Atmospheric gas-particle partitioning of polycyclic aromatic hydrocarbons in high mountain regions of Europe.
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 (Koa) and soot-air (Ksa) partitioning coefficients shows that, despite uncertainties on estimated organic matter and soot carbon contents in the sampled aerosols, Koa 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 Ksa is considered. The results point to soot carbon as the main transport medium for the long-range distribution of aerosol-associated PAH.
Fernández
Pilar
P
Department of Environmental Chemistry, Institute of Chemical and Environmental Research, CSIC, Barcelona, Catalonia, Spain. pfrqam@iiqab.csic.es
Grimalt
Joan O
JO
Vilanova
Rosa M
RM
D000042:Absorption; D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000737:chemistry; D004784:Environmental Monitoring; D005060:Europe; D005740:Gases; D010316:Particle Size; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry; D014835:Volatilization
D000336:Aerosols; D000393:Air Pollutants; D005740:Gases; D011084:Polycyclic Aromatic Hydrocarbons; D002244:Carbon