| Abstract
| - Polycyclic aromatic hydrocarbons (PAHs) were determinedin the suspended particulate matter (SPM) (21 surface and6 vertical profiles) and in the dissolved phase (DP) (7sampling sites) of the western Mediterranean seawater.Terrigenous inputs were recognized by the co-occurrenceofperylene (SPM) and trimethyl-1,2,3,4-tetrahydrochrysenes(SPM and DP) collected at the major river plumes. ThePAH patterns in the SPM (>0.7 μm) and DP (<0.7 μm)phaseswere dominated by the three-ring aromatics (i.e., phenanthrene, dibenzothiophene, and their alkylated derivatives),reflecting a predominant contribution of fossilhydrocarboninputs. Only the DP collected at the continental shelfandslope (fluoranthene), presumably of pyrolytic origin,predominated. PAHs associated with SPM were evenlydistributed in subsurficial waters, and theirconcentrationsranged from 200 to 750 pg L-1, respectively,maximizingat the Gibraltar and Sicilian Straits and at a frontalzonelocated midway between the Iberian Peninsula and theBalearic Islands. Vertical PAH profiles associated withtheSPM exhibited a surface-enrichment depth-depletiondistribution where the concentration maxima were locatedat the 20−30 m depth concurrently with fluorescenceattributable to biomass uptake or adsorption to organicrichdetritus. An enrichment in PAHs in the deeper samplesof vertical profiles was found in stations collected nearsubmarine canyons and at the sewage disposal zoneattributable to advective transport of particles.Concurrently,a higher depletion of the three-ring aromatic PAHs incomparison with the four−five-ring aromatics accordingto depth was ubiquitously found. Budget of PAHs in theSPMand DP was estimated according to a three-box modelto be 335 and 372 t, respectively, and their residencetimein the continental shelf and in the open sea were 0.95and 6.5 yr, respectively.
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