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In this study we explore the processes of sorption and mobility in experimental soil columns in order to assess the response of natural soils to a hypothetical increase of pollution. The soils were sampled in a forest catchment situated in the Bertiz Natural Park at the western end of the Pyrenees. 21 columns, reproducing 21 soil profiles, were treated with a solution of heavy metals four times more concentrated than under actual conditions of deposition. An undisturbed soil column was tested simultaneously. The competition between cations and the content of clay and oxi-hydroxide compounds in the soils were the main factors determining the mobility of metals along with the influence of temperature. Calculated distribution coefficients show retention of Cr 3+ Cu 2+ , and As 5+ , and in a lesser extent of Pb 2+ and leaching of Mn 2+ , Zn 2+ , Cd 2+ and Ni 2+. Consequently, Mn 2+ and Zn 2+ have a greater tendency to contribute to groundwater pollution, whereas Cr 3+ and Cu 2+ are more likely to remain on soil surface. In undisturbed soil column, Ni 2+ and Zn 2+ were preferably sorbed onto dissolved organic matter (DOC), and the sorption of Mn 2+ Cu 2+ and Zn 2+ was controlled by the ambient temperature. The simulation shows the presence of weakly sorbed metals and of others clearly desorbed (Ni 2+ , Cd 2+ and Pb 2+), which suggests that in the near future they will reach groundwater becoming a risk for its quality and for the biota. This kind of experiments in disturbed soils did not prove to be successful, hence their analysis in undisturbed soils is suggested.

The concentrations of 15 selected polycyclic aromatic hydrocarbons (PAHs) were determined in daily PM10 samples collected at a rural site, an urban site and a traffic site in Navarra during 2009. PAHs were extracted by microwave-assisted extraction (MAE) from the corresponding quartz filters and later analyzed by gas chromatography/mass spectrometry (GC/MS). An intensive annual study was enabled with this analytical procedure as turnover is multiplied by 50 with MAE in comparison with the classical extraction technique (Soxhlet). The annual average total concentrations of the 15 target compounds ranged from 0.6 ng m-3 to 1.2 ng m-3 at the rural and traffic sampling stations respectively, showing up to four times higher PAHs concentrations in winter than in summer. When compared to other European cities, Pamplona registered significantly lower PAHs values. Other pollutants like NOx, CO and PM10 were found to be well correlated with PAHs, and O 3 presented a negative correlation. The results of diagnostic ratios and principal component analysis (PCA) revealed the high influence of diesel and gasoline emissions in the three studied areas, although, other main sources were also found.