Simultaneous measurement of δ2H, δ17O, and δ18O in H2O using a commercial cavity ringdown spectrometer

We demonstrate that a commercial instrument that provides measurements of O-18/O-16 and DIM ratios in water samples can be modified to also provide measurements of O-17/O-16. This additional capability and associated precision allows for the discernment between conventional mass-dependent processes, such as isotope exchange and evaporation and mass-independent processes that arise from non-equilibrium chemical and photochemical processes. We demonstrate this resolution by performing a series of experiments including evaporation and reservoir-mixing with O-17 enriched water samples followed by evaporation. The ability to simultaneously measure O-16, O-17 and O-18 abundances in water samples using the procedures described here should help to facilitate multi-isotopic studies of water (and other compounds) in astrochemical, geochemical, and biological studies. (C) 2013 Elsevier B.V. All rights reserved.