Direct quantification of leaf transpiration isotopic composition

Wang, Lixin, Good, Stephen P., Caylor, Kelly K., and Cernusak, Lucas A. (2012) Direct quantification of leaf transpiration isotopic composition. Agricultural and Forest Meteorology, 154-155. pp. 127-135.

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The stable isotopic composition of plant transpired water (δ(T)) is a powerful tracer used to characterize plant processes in the fields of ecology, plant physiology and hydrology. However, δ(T) is rarely directly measured due to the general difficulty in traditional water vapor isotopic measurements. We report a new direct method with the potential to continuously monitor δ(T) utilizing a commercially available laser-based isotope analyzer coupled to a transparent leaf chamber in a flow-through system arrangement. The method is based on the mass balance of both water vapor and water vapor isotopes inside the chamber. We present the theoretical bulk water vapor and isotope mixing equations, which we verify using simulated water vapor of known isotopic compositions, producing a precision of 1.6‰ and 1.0‰ for δ2H and δ18O respectively. We demonstrate the applicability of our method to field observations and capture rapid (minute time scale) δ(T) responses to shifts in transpiration driven by variation in irradiance.

Item ID: 30280
Item Type: Article (Research - C1)
ISSN: 1873-2240
Keywords: dew point generator, hydrogen, Isotope, Kenya, mass balance, oxygen
Date Deposited: 20 Nov 2013 09:33
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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