## 4 Results and Discussion  
A summary of statistics of the investigated variables is reported in Table 3. Selected chemical elements (i.e., Cd, Sb, Tl, U, W) have not been considered as their concentrations were either below the detection limits or above detection limits in a very limited number of samples (in parenthesis after the element): Bi (1), Hg (2).  
Table 3 also includes information about Ag (9), Mo (16), Te (19), Be (29), and As (41) although they were not observed in some of the samples. All these elements were excluded from the multivariate statistical analysis (the complete dataset is reported in Supplemental Table S1). Table 2 presents some reference values used in the discussion, the background concentrations considered for some elaborations, regulatory values and the ecotoxicological sediment values. Meanwhile, Table 4 includes basic statistics relative to the various indexes calculated for describing the sediment status.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline  & **Unit** & **Mean** & **Median** & **Min** & **Max** & **Dev. St** & \(n\) \\ \hline Water content & \% & 35.8 & 36.4 & 20.2 & 59.1 & 11.3 & 64 \\ Porosity & \% & 56.3 & 58.2 & 38.1 & 77.9 & 11.9 & 64 \\ Bioclasts & \% & 1.1 & 0.1 & 0.0 & 19.6 & 3.1 & 64 \\ Sand & \% & 33.5 & 17.3 & 0.2 & 96.7 & 34.2 & 64 \\ Silt & \% & 34.9 & 38.1 & 2.4 & 61.8 & 18.5 & 64 \\ Clay & \% & 30.5 & 31.7 & 0.8 & 66.2 & 19.9 & 64 \\ TN & \% & 0.1 & 0.1 & 0.0 & 0.1 & 0.0 & 64 \\ IC & \% & 4.3 & 4.4 & 3.1 & 5.5 & 0.6 & 64 \\ OC & \% & 0.4 & 0.4 & 0.1 & 1.0 & 0.2 & 64 \\ \(\delta^{13}\)CPDB & \%e & \(-24.0\) & \(-23.7\) & \(-26.4\) & \(-21.2\) & 0.8 & 64 \\ OC/TN & & 8.8 & 8.5 & 4.9 & 11.5 & 1.2 & 64 \\ carbonates & \% & 3.7 & 3.6 & 2.4 & 5.9 & 0.7 & 63 \\ pH & & 7.3 & 7.3 & 6.8 & 8.1 & 0.3 & 64 \\ Eh & mV & \(-98.1\) & \(-125.9\) & \(-250.0\) & 143.7 & 88.3 & 64 \\ Ag & ppm & 0.2 & 0.2 & \(<\)0.3 & 1.6 & 0.2 & 9 \\ Al & \% & 4.0 & 3.7 & 2.5 & 6.0 & 1.2 & 48 \\ As & ppm & 9.1 & 9 & \(<\)3 & 31 & 5.8 & 41 \\ Ba & ppm & 272.8 & 271 & 234 & 329 & 21.6 & 48 \\ Be & ppm & 1.1 & 1 & \(<\)1 & 2 & 0.6 & 29 \\ Ca & \% & 12.8 & 13.55 & 8.9 & 15.4 & 2.1 & 48 \\ Cd & ppm & & \(<\)0.3 & & & 0 \\ Co & ppm & 7.8 & 7 & 3 & 13 & 3.2 & 48 \\ Cr & ppm & 61.5 & 61 & 27 & 101 & 15.9 & 48 \\ Cu & ppm & 14.4 & 12 & 3 & 32 & 8.0 & 48 \\ Fe & \% & 1.9 & 1.7 & 0.79 & 3.3 & 0.8 & 48 \\ Ga & ppm & 12.3 & 12.5 & 5 & 22 & 5.2 & 48 \\ Hg & ppm & 0.6 & 0.5 & 0.5 & 2.0 & 0.3 & 2 \\ K & \% & 1.4 & 1.24 & 1 & 2.4 & 0.4 & 48 \\ Mg & \% & 1.2 & 1.095 & 0.58 & 2.0 & 0.5 & 48 \\ Li & ppm & 26.8 & 23 & 8 & 53 & 14.8 & 48 \\ Mn & ppm & 703.9 & 714.5 & 506 & 873 & 67.6 & 48 \\ Mo & ppm & 1.1 & 0.5 & \(<\)1 & 4.0 & 1.0 & 16 \\ Na & \% & 1.6 & 1.52 & 1.02 & 2.4 & 0.3 & 48 \\ Ni & ppm & 32.7 & 28.5 & 10 & 63 & 17.3 & 48 \\ P & \% & 0.0 & 0.049 & 0.026 & 0.1 & 0.0 & 48 \\ Pb & ppm & 12.1 & 11 & 6 & 24 & 4.7 & 48 \\ S & ppm & 0.2 & 0.2 & 0.14 & 0.4 & 0.0 & 48 \\ Sc & ppm & 6.8 & 6.5 & \(<\)4 & 12 & 3.0 & 42 \\ Sr & ppm & 352.9 & 354 & 280 & 436 & 34.0 & 48 \\ Te & ppm & 3.0 & 1 & 1 & 12 & 3.0 & 19 \\ Ti & \% & 0.2 & 0.185 & 0.11 & 0.3 & 0.0 & 48 \\ V & ppm & 49.4 & 44.5 & 14 & 105 & 26.8 & 48 \\ Y & ppm & 13.7 & 14 & 9 & 16 & 1.7 & 48 \\ Zn & ppm & 49.0 & 45 & 15 & 93 & 25.2 & 48 \\ Zr & ppm & 35.3 & 35.5 & 11 & 60 & 13.8 & 48 \\ \hline \end{tabular}
\end{table}
Table 3: Summary statistics for the investigated variables.