Mercury mobility in harbour sediments: evidence from selective sequential extraction and short-term microcosm resuspension experiments (northern Adriatic Sea, Italy)

Coastal sediments in the Gulf of Trieste, historically contaminated by mercury (Hg) from mining activities in Idrija, Slovenia, exhibit negligible Hg mobility even when resuspended. A study analyzing 16 sediment samples found that Hg is predominantly bound to poorly soluble or insoluble compounds, such as sulfides, with over 98% of Hg remaining in solid form. Short-term microcosm experiments simulating dredging-induced resuspension showed minimal dissolved Hg (DHg) and methylmercury (DMeHg) release, with DHg concentrations stable and DMeHg below detection limits most of the time. The high partitioning coefficient (KD) further confirmed Hg's strong affinity for sediment particles over the dissolved phase. These findings suggest that short-term resuspension events, such as those expected from planned dredging in the Port of Monfalcone, would have a negligible impact on Hg mobility and water column contamination.

(Ed.). (2019). Congresso SIMP-SGI-SOGEI 2019 - Il tempo del pianeta Terra e il tempo dell’uomo: Le geoscienze fra passato e futuro. https://doi.org/10.3301/absgi.2019.05