Abstract The paper presents the results of 14 C measurements in tree rings collected near the now‑decommissioned Bilibino Nuclear Power Plant (NPP), which operated four EGP-6 graphite-water reactors with a total electric capacity of 48 MW from 1974 to 2022. The sampling site was chosen based on long‑term meteorological data to represent the area with the highest potential 14 C level in the surface atmosphere resulting from Bilibino NPP discharges. The 14 C measurements were performed using accelerator mass spectrometry at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The results obtained range from 103.5 to 139.7 pMC, allowing the reconstruction of 14 C uptake into vegetation over the period 1974–2022. The largest anthropogenic contribution to the 14 C content was 6.0 pMC in 2020, which is likely due to maintenance work on the reactor’s graphite moderator. These results enabled the annual effective doses to the population from radiocarbon releases at the Bilibino NPP to be estimated. The maximum annual effective dose, about 3 µSv, was observed in 2020, which is far below the public dose limit of 1 mSv per year.
Abstract A more accurate radiocarbon dating of short-period climate changes in the Holocene requires to take into account short-term changes in variation of the 14 C concentration in the atmosphere, which could lead to a dating error of up to 300 years. To eliminate this potential problem, Bronk Ramsey’s model was used, based on a comparison of the radiocarbon dates with the calibration curve. Using this model, a corrected (i.e., modeled) age was established for the entire series of previously determined radiocarbon dates obtained from the Nikolsko-Lyutinskoye, Shirinsky Mokh, and Sambalskoye raised bog sections in northwestern European Russia. The deviations of the average annual temperature from its modern value (∆T), presented in previous publications as graphs, were converted into digital form. Using this model, a refined calendar chronology was established. The chronology of short-period climate changes in the Holocene demonstrates the synchronicity of short-term climate fluctuations. In most cases, it agrees well with the chronology obtained in the study of natural objects (lakes, bogs, marine sediments, and polar glaciers), as well as with the advances of mountain glaciers. The chronology of short-period climate changes is compared to the changes in solar activity, established by using concentrations of cosmogenic isotopes: 14 C in tree rings, and 10 Be in polar glaciers. The synchronicity of short-term climate fluctuations and variations of solar activity in the Holocene has been established, and it suggests that changes of solar activity are one of the main causes of short-period climate fluctuations in the Holocene.
Abstract We report on 10 years of operation of a MICADAS compact tandem accelerator for radiocarbon ( 14 C) analysis at the Tandem Laboratory national research infrastructure at Uppsala University comprising analysis of over 40,000 samples. Based on the large number of analyzed samples and associated references, we perform an analysis of the target scatter of employed IAEA-C7 and SRM-4990C-standards. As a result, we show how the target scatter deduced from a single magazine run is falling below the long-term statistical average, which can result in a systematic uncertainty in 14 C results obtained from such runs. We also discuss effects of sample size on current and potential corrections for contamination or non-linearities in the measurement for standard samples spanning a wide range of activity levels, down to below 10 µg C equivalent. Finally, we discuss an observed mass dependence of stable isotope ratios in IRMS, which, if not measured by the accelerator itself, could impact 14 C determination.
Abstract Comparison of cellulose 14 C of the growth rings 1962–1965 of Norwegian Scots pine with Norwegian atmospheric 14 CO 2 over these bomb spike years indicates that tree rings can provide a good proxy for atmospheric 14 CO 2 . The sub-seasonal cellulose 14 C values of five trees from 63° to 69° N reveal local atmospheric 14 CO 2 values for the growing seasons 1950–1965. The 1950s are of special importance because there exist few direct measurements of atmospheric 14 CO 2 during this period of active atmospheric nuclear testing. First indications of bomb 14 C are seen already in 1952. The temporary halt of atmospheric testing from November 1958 to September 1961 led to a temporary maximum in atmospheric 14 C concentrations in 1959, creating the 1950s atmospheric bomb- 14 C peak. Longer atmospheric travel of 14 C from low-latitude and Southern Hemisphere tests to Norway led to the highest tree 14 C values in 1959 and 1963/’64 after testing stopped, respectively, in 1958 and 1962. The Scots pine data demonstrate that local atmospheric 14 CO 2 records with sub-annual resolution can generally be obtained. Combination with the SIPRI data base of nuclear testing, allows a focus on the production of bomb 14 C and its transport through the atmosphere to the tree and promises a better understanding of the atmospheric mixing of CO 2 . Together with high-resolution local 14 CO 2 records this can better define the exchange between the atmosphere and the other reservoirs of the carbon cycle during the period of isotopic disequilibrium caused by atmospheric nuclear testing.
Abstract The article presents first insights to radiocarbon dating of taxonomically diverse Pleistocene faunal assemblage recovered from Graniczna Cave in the Kraków-Częstochowa Upland. The material represents one of the most heterogeneous cave bone accumulations in the region, comprising remains of large and small mammals. Thirteen bone samples representing different taxa were selected for AMS radiocarbon dating, and one sediment sample was analyzed using optically stimulated luminescence (OSL) to provide an independent chronological reference. The study primarily focuses on the variable preservation state of bone collagen, which plays a critical role in the reliability of radiocarbon dating. This study highlights the inherent difficulties of dating cave-derived bone assemblages and emphasizes the need for rigorous pre-screening criteria, including collagen quality assessment and elemental composition.
