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Throughfall deposition of ammonium and sulphate during ammonia fumigation of a Scots pine forest

Cape, J.N.; Sheppard, L.J.; Binnie, J.; Arkle, P.; Woods, C.. 1995 Throughfall deposition of ammonium and sulphate during ammonia fumigation of a Scots pine forest. Water, Air and Soil Pollution, 85 (4). 2247-2252. 10.1007/BF01186168

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Abstract/Summary

The estimation of the dry deposition of sulphur dioxide to forests is confounded by the possibility of co-deposition of SO2 with NH3 on leaf surfaces. A sector of Scots pine forest was selectively fumigated with NH3 to give average concentrations up to 15 ppbV (nL L–1) above ambient, in order to test the hypothesis that increased air concentrations of NH3 would enhance the dry deposition of SO2, and the consequent amounts of SO4 2– measured in throughfall below the forest canopy. Ammonia gas, generated by evaporation of concentrated aqueous solution, was released above the canopy in proportion to wind speed when the wind direction was between south and west. Concentrations of NH3 at canopy height were measured using passive diffusion tubes; throughfall was preserved with thymol and measured weekly. Meteorological data and SO2 concentrations were recorded continuously, to permit the estimation of dry deposition input. Deposition of NH4 + in throughfall over 8 months was increased by up to 40 meq m–2 relative to control sites upwind of the NH3 release point, with largest values closest to the release point. Deposition of SO4 2– in throughfall was also enhanced in the fumigated area, by up to 20 meq m–2, even though average ambient SO2 concentrations were 2.3 ppbV. The results are discussed in terms of the factors controlling SO2 deposition on forest surfaces, the development of appropriate deposition models, and their relevance to using throughfall as an estimate of total S deposition.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/BF01186168
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry
CEH Sections: _ Pre-2000 sections
ISSN: 0049-6979
Additional Keywords: throughfall, dry deposition, sulphur dioxide, ammonia, co-deposition
NORA Subject Terms: Agriculture and Soil Science
Ecology and Environment
Atmospheric Sciences
Date made live: 22 May 2009 14:35
URI: http://nora.nerc.ac.uk/id/eprint/7242

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