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Gallego J.R.,Biotechnology and Geochemistry Group | Esquinas N.,Biotechnology and Geochemistry Group | Rodriguez-Valdes E.,Biotechnology and Geochemistry Group | Menendez-Aguado J.M.,Biotechnology and Geochemistry Group | And 2 more authors.
Journal of Hazardous Materials | Year: 2015

The abandonment of Hg-As mining and metallurgy sites, together with long-term weathering, can dramatically degrade the environment. In this work it is exemplified the complex legacy of contamination that afflicts Hg-As brownfields through the detailed study of a paradigmatic site. Firstly, an in-depth study of the former industrial process was performed to identify sources of different types of waste. Subsequently, the composition and reactivity of As- and Hg-rich wastes (calcines, As-rich soot, stupp, and flue dust) was analyzed by means of multielemental analysis, mineralogical characterization (X-ray diffraction, electronic, and optical microscopy, microbrobe), chemical speciation, and sequential extractions.As-rich soot in the form of arsenolite, a relatively mobile by-product of the pyrometallurgical process, and stupp, a residue originated in the former condensing system, were determined to be the main risk at the site. In addition, the screening of organic pollution was also aimed, as shown by the outcome of benzo(a) pyrene and other PAHs, and by the identification of unexpected Hg organo-compounds (phenylmercury propionate).The approach followed unravels evidence from waste from the mining and metallurgy industry that may be present in other similar sites, and identifies unexpected contaminants overlooked by conventional analyses. © 2015 Elsevier B.V. Source

Gallego J.R.,Biotechnology and Geochemistry Group | Rodriguez-Valdes E.,Biotechnology and Geochemistry Group | Esquinas N.,Biotechnology and Geochemistry Group | Fernandez-Brana A.,Biotechnology and Geochemistry Group | Afif E.,Biotechnology and Geochemistry Group
Science of the Total Environment | Year: 2015

Here we addressed the contamination of soils in an abandoned brownfield located in an industrial area. Detailed soil and waste characterisation guided by historical information about the site revealed pyrite ashes (a residue derived from the roasting of pyrite ores) as the main environmental risk. In fact, the disposal of pyrite ashes and the mixing of these ashes with soils have affected a large area of the site, thereby causing heavy metal(loid) pollution (As and Pb levels reaching several thousands of ppm).A full characterisation of the pyrite ashes was thus performed. In this regard, we determined the bioavailable metal species present and their implications, grain-size distribution, mineralogy, and Pb isotopic signature in order to obtain an accurate conceptual model of the site. We also detected significant concentrations of pyrogenic benzo(a)pyrene and other PAHs, and studied the relation of these compounds with the pyrite ashes. In addition, we examined other waste and spills of minor importance within the study site. The information gathered offered an insight into pollution sources, unravelled evidence from the industrial processes that took place decades ago, and identified the co-occurrence of contaminants by means of multivariate statistics.The environmental forensics study carried out provided greater information than conventional analyses for risk assessment purposes and for the selection of clean-up strategies adapted to future land use. © 2015 Elsevier B.V. Source

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