PAHs in the Ría de Arousa (NW Spain): A consideration of PAHs sources and abundance

- Parent and alkylated PAHs (Polycyclic Aromatic Hydrocarbons) in Ría de Arousa were investigated for the first time.
- The highest concentrations were found inside the estuary (7901 ng g−1 dry weight).
- Sources of PAHs concentrations and BaP TEQ (Benzo[a]pyrene Toxic Equivalent Quotient) were determined.
- Diagnostic ratios conclude that the main sources of PAHs are combustion processes.
- Parent high molecular weight PAHs of pyrolytic origin dominated in most locations.

Analysis of 35 parental and alkylated homologues of PAHs (Polycyclic Aromatic Hydrocarbons) was carried out in eleven marine sediment samples collected along a central transect in the biggest Galician ría. The samples were collected using a box-core dredge and, after freeze-drying, were kept frozen until analysis. The sediments were extracted by PLE (Pressurized Liquid Extraction) procedure and the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC-MS) with the aid of deuterated PAH internal standards. The total concentration of studied PAHs (Σ35PAHs) ranged from 44.8 to 7901 ng g−1 dry weight (d.w.). The highest PAH concentrations were found in sediments collected near the harbour (7901 ng g−1) and the cleanest positions were located in the outer zone of the ría.To date, these results are the first data presented in the area so they could be used for regular monitoring and control of future pollution episodes.