Wet deposition due to fog in the Po Valley, Italy

Abstract

Wet deposition due to radiation fog is examined in this paper. The area where the reported measurements were performed, the Po Valley, northern Italy, is characterized by both a high fog occurrence during the fall-winter months and fog water solutions of high ionic concentration and acidity. Estimated wet deposition for NH 4 + , NO inf3 sup- and SO inf4 sup2- ions due to fog droplet settling to the ground accounts for 13.2, 12.1 and 5.3 percent with respect to bulk precipitations over the same period: January–March and October–December (fog season). Fog deposition rates show that this process can be an important pathway of trace gases and particles loss from the air. First indicative results of fog removal efficiency with respect to air particulate matter are presented. Dry deposition parameters should be taken into account in evaluating the potential effect of fog droplet deposition on vegetation.