Isotope partitioning of evaporation and transpiration from the land surface: towards improved understanding of vapour-loss mechanisms

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This research centres on development, refinement and application of stable isotope techniques for tracing evaporation and transpiration in natural ecosystems. Isotopic tracing of vapour loss pathways is possible due to significant differences in behaviour of the naturally-occurring isotopic species of water during evaporation and transpiration, the former pathway being isotopically fractionating, and the latter being isotopically non-fractionating. As typically observed in natural systems, the isotopic composition of the transpiration flux will closely resemble that of soil water sources, whereas the evaporation flux will be distinctly labelled by a depleted heavy isotopic signature. Fingerprinting of vapour fluxes and residual waters using isotopes is explored to improve characterization of water and carbon budgets in complex wetland terrain, in regional surveys, large river basins and global scale modelling studies.