Concentrations and source characterization of polycyclic aromatic hydrocarbons in pine needles from Korea, Mexico, and United States

Pine needle samples were collected from Korea, Mexico, and the United States (total 9 sites) to compare the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations ranged from 31 to 563 ng g(-1) (wet wt.) and showed clear differences between rural (clean) and urban/industrialized (contaminated) sites. The lowest and highest concentrations were found in samples from a rural site in Korea and northern part of Mexico City, respectively. The PAH distribution patterns and the ratio of the sum of combustion specific PAHs (SigmaCOMB) to total PAHs (SigmaPAHs) in samples from Korea and United States were similar, implying similar sources. At these sites, three-ring PAHs accounted for 63-73% of the total PAHs and phenanthrene was the predominant compound. Samples from Mexico City, however, had different PAH patterns and much higher SigmaCOMB/SigmaPAHs ratios (0.70 and 0.73). Four-ring PAHs were dominant (similar to50%) and pyrene was the most abundant compound. Phenanthrene to anthracene and fluoranthene to pyrene ratios may provide an additional indication of different sources. The ratios of methylphenanthrene to phenanthrene suggest that the contribution of diesel-operated vehicles to the signature of PAHs is more significant in samples from Mexico City than other sites. Enriched high molecular weight PAHs and the ratios of some selected compounds found in Mexico City samples may be the results of more extensive combustion activities and a higher proportion of non-catalyst-equipped vehicles. This study confirms the usefulness of pine needles for source characterization as well as atmospheric organic contaminants monitoring on large spatial scales (e.g., national or global). (C) 2003 Elsevier Science Ltd. All rights reserved.