## 5 Conclusions  
The present work analyzes the bottom sediments in front of the Marche Region by using a multi-proxies and integrated approach. This allows us to recognize and to map the distribution of three main sedimentological and geochemical facies: the _Padanic Facies_ (BSF1), the _Coastal Facies_ (BSF2) and the _Residual Facies_ (BSF3). The Padanic BSF1 _Facies_ \begin{table}
\begin{tabular}{c c c} \hline \hline
**Element** &
\begin{tabular}{c} **Present Average Values** \\ **(ppm)** \\ \end{tabular} & \multicolumn{1}{c}{**Background Values (ppm)**} \\ \hline \hline  & (a) & \\ \hline Al & 4.03 & 6.9 \\ Ti & 0.2 & 0.3 \\ P & 0.05 & 0.06 \\ Co & 7.8 & 13.0 \\ Cr & 61.5 & 128.0 \\ Cu & 14.4 & 40.0 \\ Fe & 1.93 & 3.49 \\ Ga & 12.3 & 16.2 \\ K & 1.43 & 1.64 \\ Mg & 1.23 & 2.22 \\ Mn & 703.9 & 774.5 \\ Ni & 32.7 & 73.0 \\ P & 0.05 & 0.06 \\ Pb & 12.1 & 18 \\ Sc & 7.4 & 29.0 \\ Ti & 0.19 & 0.32 \\ V & 49.4 & 116.0 \\ Y & 13.7 & 25.0 \\ Zn & 49.0 & 74.0 \\ \hline  & (b) & \\ \hline Ca & 12.0 & 10.0 \\ Sr & 353.0 & 348.0 \\ \hline  & (c) & \\ \hline Ce & & 59 \\ Fe & & 3.49 \\ Nb & & 1.65 \\ Rb & & 115 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Elements that decrease respect to the past (a); elements that increase respect to the past (b); elements for which only the background value is available (c). is characterized by fine siliciciclastic sediments coming from Northern areas, reflecting the regional sediment dispersal pattern, mostly originating from the Po River, and transported southwards by the WAC and towards offshore by wave motion of the strongest storms. The BSF2 _Coastal Facies_ is mainly defined by coarser sediments enriched in carbonic minerals, coming from local rivers and partly mixed, by the wave motion of the stronger storms, with the sediments of the BSF1 _Facies_. The BSF3 _Residual Facies_ is mainly composed by silty sediments coming from local rivers that are partially sorted from the clayey from the wave motion. Towards the offshore, this facies mixes progressively with sediments of Padanic sources coming from the North. The distribution of these three facies is the result of two principal processes. The first is the predominance of sedimentary inputs coming from the North and from local rivers, hence, the prevalence of sediments coming from source areas with different mineral-petrographic composition. The second regards the general hydrodynamic of the Adriatic Sea such as the cyclonic circulation that mainly flows southward near the Italian coast and the wave motion of the stronger storms directed perpendicularly to the coast. The data processing of trace elements and heavy metals concentrations also allow us to determine the background reference values for the study area. It is noteworthy to stress that the Cr and Ni values recorded in the past and in the surface sediments of this study area are above the L1 threshold levels of the Italian legislation (DM 173/2016). On the other hand, the present and past concentrations of Pb are generally lower than it. This suggests a possible underestimation of Cr and Ni thresholds and an overestimation of the Pb threshold. Therefore, a further study in order to validate or reject these discrepancies on Cr, Ni and Pb reference values should be carried out. The present study also identifies a small coastal area, between the Chieti and Ete Vivo rivers, that is probably affected by an As and Ba local pollution. The high contents of As could be ascribed to local discharges of waste of fertilizer productions during the 20 th century. Moreover, the pollution of Ba is probably related to past discharges into the sea of drilling muds coming from oil platform perforation as reported for other area on the Central Adriatic Sea. Finally, the comparison between the background concentrations and the current average concentrations point to a general decrease in Al, Ti, P, Co, Cr, Cu, Ga, Ni, Pb, Sc, V, Y, and Zn and an increase in Ca and Sr.