Jakub Kaizer

Carbon and Pu isotopes in Baltic Sea sediments

Distributions of 137Cs, 239,240Pu, Δ14C and δ13C measured in sediments indicated low 137Cs and 239,240Pu activities in the Curonian Lagoon and higher levels in the open Baltic Sea. Depleted δ13CTOC values were found in the Curonian Lagoon as compared with the open Baltic Sea, while the most depleted Δ14CTOC values were found in the Gotland Deep. The global fallout Pu dominated in the deeper zones of the Baltic Sea, while higher 240Pu/239Pu atom ratios were characteristic of the coastal regions.

Radiocarbon in the Atmosphere of the Žlkovce Monitoring Station of the Bohunice NPP: 25 Years of Continuous Monthly Measurements

Radiocarbon variations in the atmosphere have been observed at the Žlkovce monitoring station of the Bohunice nuclear power plant (NPP), situated only 5 km ESE from the NPP. The observed 14 C levels provide unique evidence of a decreasing long-term impact of the Bohunice NPP on the region. Simultaneously, decreasing emissions of fossil fuel carbon dioxide in the atmosphere of the monitoring site have been found. The observed ∆ 14 C variations with time have attenuating amplitudes and decreasing mean values, showing maxima in summer and minima in winter, the latter primarily caused by increased emission of fossil CO 2 in winter months. Sporadic short-term releases of 14 C from the Bohunice NPP were observed at the Žlkovce station. The annual atmospheric ∆ 14 C variations compared with tree-ring data collected at the Žlkovce village show reasonable agreement. The observed ∆ 14 C levels after 2005 are close to the European clean-air levels as measured at the Jungfraujoch (3450 m asl) monitoring station. DOI: 10.2458/azu_rc.57.18364

Tritium and radiocarbon in the western North Pacific waters: post-Fukushima situation

Impact of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident on tritium (3H) and radiocarbon (14C) levels in the water column of the western North Pacific Ocean in winter 2012 is evaluated and compared with radiocesium (134,137Cs) data collected for the same region. Tritium concentrations in surface seawater, varying between 0.4 and 2.0 TU (47.2-236 Bq m-3), follow the Fukushima radiocesium trend, however, some differences in the vertical profiles were observed, namely in depths of 50-400 m. No correlation was visible in the case of 14C, whose surface Δ14C levels raised from negative values (about -40‰) in the northern part of transect, to positive values (∼68‰) near the equator. Homogenously mixed 14C levels in the subsurface layers were observed at all stations. Sixteen surface (from 30 in total) and 6 water profile (from 7) stations were affected by the Fukushima tritium. Surface and vertical profile data together with the calculated water column inventories indicate that the total amount of the FNPP1-derived tritium deposited to the western North Pacific Ocean was 0.7 ± 0.3 PBq. No clear impact of the Fukushima accident on 14C levels in the western North Pacific was observed.

Recent results from the AMS/IBA laboratory at the Comenius University in Bratislava: preparation of targets and optimization of ion sources

Developments of solid targets and optimizations of ion sources were carried out with the aim to produce high ion yields for applications of tandem accelerators as mass spectrometers. A comparison of Al− yields from different aluminum targets showed that the best results were obtained with AlN targets. Transmission studies of 9Be and 12C ions through the Pelletron accelerator showed highest efficiencies for 9Be2+ and 12C2+. First results obtained with a simplified version of the AMS line are presented as well.

Determination of elemental content in the Rumanová, Uhrovec, Veľké Borové, Košice and Chelyabinsk chondrites by instrumental neutron activation analysis

Chondrites are the most frequently studied extraterrestrial material. We present new data on the concentrations of 43 major and trace elements found in the Uhrovec, Veľké Borové (Nagy-Borove), Rumanová, Košice and Chelyabinsk meteorites, which were analyzed using INAA. The results are in good agreement with the mean data for an average ordinary chondrite of the respective class; normalization of the values to CI chondrites also showed similar outcome. Additionally, for the Rumanová, Košice and Chelyabinsk meteorites, INAA results of the bulk chemical composition are reasonably consistent with the data obtained by the same and/or different methods published earlier.

Radiocarbon concentration in tree-ring samples collected in the south-west Slovakia (1974–2013)

Radiocarbon measurements of tree-ring samples collected in Vysoká pri Morave were compared with tree-ring data of the Žlkovce monitoring station situated 5km south-east from the Jaslovské Bohunice Nuclear Power Plant (NPP). Radiocarbon concentrations in Vysoká pri Morave and in Žlkovce tree rings were decreasing exponentially with decay constants of 14.48±1.23 y and 17.96±1.97 y, respectively, in agreement with similar results obtained at other radiocarbon stations. The Suess effect, represented by a dilution in 14C levels by fossil fuel CO2 emissions, was observed in both tree-ring data sets. The Vysoká pri Morave 14C data were during 1974-1995 systematically lower by about 50‰ than the Schauinsland (Germany) clean air reference values due to a regional fossil-fuel impact. However, after 1996 the Vysoká pri Morave 14C data were closer to the Schauinsland data due to lower CO2 emissions as a result of closing some of the heavy industry technologies in the region.