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Edvardsson J.,University of Bern | Corona C.,University Blaise Pascal | Mazeika J.,State Research Institute Nature Research Center | Pukiene R.,Vytautas Magnus University | And 2 more authors.
Quaternary Science Reviews | Year: 2016

This study presents the first results from an ongoing initiative to develop a multi-millennial Baltic tree-ring width (TRW) chronology consisting of 12 floating records from subfossil Scots pines (Pinus sylvestris L.) extracted from three Lithuanian peat-mining areas. The floating series have been complemented with absolutely dated TRW chronologies which were obtained from living trees growing in unmanaged and unexploited peatland areas adjacent to each of the above study sites. The subfossil material has been dated by radiocarbon and shows a temporal spread over the last 6000 years, with assemblages of trees during the Holocene Thermal Maximum (HTM; 8000-4000 BP) and the onset of the Medieval Warm Period (MWP, AD 900-1350). Annual tree growth and sample replication of peatland pines reflect moisture variations and long-term climate variability. The importance of extending the TRW chronologies should not therefore be underestimated as (1) climate records of comparable length and resolution do not exist for the Baltic region, but also as (2) a result of a widespread lack of detailed moisture proxies spanning several millennia. Our data clearly show that a 6000-yr, continuous pine chronology from the Baltic region is a realistic objective, and would doubtlessly fill a major geographic gap in an ecologically sensitive region located at the interface between the temperate and boreal vegetation zones. © 2015 Elsevier Ltd. Source

Skuratovic Z.,State Research Institute Nature Research Center | Mazeika J.,State Research Institute Nature Research Center | Petrosius R.,State Research Institute Nature Research Center | Martma T.,Tallinn University of Technology
Isotopes in Environmental and Health Studies | Year: 2015

The unsaturated zone is an important part of the water cycle, governed by many hydrological and hydrogeological factors and processes and provide water and nutrients to the terrestrial ecosystem. Besides, the soils of the unsaturated zone are regarded as the first natural barrier to a large extent and are able to limit the spread of contaminants depending on their properties. The unsaturated zone provides a linkage between atmospheric moisture, groundwater, and seepage of groundwater to streams, lakes, or other surface water bodies. The major difference between water flow in saturated and unsaturated soils is that the hydraulic conductivity, which is conventionally assumed to be a constant in saturated soils, is a function of the degree of saturation or matrix suction in the unsaturated soils. In Lithuania, low and intermediate level radioactive wastes generated from medicine, industry and research were accumulated at the Maisiagala radioactive waste repository. Short-lived low and intermediate levels radioactive waste, generated during the operation of the Ignalina Nuclear Power Plant (INPP) and arising after the INPP decommissioning will be disposed of in the near surface repository close to the INPP (Stabatiske site). Extensive data sets of the hydraulic properties and water content attributed to unsaturated zone soil profiles of the two radioactive waste disposal sites have been collected and summarized. Globally widespread radionuclide tritium (3H) and stable isotope ratio (18O/16O and 2H/1H) distribution features were determined in precipitation, unsaturated zone soil moisture profiles and groundwater. © 2015 Taylor & Francis Source

Mazeika J.,State Research Institute Nature Research Center | Marciulioniene D.,State Research Institute Nature Research Center | Nedveckaite T.,State Research Institute Nature Research Center | Jefanova O.,State Research Institute Nature Research Center | Jefanova O.,Vytautas Magnus University
Journal of Environmental Radioactivity | Year: 2016

The radiological doses to non-human biota of freshwater ecosystem in the Ignalina NPP cooling pond - Lake Druksiai were evaluated for several cases including the plant's operation period and initial decommissioning activities, using the ERICA 1.2 code with IAEA SRS-19 models integrated approach and tool.Among the Lake Druksiai freshwater ecosystem reference organisms investigated the highest exposure dose rate was determined for bottom fauna - benthic organisms (mollusc-bivalves, crustaceans, mollusc-gastropods, insect larvae), and among the other reference organisms - for vascular plants. The mean and maximum total dose rate values due to anthropogenic radionuclide ionising radiation impact in all investigated cases were lower than the ERICA screening dose rate value of 10 μGy/h. The main exposure of reference organisms as a result of Ignalina NPP former effluent to Lake Druksiai is due to ionizing radiation of radionuclides 60Co and 137Cs, of predicted releases to Lake Druksiai during initial decommissioning period - due to radionuclides 60Co, 134Cs and 137Cs, and as a result of predicted releases to Lake Druksiai from low- and intermediate-level short-lived radioactive waste disposal site in 30-100 year period - due to radionuclides 99Tc and 3H.The risk quotient expected values in all investigated cases were <1, and therefore the risk to non-human biota can be considered negligible with the exception of a conservative risk quotient for insect larvae. Radiological protection of non-human biota in Lake Druksiai, the Ignalina NPP cooling pond, is both feasible and acceptable. © 2015 Elsevier Ltd. Source

Marciulioniene D.,State Research Institute Nature Research Center | Mazeika J.,State Research Institute Nature Research Center | Luksiene B.,State Research Institute Center for Physical and Technological science | Jefanova O.,State Research Institute Nature Research Center | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2015

Based on γ-ray emitting artificial radionuclide spectrometric measurements, an assessment of areal and vertical distribution of 137Cs, 60Co and 54Mn activity concentrations in bottom sediments of Lake Drukšiai was performed. Samples of bottom sediments from seven monitoring stations within the cooling basin were collected in 1988-1996 and 2007-2010 (in July-August). For radionuclide areal distribution analysis, samples from the surface 0-5cm layer were used. Multi sample cores sliced 2cm, 3cm or 5cm thick were used to study the vertical distribution of radionuclides. The lowest 137Cs activity concentrations were obtained for two stations that were situated close to channels with radionuclide discharges, but with sediments that had a significantly smaller fraction of organic matter related to finest particles and consequently smaller radionuclide retention potential. The 137Cs activity concentration was distributed quite evenly in the bottom sediments from other investigated monitoring stations. The highest 137Cs activity concentrations in the bottom sediments of Lake Drukšiai were measured in the period of 1988-1989; in 1990, the 137Cs activity concentrations slightly decreased and they varied insignificantly over the investigation period. The obtained 238Pu/239,240Pu activity ratio values in the bottom sediments of Lake Drukšiai represented radioactive pollution with plutonium from nuclear weapon tests. Higher 60Co and 54Mn activity concentrations were observed in the monitoring stations that were close to the impact zones of the technical water outlet channel and industrial rain drainage system channel. 60Co and 54Mn activity concentrations in the bottom sediments of Lake Drukšiai significantly decreased when operations at both INPP reactor units were stopped. The vertical distribution of radionuclides in bottom sediments revealed complicated sedimentation features, which may have been affected by a number of natural and anthropogenic factors resulting in mixing, resuspension and remobilization of sediments and radionuclides. The associated with particles 137Cs flux was 129Bq/(m2year). The 137Cs transfer rate from water into bottom sediments was 14.3 year-1 (or, the removal time was 25 days). The Kd value for 137Cs in situ estimated from trap material was 80m3/kg. The associated with particles 60Co flux was 21Bq/(m2year), when 60Co activity concentration in sediment trap particles was 15.7±5Bq/kg. 60Co activity concentration in soluble form was less than the minimum detectable activity (MDA=1.3Bq/m3). Then, the conservatively derived Kd value for 60Co was >90m3/kg. © 2015 Elsevier Ltd. Source

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