Retention and release of chemical species by a Northern Michigan snowpack

Abstract

Snowcore and water samples were collected during the 1981 to 82 winter at two independent sites in Northern Michigan; the Little Pigeon River and McNearney Lake. Acidic and basic species were determined in all samples. Examination of the concentration vs depth profiles of snow cores showed that all species were stable in the snowpack until the spring thaw period. During the thaw, 50 to 70% of the stored acids were released during the first 20% of the snowmelt. However, rainfall during the melt period contributed as much acidity to the environment as the snowmelt. Study of runoff showed that only 30% of the nitrate originally present in the snowpack appeared in the Little Pigeon River. Therefore, H₂SO₄ dominated the runoff acidity at the Little Pigeon River. Both nitrate and sulfate were responsible for the slight acidification of McNearney Lake during the snowmelt period.