## 2 Study Area  
The Adriatic Sea is located between the Italian peninsula and the Balkan Region; it is an elongated basin (about 800 km long and 200 km wide) oriented NW/SE and is connected to the Mediterranean Sea through the Otranto Strait. The Adriatic sea is historically divided into three distinct sectors [48]: the northern sector is characterizedby a shallow continental shelf with a very gentle slope of about 0.02\({}^{\circ}\) until the isobath of 100 m; the middle sector, between the 100 m isobath and the Gargano Promontory, where a basin, called Mid-Adriatic Depression (MAD), or Jabuka Pit or Pomo Pit, occurs; this basin exhibits three sub-trenches, with maximum depths of 255 m (Western Pit), 270 m (Central Pit), and 240 m (Eastern Pit) [49]; the southern sector, between the Gargano Promontory and the Otranto Strait, which shows a maximum depth of 1260 m in the South Adriatic Depression (SAD). The hydrodynamic of the Adriatic Sea is characterized by a general anticlockwise circulation, aligned to the coasts that reaches its maximum in winter and spring, and by weak currents resulting in a series of clockwise and anti-clockwise gyres, in summer (Figure 1). In the eastern side of the basin, the current is directed northward (The East Adriatic Current: EAC). The EAC is characterized by warmer and high saline waters coming from the Levantine Basin (Levantine intermediate water, LIW), and from Ionian Basin (Ionian surface water: ISW) and in some cases from the Modified Atlantic Waters (MAW) following the pattern of the Bimodal Oscillating System (BiOS) [50; 51; 52; 53]. The Adriatic Sea circulation is complicated by the formation of dense waters in the Northern Adriatic Sea (North Adriatic Dense Water: AdDW). These are cold and high salinity waters forming in winter in the Northern Adriatic Sea when the Bora wind blows [54; 55]. The AdDW annually or biennially, generally in spring, flows southward close to the coast and reaches partly the MAD and flowing further south [56] (Figure 1). In this context, waters and the fine sedimentary load of the Po and Apennine rivers as well as of the local rivers flowing along the South Marche coast, tend to branch out offshore in summer and to be confined near the coast in winter [4; 57]. Overall, the combined action of currents and waves induces a redistribution of bottom sediments towards the south and, to a certain extent, towards the open sea, in the Northern and Central Adriatic Sea [2; 4]. The main sedimentary inputs of the northern and central sectors of the Adriatic Sea are located along the western coasts since the contributions from the Balk  
Figure 1: Bathymetric map of the Adriatic Sea with the three morphological sectors (lower left corner), the general Adriatic Sea circulation (in the center) and the study area (on the upper right corner). WAC: Western Adriatic Current; EAC: Eastern Adriatic Current; NAdG: North Adriatic Gyre; MAdG: Mid Adriatic Gyre; SAdG = South Adriatic Gyre. AdDW: Adriatic Dense Water (in blue North Adriatic formation area of AdW-NAdDW). LIW: Levantine intermediate Water. BIOS: Adriatic-Ionian bimodal oscillating system [50; 51; 52; 53]. due to the prevalent carbonate composition of the rocks, and the confinement within the insbore basins parallel to the coast [58]. The sediment contribution of the Northern and Western Adriatic Sea rivers is represented by the northern Alpine rivers that contribute for 8 MT/y, the Po basin, contributing for 13 MT/y, and the Apennine rivers that contribute for 22 MT/y, for a total of 43 MT/y [59]. The catchment area of the Po River includes igneous, metamorphic and sedimentary rocks of the western and central Alps, carbonate rocks mainly from the northern Alpine rivers, and a mixture of carbonate and silicocalist sediments from the Po alluvial System [42]. South of the Po River mouths the solid inputs of these rivers are composed mainly of terrigenous sediments with varying contents of carbonates [60].