Mercury (Hg) methylation and methylmercury (MeHg) production in sediments represent an environmental issue of concern due to potential bioaccumulation of MeHg along the trophic chain. These processes are especially enhanced in semi-confined aquatic systems where scarce water circulation, high organic matter production and frequent hypoxia/anoxia events may promote Hg mobility and methylation. In this context, the application of sustainable sorbent amendments may be an affordable and low impact remediation approach to mitigate Hg bioavailability. This study is focused on the Marano and Grado Lagoon (northern Adriatic Sea, Italy), which is known to be contaminated with Hg from the second largest Hg mine worldwide (Idrija, Slovenia) and from a decommissioned chlor-alkali plant. Although the biogeochemical behaviour of Hg has been intensively investigated in this area, key information is lacking to understand if in situ sustainable remediation may be successfully employed to mitigate Hg mobility in porewaters and potential MeHg production. The aim of this study is to preliminary evaluate the application of vineyard pruning residues biochar on Hg contaminated sediments at a selected fish farm, one of the most productive sites devoted to aquaculture in the lagoon. Leaching tests were performed on biochar to evaluate the potential release of major and potentially toxic elements (PTEs) in solution. For porewater and sediment characterisation, two short sediment cores were collected and the surface sediment layers (0-5 cm) were extruded under an inert atmosphere: one was amended with biochar (3 % w/w) and one was untreated (control sample). Both samples were divided into different aliquots and incubated until 6 months. Porewaters were periodically extracted from both untreated and amended sediment samples and chemical analyses were performed on solid and dissolved fractions to evaluate the effect of biochar on the mobility of Hg, MeHg and other PTEs.
May biochar be a suitable amendment to mitigate mercury availability from contaminated sediments? Preliminary evidences from leaching and incubation experiments
Pavoni E.
;Petranich E.;Floreani F.;Crosera M.;Marussi G.;Covelli S.
2023-01-01
Abstract
Mercury (Hg) methylation and methylmercury (MeHg) production in sediments represent an environmental issue of concern due to potential bioaccumulation of MeHg along the trophic chain. These processes are especially enhanced in semi-confined aquatic systems where scarce water circulation, high organic matter production and frequent hypoxia/anoxia events may promote Hg mobility and methylation. In this context, the application of sustainable sorbent amendments may be an affordable and low impact remediation approach to mitigate Hg bioavailability. This study is focused on the Marano and Grado Lagoon (northern Adriatic Sea, Italy), which is known to be contaminated with Hg from the second largest Hg mine worldwide (Idrija, Slovenia) and from a decommissioned chlor-alkali plant. Although the biogeochemical behaviour of Hg has been intensively investigated in this area, key information is lacking to understand if in situ sustainable remediation may be successfully employed to mitigate Hg mobility in porewaters and potential MeHg production. The aim of this study is to preliminary evaluate the application of vineyard pruning residues biochar on Hg contaminated sediments at a selected fish farm, one of the most productive sites devoted to aquaculture in the lagoon. Leaching tests were performed on biochar to evaluate the potential release of major and potentially toxic elements (PTEs) in solution. For porewater and sediment characterisation, two short sediment cores were collected and the surface sediment layers (0-5 cm) were extruded under an inert atmosphere: one was amended with biochar (3 % w/w) and one was untreated (control sample). Both samples were divided into different aliquots and incubated until 6 months. Porewaters were periodically extracted from both untreated and amended sediment samples and chemical analyses were performed on solid and dissolved fractions to evaluate the effect of biochar on the mobility of Hg, MeHg and other PTEs.Pubblicazioni consigliate
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