Atmospheric deposition of base cations, nitrogen and sulphur in coniferous forests in Sweden — a test of a new surrogate surface

Dry deposition of base cations, nitrate, as well as particulate ammonium, and sulphate in coniferous forests was measured using a surrogate surface in combination with net throughfall measurements at 11 sites in southern Sweden. The measurement technique involved monitoring gaseous pollutants with diffusive samplers and assuming common dry deposition rates on forest and the surrogate surface. The dry deposition of base cations was important as compared to the wet deposition at all coastal (windy) sites. Correlations of the internal fluxes of potassium and calcium were identified with regard to the deposition of reduced nitrogen compounds and sulphur dioxide respectively. In addition, the results outline the significance of dry deposition compared to wet deposition and trends relating to the net throughfall of nitrogen compounds. The net throughfall of nitrogen compounds was often negative, but approached the estimated dry deposition with increasing load.