Authors:Ivo Světlík, Mihály Molnár, Milan Váňa, Václav Michálek, and Petar Stefanov
Carbon from fossil CO2 emissions, without a significant presence of 14C, causes dilution of 14C in the carbon isotopic mixture (Suess effect). Reported 14C activities are usually connected to radiocarbon amount in the carbon isotopic mixture. Our paper is aimed on estimation
of 14C/14CO2 amount in the atmosphere (and its trend), utilizing calculation of a 14C activity concentration. A parameter connected only with a 14C quantity in the volume or mass unit of air is not influenced by a fossil carbon amount. Such a “robust” parameter can be
influenced only by processes connected with 14C emissions/depositions.
Authors:G. Molnár, E. Csonka, A. Vass, Mihály Boros, and J. Kaszaki
Hypertonic small-volume resuscitation transiently restores the cardiovascular function during various circulatory disturbances. Nitric oxide (NO) is an important mediator of flow-induced peripheral and central hemodynamic changes, and therefore, we hypothesized that a decreased endogenous NO production could influence the consequences and the effectiveness of hypertonic fluid therapy. The main goal of this study was to outline and compare the circulatory effects small volume hypertonic saline-dextran (HSD, 7.5% NaCl-10% dextran; 4 ml/kg iv) infusion with (n=7) or without (n=7) artificially diminished NO production in normovolemic anesthetized dogs. HSD administration significantly increased cardiac index (CI), coronary flow (CF) and myocardial contractility, and elevated plasma nitrite/nitrate (NOx) and endothelin-1 (ET-1) levels. However, the late (2 h) postinfusion period was characterized by significantly decreased myocardial NO synthase (NOS) and enhanced myeloperoxidase activities. Pre-treatment with the non-selective NOS inhibitor N-nitro-L-arginine (NNA, 4 mg/kg) immediately increased cardiac contractility, and the HSD-induced CI and CF elevations and the positive inotropy were absent. Additionally, plasma ET-1 levels increased and NOx levels were significantly decreased. In conclusion, our results demonstrate that HSD infusion leads to preponderant vasoconstriction when endogenous NO synthesis is diminished, and this could explain the loss of effectiveness of HSD resuscitation in NO-deficient states.
Authors:Mihály Molnár, István Major, László Haszpra, Ivo Svĕtlík, Éva Svingor, and Mihály Veres
A field unit was installed in the city of Debrecen (East Hungary) during the summer of 2008 to monitor urban atmospheric fossil
fuel CO2. To establish a reference level simultaneous CO2 sampling has been carried out at a rural site (Hegyhátsál) in Western Hungary. Using the Hungarian background 14CO2 observations from the rural site atmospheric fossil fuel CO2 component for the city of Debrecen was reported in a regional “Hungarian” scale. A well visible fossil fuel CO2 peak (10–15 ppm) with a maximum in the middle of winter 2008 (January) was observed in Debrecen air. Significant local maximum
(~20 ppm) in fossil fuel CO2 during Octobers of 2008 and 2009 was also detected. Stable isotope results are in agreement with the 14C based fossil fuel CO2 observations as the winter of 2008 and 2009 was different in atmospheric δ13C variations too. The more negative δ13C of atmospheric CO2 in the winter of 2008 means more fossil carbon in the atmosphere than during the winter of 2009.
Authors:Mihály Molnár, László Palcsu, Zoltán Major, Éva Svingor, Mihály Veres, and Tamás Pintér
Investigation of the effect of nuclear fuel rods to the composition of the dissolved gas in the cooling water of the cooling
ponds of Paks Nuclear Power Plant is presented. Dissolved gases in coolant were measured for surveying the condition of the
nuclear fuel remained in service pool No. 1 of reactor unit No. 2 after its incident in April of 2003. Two different experimental
ways were applied in parallel for ensuring the better reliability of the results.
Authors:Mihály Molnár, László Palcsu, István Futó, Éva Svingor, Zoltán Major, Mihály Veres, Péter Ormai, and István Barnabás
To obtain reliable estimates of the quantities and rates of the gas production in L/ILW a series of measurements was carried
in the last 7 years in Hungary. The typical gas production rates were 0.05–0.2 STP litre gas/day for CO2 and CH4 generation, and less for H2. No explosive gas mixture was indicated in the L/ILW drums during the investigated storage period. Compositions of headspace
gases in closed L/ILW vaults were in agreement with gas generation processes observed in L/ILW drums. The stable carbon isotope
measurements show that the main source of the CO2 gas is the degradation of organic matter and indicates microbial degradation processes as the main sources of CH4. Typical tritium activity concentrations were <10 Bq/l gas in the drums and <1,000 Bq/l gas in the vaults. Typical 14C activity values of the headspace gases were <2.0 Bq/l gas in the drums and <1,000 Bq/l gas in the vaults.
Authors:Attila Demény, Alexandra Németh, Zoltán Kern, György Czuppon, Mihály Molnár, Szabolcs Leél-Őssy, Mihály Óvári, and József Stieber
Determination of the long-term behavior of cave systems and their response to changing environmental conditions is essential for further paleoclimate analyses of cave-hosted carbonate deposits. For this purpose, four actively forming stalagmites were collected in the Baradla Cave where a three-year monitoring campaign was also conducted. Based on textural characteristics and radiocarbon analyses, the stalagmites are composed of annual laminae, whose counting was used to establish age–depth relationships. Fast and slowly growing stalagmites have different stable carbon and oxygen isotope compositions as well as trace element contents that could be attributed to differences in drip water migration pathways. The stable isotope compositions were compared with meteorological data of the last ∼100 years indicating that carbon isotope compositions of the stalagmites may reflect changes in precipitation amount, while oxygen isotope compositions are more related to temperature variations. The combined textural–geochemical–meteorological interpretation lead us to select the isotope record that can best reflect variations in environmental conditions and can be used for further evaluation of the climate–proxy relationships.