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Wyszukujesz frazę "oxygen-18" wg kryterium: Wszystkie pola


Tytuł:
Comparison of two methods for the determination of nitrogen and oxygen isotope composition of dissolved nitrates
Autorzy:
Chmura, W. M.
Różański, K.
Kuc, T.
Gorczyca, Z.
Powiązania:
https://bibliotekanauki.pl/articles/146460.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
nitrates
isotope composition
denitrification
nitrogen-15
oxygen-18
Opis:
Two methods of sample preparation for isotopic analyses of nitrates dissolved in water are presented: (i) chemical conversion of NO3– to N2 and CO2, and (ii) bacterial reduction of NO3– to N2O, followed by the measurement of nitrogen and oxygen isotope composition of these gases. Both methods have been successfully used for routine isotope analyses of dissolved nitrates in different types of water. The chemical conversion method, requiring ca. 300 mi mol of NO3– yields relatively good precision, in the order of 0.3‰ for delta15N, and 0.6‰ for delta18 O. The bacterial reduction method was modified in this study to accommodate samples of intermediate size (ca. 30 mmol of NO3–) to provide sufficient amount of N2O gas for isotope analysis using conventional IRMS. The method demonstrated satisfactory results, although sample preparation was more complicated and required access to microbiological laboratory.
Źródło:
Nukleonika; 2009, 54, 1; 17-23
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distribution of stable isotopes in the River Sava in Serbia
Autorzy:
Miljević, N. R.
Golobočanin, D. D.
Nadeždić, M. L.
Ogrinc, N.
Powiązania:
https://bibliotekanauki.pl/articles/971539.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hydrogen-2
oxygen-18
evaporation
Sava river
river water
Opis:
Grab water samples were collected from the research ship ‘ARGUS’ at four locations in Serbia, Ostružnica (17 rkm), Šabac (103.6 rkm), Sremska Mitrovica (136.4 rkm), and Jamena (195.0 rkm) from the mid-river, and near the left and right banks during longitudinal survey of the River Sava performed in August 2006. The stable isotope ratios of hydrogen and oxygen (2H/1H and 18O/16O) were determined along with other physicochemical and biological parameters. The δ18O values of river water ranged from −9.2‰ to −8.5‰, and δ2H values ranged from −66‰ to −61‰. Samples taken from the mid-river along the main stem of the Sava at all examined locations appeared to be isotopically the same stream water with a value of −9.0 ± 0.1‰ for δ18O and −65 ± 1.0‰ for δ2H. The results are considered in relation to the isotopic changes known to occur in water subjected to evaporation and mixing.
Źródło:
Nukleonika; 2008, 53, suppl. 2; 129-135
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable isotope deuterium as a natural tracer of mixing processes in rivers
Autorzy:
Palige, J.
Ptaszek, S.
Zimnicki, R.
Chmielewski, A. G.
Wierzchnicki, R.
Powiązania:
https://bibliotekanauki.pl/articles/146756.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
stable isotopes
tracer
deuterium
oxygen-18
river
water flow
Opis:
The possibility of application of naturally existing differences in isotope contents 18O/16O, 2H/1H in waters for investigation of transport and mixing of various waters in the tributary-river system is presented. Experiments carried out on the Bug-Narew rivers-Zegrze Lake and the BugoNarew-Vistula rivers systems have indicated that the hydrogen isotope ratio 2H/1H can be used as an intrinsic tracer of natural mixing processes occurring in rivers. The IRMS methodology was used for isotope ratio measurement of water samples. The degrees of water mixing as a function of distance from the confluence point of rivers were determined. The obtained results indicate that in water systems where the natural differences in ?2H are higher than 5‰ this technique can replace the time-consuming and expensive dye (or radiotracer) dispersion tests for evaluation of pollutant transport in rivers.
Źródło:
Nukleonika; 2008, 53, 2; 63-67
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seasonal variability of the soil CO2 flux and its isotopic composition in southern Poland
Autorzy:
Gorczyca, Z.
Rozanski, K.
Kuc, T.
Michalec, B.
Powiązania:
https://bibliotekanauki.pl/articles/148390.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
carbon-14
carbon-13
isotopic composition
soil CO2
oxygen-18
Opis:
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.
Źródło:
Nukleonika; 2003, 48, 4; 187-196
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The use of the stable oxygen isotope (18 O) to trace the distribution and uptake of water in riparian woodlands
Autorzy:
Lambs, L.
