Stable hydrogen and oxygen isotopes in the water cycle.

Abstract

The isotope ratios D/H and 18O/16O vary in natural waters as a result of isotope fractionation during evaporation and condensation, as a result of the lower vapour pressures of HD16O and H218O compared with H216O. Heavy isotope concentrations decrease towards higher latitudes as a result of lower temperatures, and similarly vary seasonally with temperature. They also decrease towards continental interiors and with increasing altitude. The stable isotope characteristics of meteoric waters are sufficiently distinct for such waters to be identified in geothermal waters. -B.Yardley