Chemical deposition to a high elevation red spruce forest

A preliminary analysis of O sub(3), SO sub(2), SO sub(4) super(2) super(-), and total NO sub(3) super(-) deposition to the red spruce forest on the summit of Whitetop Mountain, Virginia, illustrates uncertainties in analysis methodologies, establishes the relative importance of three deposition pathways, and suggests areas for further research. Results are presented here for an analysis of the dry, wet (precipitation), and cloud water deposition pathways for the four chemical species during a 26-day period in April and May 1986. Dry and cloud water depositions are estimated using available models along with air and cloud water chemistry measurements made at the summit. For water soluble species, depositions by precipitation and cloud interception are found to be comparable in magnitude, while dry deposition appears to be about an order of magnitude less. High levels of atmospheric O sub(3) lead to a large estimate of O sub(3) deposition (on a mass flux basis) when compared to the estimated deposition of gaseous SO sub(2).