LABORATORY INVESTIGATIONS OF THE PARTITIONING OF ORGANOCHLORINE COMPOUNDS BETWEEN THE GAS-PHASE AND ATMOSPHERIC AEROSOLS ON GLASS-FIBER FILTERS

An experimental system was designed to equilibrate urban air particulate matter on a glass fiber filter (GFF) with gas-phase organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) at controlled temperature, humidity, and vapor concentrations. Particle-loaded filters (PLFs) were backed up by clean filters (CFs) to correct for gaseous semivolatile organic compound (SOC) adsorption to the filter matrix. Analysis of the CF indicated the presence of a complex mixture of alkanes and other organic compounds in addition to the OC pesticides introduced in the experiment. Gaseous OC adsorption was very low when two CFs were used in series instead of a PLF followed by a CF. Our interpretation is that organic compounds present on the PLF bleed off and are adsorbed by the backup CF, where they act as a stationary phase to cosorb the gaseous OCs. This artifact limits the use of filter-adsorbent samplers for estimating gas/particle distributions in the atmosphere. Relative humidity in the 30-95% range had little effect on OC adsorption to the particles. Experiments at 0-30-degrees-C yielded heats of desorption, which ranged from 72 to 130 kJ mol-1.