GAS-TO-PARTICLE PARTITIONING OF POLYCYCLIC AROMATIC-HYDROCARBONS IN AN URBAN ATMOSPHERE

Semi-volatile organic compounds (SOCs) are present in the atmosphere a s vapors and are adsorbed to particulate matter. Knowledge of the gas- to-particle distribution of these compounds is important in understand ing their atmospheric fate and transport. A baseline experimental stud y to estimate the vapor- and particle-phase-associated concentrations of the SOCs (specifically, polycyclic aromatic hydrocarbons, PAHs) in the Baton Rouge (Louisiana) air was carried out. A comparison of the l evels of concentrations of PAHs obtained in Baton Rouge to those obtai ned in other parts of the world is made. The sampling artifacts associ ated with a traditional high-volume sampler introduced errors in the e stimation of the partition coefficient. Different air sampling procedu res (a modified low-volume sampler and an annular denuder) were evalua ted in order to obtain a more accurate measure of the gas-to-particle partition coefficient. The effects of temperature and precipitation on the partitioning of PAHs between the vapor and particulate phase were ascertained.