## 1 Introduction  
The biogeochemical and sedimentological properties of bottom marine sediments are the results of complex interactions between their composition, sourcing areas, transport, depositional, and early diagenesis processes [1]. Additionally, anthropic activities by discharging contaminants can further influence the natural composition of the sediments. Considering all the factors affecting the biogeochemical and the sedimentological composition of the bottom marine sediments, information about the source area, the sedimentological processes, and the anthropic inputs can be inferred [2; 3; 4; 5; 6; 7]. Wastewater discharges such as domestic wastes, drugs, fertilizers, and zootechnical byproducts represent the major anthropogenic contributions in marine coastal area [8]. Anthropogenic chemicals can be introduced into the marine environments by different sources (i.e., effluent treatment plants, accidental discharges, dumping, riverine inputs, surface runoff,atmospheric deposition, etc.) and then accumulate in sediments [9; 10; 11; 12; 13; 14; 15]. In coastal marine sediment, however, heavy metals might be sourced by anthropic activity or by natural sources [8; 16] and could represent a serious hazard due to their toxicity, bioavailability and persistence [17; 18]. Because of the adsorption, hydrolysis, and co-precipitation of metal ions, most of the water column metals are deposited in the marine sediment and only a small portion of these ions remains dissolved in the water column [19]. Then, marine sediments enriched in metals can release them by various embolization processes to the water column [1]. Marine sediments are preferred over seawater for monitoring environmental quality because pollutants are much higher and less variable in time and space than in seawater, and they reflect in an integrated manner the pollution level in the area [7; 20; 21; 22]. Marine sediments act not only as a reservoir of contaminants, but also serve as a source of toxicants to marine fauna. This can be due to the ingestion of bottom or resuspended sediment particles [23; 24], or to the adsorption of solutes present in the pore waters and on the bottom. The solutes present near the bottom can be the consequence of diffusive or bio-irrigation fluxes or resuspension [1], resuspension that can be due to natural (by storms, waves, tidal currents) or anthropogenic (dredging, trawling) processes [25; 26]. For these reasons, sediments are commonly targeted in marine pollution surveillance programs [27; 28; 29]. Generally, natural metal concentrations in sediments are not detrimental to inhabiting organisms [30]. For metabolism, organisms essentially require some key micronutrients (i.e., iron, copper, zinc, manganese, cobalt) [31] but at high metals concentration can pose a toxicological threat to marine organisms [8; 32; 33]. Sediment features such as mineralogy, sediment texture, metal properties, pH, organic matter, oxidation-reduction potential, and adsorption and desorption processes are important controlling factors for the accumulation and availability of heavy metals in the sediment [34; 35; 36; 37; 38; 39; 40; 41; 42]. Thus, sediments are considered as sources of heavy metals in marine environments and play a key role in their deposition and transmission along the trophic chain and must be therefore monitored. The current European Union (EU) legislation for the protection and conservation of the marine environment emphasizes the need to evaluate and limit the concentrations of contaminants, and to undertake preventive measures to re-establish a Good Environmental Status in impacted marine areas, as requested by Marine Strategy Framework Directive (MSFD, 2008/56/EC, Commission Decision 2010/477/EU). The present study aims to recognize the sedimentological processes that drove the formation of the present sediment bodies on the base of the geochemical and sedimentological properties of the superficial marine sediments in a central Italian Adriatic Sea coastal area.