Loudes, J.
Berthelot, M.
Powiązania:
https://bibliotekanauki.pl/articles/147005.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
oxygen isotope
riparian forest
water origin
xylem sap
Opis:
Streamside vegetation forming narrow "corridors" in temperate regions, is typically dominated by deciduous tree species reflecting strong influences by human activities. Riparian woodlands depend on hydrological resources and have to adapt to rapid changes in water levels and soil moisture conditions. Three main water sources are typically present in the riparian zone: river water originating in the mountains, ground water and rainfall. Stable isotopes, such as oxygen-18, are useful tools which allow for water movement to be traced within the riparian zone and which help to identify water sources utilised by the trees growing in these areas.
Źródło:
Nukleonika; 2002, 47,suppl.1; 71-74
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cooling and warming of climate of the Earths Northern Hemisphere (on the basis of fluctuations of the oxygen isotope δ18O and dendrological data)
Autorzy:
Boryczka, Jerzy
Stopa-Boryczka, Maria
Unton-Pyziołek, Arleta
Gieszcz, Piotr
Miłaszewska, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2034147.pdf
Data publikacji:
2010-06-01
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Tematy:
isotope δ18O
Devon Island
Pinus sylvestris
Picea abies
tree the ring widths
solar radiation
periods
moment of inertia of planets
mass momentum of largest planets
forecast
Opis:
Content fluctuations of the oxygen isotope δ18O in the Devon Island ice core during the last 100 000 years are a measure of climate fluctuations in the Northern Hemisphere. The course of content of the oxygen isotope δ18O and the sums of solar radiation reaching the upper edge of the atmosphere are characterized by approximate minima and maxima (by positive correlation). This proves that, during the last hundred thousand years, climate fluctuations (cooling and warming) in the Northern Hemisphere were conditioned by long-term changes of the orbit and altitude of the Earth's axis. Climate fluctuation forecasts for the Northern Hemisphere were developed for the next 40 000 years on the basis of the established periods of change of the oxygen isotope δ18O and the known solar radiation periodicity. Climate changes in Europe during the last 25000 years were presented together with a forecast for 1000 years (according to organic substances in deposits and radiation) as well as climate changes in Europe in the period from -500 years BP to 2100 AD (according to δ18O and pine tree-rings). It showed that climate changes depended on the concentration of planet mass in relation to the ecliptic plane (from the gravitational impact of planets on the Sun). Concentration courses of planet mass in the Solar System and climate fluctuations in the Northern Hemisphere were compared. Of interest are examples of synchronic fluctuations, i.e. dispersal of planet mass in the Solar System, the widths of pine and spruce tree rings and air temperatures in Europe.
Źródło:
Miscellanea Geographica. Regional Studies on Development; 2010, 14; 47-58
0867-6046
2084-6118
Pojawia się w:
Miscellanea Geographica. Regional Studies on Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zmiany klimatu półkuli północnej (na podstawie wahań promieniowania słonecznego i izotopu tlenu δ18O)
Changes of climate of the northern hemisphere (on the basis of fl uctuations of the solar radiation and oxygen isotope δ18O)
Autorzy:
Boryczka, J.
Stopa-Boryczka, M.
Unton-Pyziolek, A.
Gieszcz, P.
Powiązania:
https://bibliotekanauki.pl/articles/2084536.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Tematy:
zmiany klimatyczne
polkula polnocna
promieniowanie sloneczne
izotop tlenu δ18O
prognozy
klimat
Źródło:
Prace i Studia Geograficzne; 2011, 47; 25-32
0208-4589
Pojawia się w:
Prace i Studia Geograficzne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen Emissions from Single-Crystalline Fe$\text{}_{3}$O$\text{}_{4}$ Surfaces Induced by Low-Energy Ion Bombardments
Autorzy:
Kim-Ngan, N.-T. H.
Soszka, W.
