The Control of SO2 Dry Deposition on to Natural Surfaces by NH3 and its Effects on Regional Deposition

Fowler, D.; Sutton, M.A.; Flechard, C.; Cape, J.N.; Storeton-West, R.; Coyle, M.; Smith, R.I.. 2001 The Control of SO2 Dry Deposition on to Natural Surfaces by NH3 and its Effects on Regional Deposition. Water, Air and Soil Pollution: Focus, 1 (5-6). 39-48.

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Two years of continuous measurements of SO2deposition fluxes to moorland vegetation are reported. The mean flux of 2.8 ng SO2 m-2 s-1 is regulated predominantly by surface resistance (r c) which, even for wet surfaces, was seldom smaller than 100 s m-1. The control of surface resistance is shown to be regulated by the ratio of NH3SO2 concentrations with an excess of NH3 generating the small surface resistances for SO2. A dynamic surface chemistry model is used to simulate the effects of NH3 on SO2 deposition flux and is able to capture responses to short-term changes in ambient concentrations of SO2, NH3 and meteorological conditions. The coupling between surface resistance and NH3/SO2 concentration ratios shows that the deposition velocity for SO2 is regulated by the regional pollution climate. Recent long-term SO2 flux measurements in a transect over Europe demonstrate the close link between NH3/SO2 concentrations and rc (SO2). The deposition velocity for SO2 is predicted to have increased with time since the 1970s and imply a 40% increase in v d at a site at which the annual mean ambient SO2 concentrations declined from 47 to 3 g m-3 between 1973 and 1998.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry
UKCEH and CEH Sections/Science Areas: _ Atmospheric Sciences
ISSN: 0049-6979
Additional Keywords: canopy resistance, deposition, non-linearity, SO2, velocity
NORA Subject Terms: Ecology and Environment
Atmospheric Sciences
Date made live: 20 May 2009 08:36 +0 (UTC)

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