Mass transfer coefficients for polycyclic aromatic hydrocarbons (PAHs) to the water surface sampler: comparison to modeled results

A sampling program was conducted between dune and October 1995 in Chicago, IL using a modified water surface sampler (WSS) and dry deposition plates t o measure the particulate dry deposition and gas exchange of PAHs. Oxygen t ransfer experiments were also conducted to evaluate the collection properti es of the WSS for gas-phase compounds. Gas-phase fluxes were determined by subtracting the dry deposition plate fluxes (particulate) from WSS fluxes ( particulate + gas). These fluxes were divided by concurrently measured ambi ent concentrations to obtain overall gas phase mass transfer coefficients. Two different two-film models, one developed based on experiments performed with the WSS and, one previously published, were compared to these results . Experimentally determined average gas phase overall mass transfer coeffic ient (K-g) for seven PAHs was 0.74 +/- 0.52 cm s(-1). Experimental K-g valu es agreed well with those predicted by the model developed for WSS, The val ues predicted by previously proposed models were within a factor of 3 of th e experimental ones. (C) 2001 Elsevier Science Ltd. All rights reserved.