The goals of this paper are to briefly describe experimental methods t
hat are used to measure SO2 dry deposition, and to discuss the physica
l, biological and chemical processes that control SO2 deposition fluxe
s over vegetation and to describe how these fluxes are modelled. The p
redominant pathway for gaseous SO2 uptake to dry vegetation is via tur
bulent transfer through the atmosphere surface boundary layer and mole
cular diffusion through the leaf laminar boundary layer and the stomat
a. The soil surface is a significant, but weaker sink for sulphur, esp
ecially when frozen or covered with snow. The appreciable solubility o
f SO2 causes its uptake to be enhanced greatly in the presence of mois
ture on leaves and the soil. The aqueous uptake of SO2, however, cause
s the pH of a solution to decrease which in turn produces a reduction
in the solubility of SO2. Neutralising species (ammonia, inner plant s
pecies) may cancel this reduction. A method is proposed to estimate lo
cal scale dry deposition fluxes of SO2 in Europe. The method combines
long-range transport modelling results, land use and surface specific
data and an inferential approach.