Alex Vermeulen
Manager
The impact of canopy exchange on differences observed between atmospheric deposition and throughfall fluxes
Author
Summary, in English
To study the impact of canopy exchange on differences observed between atmospheric deposition and throughfall fluxes, several-held experiments were performed at the Speulder forest in The Netherlands. Relevant information was obtained by (i) measuring open-field precipitation and throughfall fluxes with different time resolutions, using two canopy exchange models, (ii) by comparing results from surface wash experiments using real and artificial twigs, respectively, and (iii) by comparing throughfall flux estimates with atmospheric deposition estimates from micrometeorological measurements and inferential modelling. Canopy uptake of gases through stomata was estimated using measured air concentrations and a stomatal conductance model. Specific information on canopy leaching of soil-derived sulphate was provided by a S-35 tracer experiment. Sulphur was found to behave conservatively within the canopy, with SO2 uptake more or less balancing leaching of soil-derived SO42-. Significant stomatal uptake of NO2, HNO2 and NH3 was calculated as well as uptake of H+ and NH4+ from water layers covering the tree surface. Experiments did not indicate significant uptake of NO3- in solution. Canopy uptake of H+ and NH4+ was countered by leaching of K+, Ca2+ and Mg2+. Part of the leaching of K+, Ca2+ and Mg2+ (15%) took place along with weak organic acids. No significant canopy exchange was found for Na+ and Cl-. Differences observed between atmospheric deposition and throughfall fluxes could almost completely be explained by canopy exchange, the difference between NOy deposition and NO3- throughfall flux being the only exception. Copyright (C) 1996 Elsevier Science Ltd
Publishing year
1997
Language
English
Pages
387-397
Publication/Series
Atmospheric Environment
Volume
31
Issue
3
Document type
Journal article
Publisher
Elsevier
Topic
- Meteorology and Atmospheric Sciences
Keywords
- atmospheric deposition
- throughfall
- canopy exchange
- micrometeorological measurements
- inferential modelling
- surface wash
- experiments
- tracer experiment
Status
Published
ISBN/ISSN/Other
- ISSN: 1352-2310