scholarly journals Mercury Stable Isotope Fractionation during Abiotic Dark Oxidation in the Presence of Thiols and Natural Organic Matter

2018 ◽  
Vol 53 (4) ◽  
pp. 1853-1862 ◽  
Author(s):  
Wang Zheng ◽  
Jason D. Demers ◽  
Xia Lu ◽  
Bridget A. Bergquist ◽  
Ariel D. Anbar ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Natural Organic Matter ◽  
Isotope Fractionation ◽  
Stable Isotope Fractionation

scholarly journals Trimethylamine and Organic Matter Additions Reverse Substrate Limitation Effects on the δ13C Values of Methane Produced in Hypersaline Microbial Mats

2014 ◽  
Vol 80 (23) ◽  
pp. 7316-7323 ◽  
Author(s):  
Cheryl A. Kelley ◽  
Brooke E. Nicholson ◽  
Claire S. Beaudoin ◽  
Angela M. Detweiler ◽  
Brad M. Bebout
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Natural Organic Matter ◽  
Methane Production ◽  
Isotope Fractionation ◽  
Microbial Mats ◽  
Hypersaline Environments ◽  
Substrate Limitation ◽  
Main Substrate ◽  
Isotope Measurements

ABSTRACTMethane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of noncompetitive substrates, such as the methylamines, dimethylsulfide and methanol. Stable isotope measurements of the produced methane have also suggested that the methanogens are operating under conditions of substrate limitation. Here, substrate limitation in gypsum-hosted endoevaporite and soft-mat hypersaline environments was investigated by the addition of trimethylamine, a noncompetitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ13C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ13C values of the methane produced in the amended vials were statistically lower (by 10 to 71‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more13C-depleted methane. Trimethylamine-amended samples produced lower methane δ13C values than the mat-amended samples. This difference in the δ13C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. It is hypothesized that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2concentrations and increased CO2/H2methanogenesis.

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
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