REPORTING OF STABLE HYDROGEN, CARBON, AND OXYGEN ISOTOPIC ABUNDANCES

To eliminate possible confusion in the reporting of isotopic abundances on non-corresponding scales, the Commission on Atomic Weights and Isotopic Abundances recommended at the 37th General Assembly at Lisbon, Portugal that (i) H-2/H-1 relative ratios of all substances be expressed relative to VSMOW (Vienna Standard Mean Ocean Water) on a scale such that H-2/H-1 of SLAP (Standard Light Antarctic Precipitation) is 0.572 times that of VSMOW, (ii) C-13/C-12 relative ratios of all substances be expressed relative to VPDB (Vienna Peedee belemnite) on a scale such that C-13/C-12 of NBS 19 carbonate is 1.00195 times that of VPDB, and (iii) O-18/O-16 ratios of all substances be expressed relative to either VSMOW or VPDB on scales such that O-18/O-16 of SLAP is 0.9445 times that of VSMOW.