Spatial variation in annual nitrogen deposition in a rural region in Switzerland

We studied the spatial variation in annual nitrogen deposition to the Seela nd region of Switzerland by combining (1) mesoscale atmospheric modeling of gaseous dry deposition, (2) wet deposition data measured within the study area as well as published data, and (3) estimates of dry deposition of aero sol particles based on concentration measurements and sedimentation samples from a nearby region. Gaseous dry deposition shows greatest regional varia tion. Total nitrogen input to this region is in the range of 22-51 kg N ha( -1) year(-1) (13-42 kg N gaseous dry deposition; 7-8 kg N wet deposition; a pproximate to 2 kg N dry deposition of aerosol particles). Gaseous dry depo sition is dominated by reduced nitrogen components from agricultural source s. The highest nitrogen inputs were found over lakes (51 kg N ha(-1) year(- 1)). Our results indicate that current nitrogen loads exceed the nutrient c ritical loads by several kg N ha(-1) year(-1) in all nitrogen-sensitive eco system types occurring in our 70x50 km(2) study area.