Anthropogenic mercury in the former mining area of abbadia san salvatore (Siena, central Italy)

Mercury exploitation in the Mt. Amiata area (Italy) lasted about 130 years (1847-1974) and affected the local economic conditions. About 100,000 tons of mercury were produced from roasted cinnabar. The mining complex covers about 65 ha and contains mining structures and workers' edifices. Since 2010, efforts by the local authorities were done to increase the knowledge about the environmental issue. Gaseous Elemental Mercury (GEM) concentrations and total- and leached-Hg contents on paints, plasters, roof tiles, concretes, metals, dust, wood structures and soils were determined. Criticalities and perspectives for the remediation process are presented, the ultimate goal being to recover the area as a mining museum. The environmental impact was evaluated according to the most recent regulatory laws. GEM (July 2011-November 2018) showed strong spatial and temporal variability, depending on the distance from the mining structures and ambient temperature, respectively. Surveys in summertime (June to September) showed high GEM concentrations (>50,000 ng m-3). High total and leached mercury concentrations, up to 46,580 mg kg-1 and 4,470 mg L-1, respectively, were measured in anthropogenic materials and soils. In the underground waters, most contents were >10 mg L-1. Such a geochemical characterization has relevant interest for the operational cleanings during the reclamation activities.