The potential role of mechanistic models for interpreting passive air sampling data for semi-volatile organic chemicals.

ARMITAGE, JAMES; WANIA, FRANK; SILVA BARNI, MARÍA FLORENCIA

Orlando

Congreso; 7th SETAC World Congress SETAC North America 37th Annual Meeting; 2016

Passive air sampling is now well-established in the contaminant monitoringcommunity and there are a variety of passive air sampler (PAS) designsdescribed in the literature. Although PAS can differ with respect to samplermaterial (e.g., polyurethane foam, XAD resin, activated carbon felt, polyethylene,polydimethylsiloxane) and housing (e.g., none, ?flying saucer?,cylindrical), the uptake and depuration kinetics are typically assumedto conform to the same theoretical model (Whitman Two-Film Theory).However, as the old aphorism goes, ?All models are wrong but some areuseful?. Potential errors inherent to any modeling approach relate not onlyto the validity of the assumptions made (e.g., air-side resistance dominatesexchange) but also the reliability of required input parameters (e.g., samplerairpartition coefficients and their temperature-dependence). The mainobjective of this presentation is to examine the underlying assumptionsadopted in the PAS community with respect to uptake and depuration kineticsof semi-volatile organic chemicals (SVOCs) using the modeling tooldeveloped within our research group (PAS-SIM). Insights from previousmodel evaluations using concurrent passive XAD-2 and active air samplingdata are highlighted along with simulations of depuration compounds underdifferent environmental conditions (e.g., temperature profiles and windspeeds). These model applications are used to discuss the advantages anddisadvantages of applying mathematical tools to convert the mass of chemicalaccumulated on a PAS during deployment to air concentrations and alsoto identify key data gaps and research needs in this area.