The long range transport of sulphur dioxide

Abstract

The annual deposition of sulphur by dry deposition and precipitation scavenging is estimated using data on the emission of sulphur dioxide in Europe. Sulphur travels, on average, hundreds of kilometres from its source being removed from the atmosphere. At such distances the annual deposition of sulphur per unit area is much reduced because of the variations in wind direction over a year. An attempt is made to compare the deposition of sulphur over the U.K., Sweden and the rest of Europe. The deposition of sulphur over the U.K. is found to be mainly of British origin and, per unit area, the mean annual deposition over rural England is about three times the mean annual deposition over rural Sweden. The British contribution to deposition over rural Sweden is found to be about one half of the Swedish contribution and ca. 10 per cent of the total deposition. At long distances from its source the annual deposition of sulphur is not too sensitive to assumptions about meteorological and physical conditions. This is not the case near to the source. When a choice of assumptions or conditions proves difficult the near field contribution to deposition, rather than the far field contribution, has been under-estimated. The annual deposition in urban areas has been neglected and is much higher than the highest deposition rates found in this paper.