Large variations in [delta][sup.13][C.sub.CH4] values from the IsoJar[TM] measurements (Figure 1) were attributed to methane-oxidizing bacterial activity using sulfate ions in the deep underground environment or to isotopic fractionation
during gas migration through fractures .
Liu, "Sulfur isotopic fractionation
and mechanism for Thermochemical Sulfate Reduction genetic [H.sub.2]S," Acta Petrologica Sinica, vol.
Experiment 1 - Determination of isotopic fractionation
The abundance of [.sup.13]C in marine organic matter and isotopic fractionation
in the global biogeochemical cycle of carbon during the past 800 Ma.
It is possible that the Fe isotopic fractionation
between the F1 and F2 fractions in the upper 30 cm and lower 30 cm reflects a soil redox change with the lower (deeper?) soils being enriched in [Fe.sup.2+].
Since the analytes underwent physical adsorption and desorption processes before the carbon isotope analysis, several experiments had to be conducted to detect whether carbon isotopic fractionation
has occurred during the SPME extraction processes.
Thus, the reaction required to mobilize copper for sedimentary deposits involves the reduction of copper, which would be expected to induce isotopic fractionation
favoring [sup.63]Cu, assuming that copper extraction from the source material was incomplete.
reported that the Fe dissimilatory reduction (DIR) promoted by Geobacter sulfurreducens and Shewanella putrefaciens strains caused Fe isotopic fractionation
of approximately 2.2[per thousand], with final Fe(II) species enriched in light isotopes , which demonstrated that the Fe isotope composition of Fe[(II).sub.aq] is largely controlled by isotopic exchange with a reactive Fe(III) pool that lies in the outer layers of the ferric oxide substrate.
The stable isotope ratios of individual elements are affected by two main factors, namely isotopic fractionation
and radioactive decay.
We considered an isotopic fractionation
across trophic levels of 3.4 [per thousand] for [delta][sup.15] and 1.0 [per thousand] for [delta][sup.13]C (Vander-Zanden & Rasmussen, 2001; Post, 2002; Wing et al., 2008).
Among the topics are instrumental isotopic fractionation
, measurement strategies, chemical imaging, inductively coupled plasma mass spectroscopy, thermal ionization mass spectrometry, secondary ion mass spectroscopy, and gas source isotope ratio mass spectrometry for analyzing noble gases.