scholarly journals A new class of oxygen isotopic fractionation in photodissociation of carbon dioxide: Potential Implications for atmospheres of Mars and Earth

2000 ◽  
Vol 27 (10) ◽  
pp. 1459-1462 ◽  
Author(s):  
Sourendra K. Bhattacharya ◽  
Joël Savarino ◽  
Mark H. Thiemens
Keyword(s):  
Carbon Dioxide ◽  
Isotopic Fractionation ◽  
New Class ◽  
Oxygen Isotopic

scholarly journals Rapid Production of Graphite Without Contamination for Biomedical AMS

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 344-350 ◽  
Author(s):  
John S. Vogel
Keyword(s):  
Isotopic Fractionation ◽  
Cross Contamination ◽  
Biological Variability ◽  
Muffle Furnace ◽  
New Class ◽  
Large Numbers ◽  
Rapid Production ◽  
Disposable Plastic ◽  
Single Reaction

The application of AMS to the detection of 14C makes possible a new class of sensitive experiments in molecular biology. Such experiments inherently produce large numbers of samples for the determination of biological variability in molecular interactions. The samples vary in 14C concentration over many orders of magnitude. We added TiH2 to aid the reduction of CO2 by zinc in a sealed tube to reproducibly make graphite without sample cross-contamination. The CO2 is transferred from a combustion tube to the reaction tube through a disposable plastic manifold. The sealed tubes are heated to a single-reaction temperature in a muffle furnace. The process is complete within 5 h. Bulk isotopic fractionation in the finished graphite is less than 0.5%.

Hydrogen and Oxygen Isotopic Fractionation During Heterotrophic Cellulose Synthesis

1992 ◽  
Vol 43 (1) ◽  
pp. 47-50 ◽  
Author(s):  
YAO-HUA LUO ◽  
LEONEL DA SILVEIRA LOBO STERNBERG
Keyword(s):  
Isotopic Fractionation ◽  
Cellulose Synthesis ◽  
Oxygen Isotopic

scholarly journals A new class of organoplatinum-based DFNS for the production of cyclic carbonates from olefins and CO2

RSC Advances ◽  
2020 ◽  
Vol 10 (26) ◽  
pp. 15044-15051
Author(s):  
Maryam Abassian ◽  
Rahele Zhiani ◽  
Alireza Motavalizadehkakhky ◽  
Hossein Eshghi ◽  
Jamshid Mehrzad
Keyword(s):  
Carbon Dioxide ◽  
Potential Application ◽  
Cyclic Carbonates ◽  
New Class ◽  
Supported Platinum ◽  
Recoverable Catalyst

We studied the potential application of an efficient, reusable, and easily recoverable catalyst of dendritic fibrous nanosilica (DFNS)-supported platinum(ii) complexes (DFNS/Pt(ii) NPs) to form cyclic carbonates in the presence of epoxides by converting carbon dioxide.

Forsterite reprecipitation and carbon dioxide entrapment in the lithospheric mantle during its interaction with carbonatitic melt: a case study from the Sung Valley ultramafic–alkaline–carbonatite complex, Meghalaya, NE India

2020 ◽  
pp. 1-12
Author(s):  
Shubham Choudhary ◽  
Koushik Sen ◽  
Santosh Kumar ◽  
Shruti Rana ◽  
Swakangkha Ghosh
Keyword(s):  
Carbon Dioxide ◽  
Lithospheric Mantle ◽  
Experimental Studies ◽  
Carbonatite Complex ◽  
Kerguelen Plume ◽  
Ne India ◽  
Isotopic Analyses ◽  
Oxygen Isotopic ◽  
Carbonatite Magma

Abstract Carbonatite melts derived from the mantle are enriched in CO2- and H2O-bearing fluids. This melt can metasomatize the peridotitic lithosphere and liberate a considerable amount of CO2. Experimental studies have also shown that a CO2–H2O-rich fluid can form Fe- and Mg-rich carbonate by reacting with olivine. The Sung Valley carbonatite of NE India is related to the Kerguelen plume and is characterized by rare occurrences of olivine. Our study shows that this olivine is resorbed forsterite of xenocrystic nature. This olivine bears inclusions of Fe-rich magnesite. Accessory apatite in the host carbonatite contains CO2–H2O fluid inclusions. Carbon and oxygen isotopic analyses indicate that the carbonatites are primary igneous carbonatites and are devoid of any alteration or fractionation. We envisage that the forsterite is a part of the lithospheric mantle that was reprecipitated in a carbonatite reservoir through dissolution–precipitation. Carbonation of this forsterite, during interaction between the lithospheric mantle and carbonatite melt, formed Fe-rich magnesite. CO2–H2O-rich fluid derived from the carbonatite magma and detected within accessory apatite caused this carbonation. Our study suggests that a significant amount of CO2 degassed from the mantle by carbonatitic magma can become entrapped in the lithosphere by forming Fe- and Mg-rich carbonates.

