Hazardous wastes from large-scale metal extraction. Environ Sci Technol

Environmental Science and Technology (Impact Factor: 5.33). 09/1990; 24(9). DOI: 10.1021/es00079a001
    • "For instance, the mobility and bioavailability of elements such as arsenic largely depend on their chemical speciation (Williams, 2001; Liu et al., 2012), and not all forms are equally toxic; arsenite compounds (As(III)) are considered slightly more toxic than arsenate (As(V)). Consequently, given the complexity of pollution, the fate and origin of contaminants are studied by complementary analytical methods (sequential extraction, speciation, etc.), including mineralogical composition and textures (Moore and Luoma, 1990; Ahn et al., 2005; Haffert and Craw, 2008). Another interesting approach is Pb-isotope studies, which have demonstrated that a specific anthropogenic Pb source is recorded by Pb isotopic signatures that differ from those of unpolluted areas and from those of distinct sources of pollution (Komárek et al., 2008). "
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    ABSTRACT: 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.
    No preview · Article · Oct 2015 · Science of The Total Environment
    • "Despite the environmental threat of these sites, there are still many in which the wastes have not been recovered; thus, continuous remobilization of the remaining waste piles is a major source of pollution. Knowledge of the mechanisms that regulate the release, mobility , and natural attenuation of contaminants is essential to minimize environmental risks [25] [26]. This includes not only the presence of pollutants in a site, but also the study of their origin by complementary analytical methods, including mineralogical composition and textures [16,27–29]. "
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    ABSTRACT: 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. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Aug 2015 · Journal of hazardous materials
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    • "Over the past 150 years, base metal mining released significant amounts of metals (most notably Pb, As, Zn and Cu) into the Clark Fork River/floodplain system at levels toxic to the environment, resulting in the largest Superfund complex in the United States. Approximately 100 years ago the Milltown Dam was built 200 river km downstream from the source area of the contamination, and it was estimated that many thousands of metric tons of these metals had accumulated in the reservoir behind the dam (Moore and Luoma, 1990). In 2007 a large-scale project was put into place to remove the dam and restore the channel at the former dam site, and by March 2008 the river was allowed to flow freely again. "
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    ABSTRACT: Nanominerals and mineral nanoparticles from a mining-contaminated river system were examined to determine their potential to co-transport toxic trace metals. A recent large-scale dam removal project on the Clark Fork River in western Montana (USA) has released reservoir and upstream sediments contaminated with toxic trace metals (Pb, As, Cu and Zn), which had accumulated there as a consequence of more than a century and a half of mining activity proximal to the river's headwaters near the cities of Butte and Anaconda. To isolate the high-density nanoparticle fractions from riverbed and bank sediments, a density separation with sodium polytungstate (2.8g/cm3) was employed prior to a standard nanoparticle extraction procedure. The stable, dispersed nanoparticulate fraction was then analyzed by analytical transmission electron microscopy (aTEM) and flow field-flow fractionation (FlFFF) coupled to both multi-angle laser light scattering (MALLS) and high-resolution, inductively coupled plasma mass spectrometry (HR-ICPMS). FlFFF analysis revealed a size distribution in the nano range and that the elution profiles of the trace metals matched most closely to that for Fe and Ti. aTEM confirmed these results as the majority of the Fe and Ti oxides analyzed were associated with one or more of the trace metals of interest. The main mineral phases hosting trace metals are goethite, ferrihydrite and brookite. This demonstrates that they are likely playing a significant role in dictating the transport and distribution of trace metals in this river system, which could affect the bioavailability and toxicity of these metals. © 2012 Elsevier Ltd.
    Full-text · Article · Feb 2013
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