Atmospheric Particles: Their Physical and Chemical Characteristics, and Deposition Processes Relevant to the Chemical Composition of Glaciers

Abstract

Atmospheric particles originate from a variety of natural and anthropogenic sources. Estimates of man’s contribution to the total particle mass loading of the atmosphere range from 5 to 48%. Much of this is initially in the form of gases (SO2, NO2, hydrocarbons) that convert to particles while being transported to glacial receptors where they are incorporated into snow. The complex physical and chemical processes involved in the deposition of atmospheric particles to glaciers are reviewed. Both wet and dry deposition contribute to the pollutant loading of a snowfield. However, except in the case of low snowfall (<60 kg m−2 a−1) or exceptionally large particle sizes, such as might be released by volcanoes or when unrimed snowfall predominates, wet deposition is dominant. Estimates of the relative importance of wet and dry deposition based on scavenging ratios for rimed snowfall and dry deposition velocities agree well with observations in southern Greenland.