Study of geographical trends of polycyclic aromatic hydrocarbons using pine needles

In this work, pine needles were used as polycyclic aromatic hydrocarbons (PAHs) markers to study the PAHs distribution over several geographical locations in Portugal and over time. Four pine needle sampling campaigns (winter, spring, summer and autumn 2007) were carried out in 29 sites, covering the major urban centres, some industrial points, smaller cities, rural areas and remote locations. Needles from Pinus pinaster Ait. and Pinus pinea L trees were collected from 2005 and 2006 shoots, corresponding to one up to three years of exposure. Spatial trends of the incidence of PAHs indicate an increase from the remote to the urban and industrial sites. The mean values for the sum of 16 PAHs ranged from 96 +/- 30 ng g(-1) (dry weight) for remote sites to 866 +/- 304 ng g(-1) (dw) for industrial sites for P. pinaster needles and from 188 +/- 117 ng g(-1) (dw) for rural sites to 337 +/- 153 ng g(-1) (dw) for urban sites for P. pinea. Geographic information system tools and principal component analysis revealed that the contamination patterns of PAHs are somehow related to several socio-geographic parameters of the sampling sites. The geographical trend for the PAHs is similar between seasons in terms of PAH levels, but some diverse behaviour is found on the separation of lighter and heavier PAHs. Differences between P. pinaster and P pinea needles are stronger in terms of PAH uptake loads than in the site type fingerprints. (C) 2011 Elsevier Ltd. All rights reserved.