title: Leaf water oxygen isotope measurement by direct equilibration.
abstract: The oxygen isotope composition of leaf water imparts a signal to a range of molecules in the atmosphere and biosphere, but has been notoriously difficult to measure in studies requiring a large number of samples as a consequence of the labour-intensive extraction step. We tested a method of direct equilibration of water in fresh leaf samples with CO2 , and subsequent oxygen isotope analysis on an optical spectrometer. The oxygen isotope composition of leaf water measured by the direct equilibration technique was strongly linearly related to that of cryogenically extracted leaf water in paired samples for a wide range of species with differing anatomy, with an R(2) of 0.95. The somewhat more enriched values produced by the direct equilibration method may reflect lack of full equilibration with unenriched water in the vascular bundles, but the strong relationship across a wide range of species suggests that this difference can be adequately corrected for using a simple linear relationship.
authors.affiliation: Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia.
authors.forename: Xin
authors.initials: X
authors.lastname: Song
authors.affiliation: Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia.|Landcare Research, PO Box 40, Lincoln, 7640, New Zealand.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Barbour
mesh_terms: D057168:Distillation; D007553:Isotope Labeling / Q000379:methods*; D010103:Oxygen Isotopes / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D006109:Poaceae / Q000378:metabolism*; D014618:Vacuum; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*
chemical_list: D010103:Oxygen Isotopes; D014867:Water
keywords: isotope analysis; isotope ratio mass spectrometer; leaf water enrichment; oxygen isotope; tunable diode laser