## 2 Materials and Methods  
### Sampling Area and Sample Pre-Treatments  
Waters, sediments and biota were sampled in the Ligurian Sea, in an offshore area (12.5 nautical miles off the Italian coast), above the continental shelf, at the border with Northern Tyrrhenian Sea, the same study area of previous research [5] and included the following stations: (i) 43\({}^{\circ}\)29\({}^{\prime}\)40\({}^{\prime\prime}\) N-10\({}^{\circ}\)01\({}^{\prime}\)45\({}^{\prime\prime}\) E, (ii) 43\({}^{\circ}\)28\({}^{\prime}\)10\({}^{\prime\prime}\) N, 10\({}^{\circ}\)01\({}^{\prime}\)55\({}^{\prime\prime}\) E and (iii) 43\({}^{\circ}\)27\({}^{\prime}\)10\({}^{\prime\prime}\) N, 10\({}^{\circ}\)03\({}^{\prime}\)00\({}^{\prime\prime}\) E (see Figure S1 of Supplementary Material). The area was considered of great interest for several reasons. In fact, it is characterized by one of the highest levels of shipping in the Mediterranean basin; moreover, a strong anthropogenic influence and impact are present due to several commercial, industrial and harbor activities. The investigated area hosts the \"Cetacean Sanctuary\", an extensive marine protected area where the number of cetaceans is at least double that of any other part of the Mediterranean. Finally, the area is subjected to a high dynamic water current equilibrium, since both perpetual and seasonal currents influence the possible dispersion and partition of micropollutants originating from the highly developed coastline of Italy.  
Two samplings were carried out for both water column and marine biota during summer 2017 and winter 2018, in order to assess the possible contribution of seasonality. For the sediment, a single sample was collected in summer 2017, due to the low effect of the seasonality on the circaltitoral mud sediments.  
Sampling methods were performed as follows: (i) water column, 5 L collection for each sampling using a PVC Niskin bottle water sampler (collected at 5 m depth). Subsequently, the samples were filtered via qualitative paper and refrigerated until analysis; (ii) sediments, sampled using a 18 L Van Veen grab sampler on the seabed at 110 m depth. Moisture evaporation (at 60 \({}^{\circ}\)C for 12 h) was performed prior to micropollutant extraction and analysis; (iii) marine biota (mesozoplankton and ichthyoplankton) was collected in a surface haul, using a WP-2 standard net (200 \(\upmu\)m mesh size and diameter 57 cm). The horizontal sampling time was approximately 15 min (2 knots vessel cruising speed). The net was fitted with a flow-meter (KC Denmark model 23.090) to measure volume of water filtered. After collection, each zooplankton sample was washed, on board first, with filtered seawater from the sampling site, in order to remove terrigenous or inorganic particles, and hence washed with distilled water. After the washing procedure, samples were immediately fixed in 70% ethanol and seawater and stored in the dark.  
In the laboratory, a qualitative-quantitative analysis of the marine biota was performed with a Leica stereomicroscope and microscope, which allowed the identification and regrouping of the following four taxa: hyperbenthic Isopoda, holoplanktonic crustaceans' copepods both herbivores and carnivorous and fish larvae (ichthyoplankton). Samples were dried at 80 \({}^{\circ}\)C for 12 h before extraction and analysis.