title: Effect of temperature on the release and remobilization of ecotoxic elements in AMD colloidal precipitates: the example of the Libiola copper mine, Liguria, (Italy).
abstract: Due to their characteristics, colloidal particles are able to control the dispersion of many organic and inorganic pollutants in soils and streams. Colloidal precipitates generated by acid mine drainage (AMD) process are usually amorphous or nanocrystalline materials, and their stability plays a crucial role in controlling the fate of metals released by sulphide oxydation. This paper describes a study of elements release (Fe, Al, Mn, Cd, Co, Cr, Cu, Ni, S, Zn) due to desorption or destabilization of three different colloidal precipitates, two ochreous and a greenish-blue precipitate, sampled at the Libiola mine site (northwest Italy). The samples were heated at high temperature in order to verify this treatment as inertization process. At room temperature, the most easily extracted element was S (with released percentages from 8.39 to 29.17 %), but considerable amounts of Cu, Zn and Mn (up to 16.6, 610.6 and 595.6 mg/kg, respectively) were also observed in the leachates for greenish-blue precipitates. The highest release of elements (S > Cu, Zn, Mn, Cd > Co, Ni > Al, Fe, Cr), with minor differences depending on the mineralogical composition of the samples, was observed for heat-treated samples obtained through moderate heating and mainly formed by anhydrous phases. Samples treated at high temperature had the lowest release, with only Cu showing a significant concentration in the leachate of greenish-blue precipitates. The results showed that dissolution/desorption is limited from ochreous natural colloidal precipitates occurring at the Libiola mine site but also that high amounts of some metals can be remobilized from greenish-blue precipitates. The destabilization of all percipitates through dehydratation-dehydroxylation can further remobilize important amounts of ecotoxic elements. Heat treatment at high temperature could be a definitive, although expensive, way to fix heavy metals in the solid fraction, preventing their dispersion in the surrounding environment.
authors.affiliation: DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy. sirio.consani@edu.unige.it.
authors.forename: S
authors.initials: S
authors.lastname: Consani
authors.affiliation: DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Carbone
authors.affiliation: Dipartimento di Geoscienze, University of Padova, Via Gradenigo 6, Padova, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Salviulo
authors.affiliation: Dipartimento di Geoscienze, University of Padova, Via Gradenigo 6, Padova, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Zorzi
authors.affiliation: BiGeA, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, University of Bologna, Via Selmi 3, Bologna, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Dinelli
authors.affiliation: DICAT, Faculty of Engineering, University of Genova, Piazzale. J.F. Kennedy, Pad. D, Genova, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Botter
authors.affiliation: IENI, Istituto per l'Energetica e le Interfasi, CNR, Corso Stati Uniti, 4, Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Nodari
authors.affiliation: Dipartimento di Scienze Chimiche, University of Padova, Via Marzolo 1, Padova, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Badocco
authors.affiliation: DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Lucchetti
mesh_terms: D011232:Chemical Precipitation; D003102:Colloids; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007558:Italy; D008670:Metals / Q000737:chemistry*; D008906:Mining; D012989:Soil Pollutants / Q000737:chemistry*; D013696:Temperature; D018505:Waste Management / Q000379:methods
chemical_list: D003102:Colloids; D007220:Industrial Waste; D008670:Metals; D012989:Soil Pollutants
keywords: AMD; Bulk leaching test; Colloidal particles; Desorption; Ecotoxic elements; Libiola mine; Temperature treatment