A radiocarbon (14C) activity analysis in the tree rings around Ignalina nuclear power plant (INPP) has been carried out with the aim to test the hypothesis to use 14C tree-ring analysis data as a tool for the reconstruction of gaseous releases from NPP to the environment. The INPP has been in decommissioning state since the end of 2009. Tree-ring samples for 14C analysis were collected 7 yr after final power unit shutdown from the INPP vicinity. The samples from 5 sampling locations were collected, prepared and measured using the Single Stage Accelerator Mass Spectrometer (SSAMS). Data analysis represents observable Ignalina NPP influence by 14C increase up to 15 pMC (percent modern carbon) in tree rings. Good correlations of the 14C concentrations and wind direction were obtained. The main purpose of this article was to match 14C measurement data along with the atmospheric dispersion modeling of emissions in order to retrospectively characterize the emission source.
The vertical distribution of radiocarbon ( 14 C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for”Channelized Large Power Reactor”). 14 C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210 Pb and 137 Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947–2013 period. In addition, 14 C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947–1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14 C specific activity in both fractions increased by 11.4–13.6 pMC during the first 15 years of plant operation. However, during the 2000–2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14 C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14 C contained in liquid effluences from the INPP in 2000–2009. The discrepancy between 14 C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14 C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.
In this study, we examined how land use and urbanization changes in adjacent areas affected biological productivity and carbon cycling in a lake ecosystem over 100 years and how these changes are reflected in carbon isotope variations. We performed radiocarbon (14C) activity and stable carbon isotope ratio analysis in two organic fractions: humin and humic acids of lake sediment. Additionally, we performed pigment and diatom analysis and determined the carbonate and organic matter (OM) content in sediments. Over the last century, the estimated 14C reservoir age in both sediment organic fractions varied from 1136 ± 112 yr to 5733 ± 122 yr. The increase in the reservoir age by 1175 ± 111 yr was related with higher inputs of pre-aged organic carbon and 14C depleted hard water due to the opening of the channel connecting two lakes. Nuclear weapons tests caused an increase in the reservoir age of up to 5421 ± 135 yr and 5733 ± 122 yr in humin and humic acids, respectively. 13C values in the humic acid fraction showed a tendency to decrease, depending on the content of autochthonous versus allochthonous OM in sediments, while changes in the sources of OM had a minor impact on the stable carbon isotope composition in the humin fraction.
The emergence and widespread distribution of eye fibulae as adornment objects, from the northern provinces of the Roman Empire to northeastern Europe and Scandinavia, as well as their typology have been widely explored. Currently in Lithuania, a total of 209 eye fibulae dating to the 1st and 2nd centuries are known. The geographical distribution, typology and chronology of these Early Roman Period jewelry artifacts do not present any problem. However, the technology of manufacture of these fibulae has been much less studied. The present article analyzes the technology of manufacture of Prussian series eye fibulae, including the previously unknown specific manufacturing techniques, such as the use of wooden axes to modify the construction of the fibula and make it more durable and long lasting. Radiocarbon (14C) dating has unambiguously confirmed that the wooden axes are contemporaneous with the time of the use of the fibulae, while observation under the scanning electron microscope has identified wood species used for making the wooden axes. The X-ray fluorescence spectrometry (XRF) analysis was used to determine the copper alloys, of which eye fibulae were made. The manufacturing technologies of eye fibulae (forging and casting) are discussed in the context of analytical and experimental studies.
<p>The intensive development of industry, agriculture, and transportation causes many issues related to the negative impact on the environment and human health. Harmful products of human technogenic activity accumulate in the environment. Due to increasing concentrations of greenhouse gases (methane, carbon dioxide, etc.), the effects of global warming are already being observed. Research that addresses the challenges of climate change mitigation and creates science-based assumptions for new environmental monitoring systems and technologies is becoming more and more relevant.</p><p>A new two drone system with a variable optical path for measuring greenhouse gases (CH<sub>4</sub>, CO<sub>2</sub>) is currently in development. Here, we will present a distributed feedback (DFB) quantum cascade laser absorption spectroscopy system which is used for measuring methane concentrations in the atmosphere. The DFB laser for methane measurements is being operated at 3371.5 nm and 3368.8 nm, for higher and lower concentrations respectively.</p><p>The results of the Allan-Werle deviation analysis will be introduced. Also, measurement capabilities and detection limits of the system will be presented and discussed.</p>
The Ignalina Nuclear Power Plant (INPP) in Lithuania is a rare case when lake water is used instead of river or sea water for cooling. Lake Drūkšiai with water residence time of 3–4 year and undisturbed sediment layers is a unique system to assess the impact of a nuclear facility on the aquatic ecosystem with a sufficiently high temporal resolution. We constructed a model of radiocarbon cycling processes in lake ecosystem which evaluates the 14C specific activity vertical distribution in two organic sediment fractions: alkali-soluble and alkali-insoluble. Model calculations proved that during the first 15 years of operation since 1983, 14C annual aqueous releases from the INPP were in water dissolved inorganic carbon form and varied in the range of 2.4 ÷ 3.7 × 108 Bq/year. The results of the modeling of hypothetic scenarios also showed that there was the only one episode of elevated releases from the INPP in 2000–2001, which changed the interaction between the two organic sediment fractions for the period of 2000–2006. It was caused most probably by released chemicals from INPP but not by 14C contamination. Interaction processes between both sediment fractions recovered to its original state after 2006, indicating that the released additional chemical compounds lake ecosystem have been cleaned-up.
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