Model-calculated interannual variability of concentration, deposition and transboundary transport of anthropogenic sulphur and nitrogen in Alberta

The 10-yr (1981–1990) mean and annual variation of concentration, wet and dry deposition and transboundary fluxes of SO2, H2SO4, (NH4)2SO4, NOx, HNO3 and NH4NO3 were simulated using the REgional Lagrangian Acid Deposition (RELAD) model. The results suggest that the distribution of the concentration and dry deposition are determined primarily by the location of sources, with some effects of prevailing meteorology. In the southern portion of the province, annual variation of concentration is less than 10% of the mean value, while in northern Alberta there is a 20% fluctuation about the average. The variation in meteorology has a greater effect on dry deposition, with the annual variation of dry deposition about double that of concentration. Both the wind flow and precipitation affect wet deposition, with the annual variation of wet deposition about three to four times that of concentration. Transboundary transport of sulphur and nitrogen across the borders of Alberta show annual variations in the range of 7–31 % about the mean value.