## 3 Materials and Methods
### Inorganic Geochemistry
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **Unit** & \
\begin{tabular}{c} **Marine** \\ **Shales (1)** \\ \end{tabular} &
\begin{tabular}{c} **Local** \\ **Background** \\ \end{tabular} & **L1 DM** & **L2 DM** & **DM** & **TL2 DM** & **DM** & **TEL** & **ERL** & **PEL** & **ERM** \\ \hline Ag & ppm & 0.07 & & & & & 1 & & & \\ Al & \% & 8 & 6.9 & & & 1 & & & & \\ As & ppm & 13 & 10 & 12 & 20 & 1 & 5.9 & 33 & 17 & 85 \\ Ba & ppm & 580 & 295 & & & & & & & \\ Be & ppm & 3 & & & & & & & & \\ Ca & \% & 1.6 & 11 & & & & & & & \\ Cd & ppm & 0.3 & & 0.3 & 0.8 & 0.03 & 0.6 & 5 & 3.53 & 9 \\ Co & ppm & 19 & 13 & & & & & & & \\ Cr & ppm & 90 & 128 & 50 & 150 & 1 & 37 & 70 & 90 & 145 \\ Cu & ppm & 45 & 40 & 40 & 52 & 1 & 36 & 70 & 197 & 390 \\ Fe & \% & 4.72 & 3.5 & & & 1 & & & & \\ Ga & ppm & 19 & 16.2 & & & & & & & \\ Hg & ppm & 0.04 & & & 0.3 & 0.8 & 0.03 & 0.2 & 0.2 & 0.49 & 1.3 \\ K & \% & 2.66 & 1.6 & & & & & & & \\ Li & ppm & 66 & 2.2 & & & & & & & \\ Mg & \% & 1.5 & & & & & & & & \\ Mn & ppm & 850 & 774.5 & & & & & & & \\ Mo & ppm & 2.6 & & & & & & & & \\ Na & \% & 0.96 & & & & & & & \\ Nb & ppm & 11 & & & & & & & & \\ Ni & ppm & 68 & 73 & 30 & 75 & 1 & 18 & 30 & 36 & 50 \\ P & ppm & 700 & 0.06 & & & & & & & \\ Pb & ppm & 20 & 18 & 30 & 70 & 1 & 35 & 35 & 91.3 & 110 \\ S & ppm & 2400 & n.a & & & & & & & \\ Sc & ppm & 13 & 29 & & & & & & & \\ Sr & ppm & 300 & 348 & & & & & & & \\ Te & ppm & 0.08 & n.a & & & & & & & \\ Ti & ppm & 4600 & 0.3 & & & & & & & \\ V & ppm & 130 & 116 & & & & & & & \\ Y & ppm & 26 & 25 & & & & & & \\ Zn & ppm & 95 & 48 & 100 & 150 & 1 & 123 & 120 & 315 & 270 \\ Zr & ppm & 160 & 97 & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Reference values, local background, normative limits and ecotoxicological reference concentrations for the elements investigated in the present study, when available 1 [70]. Contamination factor (C\({}_{f}\)). The C\({}_{f}\)[5] is an index developed to evaluate the contamination of a given toxic substance in a basin, and it is calculated as:  
\[\text{C}_{fi}\ =\ \frac{\text{C}_{ei}}{\text{C}_{bi}} \tag{1}\]  
where C\({}_{ei}\)is the concentration of the substance \(i\) in sediment samples, and C\({}_{bi}\) is the background values of the same substance indicated in Table 2. In this work, the C\({}_{fi}\) was calculated for all elements even if only trace elements that may be affected by human activities (As, Ba, Co, Cr, Cu, Ni, Pb, V, and Zn) or that can be indicative of peculiar processes (Ga, Sc, Sr, Y, and Zr) have been discussed. The background values (C\({}_{bi}\)) of the element \(i\) and of the other elements not considered for the calculation of C\({}_{fi}\) (Table 2) were deduced by using the concentrations in the sample collected at a depth of 105 cm of the sediment core 47 recovered in the study area (Figure 2a, green star) during the PRISMA1 project [4]. The element concentration in the core of the PRISMA1 project were determined by XRF following the method specified in [5] so that the concentrations can be compared to those determined by strong acid dissolution, both referring to the total concentrations. The core 47 is located inside the study area and the level 105 is referred to a time previous the industrial age as deduced by the radiometric and metal anthropogenic data of the PRISMA1 and by the accumulation rates determined in this area by previous studies [72] so that is not affected by anthropic inputs. Furthermore, by the normalization respect to the Al or Ti content determined in the same sample, it can be compared to samples with different grain size composition. Other methods such as those used in an area in front of the Abruzzo coast [73] can be useful applied when available only superficial samples. Enrichment factor (EF). The EF has been developed to evaluate the metal contamination.