Environmental Pollution, Nov, 2012, Vol.170, p.39(4)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2012.05.028 Byline: Johan Uddling (a), Rainer Matyssek (b), Jan B.C. Pettersson (c), Gerhard Wieser (d) Abstract: Pre-requisite for reliable O.sub.3 risk assessment for plants is determination of stomatal O.sub.3 uptake. One unaddressed uncertainty in this context relates to transpiration-induced molecular collisions impeding stomatal O.sub.3 influx. This study quantifies, through physical modelling, the error made when estimating stomatal O.sub.3 flux without accounting for molecular collisions arising from transpiratory mass flow of gas out of the leaf. The analysis demonstrates that the error increases with increasing leaf-to-air water vapour mole fraction difference ([DELTA]w), being zero in water vapour saturated air and 4.2% overestimation at [DELTA]w of 0.05. Overestimation is approximately twice as large in empirical studies quantifying stomatal O.sub.3 flux from measured leaf or canopy water flux, if neglecting both water vapour-dry air collisions (causing overestimation of leaf conductance) and collisions involving O.sub.3. Correction for transpiration-induced molecular collisions is thus relevant for both empirical research and for large-scale modelling of stomatal O.sub.3 flux across strong spatial [DELTA]w gradients. Author Affiliation: (a) Department of Biological and Environmental Sciences, University of Gothenburg, P. O. Box 461, SE-405 30 Goteborg, Sweden (b) Ecophysiology of Plants, Technische Universitat Munchen, von-Carlowitz Platz 2, D-85354 Freising-Weihenstephan, Germany (c) Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Goteborg, Sweden (d) Department of Alpine Timberline Ecophysiology, Federal Office and Research Centre for Forests, Rennweg 1, A-6020 Innsbruck, Austria Article History: Received 10 November 2011; Revised 28 May 2012; Accepted 30 May 2012
Water -- Analysis
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