Atmospheric Gas-Particle Partitioning of Polycyclic Aromatic Hydrocarbons in High Mountain Regions of Europe

• Published in: Environmental science & technology 2002-03, Vol.36 (6), p.1162-1168
• Main Authors: Fernández, Pilar, Grimalt, Joan O, Vilanova, Rosa M
• Format: Article
• Language: English
• Subjects: Absorption; Aerosols; Air Pollutants - analysis; Air pollution; Applied sciences; Atmosphere; Atmospheric pollution; Carbon - chemistry; Environmental Monitoring; Europe; Exact sciences and technology; Gases; Hydrocarbons; Particle Size; Pollution; Pollution sources. Measurement results; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - analysis; Polycyclic Aromatic Hydrocarbons - chemistry; Volatilization
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es010190t

Atmospheric concentrations and gas-particle partitioning of polycyclic aromatic hydrocarbons (PAH) have been determined at three remote mountain areas in Europe. Gas-phase mean concentrations of total PAH (20 individual compounds) were very similar at all sites, ranging from 1.3−2.6 ng m-3 in the Pyrenees (Spain) to 2.7−3.7 ng m-3 in the Alps (Austria) and Caledonian mountains (Norway). A seasonal variability was observed, with the highest levels found in winter. The seasonal differences were reflected better in the particle-associated PAH, showing the increase of PAH emissions in the colder months and a temperature dependence of the gas-particle partitioning. Significant geographical differences were also observed for particulate PAH, indicating a greater influence of regional sources than in the gas phase. Partitioning of PAH between gas and particulate phases was well-correlated with the subcooled liquid vapor pressure in all samples, but with slopes significantly steeper than the expected value of −1. These steeper slopes may reflect the occurrence of a nonexchangeable PAH fraction in the aerosols, likely associated to the soot carbon phase. Comparison of absorption to organic matter and soot carbon using the octanol−air (K oa) and soot−air (K sa) partitioning coefficients shows that, despite uncertainties on estimated organic matter and soot carbon contents in the sampled aerosols, K oa underpredicts aerosol PAH concentrations by a factor of 0.6−2 log units. In contrast, predicted and measured high mountain aerosol PAH differ by 0.2−0.6 log units when K sa is considered. The results point to soot carbon as the main transport medium for the long-range distribution of aerosol-associated PAH.