SOURCE ATTRIBUTION OF AMBIENT AIR TOXIC AND OTHER VOCS IN COLUMBUS, OHIO

Chemical mass balance (CMB) source apportionment modeling was conducte d on a data set of 142 3 h integrated air samples collected at 6 diffe rent sites in 3 separate campaigns during the summer of 1989 in Columb us, Ohio; source contributions to 19 light hydrocarbon and toxic VOC s pecies, including formaldehyde and acetaldehyde, were modeled. Overall , the results indicated that area sources, and in particular vehicle e xhaust and organic solvent usage by small industrial/commercial facili ties, are important contributors to the major toxic VOCs measured in u rban air. In addition, the temporal resolution of the measurements all owed a number of observations regarding the short-term variability of these area sources, including diurnal trends in vehicle exhaust, gasol ine vapor, and natural gas sources. The natural gas source was identif ied as a significant source of light hydrocarbons in the Columbus area , a finding similar to that of several other recent source apportionme nt studies of VOCs in urban areas. The temporal and spatial variabilit y in gasoline vapor contributions suggested that the source is associa ted more with mobile sources (running losses, evaporative emissions fr om vehicles), rather than with fixed sites such as service stations. F inally, CMB modeled source contributions were coupled with a simple bo x model of the study area to provide estimates of the emission rates o f various area sources. The results of these calculations suggest that there are probably substantial emissions From area sources that are n ot included in current emissions inventories. Copyright (C) 1996 Elsev ier Science Ltd