Analysis of airborne particles sampled in the southern Appalachian mountains

Abstract

Over 3 yr of particulate measurements were made at two high elevation sites in the southern Appalachian Mountains of Tennessee and Virginia. Both dichotomous samplers and filter packs were used to obtain day and night, week-long samples for subsequent elemental and ionic analysis. Total No ^sup−_inf3 (HNO₃ + No ^sup−_in3 ) and SO ^sup2−_inf4 averaged, respectively, 1.1 and 5.0 µg m⁻³ at Look Rock, Tennessee and 2.0 and 6.4 µg m⁻³ at Whitetop Mountain, Virginia. At Whitetop Mountain, the spring and summer seasons had the highest average SO ^sup2−_inf4 concentrations. Seasonally, total N03 varied little. The diurnal variation of elements and SO ^sup2−_inf4 was small. Only total NO ^sup−_inf3 varied substantially with highest values during the day. The fine fraction (particle diameter < 2.5 µm) accounted for about 67% of the total mass. Fine mass and elemental concentrations were generally higher at Look Rock. The elements comprising the principal mass fraction of the coarse samples (2.5 gm < particle diameter < 10 to 15 µm) were of crustal origin (e.g., Al, Si, Ca, Fe) while the element comprising the principal mass fraction of the fine samples (i.e., S) was of manmade origin. Cluster analysis identified two groups of elements at Whitetop Mountain. These groups, in both the coarse and fine fraction, were associate with a soil and an automobile emission component. At Look Rock, only a soil component was obvious.