Carbon-14 in Tree Rings in the Vicinity of Ignalina Nuclear Power Plant, Lithuania
The results of 14C measurements in the annual tree rings from the Ignalina Nuclear Power Plant (INPP) vicinity, Lithuania, for the period of its operation from 1984 to 2002 are presented. The terrestrial samples, mainly moss and related topsoil, are studied in places as well. The tree rings have shown the slightly enhanced 14C activity due to operation of the nuclear power plant. The maximal calculated normalized 14C release of 11 TBq/GWe/year and the maximal effective dose of 2.0x10-3 mSv/year resulting from the 14C were estimated for 1999. The excess of 14C specific activity measured in the moss and soil samples from moss-covered sites near the nuclear power plant (up to 0.5 km) showed highly elevated 14C contents (up to 813 pMC), probably indicating releases of the particulate material.
The sediments of two lakes located in the Baltic Uplands, the western part of the East European Plain (East Lithuania and North East Poland), were studied. Activity concentration of 210Pb was determined using two nuclear analytical techniques: determination of 210Pb in equilibrium with its beta emitting daughter 210Bi using liquid scintillation counter (LSC), and direct determination of 210Pb (and other radionuclides) by low-background gamma-ray spectrometer with a well type HPGe detector. For the 210Pb determination by LSC the methodology of lead separation based on the anion exchange resin in Cl– form (Eichrom) was used. Several steps of radiochemical procedures and respective parameters were investigated additionally. The optimized procedures for LSC method were used for case study with two lake cores. The activity concentration of 210Pb in lake sediment samples based on both nuclear analytical techniques (LSC and HPGe) were compared. 210Pb dating of cores was performed according to Constant Rate of 210Pb Supply (CRS) model with some modifications. Both techniques in the range of uncertainties gave similar results. From two considered lakes, the more eutrophic one exhibited higher sediment mass accumulation rate (MAR) values.
The Use of Carbon-14 and Tritium For Peat and Water Dynamics Characterization: Case of Čepkeliai Peatland, Southeastern Lithuania
The present investigation conducted in Čepkeliai peatland (south-eastern Lithuania) deals with two radioisotope methods - carbon-14 (14C) and tritium (3H). 14C was applied to peatland chronology and sedimentation rate estimation and 3H to peat water dynamics characterization. According to 14C data, peatland development began since 12650-11350 years cal BP and peat accumulation since 10550-9700 years cal BP with peat accumulation rate of 0.27-0.79 mm/year in the central part of the peatland. The peat water mean residence time and basic groundwater flow was estimated to be respectively about 27±6 years and 62±15 mm based on 3H data. The obtained data showed relatively undisturbed natural condition of Čepkeliai peatland in the studied sites.
Sub-fossil oaks from Smarhoń in Belarus have been investigated and tree-ring chronologies were assembled. According to radiocarbon dating, the oldest oak grew from 5782–5612 cal BC and the youngest from 1575–1747 cal AD. Radiocarbon and dendrochronological dating of 97 samples, four single series, 10 mean curves (containing 2–9 series) and three chronologies (10–25 series) were constructed. The longest chronology (No. 16), covering 549 years, was absolutely dated against various oak chronologies of Polish/Baltic origin to AD 778–1326. Germination and dying-off phases were assessed from the three best replicated chronologies. A spectral analysis of the chronologies provided cycles of variable length, on average of 25 years.
The effects of 5 s–24 h exposure to CuO nanosuspension (nCuO) and CuSO4 on mortality of Nitellopsis obtusa cells within 48 days were investigated. Based on LED50 kinetics, a toxicological endpoint of lethal exposure duration that induces 50% cell mortality, it was shown that mortality response of 10-min treated cells (by 3.2 and 24–79.9 mg Cu/l, respectively CuSO4 and nCuO) did not differ after 12th day rewash in control medium. Larger amount of total Cu (in mg/g cell DM) was measured in charophyte cells exposed to nCuO (79.9 mg Cu/l) than to ionic Cu (3.2 mg Cu/l). The lower nCuO-induced mortality than that of Cu2+ during earlier rewash period could be related to the sorption of nanoparticles on the cell wall, which was confirmed by scanning electron microscope images and energy dispersive X-ray spectrum data. Effect threshold, the shortest exposure duration that induces cell mortality significantly different from the control during a post-exposure period, comprised 30 s in 24 mg Cu/l of nCuO, however, it could not be identified and was less than 5 s in 79.9 mg Cu/l of nCuO.