DRY DEPOSITION OF REACTIVE NITROGEN-COMPOUNDS - A REVIEW OF LEAF, CANOPY AND NON-FOLIAR MEASUREMENTS

This review summarizes dry deposition data for several reactive nitrogen compounds (gases and particles) for both foliar and non-foliar sites of deposition, and differentiates these data with respect to the techniques by which they were obtained. Brief summaries of the atmospheric behavior of reactive nitrogen gases, the processes governing their deposition, and a discussion of the relative importance of dry deposition to total landscape N deposition are also included. Estimates of dry deposition velocities for these species vary significantly depending on the method used and vegetation studied. Leaf-level conductances to the principal reactive nitrogen gases are typically 4-20 times lower than canopy deposition velocity measurements, but this difference can be partially reconciled if canopy leaf area is accounted for when scaling from the leaf to canopy level. Field data indicate that dry deposition of N compounds to plant surfaces is comparable to wet deposition, contributing from 20 to 70% of total atmospheric nitrogen inputs.