Ammonia and nitric acid dry deposition and throughfall.

Since 1991 measurements of fluxes of ammonia have been carried out periodically at a forest location in the western part of Denmark. The ammonia deposition velocities and fluxes are estimated from gradient measurements done by denuders and micrometeorology. The deposition velocities showed a large variation, ranging from deposition mainly governed by the atmospheric transport with fast adsorption at the surface to emission. Nitric acid deposition velocities and fluxes were measured in a period in May 1993 and the data indicate deposition mainly governed by the atmospheric transport and fast adsorption at the surface. The measured ammonia fluxes and an estimate for the particulate ammonium flux are compared to a nine year mean value of the net throughfall from Norway Spruce at the location.