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Title: Evolution of the composition isotopic of the continuum soil-plant-atmosphere

Abstract

Intensive daily sampling of the soil-plant-atmosphere continuum was carried out to determine the vertical evolution of diurnal variation of the isotopic composition of (1) water in leaves from a maize canopy at the experimental site of Villeau, Eure et Loir (France) and (ii) water vapor in the atmosphere above and within the canopy. Applying some reasonable assumptions, the isotopic model of the transpiration process (I.M.T.) fits well the daily enrichment cycle of {sup 18}O and {sup 2}H in the leaf water sampled at different levels of the plants. The most important factors influencing the variations of {sup 18}O and {sup 2}H content are the relative humidity of the air and the kinetic enrichment factor occurring during transpiration. The discrepancies between the measured and the calculated values seem to be closely related to the differences between the isotopic composition of the water pools in the leaf. Without experimental data on the transpiration flux and the root water uptake, the I.M.T. allows a relatively precise determination of the nature (transient or stationary) of the isotopic state of the water in the leaf. When {delta}{sup 18}O and {delta}{sup 2}H present steady-state values, the water fluxes are always conservative in the transpiring pools ofmore » the leaf. When the heterogeneity of the pools of the leaf is taken into account, it appears that the leaf does not present systematically an instantaneous isotopic steady-state. The results reported here indicate that the assumption of the constancy of {epsilon}{sub k} values is invalid: the discrepancy in {epsilon}{sub k} values between the leaves at the top of the canopy and the other ones can be related to the increase of the turbulence of the atmosphere with height in the canopy.« less

Authors:
; ;  [1]
  1. Universite Pierre et Marie Curie, Paris (France)
Publication Date:
OSTI Identifier:
6935754
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta; (USA)
Additional Journal Information:
Journal Volume: 54:2; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; PLANTS; AIR-BIOSPHERE INTERACTIONS; BIOGEOCHEMISTRY; BIOLOGICAL ACCUMULATION; DEUTERIUM; FRANCE; ISOTOPE RATIO; OXYGEN 18; SEASONAL VARIATIONS; TRANSPIRATION; WATER VAPOR; CHEMISTRY; EUROPE; EVEN-EVEN NUCLEI; FLUIDS; GASES; GEOCHEMISTRY; HYDROGEN ISOTOPES; ISOTOPES; LIGHT NUCLEI; NUCLEI; ODD-ODD NUCLEI; OXYGEN ISOTOPES; STABLE ISOTOPES; VAPORS; VARIATIONS; WESTERN EUROPE; 580000* - Geosciences

Citation Formats

Bariac, T, Jusserand, C, and Mariotti, A. Evolution of the composition isotopic of the continuum soil-plant-atmosphere. United States: N. p., 1990. Web. doi:10.1016/0016-7037(90)90330-N.
Bariac, T, Jusserand, C, & Mariotti, A. Evolution of the composition isotopic of the continuum soil-plant-atmosphere. United States. https://doi.org/10.1016/0016-7037(90)90330-N
Bariac, T, Jusserand, C, and Mariotti, A. 1990. "Evolution of the composition isotopic of the continuum soil-plant-atmosphere". United States. https://doi.org/10.1016/0016-7037(90)90330-N.
@article{osti_6935754,
title = {Evolution of the composition isotopic of the continuum soil-plant-atmosphere},
author = {Bariac, T and Jusserand, C and Mariotti, A},
abstractNote = {Intensive daily sampling of the soil-plant-atmosphere continuum was carried out to determine the vertical evolution of diurnal variation of the isotopic composition of (1) water in leaves from a maize canopy at the experimental site of Villeau, Eure et Loir (France) and (ii) water vapor in the atmosphere above and within the canopy. Applying some reasonable assumptions, the isotopic model of the transpiration process (I.M.T.) fits well the daily enrichment cycle of {sup 18}O and {sup 2}H in the leaf water sampled at different levels of the plants. The most important factors influencing the variations of {sup 18}O and {sup 2}H content are the relative humidity of the air and the kinetic enrichment factor occurring during transpiration. The discrepancies between the measured and the calculated values seem to be closely related to the differences between the isotopic composition of the water pools in the leaf. Without experimental data on the transpiration flux and the root water uptake, the I.M.T. allows a relatively precise determination of the nature (transient or stationary) of the isotopic state of the water in the leaf. When {delta}{sup 18}O and {delta}{sup 2}H present steady-state values, the water fluxes are always conservative in the transpiring pools of the leaf. When the heterogeneity of the pools of the leaf is taken into account, it appears that the leaf does not present systematically an instantaneous isotopic steady-state. The results reported here indicate that the assumption of the constancy of {epsilon}{sub k} values is invalid: the discrepancy in {epsilon}{sub k} values between the leaves at the top of the canopy and the other ones can be related to the increase of the turbulence of the atmosphere with height in the canopy.},
doi = {10.1016/0016-7037(90)90330-N},
url = {https://www.osti.gov/biblio/6935754}, journal = {Geochimica et Cosmochimica Acta; (USA)},
issn = {0016-7037},
number = ,
volume = 54:2,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 1990},
month = {Thu Feb 01 00:00:00 EST 1990}
}