Powiązania:
https://bibliotekanauki.pl/articles/2046830.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.-p
61.18.Bn
Opis:
Negative-charged ion energy spectra of the Fe$\text{}_{3}$O$\text{}_{4}$ (001) and (111) surface revealed large peaks attributed to the O$\text{}^{-}$ recoils from a binary collision. Under Ar$\text{}^{+}$ ion bombardments such an emission was largely affected by the screening effect of the Fe ions. A distinguished peak related to the O$\text{}^{+}$ recoil ions was observed under Ne$\text{}^{+}$ ion bombardments, while such a peak was merged into the high background in the case of Ar$\text{}^{+}$ ion ones. A weak effect from the Verwey transition was found on oxygen emissions. For the (111) surface a small peak characteristic of the O$\text{}^{+}$ recoils from double collisions appeared in the energy spectra around 140-170 K and a minimum was observed in both R$\text{}^{+}$(T) and R$\text{}^{-}$(T) curves under 6 keV Ne$\text{}^{+}$ ion beam.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 715-721
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elementy walidacji metody oznaczania δ18O i δD próbek ciekłych (EA-IRMS)
Validation of δ18O i δD determination method in aqueous samples (EA-IRMS)
Autorzy:
Janiga, M.
Bieleń, W.
Powiązania:
https://bibliotekanauki.pl/articles/1835465.pdf
Data publikacji:
2017
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
skład izotopowy tlenu
skład izotopowy wodoru
δ18O
δD
EA-IRMS
walidacja
oxygen isotopic composition
hydrogen isotopic composition
validation
Opis:
Celem pracy było wykonanie elementów walidacji metodyki oznaczeń składu izotopowego tlenu i wodoru próbek ciekłych (wody) przy użyciu spektrometru masowego połączonego z analizatorem elementarnym (EA-IRMS). Zarówno w przypadku oznaczeń składu izotopowego wodoru, jak i tlenu wykonano kalibrację przy zastosowaniu wzorca VSMOW2 oraz wyznaczono stretching factor (wykorzystując wzorzec SLAP2). Dla obydwu pierwiastków metody są dokładne (wartości rzeczywiste wzorca znajdują się w wyznaczonych przedziałach). Odchylenia standardowe powtarzalności i odtwarzalności są na niskim poziomie (dla tlenu: 0,15‰ i 0,21‰; dla wodoru: 1,2‰ i 1,3‰). Wartość niepewności pomiaru w przypadku oznaczeń składu izotopowego tlenu wynosi 0,569885% (czyli 0,310644‰ po przeliczeniu dla wzorca SLAP2), a w przypadku wodoru: 0,479804% (czyli 2,022375‰ po przeliczeniu dla wzorca SLAP2).
The aim of the study was to perform validation of a methodology of isotopic composition determinations of oxygen and hydrogen liquid samples (water) using a mass spectrometer combined with an elemental analyzer (EA-IRMS). For the determination of both the hydrogen and oxygen isotopic composition, calibration was performed by using VSMOW2 standard, and stretching factor was determined using the SLAP2 standard. For both elements methods are accurate (the actual value can be found at designated intervals). The standard deviations of repeatability and reproducibility are low (for oxygen 0.15‰ and 0.21‰, for hydrogen 1.2‰ and 1.3‰). The value of measurement uncertainty for the determination of the isotopic composition of oxygen is 0.569885% (or 0.310644‰ after calculation for the SLAP2 standard) and for hydrogen is 0.479804% (or 2.022375 ‰ after calculation for SLAP2 standard).
Źródło:
Nafta-Gaz; 2017, 73, 7; 473-478
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen isotope analysis of shark teeth phosphates from Bartonian (Eocene) deposits in Mangyshlak peninsula, Kazakhstan
Autorzy:
Pelc, Andrzej
Hałas, Stanisław
Niedźwiedzki, Robert
Powiązania:
https://bibliotekanauki.pl/articles/2086485.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mineralogiczne
Tematy:
Bartonian
carbonate
Mangyshlak peninsula
phosphate
shark teeth
δ18O
δ13C
Opis:
We report the results of high-precision (±0.05‰) oxygen isotope analysis of phosphates in 6 teeth of fossil sharks from the Mangyshlak peninsula. This precision was achieved by the offline preparation of CO2 which was then analyzed on a dual-inlet and triple-collector IRMS. The teeth samples were separated from Middle- and Late Bartonian sediments cropping out in two locations, Usak and Kuilus. Seawater temperatures calculated from the δ18O data vary from 23–41oC. However, these temperatures are probably overestimated due to freshwater inflow. The data point at higher temperature in the Late Bartonian than in the Middle Bartonian and suggest differences in the depth habitats of the shark species studied.
Źródło:
Mineralogia; 2011, 42, 1; 53--61
1899-8291
1899-8526
Pojawia się w:
Mineralogia
Dostawca treści:
Biblioteka Nauki
Artykuł

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