Temporal Variations in Acidity and Ion Concentrations of Precipitation, Snowpack and Outflow from Snowpack in a Temperate Snow area of Japan

Abstract

This paper describes the temporal variations in acidity and main dissolved ion concentrations of precipitation, snowpack, and outflow from snowpack in a temperate snow area of Japan. In order to understand the characteristics of snow chemistry and the effect of rainfall and surface snowmelt on chemistry outflow from snowpack, snow sampling and water quality measurements (pH, electric conductivity, Cl-, N03-, SO4 2-, Na+, NH4+, K+, Mg2+, Ca2+) were conducted from December 2008 to March 2009 at Tohkamachi experimental station, Japan. The mean pH of precipitation and outflow from snowpack were approximately 4.6 and 5.0, respectively. The acidified precipitation and outflow were high electric conductivity and mainly governed by sulfate. However, the chemical solutes derived from windblown mineral dust decreased acidification of snowfall in February with high electric conductivity. Temporary acidification of outflow occurred at the abrupt runoff after the stable and low outflow fed by largely bottom snowmelt due to ground heat. Ion fluxes at the snow surface and snow bottom suspect that percolation of surface snowmelt or rainfall to snow bottom flows the solutes eluted on the ice grain within snowpack and leads to temporary acidification and further ion-concentration enrichment of outflow.