Possible source areas and influential factors for sulphur compounds in Morvan, France

A trajectory statistics method has been used to examine the causes of variability and seasonality of sulphur dioxide, particulate sulphate and non-sea-salt sulphate in precipitation measured at a French rural site. This methodology has permitted to define the likely contributing sources for two seasons, a warm and a cold, that show different patterns. The general results suggest the impact of the long-range transport of SO2 and SO2 secondary species from high anthropogenic sources. The increase of photochemical activity during the warm period, the seasonal large-scale wind movements responsible for precipitation and the removal processes during atmospheric transport may also significantly influence sulphur concentrations at Morvan.