Mercury speciation and mobilization in contaminated soils of the Valle del Azogue Hg mine (SE, Spain)

Geochemistry and environmental threats of soils surrounding an abandoned mercury mine

“…The natural release of Hg into the atmosphere facilitated a near-surface deposition of Hg 0 in soils and sediments, which was added to the Hg 0 accumulated from the furnaces. The threats posed by this area due to the high contents of heavy metals and their potential mobilization were confirmed by subsequent geochemical studies (Navarro et al 2006;Navarro et al 2009a). Despite those potential threats, to date the risk assessment of the area has only been performed by chemical and mineralogical analysis.…”

“…Due to mining and metallurgical activities, plants have disappeared from the area or have been severely affected by high contents of mercury and other metals (Viladevall et al 1999). The main ore is composed of stibnite, cinnabar, arsenic minerals (realgar and orpiment), sphalerite, siderite, chalcopyrite, pyrite, quartz, calcite and barite (Navarro et al 2006). Together with the Iberian Pyrite Belt and the Cartagena mining district, this abandoned mining area is one of the oldest metallurgical and mining areas in the Iberian Peninsula (Navarro et al 2006).…”

“…The main ore is composed of stibnite, cinnabar, arsenic minerals (realgar and orpiment), sphalerite, siderite, chalcopyrite, pyrite, quartz, calcite and barite (Navarro et al 2006). Together with the Iberian Pyrite Belt and the Cartagena mining district, this abandoned mining area is one of the oldest metallurgical and mining areas in the Iberian Peninsula (Navarro et al 2006). Samples were collected from seven sites spread throughout the mining district in order to have a representative characterization of the area (Fig.…”

“…The quality of the measurements was ensured through reference materials. Hg phases were determined by solid-phase-Hg-thermo-desorption (SPTD) based on the specific thermal desorption or decomposition of Hg compounds from solids at different temperatures (Biester and Scholz 1997;Navarro et al 2006). Mercury thermo-desorption curves were determined by means of an in-house apparatus, consisting of an electronically controlled heating unit and an Hg detection unit.…”

“…The only existing references to this deposit are by Cortazar (1875) and Becker (1888), who reported the presence of Hg mineralization associated with exhalative deposits. Cinnabar (HgS) was the main ore although high contents of Sb, As, Au, Ag, Pb, Zn and Ba were also reported in the mineralized veins (Navarro et al 2006). Calcines and secondary Hg and Fe minerals (mainly metacinnabar and Fe oxides) produced during the roasting of the mineral ore were dumped near the metallurgical facilities, where they have become a potential source of particulate and soluble Hg species (Rytuba 2005) that might be transported as Hg 0 vapor (Navarro et al 2000;Gustin et al 2002), ionic soluble phases or colloid particles (Shaw et al 2001;Lowry et al 2004).…”