Large-Scale Mercury Dispersion at Sea: Modelling a Multi-Hazard Case Study from Augusta Bay (Central Mediterranean Sea)

Abstract

This contribution discusses an example of potential multi-hazard effects resulting from an earthquake in a highly seismogenic area of the Mediterranean Sea, the Augusta Bay, which presents high levels of contamination in sediments and seawater, due particularly to high-concentrations of mercury as a result of a long-term industrial exploitation. In particular, a high-resolution hydrodynamic and transport model is used to calculate the effects of enhanced mercury spreading in the open sea after significant damage and collapse of the artificial damming system confining the embayment where a very high concentration of Hg occurs in seafloor sediments and seawater. Coupling high-resolution 3D dynamic circulation modelling and sediment–seawater Hg fluxes calculated using the HR3DHG diffusion–reaction model for both inorganic and organic Hg species offers a valuable approach to simulating and estimating the effects of spatial dispersion of this contaminant due to unpredictable hazard events in coastal systems, with the potential attendant enhanced effects on the marine ecosystem. The simulated scenario definitely suggests that a combination of natural and anthropogenic multi-hazards calls for a thorough re-thinking of risk management in marine areas characterised by significant levels of contamination and where a deep understanding of the biogeochemical dynamics of pollutants does not cover all the aspects of danger for the environment.

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“…[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].…”

“…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].…”

“…The industrial process able to produce PCDD/Fs as by-product was identified, but The industrial process able to produce PCDD/Fs as by-product was identified, but the so-called smoking gun had still to be found, i.e., a case study that linked undoubtedly the process of Cu extraction from pyrite ashes to PCDD/F production. A new literature search brought to light the "Kieselrot" case [59]. Kieselrot (German for red pebble) is the name given to the red siliceous slag obtained from Cu extraction processes which were carried out in Marsberg (North Rhine-Westphalia, Germany), until 1945.…”