scholarly journals The redox dependence of titanium isotope fractionation in synthetic Ti-rich lunar melts

2021 ◽  
Vol 176 (3) ◽  
Author(s):  
Laura J. A. Rzehak ◽  
Sebastian Kommescher ◽  
Florian Kurzweil ◽  
Peter Sprung ◽  
Felipe P. Leitzke ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Experimental Approach ◽  
Mare Basalt ◽  
Stable Isotope Fractionation ◽  
Ti Oxides ◽  
Reducing Conditions ◽  
Lunar Samples ◽  
Lunar Basalts ◽  
A Minor

AbstractEquilibria between Ti oxides and silicate melt lead to Ti isotope fractionation in terrestrial samples, with isotopically light Ti oxides and isotopically heavy coexisting melt. However, while Ti is mostly tetravalent in terrestrial samples, around 10% of the overall Ti is trivalent at fO2 relevant to lunar magmatism (~ IW-1). The different valences of Ti in lunar samples, could additionally influence Ti stable isotope fractionation during petrogenesis of lunar basalts to an unknown extent. We performed an experimental approach using gas mixing furnaces to investigate the effect of Ti oxide formation at different fO2 on Ti stable isotope fractionation during mare basalt petrogenesis. Two identical bulk compositions were equilibrated simultaneously during each experiment to guarantee comparability. One experiment was investigated with the EPMA to characterize the petrology of experimental run products, whereas the second experiment was crushed, and fabricated phases (i.e., oxides, silicates and glass) were handpicked, separated and digested. An aliquot of each sample was mixed with a Ti double-spike, before Ti was separated from matrix and interfering elements using a modified HFSE chemistry. Our study shows fO2-dependent fractionation within seven samples from air to IW-1, especially ∆49Tiarmalcolite-melt and ∆49Tiarmalcolite-orthopyroxene become more fractionated from oxidized to reduced conditions (− 0.092 ± 0.028-  − 0.200 ± 0.033 ‰ and  − 0.089 ± 0.027- − 0.250 ± 0.049 ‰, respectively), whereas ∆49Tiorthopyroxene-melt shows only a minor fractionation (− 0.002 ± 0.017-0.050 ± 0.025 ‰). The results of this study show that Ti isotope fractionation during mare basalt petrogenesis is expected to be redox dependent and mineral-melt fractionation as commonly determined for terrestrial fO2 may not be directly applied to a lunar setting. This is important for the evaluation of Ti isotope fractionation resulting from lunar magmatism, which takes place under more reducing conditions compared to the more oxidized terrestrial magmatism.

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

Redox Driven Stable Isotope Fractionation

2011 ◽  
pp. 345-359 ◽  
Author(s):  
Jay R. Black ◽  
Jeffrey A. Crawford ◽  
Seth John ◽  
Abby Kavner
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Stable Isotope Fractionation

scholarly journals Carbon and Hydrogen Stable Isotope Fractionation during Aerobic Bacterial Degradation of Aromatic Hydrocarbons

2002 ◽  
Vol 68 (10) ◽  
pp. 5191-5194 ◽  
Author(s):  
Barbara Morasch ◽  
Hans H. Richnow ◽  
Bernhard Schink ◽  
Andrea Vieth ◽  
Rainer U. Meckenstock
Keyword(s):  
Stable Isotope ◽  
Pseudomonas Putida ◽  
Aromatic Hydrocarbons ◽  
Isotope Fractionation ◽  
Bacterial Degradation ◽  
Aerobic Degradation ◽  
Bacterial Strains ◽  
Stable Isotope Fractionation ◽  
Substrate Degradation ◽  
Different Types

ABSTRACT 13C/12C and D/H stable isotope fractionation during aerobic degradation was determined for Pseudomonas putida strain mt-2, Pseudomonas putida strain F1, Ralstonia pickettii strain PKO1, and Pseudomonas putida strain NCIB 9816 grown with toluene, xylenes, and naphthalene. Different types of initial reactions used by the respective bacterial strains could be linked with certain extents of stable isotope fractionation during substrate degradation.

Sign in / Sign up

Export Citation Format

Share Document