## 4 Conclusions  
This work represents the first study devoted to the comprehensive investigation of 16 PAHs and 14 PCBs (including dioxin-like congeners) in the seawater, sediment and biota of the Ligurian Sea. For both PAHs and PCBs, the overall results indicate that the contamination levels are equivalent to those typically found in other areas of the Mediterranean Sea characterized by moderate to high pollution. Moreover, this study reveals that PAHs origin is mainly ascribed to pyrogenic activities (combustion, transport, etc). A seasonal trend was observed for the presence of PAHs and PCBs in seawater, since micropollutant concentrations measured in summer were higher than those measured in winter, in agreement with increased touristic and harbor activities and with the higher stratification of water layers. Micropollutant partition between water and sediment was confirmed to be influenced by the hydrophobicity of the pollutant molecules. To elucidate, higher molecular weight pollutants were preferentially detected in sediment, with organic matter acting as adsorbent. Bioaccumulation on biota was also assessed for copepods. In addition, partition pathways were investigated within four different taxa (hyper-benthic Isopoda, herbivores and carnivorous holoplanktonic crustaceans copepods and fish larvae-ichthyoplankton), by the calculation of BAF values. The effects of living habits were shown to strongly influence bioaccumulation, as the congeners detected in sediment were preferentially discovered in taxa that spent most of their lives there. Moreover, feeding habits were found to influence the bioaccumulation of PAHs and PCBs, and a positive correlation between BAF values and hydrophobicity was confirmed. This study performed in the Southern Ligurian Sea, provides a novel insight into PAH and PCB distribution in marine zooplankton, which represents the main food constituent of most fish of the coastal waters, thus playing an important role in the transfer of pollutants through the food web. The experimental approach here followed can be transposed to other geographical areas of strategic importance to understand peculiar distributions patterns. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12052564/s1](https://www.mdpi.com/article/10.3390/app12052564/s1)]([https://www.mdpi.com/article/10.3390/app12052564/s1](https://www.mdpi.com/article/10.3390/app12052564/s1)), Figure S1. Ligurian Sea (Western Mediterranean): study area and location of sampling stations; Figure S2: average (\(n=3\)) PAH and PCB recoveries from seawater samples. Recoveries were calculated using surrogates as described in the Materials and Methods Section; Figure S3: average (\(n=3\)) PAH and PCB recoveries from sediment samples. Recoveries were calculated using surrogates as described in the Materials and Methods Section; Figure S4: average (\(n=3\)) PAH and PCB recoveries from biota samples. Recoveries were calculated using surrogates as described in the Materials and Methods Section; Table S1: MDL and MQL of PAHs in seawater, sediment and biota, using optimized analytical protocols, compared with their regulation limits reported by 2013/39/EU normative and Italian Legislative Decree 172/2015; Table S2: MDL and MQL of PCBs in seawater, sediment and biota, using optimized analytical protocols, compared with their regulation limits reported by 2013/39/EU normative and Italian Legislative Decree 172/2015. Conceptualization, L.R., M.C., N.N. and M.C.B. ; Formal analysis, M.C. ; Funding acquisition, M.C.B. ; Investigation, L.R., N.N., M.B., R.M.S. and M.C.B. ; Methodology, L.R., M.C., N.N. and M.C.B. ; Project administration, M.C.B. ; Supervision, M.C.B. ; Validation, L.R. and M.C. ; Visualization, M.B., L.F. and M.C.B. ; Writing--original draft, L.R. ; Writing--review and editing, L.R., N.N., R.M.S. and M.C.B. All authors have read and agreed to the published version of the manuscript. This research was funded by Ministero dell'Universita e della Ricerca, Ex60%. Not applicable.