Isotope ratios light stable

The ratios of stable isotopes (red dots) fall within a narrow range, referred to as the "belt of stability." For light isotopes of small atomic number the stable ratio is 1 1. For heavier isotopes the ratio gradually increases to about 1.5 1. Isotopes outside the band of stability are unstable and radioactive. There are no stable isotopes for elements of atomic number greater than 83 (Bi). 

The ratios of heavy to light stable isotopes of hydrogen H/iH (or D/H), carbon i C/i C, nitrogen oxygen i 0/i 0, and sulfur 3 5/325 show distinctive patterns of... 

Any of these data banks, those parts from the ice ages, can have their stable isotope ratios perturbed by the huge ice reserves which were removed from the sea and piled up on land, because the ice depletes the oceans in the light isotopes, and therefore significantly enriches the sea in the heavy isotopes, so that sea sediments and continental precipitation, rain and snow, reflect this perturbation as well as perturbations caused by temperature changes alone. 

Each species and phase of an element with two or more stable isotopes consists of light and heavy isotopes in proportions that can be measured by using a mass spectrometer (e.g., Faure, 1986). The isotope ratio R is the quotient of the number of moles of a heavy isotope (such as 18 O) to the number of moles of a light isotope (such as 160). 

Stern, B., Clelland, S.J., Nordby, C.C. and Urem-Kotsou, D. (2006). Bulk stable light isotopic ratios in archaeological birch bark tars. Applied Geochemistry 21 1668-1673. 

Barrie, A., Prosser, S.J. Automated analysis of light-element stable isotopes by isotope ratio mass spectrometry. Unpublished Materials. Europa Scientific Ltd. Crewe, Cheshire, England, 2000. 

Stichler, W. 1995. Interlaboratory comparison of new materials for carbon and oxygen isotope ratio measurements. Pp. 67-74 in Reference and Intercomparison Materials for Stable Isotopes of Light Elements, Vienna International Atomic Energy Agency, LAEA-TECDOC-825. 

Until only a few years ago, I would never have imagined that a volume on the stable isotope geochemistry of elements like Mg, Fe or Cu would be written. In fact, a comic book of blank pages entitled The Stable Isotope Geochemistry of Fluorine would have been a more likely prospect. In volume 16 of this series, published in 1986, I wrote Isotopic variations have been looked for but not found for heavy elements like Cu, Sn, and Fe.. .. Natural variations in isotopic ratios of terrestrial materials have been reportedfor other light elements like Mg and K, but such variations usually turn out to be laboratory artifacts. I am about ready to eat those words. 

The molecules found to date are composed of the elements H, C, N, O, Si, S, and Cl with the bulk of the molecules containing H, C, N, and O. The light elements H, D, and He are of cosmological origin and are therefore tracers of the early universe. On the other hand the heavier elements C, N, O,... are produced in stars by the processes of stellar nucleosynthesis. In addition to the most abundant isotopic forms many stable isotopes such as D, 13C, 170, lsO, 15N, 30Si, 33S, and 34S have been detected (see Appendix 1). The detailed determination of isotopic ratios — though often beset with formidable difficulties — has become a useful indicator of the chemical evolution of molecular clouds and the past chemical history of the galaxy. 

Figure 1 Studies published between 1988 and 1997 reporting use of secondary ion mass spectrometry (SIMS) in geochemistry and cosmochemistry. Papers are subdivided according to theme Hvy Iso, studies of heavy isotope ratios, principally for U-Pb dating Lt Iso, studies of light stable isotope ratios (H, B, C, O, S) Hvy El, studies primarily focused on analysis of elements >40 amu (e.g., rare earth elements) Lt El, studies primarily focused on analysis of elements <40 amu (e.g., water content) Prec Met, analysis of precious metal contents (e.g., Au, Ag, Pt) Expt, analysis of experimental run products Misc, other mis-cellanous studies utilizing SIMS.

Quay et al. (1995) reported lower respiration to production ratios (1 to 1.7) in seven Amazon floodplain lakes. These ratios were derived from stable isotope ratios of dissolved oxygen in surface waters where light availability and photosynthesis are often high. The higher ratios calculated by B. R. Forsberg were based on depth-integrated rates and thus more accurately reflect the total pelagic carbon balance. 

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