Analysis of VOC data in support of pollutat transport studies in shasta county, calfiornia

摘要

The Shasta County Air Pollution Control Districict (California) has funded a study to investigate the orignin and extent of ozone and ozone precursor concentrations that are due to upwind transoprt. As a prt of the study, air quality measurements were made aloft during September 1995. Hydrocarbon measurements were made aloft for use as tracters of opportunity for analyzing the source of the air mass. Total nonmethane hydrocarbon, speciated hydrocarbons, and "exotics" including Fecon 12, Freon 11, Freon 113, chloroform, 1, 1, 1-trichloroethane, carbon tetrachloride, trichlorethylene, and perchloroethlene were quantified. In earlier studies of transport in this region, a hydrocarbon and exotic species signature for the Sacramento metropolitan area was identified. This signature was compared to the s ignatures developed from samples collected in Shasta County to determine evidence of transport. The relative age of air parcels entering the area were also determined using the ratios of more reactive species to less reactive species concentrations; lower ratios correspond to more aged hydrocarbon mixtures. This paper disucsses the analyses of the hydrocarbon and exotics data and the implications of the results to transport in the region.