Stable carbon isotope ratio of submerged freshwater macrophytes1,1

New approaches for stable isotope ratio measurements

We demonstrate the first successful application of infrared laser spectrometry to the accurate, simultaneous determination of the relative H/H, O/O, and O/O isotope abundance ratios in natural water. The method uses a narrow line width color center laser to record the direct absorption spectrum of low-pressure gas-phase water samples (presently 10 μl liquid) in the 3 μm spectral region. The pre...

Gas chromatography/combustion/isotope ratio mass spectrometric analysis of the stable carbon composition of tetrols.

The stable carbon isotope compositions of tetrols, erythritol and threitol were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using four tetrols with various delta(13)C values derivatized by methylboronic acid, the carbon isotope analysis method achieved excellent reproducibility and high accuracy. There was no carbon isotopic fractionation during the ...

Carbon isotope ratio in carbon stars of the galactic halo

Weanalysed CN red system (∼8000 Å) andC2 Swan system (∼4700 Å) to know carbon isotope ratios (12C/13C) for carbon stars in the Galactic halo, named CH stars. The isotope ratios are obtained for 6 CH stars by the curve-of-growth analysis of the isolated 12CN and 13CN lines. In this analysis, we compared directly 12CN and 13CN lines of similar intensities (iso-intensity method), and the resulting...

Stable Carbon Isotope Ratio Measurements of the Carboxyl Carbons in Bone Collagen

Stable Carbon Isotope Fractionation by Methanogens

Introduction: Methanogenic archaea, which consume CO2 and H2, have been considered models for possible life forms on Mars for a long time, even before the discovery of methane in the Martian atmosphere (1-8). Several intensive experimental studies have been conducted to investigate survivability of methanogens under conditions that approach those found on Mars (2, 3, 9). Various potential sourc...