APPLICATION OF COMMON Y-INTERCEPT REGRESSION PARAMETERS FOR LOG KP VS1/T FOR PREDICTING GAS PARTICLE PARTITIONING IN THE URBAN-ENVIRONMENT

Gas-particle partitioning is examined using a partitioning constant K(p) = (F/TSP)/A, where F (ng m-3) and A (ng m-3) are the particulate-associated and gas-phase concentrations, respectively, and TSP is the total suspended particulate matter level (mu-gm-3). Compound-dependent values of K(p) depend on temperature (T) according to K(p) = m(p)/T + b(p). Limitations in data quality can cause errors in estimates of m(p) and b(p) obtained by simple linear regression (SLR). However, within a group of similar compounds, the b(p) values will be similar. By pooling data, an improved set of m(p) and a single b(p) can be obtained by common y-intercept regression (CYIR). SLR estimates for m(p) and b(p) for polycyclic aromatic hydrocarbons (PAHs) sorbing to urban Osaka particulate matter are available (Yamasaki et al., 1982, Envir. Sci. Technol. 16, 189-194), as are CYIR estimates for the same particulate matter (Pankow, 1991, Atmospheric Environment 25A, 2229-2239). In this work, a comparison was conducted of the ability of these two sets of m(p) and b(p) to predict A/F ratios for PAHs based on measured T and TSP values for data obtained in other urban locations, specifically: (1) in and near the Baltimore Harbor Tunnel by Benner (1988, Ph.D thesis, University of Maryland) and Benner et al. (1989, Envir. Sci. Technol. 23, 1269-1278); and (2) in Chicago by Cotham (1990, Ph.D. thesis University of South Carolina). In general, the CYIR estimates for mp and bp obtained for Osaka particulate matter were found to be at least as reliable, and for some compounds more reliable than their SLR counterparts in predicting gas-particle ratios for PAHs. This result provides further evidence of the utility of the CYIR approach in quantitating the dependence of log K(p) values on 1/T.