scholarly journals Rudjer Bošković Institute Radiocarbon Measurements XII

Radiocarbon ◽  
1992 ◽  
Vol 34 (1) ◽  
pp. 155-175 ◽  
Author(s):  
Dušan Srdoč ◽  
Nada Horvantinčić ◽  
Ines Krajcar Bronić ◽  
Bogomil Obelić ◽  
Adela Sliepčević
Keyword(s):  
Stable Isotope ◽  
Aquatic Plants ◽  
Environmental Conditions ◽  
Half Life ◽  
Isotope Fractionation ◽  
Sample Pretreatment ◽  
New Techniques ◽  
Stable Isotope Fractionation ◽  
Calcareous Deposits ◽  
Standard Deviations

We present here radiocarbon analyses made since our previous list (Srdoč et al. 1989). Sample pretreatment, combustion and counting techniques are essentially the same as described previously (Srdoč, Breyer & Sliepčević 1971), supplemented by new techniques for groundwater processing (Srdoč et al. 1979). The calculation of ages follows conventional protocol (Stuiver & Polach 1977). These ages can be converted from the 5570-year half-life to the chronometrically more correct half-life of 5730 years by multiplying by the factor, 1.029. Ages and standard deviations of all samples are adjusted for stable isotope fractionation according to the recommendations in Stuiver and Polach (1977), except for groundwater, calcareous deposits and aquatic plants. The δ13C values of the latter reflect the environmental conditions during their formation or growth rather than fractionation (Mook 1976; Krajcar Bronić et al. 1986; Marčenko et al. 1989). Thus, any percent modern (pMC) correction based on δ13C values is meaningless or even misleading. Sample descriptions are prepared in collaboration with collectors and submitters. Calibrated ages were calculated using the program of Stuiver and Reimer (1987).

scholarly journals Rudjer Bošković Institute Radiocarbon Measurements XI

Radiocarbon ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Dušan Srdoč ◽  
Bogomil Obelić ◽  
Nada Horvatinčić ◽  
Ines Krajcar Bronić ◽  
Adela Sliepčević
Keyword(s):  
Stable Isotope ◽  
Data Processing ◽  
Half Life ◽  
Isotope Fractionation ◽  
Sample Pretreatment ◽  
Groundwater Model ◽  
Initial Activity ◽  
New Techniques ◽  
Stable Isotope Fractionation

This is a list of radiocarbon analyses determined since our previous list (R, 1987, v 29, no. 1, p 135–147). As before, with the exception of speleothems and groundwaters, the calculations follow conventional radiocarbon protocol (Stuiver & Polach, 1977). Sample pretreatment, combustion and counting techniques are essentially the same as described in R, 1971, v 13, no. 1, p 135–140, supplemented by new techniques for groundwater processing (R, 1979, v 21, no. 1, p 131–137). Speleothem and groundwater model ages (given in the comment section of each listing) are based on an initial activity of 85 ± 10 percent modern carbon (pMC), as recommended in Srdoč et al (1986), without adjustment for δ13C. These model ages can be converted from the 5570-yr half-life to the chronometrically more correct half-life of 5730 yr by multiplying by the factor 1.029. The “± figures” on these model ages are statistical combinations of the 1σ counting uncertainty and the ± 10% uncertainty in the assumed 85 pMC. Ages and “± figures” of all other samples are adjusted for stable isotope fractionation according to the recommendations in Stuiver and Polach (1977). Data processing is done by computer (Obelić & Planinić, 1977; Obelić, 1980). Sample descriptions are prepared in collaboration with collectors and submitters.

scholarly journals Unravelling the process of petroleum hydrocarbon biodegradation in different filter materials of constructed wetlands by stable isotope fractionation and labelling studies

2021 ◽  
Author(s):  
Andrea Watzinger ◽  
Melanie Hager ◽  
Thomas Reichenauer ◽  
Gerhard Soja ◽  
Paul Kinner
Keyword(s):  
Stable Isotope ◽  
Constructed Wetlands ◽  
Hydrogen Isotope ◽  
Petroleum Hydrocarbon ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Filter Material ◽  
Hydrocarbon Biodegradation ◽  
Stable Isotope Fractionation ◽  
Filter Materials

