, Cumbria, UK. The extent and directional dispersion of the released 14C is established and its variability over an extended period assessed. Results of measurements taken during three sampling seasons (1981, 1982, 1983) of the 14C activity in hawthorn berries collected over a wide area are presented and the dispersion pattern contours constructed from them are examined. Only limited agreement of the results with the theoretical relationship 1/r is found and both meteorology and topography are seen to be important in determining the shape of the observed patterns.

Hessel de Vries contributed to radiocarbon (14C) dating for only one short decade. Yet, his development of proportional CO2 counting greatly facilitated 14C measurements, improved their reproducibility, and lowered both the amount of carbon needed for a measurement and the 14C detection limit by at least a factor ten. Validating Libby’s 14C method by checking its basic assumptions with improved sensitivity, de Vries documented relatively minor violations. Natural variations in atmospheric 14C concentrations, found in tree rings, marked the start of 14C tree-ring calibration. Variable differences in 14C concentration between the atmosphere and aquatic reservoirs revealed reservoir ages, leading to further studies. De Vries applied analogue modeling to gain a better understanding of the influence of cosmogenic 14C production and the global carbon cycle, inclusive CO2 exchange across the air-water boundary, on atmospheric 14C concentrations. In close collaboration with colleagues in archaeology and geology, de Vries documented climate fluctuations and archaeological developments over the last 50,000+ years and placed them on a common 14C time scale.

Travertine deposits occur abundantly at past and present sites of waterfalls in the Arbuckle Mountains region of Oklahoma. This area (1600km2) consists of folded and faulted Prepaleozoic and Paleozoic rocks, with abundant outcrops of Paleozoic carbonate rocks. Samples of recently deposited and old travertine from the Turner Falls area were collected during a 1987 field trip and analyzed for 13C, 14C and 18O content. The aquatic chemistry of travertine depositing creeks was investigated systematically and compared with those of similar areas in SE and central Europe.

A major collective effort was made to develop a data base for establishing the relationship between 14C and calendric ages (Stuiver, 1982). The early “cosmic schwung” fit between the two ages (Suess, 1970a, p 310) and the 10,350 yr period of the grand trend (Suess, 1970b, p 596) have recently been replaced by the period of 12,100 yr (Suess, 1980). The period of the grand trend was estimated by correlating the data with an a priori postulated sine function (Suess, 1970, p 596), or more recently a polynomial fit of the sixth degree was used (Klein et al, 1982). In the detrended data, periods (wiggles) of between 2400 yr and 104 yr were identified by conventional time series analysis. This approach could not be used to estimate the period of the grand trend, because the time series includes less than one cycle, whereas several cycles are required in order to get a meaningful result.

Karst springs are abundant in Hungary, and many are thermal (temperatures >30°). As thermal springs are a significant part of Hungary's water resources, it is important to quantify their travel times in the karst systems. Thus, we chose to measure T and δ18O in the water and δ13C and 14C in dissolved inorganic carbon (DIC) in water from 50 thermal and nonthermal springs and wells in the Bükk Mountains, northeastern Hungary. Environmental isotope data confirm the karst water-flow pattern implied by earlier studies. We found the water in warm springs and boreholes to be mixtures of cold young and old thermal water. We also determined short mean-residence times for some large cold springs. The 14C activities measured in these springs indicate that the recharge area of the karst aquifer is open to the atmosphere, and atmospheric CO2 contributes to the 14C activity of these groundwaters. We observed good correlation between 14C and 3H activities and we determined negative correlations between 14C concentration and δ13C values and temperature. From the δ18O values of the oldest thermal waters, we attribute their origin to precipitation during colder temperatures than at present.

Treatment of samples and counting equipment have remained essentially the same as described previously (R, 1974, v 16, p 404-306). Sample CO2 is used to fill a 1.2L steel proportional counter at 740mmHg.

This paper presents a set of accelerator mass spectrometry (AMS) radiocarbon dates obtained from various archaeological samples collected from 3 shellmounds—CA-MRN-114, CA-MRN-115, and CA-MRN-328—within China Camp State Park, Marin County, California, USA.

