Vertical distribution of PAHs in marine sediments (particulate fraction and interstitial water) from eight Iberian Mediterranean areas

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have been determined in sediment cores from eight Iberian Mediterranean coastal areas (Barcelona, Tarragona, Ebro Delta, Valencia, Castellón, Cartagena, Almería y Málaga), considering both interstitial water and solid fraction. Three sediment cores were taken in three different sampling sites per area by using a box corer. Cores were cut into 1-cm-thick sections between 0 and 18-cm depth, interstitial water was obtained by centrifugation and samples from every site were pooled. Fourteen polycyclic aromatic hydrocarbons (fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, crysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[g,h,i]perylene, dibenzo[a,h]anthracene and indeno[1,2,3-c,d]pyrene) were determined in interstitial water by stir bar sorptive extraction coupled to GC/MS and solid fraction by Soxhlet extraction and HPLC with fluorescence detection. As result of PAHs hydrofobicity, their concentrations were several magnitude order higher in sediment (solid phase) than interstitial water. Total PAH concentration in sediment varied from 1 to 1321 g•kg-1 d.w and from 4.9 to 274 ng•L-1 in interstitial water. Vertical PAHs distributions in sediments were homogeneous in some areas, however, sharp concentration decreases were observed at deeper layers from some sampling sites. However, their maximum concentrations in interstitial water were found mainly in upper or in deeper layers, depending on the specific characteristics of the area and sediments.