AbstractMaintaining and supporting complete biodegradation during remediation of petroleum hydrocarbon contaminated groundwater in constructed wetlands is vital for the final destruction and removal of contaminants. We aimed to compare and gain insight into biodegradation and explore possible limitations in different filter materials (sand, sand amended with biochar, expanded clay). These filters were collected from constructed wetlands after two years of operation and batch experiments were conducted using two stable isotope techniques; (i) carbon isotope labelling of hexadecane and (ii) hydrogen isotope fractionation of decane. Both hydrocarbon compounds hexadecane and decane were biodegraded. The mineralization rate of hexadecane was higher in the sandy filter material (3.6 µg CO2 g−1 day−1) than in the expanded clay (1.0 µg CO2 g−1 day−1). The microbial community of the constructed wetland microcosms was dominated by Gram negative bacteria and fungi and was specific for the different filter materials while hexadecane was primarily anabolized by bacteria. Adsorption / desorption of petroleum hydrocarbons in expanded clay was observed, which might not hinder but delay biodegradation. Very few cases of hydrogen isotope fractionation were recorded in expanded clay and sand & biochar filters during decane biodegradation. In sand filters, decane was biodegraded more slowly and hydrogen isotope fractionation was visible. Still, the range of observed apparent kinetic hydrogen isotope effects (AKIEH = 1.072–1.500) and apparent decane biodegradation rates (k = − 0.017 to − 0.067 day−1) of the sand filter were low. To conclude, low biodegradation rates, small hydrogen isotope fractionation, zero order mineralization kinetics and lack of microbial biomass growth indicated that mass transfer controlled biodegradation.

Effects of food quality, starvation and life stage on stable isotope fractionation in Collembola

Pedobiologia ◽  
2005 ◽  
Vol 49 (3) ◽  
pp. 229-237 ◽  
Author(s):  
Dominique Haubert ◽  
Reinhard Langel ◽  
Stefan Scheu ◽  
Liliane Ruess
Keyword(s):  
Stable Isotope ◽  
Food Quality ◽  
Isotope Fractionation ◽  
Life Stage ◽  
Stable Isotope Fractionation

Magnesium stable isotope fractionation in marine biogenic calcite and aragonite

2011 ◽  
Vol 75 (19) ◽  
pp. 5797-5818 ◽  
Author(s):  
F. Wombacher ◽  
A. Eisenhauer ◽  
F. Böhm ◽  
N. Gussone ◽  
M. Regenberg ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Stable Isotope Fractionation

Compound-Specific Stable Isotope Fractionation of Pesticides and Pharmaceuticals in a Mesoscale Aquifer Model

2016 ◽  
Vol 50 (11) ◽  
pp. 5729-5739 ◽  
Author(s):  
Heide K. V. Schürner ◽  
Michael P. Maier ◽  
Dominik Eckert ◽  
Ramona Brejcha ◽  
Claudia-Constanze Neumann ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Stable Isotope Fractionation

scholarly journals Nyitni vagy nem nyitni? – Pilisi barlangok szellőzöttsége a geokémiai adatok tükrében

2021 ◽  
Vol 145 (3) ◽  
pp. 224-231
Keyword(s):  
Stable Isotope ◽  
Environmental Conditions ◽  
Isotope Fractionation ◽  
Environmental Parameters ◽  
Basic Research ◽  
Geochemical Analysis ◽  
Cave System ◽  
Cave Environment ◽  
Carbonate Formations ◽  
The Given

Speleothem formations are one of the most important and informative objects in paleoclimatological research. However, in order to interpret the data that reflect environmental conditions, we have to know the operation of the given cave, and it should be determined how the composition of the carbonate formed at the given site is related to the changes in the environmental parameters. The study presents the results of stable isotope geochemical analysis of speleothem formations and carbonate precipitated on glass plates collected in the Vacska Cave (Pilis Hills). The youngest layer of carbonate formations, formed in the last 1-2 decades, shows an isotope fractionation sign indicating strong ventilation, with the exception of a single site farthest from the entrance to the cave. The isotope shift was also accompanied by a change in carbonate fabric. Preceding the fabric change, the carbonate of the speleothem formations did not show ventilation-related shifts in the isotope compositions, suggesting that the exploration and opening of the cave areas may have caused the change. Based on this, we recommend the installation of local closures in the Vacska Cave and in the entire Ariadne cave system. The study provides a good example of how the results of basic research can be utilized in practical environmental protection, in the preservation of a strictly protected cave environment.

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