Wintertime wet and dry deposition in northern Michigan

Abstract

Wet and dry deposition were monitored at the University of Michigan Biological Station in rural northern Michigan for three winters. Dry deposition was measured by both the conventional bucket method and by measuring increases in concentration in exposed, elevated snow samples. Average results of the two methods were in reasonable agreement. The cumulative wet and dry deposition quantities are in good agreement with snowpack accumulations until the first thaw period. Dry deposition to snow accounts for less than 15% of the total H+, SO2-4, NO-3 and NH+4 and approximately 25% of the Ca 2+, Mg 2+, Na+, K+ and Cl- during an average precipitation year. Snowpack measurements were also made under deciduous and red pine canopies. Decreases in H+ and NO-3 were observed under the red pine canopy.