EVALUATION OF PRECIPITATION SAMPLERS FOR ASSESSING ATMOSPHERIC FLUXES OF TRACE ORGANIC CONTAMINANTS

Four automated, wet-only integrating precipitation samplers were deployed at a site 50 km north of Minneapolis, MN in 1986 to assess the ability of each to collect and isolate selected semi-volatile organic chemicals in rain. The four samplers were evaluated on the basis of rainfall collection efficiency, mechanical reliability and ability to provide precise measures of concentrations and fluxes. Rain samples were analyzed for about 70 compounds including 17 PAHs, 38 PCB congeners and suite of 9 chlorinated pesticides and benzenes. The samplers performed about equally in rain and compound collection efficiency although mechanical problems are not uniform amongst samplers. All samplers exhibited organic compound retention on the collection surface and/or sampling train averaging 26% of the PAH and 40% of total PCBs. Although not a problem in assessing total concentrations and fluxes, this phenomenon makes the determination of organic compound speciation and of atmospheric removal processes in integrated rain samples problematic.