A

Abstract--An equation that can successfully parameterize gas-particle partitioning is Kp(m3/~g-1) =(F/TSP)/A, where Kp is a partitioning constant, TSP (pgm-3) is the concentration of total suspended particulate material, and F (ngm-3) and A (ngm-3), respectively, are the particulate-associated an gaseous concentrations of the compound of interest. By itself, this equation does not indicate whether the partitioning isprimarily adsorptive to surfaces, primarily absorptive into some phase(s), or some combina-tion thereof. Much past research as indicated that plots of log Kp vs log p O (compound vapor pressure) tend to be highly correlated, with slopes near- 1. Such correlation isconsistent with (though not proof of) adsorption. The governing equations are now developed for absorptive partitioning into an organic material (om) phase making up part of the TSP. The equations indicate that absorptive partitioning could well be an important sorption mechanism inthe urban environment. Plots of log Kp vs log pO are predicted to be linearly correlated when the sorption is absorptive, just as earlier theoretical work predicted such correlatability when the sorption is adsorptive. In the general case, observed Kp values may contain contributions from both mechanisms. Regardless of the relative importance of adsorptive vs absorptive partitioning in any given situation, aplot of log Kp values vs log p ° Lvalues will be correlated with a slope of near- 1