نتایج جستجو برای: isotope fractionation

تعداد نتایج: 49992  

2001
ROBERT G. CLARK

Studies using stable-isotope analysis to infer diet require a knowledge of how stable-isotope ratios in consumer tissues are related to dietary values. We determined 6°C and VN diet-tissue fractionation factors for blood, liver, muscle, bone collagen and feathers of domestic chickens (Gallus gullus), Japanese Quail (Coturnix juponica) and Ring-billed Gulls (Lams deluwarensis) and for blood and ...

2000

Compound-specific carbon isotope ratio analysis is a promising tool to assess the origin and fate of organic contaminants in groundwater. The aim of this study was to develop and evaluate a reliable, fast method to determine carbon isotope ratios of chlorinated methanes, ethanes, and ethenes in aqueous samples. Direct solid-phase microextraction (dSPME) and headspace solid-phase microextraction...

2003

of isotopically labelled vitamin D metabolites by HPLC. Journal of Chromatography 303: 229}233. Kaspersen FM, van Acquoy J, van de Laar GLM, Wagenaars GN and Funke CW (1984) Deuterium isotope effects in mianserin. Recueil Travaux Chimique de Pay-Bas 103: 32}36. Klein PD (1966) Occurence and signiRcance of isotope fractionation during analytical separation of large molecules. Advances in Chromat...

2002
ANDREW L. HERCZEG RICHARD G. FAIRBANKS

A stable isotope mass-balance of dissolved inorganic carbon during a blue-green algae bloom in a softwater lake demonstrates that at low partial pressure of carbon dioxide there must be a large net negative carbon isotope fractionation between atmospheric CO1 and the CO2 absorbed by lake water at pH = 9.5. The net fractionation of CO*(g) with respect to HCO; was about -13%~ compared with about ...

Journal: :Applied and environmental microbiology 2006
Piyapawn Somsamak Hans H Richnow Max M Häggblom

Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope a...

2010
Sebastian Hermann Maria Zuber

Archean sulfur mass-independent fractionation (S-MIF) has been widely recognized as one of the strongest indicators for the rise of atmospheric oxygen in the Early Proterozoic. A decade after its discovery, the wide-ranging implications of Archean sulfur MIF have been discussed extensively and despite a number of recent studies on the gas-phase chemistry of sulfur, no definite overall picture h...

2004
Mao-Chang Liang Geoffrey A. Blake Yuk L. Yung

[1] We have developed a semianalytic model for computing the photo-induced isotopic fractionation in simple molecules of interest to the atmospheric science community. The method is based on the Born-Oppenheimer approximation and the Reflection Principle. It has the main advantage of using commonly available input data, namely, the photolysis cross sections for the standard isotopologue/isotopo...

Journal: :Applied and environmental microbiology 2004
Barbara Morasch Hans H Richnow Andrea Vieth Bernhard Schink Rainer U Meckenstock

Stable isotope fractionation was studied during the degradation of m-xylene, o-xylene, m-cresol, and p-cresol with two pure cultures of sulfate-reducing bacteria. Degradation of all four compounds is initiated by a fumarate addition reaction by a glycyl radical enzyme, analogous to the well-studied benzylsuccinate synthase reaction in toluene degradation. The extent of stable carbon isotope fra...

2017
Pertti Ala-Aho Doerthe Tetzlaff James P McNamara Hjalmar Laudon Patrick Kormos Chris Soulsby

Use of stable water isotopes has become increasingly popular in quantifying water flow paths and travel times in hydrological systems using tracer-aided modeling. In snow-influenced catchments, snowmelt produces a traceable isotopic signal, which differs from original snowfall isotopic composition because of isotopic fractionation in the snowpack. These fractionation processes in snow are relat...

2016
Rongfei Wei Qingjun Guo Hanjie Wen Congqiang Liu Junxing Yang Marc Peters Jian Hu Guangxu Zhu Hanzhi Zhang Liyan Tian Xiaokun Han Jie Ma Chuanwei Zhu Yingxin Wan

Cadmium (Cd) isotopes provide new insights into Cd uptake, transport and storage mechanisms in plants. Therefore, the present study adopted the Cd-tolerant Ricinus communis and Cd-hyperaccumulator Solanum nigrum, which were cultured under controlled conditions in a nutrient solution with variable Cd supply, to test the isotopic fractionation of Cd during plant uptake. The Cd isotope composition...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید