Synergy between Secondary Organic Aerosols and Long-Range Transport of Polycyclic Aromatic Hydrocarbons
| Autor: | Josef Beranek, Alla Zelenyuk, J. M. Wilson, ManishKumar Shrivastava, D. Imre, Evan H. Abramson |
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| Rok vydání: | 2012 |
| Předmět: |
Aerosols
Air Pollutants Range (particle radiation) Volatilisation Secondary organic aerosols Evaporation General Chemistry Mass Spectrometry Dilution Aerosol chemistry.chemical_compound Adsorption Models Chemical chemistry Environmental chemistry Environmental Chemistry Particle Gases Polycyclic Aromatic Hydrocarbons Volatilization Oxidation-Reduction |
| Zdroj: | Environmental Science & Technology. 46:12459-12466 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/es302743z |
| Popis: | Polycyclic aromatic hydrocarbons (PAHs), known for their harmful health effects, undergo long-range transport (LRT) when adsorbed on and/or absorbed in atmospheric particles. The association between atmospheric particles, PAHs, and their LRT has been the subject of many studies yet remains poorly understood. Current models assume PAHs instantaneously attain reversible gas-particle equilibrium. In this paradigm, as gas-phase PAH concentrations are depleted due to oxidation and dilution during LRT, particle-bound PAHs rapidly evaporate to re-establish equilibrium leading to severe underpredictions of LRT potential of particle-bound PAHs. Here we present a new, experimentally based picture in which PAHs trapped inside highly viscous semisolid secondary organic aerosol (SOA) particles, during particle formation, are prevented from evaporation and shielded from oxidation. In contrast, surface-adsorbed PAHs rapidly evaporate leaving no trace. We find synergetic effects between hydrophobic organics and SOA - the presence of hydrophobic organics inside SOA particles drastically slows SOA evaporation to the point that it can almost be ignored, and the highly viscous SOA prevents PAH evaporation ensuring efficient LRT. The data show the assumptions of instantaneous reversible gas-particle equilibrium for PAHs and SOA are fundamentally flawed, providing an explanation for the persistent discrepancy between observed and predicted particle-bound PAHs. |
| Databáze: | OpenAIRE |
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