An applied mineralogical investigation of concrete degradation in a major concrete road bridge

1990 ◽  
Vol 54 (377) ◽  
pp. 637-644 ◽  
Author(s):  
G. Macleod ◽  
A. J. Hall ◽  
A. E. Fallick
Keyword(s):  
Carbon Dioxide ◽  
Cement Paste ◽  
Atmospheric Carbon Dioxide ◽  
Meteoric Water ◽  
Isotope Analysis ◽  
Isotopic Fractionation ◽  
Physical Growth ◽  
Carbon Isotopic ◽  
Mineralogical Investigation ◽  
Atmospheric Carbon

AbstractA core of concrete taken from a major road bridge in the Strathclyde Region, Scotland, has been subjected to an applied mineralogical investigation, which involved stable isotope analysis, petrography, X-ray diffraction and scanning electron microscopy.The structure is actively undergoing severe degradation due to mineral growth which is related to chemical reactions between the concrete and pore fluid. The physical growth of minerals causes disfigurement and structural weakening.Pyrite and pyrrhotine hosted by dolerite aggregate appear to have been oxidized, providing sulphate for the deposition of ettringite and minor gypsum, in spheroidal cavities within the cement paste. The rainwater which passes through the structure mobilising sulphate from original gypsum in the paste and oxidizing the iron sulphides is also involved in the further leaching of elements from the cement paste and in the deposition of calcite. The isotopic values of calcites forming a crust on the concrete and a stalactite under the bridge are similar with δ13C= −19‰ PDB and δ18‰= +16‰ SMOW. We suggest that atmospheric carbon dioxide was the carbon source. The carbon isotopic fractionation of −12‰ from atmospheric carbon dioxide of δ13C= −7‰, (O'Neil and Barnes, 1971) can best be explained as due to a kinetic fractionation related to the hyper-basicity of the pore water. The equilibrium formation temperature of about 45°C calculated from the oxygen isotope values and assuming a δ18O value of meteoric water of −8‰ SMOW, is considered unreasonable. The exceptionally low δ18O values are attributed mainly to reaction kinetics and the calcite inheriting its oxygen, two-thirds from atmospheric carbon dioxide and one third from the meteoric formation water (O'Neil and Barnes, 1971). A δ18O value of atmospheric carbon dioxide of +41‰ SMOW and a δ18O value of meteoric water of −8‰ SMOW, lead to a calculated δ18O value for the calcites of +10‰ SMOW. The calcites analysed have a value of +16‰ and this may be due to partial re-equilibration towards a calculated value of +21‰ for calcite in equilibrium with the meteoric water at 20°C.

scholarly journals Gliwice Radiocarbon Dates VII

Radiocarbon ◽  
1982 ◽  
Vol 24 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Anna Pazdur ◽  
Romuald Awsiuk ◽  
Andrzej Bluszcz ◽  
Mieczysław F Pazdur ◽  
Adam Walanus ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Oxalic Acid ◽  
Integrated Circuit ◽  
Proportional Counter ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
Proportional Counters ◽  
Typical Measurement ◽  
Contemporary Standard

The following list contains the measurements of archaeologic samples made during 1978 and 1979 using carbon-dioxide-filled proportional counters. Most of the samples were dated with counter No. 3 (L3) filled to 1 or 2 atm pressure (Mościcki and Zastawny, 1977). Our counter No. 1 (L1) previously described (Mościcki and Zastawny, 1976) has been remounted and is now operating at 2 atm pressure of carbon dioxide. Samples measured with this counter have date numbers starting with Gd-1000. Parameters of proportional counters are listed in Table 1. Our transistorized electronics is being gradually replaced by more compact integrated-circuit electronics in CAMAC system (Bluszcz and Walanus, 1980). Counts from proportional counter and guard counters are recorded in 5 channels and punched every 100 minutes. Typical measurement of any sample, including background and oxalic acid samples, consists of a series of 20 to 25 partial measurements. Partial results obtained in such series are analyzed on ODRA 1325 computer at the Computing Centre of the Silesian Technical University according to code C14C written in ALGOL (Pazdur and Walanus, 1979). Age calculations are based on contemporary value equal to 0.95 of the activity of NBS oxalic acid standard and on the Libby value for the half-life of radiocarbon. Ages are reported as conventional radiocarbon dates in years before ad 1950. Corrections for isotopic fractionation in nature are made only for some samples with indicated values of δ13C Errors quoted (±1σ) include estimated overall standard deviations of count rates of the unknown sample, contemporary standard, and background (Pazdur and Walanus, 1979).

Sign in / Sign up

Export Citation Format

Share Document