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The use of carbon-14 and tritium for peat and water dynamics characterization: case of Čepkeliai peatland, southeastern Lithuania

Mažeika J., Guobyte R., Kibirkštis G., Petrošius R., Skuratovič Ž., Taminskas J.

Geochronometria

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2009

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Vol. 34

41-48

EN

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.

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Synthesis of Deuterium, Tritium and 14-Carbon Labelled Isotopomers of L-DOPA

Kozłowska M., Kańska M.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 10

1763-1763

EN

The synthesis of five isotopomers of L-DOPAlabelled selectivelywith deuterium, tritium and 14C is reported. The isotopomers of L-tyrosine, the intermediate substrates for this synthesis, were obtained using chemical and enzymatic methods. Selectively labelled isotopomers of L-tyrosine were hydroxylated respectively to [3R-3H]-L, [5-2H]-L, [2 ,6 -2H2]-L, doubly labelled [5-2H/3H]-L, and [1-14C]-L-DOPA using activity of enzyme tyrosine (EC 1.14.18.1) isolated from mushrooms.

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Carbon-14 in tree rings in the vicinity of Ignalina Nuclear Power Plant, Lithuania

Mazeika J., Petrosius R., Pukiene R.

Geochronometria

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2007

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Vol. 28

31-37

EN

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 2.0×10-3 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.

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Tritium kinetic isotope effects on enzymatic decomposition of L-tryptophan

Boroda E., Kański R., Kańska M.

Nukleonika

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2006

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Vol. 51,suppl.2

17-19

EN

The tritium kinetic isotope effect on position 2 has been determined in the reaction of decomposition of L-tryptophan, L-Trp, catalyzed by enzyme TPase, (EC 4.1.99.1). The numerical values of isotope effects in the course of reaction were obtained by the competitive method using [1-14C]-L-tryptophan as internal radiometric standard.

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Synthesis of ring labeled [1'-14C]-L-tyrosine

Kański R., Augustyniak W., Kańska M.

Nukleonika

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2006

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Vol. 51,suppl.2

13-16

EN

The synthesis of specifically ring labeled isotopomer of L-tyrosine, (l-Tyr), using chemical and enzymatic methods is reported. The carbon-14 labeled [1’-14C]-L-Tyr has been synthesized by a 6-step conversion of [2-14C]-malonic acid into [4’-14C]-phenol and its subsequent condensation with S-methyl-L-cysteine using enzyme tyrosine phenol lyase from Citrobacter freundii.

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A convenient method for synthesis of 11-[14C]-loxapine

Saemian N., Shirvani G., Matloubi H.

Nukleonika

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2005

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Vol. 50, nr 4

139-141

EN

8-Chloro-11-(4-methyl-1-piperazinyl)-dibenz[b,f][1,4]oxazepine labeled with carbon-14 in 11-position has been synthesized as part of a 5-step sequence from potassium [14C] cyanide.

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Seasonal variability of the soil CO2 flux and its isotopic composition in southern Poland

Gorczyca Z., Rozanski K., Kuc T., Michalec B.

Nukleonika

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2003

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Vol. 48, nr 4

187-196

EN

The flux and isotopic composition of soil CO2 has been monitored at three sites located in the southern Poland, during the time period: January 1998 - December 2000. The sites represent typical ecosystems appearing in central Europe: mixed forest, cultivated agricultural field and grassland. To monitor the flux and isotopic composition of soil CO2, the method based on the inverted cup principle was used. The flux of soil CO2 reveals distinct seasonal fluctuations, with maximum values up to ca. 20 mmolźm-2 h-1 during summer and around ten times lower values during winter. Also significant differences among the monitored sites were detected, the CO2 flux being the highest for the mixed forest site and ca. two times lower for the grassland site. The 13C content of the soil CO2 flux is nearly constant throughout the year, with d13C values essentially reflecting the isotopic composition of the soil organic matter and the vegetation type. The 18O content of the soil CO2 flux shows a remarkable seasonality, with distinctly less negative d18O values recorded during summer. This seasonality is highly reduced in the CO2 sampled from different depths of the soil. The radiocarbon content of the CO2 flux turned out to be non-distinguishable, within the uncertainty of the measurements, from current 14C levels in atmospheric carbon dioxide. However, significant reduction of the radiocarbon content was measured in the soil CO2 sampled at 80 cm, when compared to the uppermost layer, reflecting increasing age of soil organic matter with depth.

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Carbon-14 kinetic isotope effects in the debromination of p-nitrodibromocinnamic acid

Bukowski J., Kanski R., Kanska M.

Nukleonika

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2002

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Vol. 47, nr 4

133-136

EN

The kinetic isotope effect (KIE) method was applied to study the mechanism of elimination of bromine from p-nitro-erythro-alfa,beta-dibromocinnamic acid labeled at the alfa-carbon. This compound was obtained starting from [2-14C]malonic acid via [2-14C]cinnamic acid and subsequent addition of bromide. The value of 14C KIE determined for alfa-position of side chain of p-nitro-erythro-alfa,beta-dibromocinamic acid proves that elimination of bromine leading to formation of (E)-p-nitrocinnamic acid proceeds via E2 mechanism.

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Carbon-13 fractionation in the oxidation of propionate of natural isotopic composition with permanganate and manganate

Zieliński M., Fry A., Zielińska A., Ogrinc N., Papiernik-Zielińska H., Kobal I.

Nukleonika

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2000

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Vol. 45, nr 4

221-224

EN

Carbon-13 fractionation in the oxidation of sodium propionate of natural isotopic composition with permanganate in water solution and with manganate in alkaline solution has been investigated and compared with carbon-14 kinetic isotope effects in the oxidation of (3-14C) – and (2-14C) propionate with permanganate. The experimental carbon-13 isotope ratios, R(13C/12C)cumul., corrected for dilution of R(13C/12C)a by carbon dioxide derived from all external sources and by carbon dioxide derived from (C-1) and from (C-3) of propionate at its complete and partial oxidations, used for calculation of 13C alfa KIE, provided the carbon-13 isotope effects corresponding to initial oxidation of alpha carbon, which correlate well with (2-14C) KIE determined previously, (k12/k13 -1)?100 ? 1/2(k12/k14 -1)?100 ? 1/2(4.6š0.3) at 373 K. The possibility of extension of isotope ratio measurements, using modern double collector mass spectrometers, from geochemical, biomedical, agriculture and environmental research to carbon-13 isotope effects studies in chemical organic reactions is briefly discussed.