Snowpack Chemistry During Snow Accumulation and Melt in Mature Subalpine Forest and Regenerating Clear-Cut in the Southern Interior of B.C.

Abstract

Chemical profiles in snowpacks were observed during snow accumulation and melt periods at subalpine sites in the southern interior of British Columbia. During accumulation periods, concentrations of nitrate, sulphate, chloride and sodium were higher than those of bulk snowfall in surface snowpack layers and lower in middle and basal layers. During melt periods, the opposite was true. This process of chemical profile reversals was found to repeat itself through successive cycles of melt and non-melt periods that typically occur at the site during the spring. This recurring cycle of chemical enrichment resulted in two distinct processes of ion elution. A “seasonal” process was observed in which there is an initial ion pulse followed by a slow exponential decline in concentration. An event based process consisting of ion pulses due to leaching of enriched surface layers was superimposed on the seasonal process. Forest cover type was found to exert an influence on snowpack chemistry during accumulation and melt. Significant differences between forest cover types were found among average chemical concentrations in enriched and depleted layers, suggesting that canopy density causes differences in chemical metamorphosis of snowpacks.