ION ELUTION AND RELEASE SEQUENCE FROM DEEP SNOWPACKS IN THE CENTRAL SIERRA-NEVADA, CALIFORNIA

Elution of Cl-, SO42-, NO3-, and H+ often occurred in that order at a site in the central Sierra Nevada, California, that receives an annual average of 1000 cm of snowfall which is low in acidic components. During eight winter periods of above-base level snowpack outflow, and one spring melt period, on the average 25% of the ions were discharged at the following percentages of outflow volumes: Cl- at 11%, NO3- at 13%, SO42- at 18%, and H+ at 20%. Seven of eight winter outflows were associated with low ionic strength rainfall onto the snowpack. Mean solute concentrations during the first 25% and first 50% of the total outflow were significantly greater than during the last 75% and last 50% of the total outflow for Cl-, NO3-, and SO42-, but not for H+. Maximum solute concentrations were up to 2.9 times the overall event volume-weighted mean concentrations for Cl-, 3.7 times for NO3-, 3.0 times for SO42-, and 2.9 times for H+.