The Radiocarbon Dating Laboratory of Tehran University Nuclear Centre began operation in autumn 1970. Benzene synthesis and liquid scintillation counting was chosen as the best method for processing a large number of archaeologic specimens most of whose ages are less than twice the half-life of C14. Advantage of benzene synthesis; ease of chemical processing light transfer properties, lack of isotopie fractionation and radioactive contamination, removal of radon, and improbability of cross-contamination, have been discussed (Noakes et al., 1964; Noakes, Stipp, and Hood, 1964; Kowalski, 1965).

Facilities for radiocarbon dating were established at the University of Frankfurt/Main in the Institute of Anthropology. The Radiocarbon Laboratory provides assistance to the Amino-Acid-Dating Laboratory. This list reports on 14C dates measured up to September 1983.

The laboratory is installed in the basement of a three-story building and is equipped with a 2L copper proportional counter filled to 1013 mbar with purified CO2. The counter is protected against cosmic and surrounding radiation by a 3.5 ton lead shield and a copper multiwire anticoincidence ring-counter flushed with purified 90Ar/10CH4. Electronics are of the commercial NIM type. Charcoal and wood samples are treated by standard acid-alkali-acid methods. Bone samples are treated according to the collagen methods described by Berger, Horney, and Libby (1964), Longin (1971), Protsch (1972; 1975), and Protsch and Berger (1973).

The following radiocarbon measurements are a partial list of projects and samples dated since January 1975. The technique used is described in R, v 16, pp 402-408 and R, v 18, pp 210-220. Dates are calculated using 14C half-life of 5568 yr and errors are reported as one-standard deviation.

The following list sums up the results of radiocarbon dating of geologic samples obtained mostly during 1978 and 1979. Measurements have continued with the same proportional counters, pretreatment procedures, carbon dioxide purification, measurement and calculation as described previously (Pazdur et al, 1982). Ages are reported as conventional radiocarbon dates in years before ad 1950. No corrections for 13C/12C ratio were made for samples reported in this date list. Infinite dates are based on a 2-sigma criterion (Pazdur and Walanus, 1979). Sample descriptions and comments are based on information provided by the submitters.

The present list includes 74 dates of geologic samples determined using the liquid scintillation 14C method at the Geobiochemical sector of the Institute of Zoology and Botany, Academy of Sciences, Estonian SSR.

The article presents results of measurements of radiocarbon (14C) concentration in sub-annual dendrochronologically dated tree rings of English oak (Quercus robur L.) from Grabie village near Kraków (southern Poland). Samples of early wood (EW) and late wood (LW) spanning the years 664–658 BCE. α-cellulose was extracted from each sample and their radiocarbon content was measured at the ATOMKI laboratory in Debrecen, Hungary. The EW and LW data confirm a prolonged increase in Δ14C values around 665–663 as was observed by Park et al. (2017), Rakowski et al. (2019), or Sakurai et al. (2020). In addition, we found that this event may consist of two relatively small events, as was proposed by Sakurai et al. (2020). Based on obtained in this and previous study data we estimate that the occurrence of the two events were between 665 and 664 BCE (Rakowski et al. 2019), and in late spring of 663 BCE (May–June, before beginning of LW formation).

The dates listed were obtained using a stainless steel counter with an active volume of 1.3 L and a background of 16.3 cpm at an absolute filling pressure of 152 cm Hg. The present proportional counter in use is made of O.F.H.C. copper, and has an active volume of 1.25 L and a background of 5.2 cpm, at an absolute counter filling pressure of 152 cm Hg. CO2 is used as the counting gas and the counter is filled to a pressure of between 76 cm and 228 cm of Hg (depending on the sample size) at a temperature of 23 ± 0.3°C. The counter is shielded, starting from the top, by 5 cm of lead and 26 cm of iron, and is surrounded by an array of 22 Geiger tubes, and then finally by 2.5 cm of mercury. The thickness of the sides and base is greater than 10 cm of iron. As yet no neutron shielding is used and this probably accounts for the large fluctuations of background with barometric pressure (0.32 cpm per 1 cm Hg change in the pressure).