title: Enhanced diffusion of polycyclic aromatic hydrocarbons in artificial and natural aqueous solutions.
abstract: Uptake of hydrophobic organic compounds into organisms is often limited by the diffusive transport through a thin boundary layer. Therefore, a microscale diffusion technique was applied to determine the diffusive mass transfer of 12 polycyclic aromatic hydrocarbons through water, air, surfactant solutions, humic acid solutions, aqueous soil and horse manure extracts, digestive fluid of a deposit-feeding worm, and root exudates from willow plants. In most cases the diffusive mass transfer of PAHs was much higher through the tested media than through water, and the enhancement factors increased with increasing hydrophobicity of the PAHs. The diffusive flux of benzo[a]pyrene was for instance enhanced 74 times through gut fluid of a deposit-feeding worm when compared to water. These findings demonstrate that a wide variety of dissolved organic carbon (DOC) at environmental levels can enhance diffusive mass transfer in various transport scenarios. The diffusive uptake of PAHs into sediment dwelling organisms is particularly efficient within the gut and at direct contract with the sediment matrix. Bioremediation might be enhanced bythe addition of auxiliary agents that enhance diffusive mass transfer. Enhanced diffusion needs also to be considered in dynamic transport models and for the operation and calibration of passive sampling techniques.
authors.affiliation: National Environmental Research Institute, University of Aarhus, P.O. Box 358, 4000 Roskilde, Denmark. phm@dmu.dk
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer
authors.forename: Margit M
authors.initials: MM
authors.lastname: Fernqvist
authors.forename: Peter S
authors.initials: PS
authors.lastname: Christensen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Karlson
authors.forename: Stefan
authors.initials: S
authors.lastname: Trapp
mesh_terms: D000327:Adsorption; D000388:Air; D000818:Animals; D001692:Biological Transport; D002244:Carbon / Q000032:analysis / Q000737:chemistry; D004058:Diffusion; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry; D006736:Horses; D006812:Humic Substances; D057927:Hydrophobic and Hydrophilic Interactions; D018517:Plant Roots / Q000737:chemistry; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006812:Humic Substances; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; D012996:Solutions; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D014867:Water; D002244:Carbon