## 4 Results and Discussion
### Assessment of Hg Delivery to the Augusta Harbor: Direct Inputs or Resuspension?
This was likely linked to the mobilization of polluted sediments deposited in the period 1958-1980 by dredging and/or ship traffic. This process can also explain the lower values of \({}^{210}\)Pb observed in levels dated around the 1980s (Figure 2b), when dredging activities began [27]. For example, core L activities measured at 15 cm depth (dated with the CF-CS model around the 1980s; Figure 2b) are lower than those of the immediately deeper levels, suggesting the influence of relatively older sediments (and therefore with lower \({}^{210}\)Pb activities). These sediments add to those naturally settling in that area and have the effect of lowering the detected total activity. No evidence was found that could prove the existence of direct inputs from productions, at least in the northern sector of the Augusta Harbor at the time of sampling. The second option was then held responsible for the high Hg values at the sediment surface. Consequently, management recommendations derived by this research included the adoption of all possible measures to control the re-suspension and re-deposition of sediments whenever dredging activities were necessary or during ship transit [55; 56]. Indeed, other research studies in the following years focused on the possibility that Hg discharged in the Augusta Harbor might be a primary source to the adjacent marine system through the outflow of bottom waters along its steep slope and gullies [57] and a secondary source through reworking, resuspension, and transport [58]. In addition, ref. [57] also recognized that a substantial contribution to Hg contamination in the Augusta Bay might result from past uncontrolled dredging activities that deposited part of the contaminated sediments on the slope system outside the harbor (Figure 1a). Additional risks posed by the high seismicity of the area were measured with the modelling of the sudden breaching and complete collapse of the system damming by a destructive earthquake [59]. The resulting dispersion of contaminants (using Hg as an example of those present in the study area) is expected to occur almost instantaneously at a large scale, suggesting that natural and artificial hazards are inextricably connected and demand innovative methodological approaches for planning appropriate risk reduction and policy management [59]. As the environmental persistence of Hg and HCB availability facilitates their bioaccumulation and affects the health status of marine organisms, the possible implications for environmental risk, pollutant transfer, and human health were investigated by other studies in the same years [35; 60]. Specific analyses on Hg content and the Hg isotopic signatures of sediments, fish, and human hair shown as pelagic fish consumption is the principal transfer mechanism to the human population [35]. In addition, ref. [60] observed the progressive decrease of bioavailability and biological effects on local fauna over the last 20 years, is likely linked to the closure of many industrial facilities. The origin of PCDD/F Contamination in the Industrial Area of Porto Marghera: A Compelling Scientific Investigation  
The identification of specific industrial processes responsible for the presence of PCDD/Fs in the area of Porto Marghera (Venice) was the core of the trial against past and contemporary managers of the petrochemical plants during the late 1990s-early 2000s [6; 28]. Research studies aiming at providing scientific evidences on this regard started from the observation of contaminant concentration distribution and the relative congener composition pattern (i.e., PCDD/F signatures or fingerprints) within industrial canals and lagoon environments.