CONTRIBUTION OF SEMI-VOLATILE ORGANIC MATERIAL TO AMBIENT PM2.5

Both annual 24-h average and seasonal diurnal samples collected at NETL during the research program have been analyzed. The fine particulate components determined include PM{sub 2.5} mass, ammonium sulfate, ammonium nitrate, elemental and organic carbonaceous material and trace elements. The analysis of the nitrate and organic material includes both the identification of nonvolatile material retained by the particle collection filter and semi-volatile material lost from the particles during sample collection. The results obtained in these analyses indicate that both the semivolatile and nonvolatile organic material in the fine particles sampled at the NETL site originate from mobile emissions in the local area. However, the majority of the nonvolatile material is associated with primary emissions and the majority of the semi-volatile material is secondary, being formed from photochemical processes in the atmosphere. In contrast, the fine particulate sulfate does not originate from the local area but is transported into the study region, mostly from sources in the Ohio River Valley. These observations have been supported by both detailed meteorological and apportionment analysis of the data