Relocation of major ions in snow along the tundra-taiga ecotone

Abstract

Deposition of ions in winter occurs largely through the redistribution of wind-blown snow. While dominated by this snow redistribution, the loading of most ions, except for SO42-, does not scale exactly with that of snow, there being several mechanisms by which ion concentrations become relatively enriched or depleted in various landscape units. Vaporisation during temperature-gradient metamorphism in shallow-snow and uptake during either photochemical reactions or gaseous scavenging to well-exposed snow transformed concentrations of NO3- by 50%. Dry deposition of aerosols to forested terrain and valley bottoms enriched Cl-, Na+, Mg2+, K+ and Ca2+ concentrations up to more than two-fold, however scavenging of aerosols to blowing snow particles contributed an additional 40% to the sea-salt enrichment and 20% to the Ca2+ enrichment in wind-blown treeline forests. Central measurements of snow chemistry in the Arctic cannot be reliably extrapolated without reference to changes caused by over-winter physical and chemical metamorphic processes. -from Authors