An experimental study of the dry deposition of gaseous nitric acid to snow

Abstract

A chamber placed in a constant temperature freezing room was used to study the surface resistance during deposition of HNO 3 to a snow surface. The resistance decreased with increasing temperature from larger than 5 s mm −1 at − 18°C to about l s mm −1 at −3°C. Measurements of gaseous and particulate nitrate concentrations during winter at a rural site in south central Sweden gave concentrations in the range of 0.4–5 μg HNO 3 m −1 and 0.3–3 μg NO − 3 m −3 with a mean value of 1.3 μg HNO 3 m −3 and 0.7 μg NO − 3 m −3, respectively. The results indicate that for periods with temperatures below − 2°C estimated dry deposition of HNO 3 to snow is at most 4 % of measured wet deposition of nitrate in the area.