Nordstrom DK, Alpers CN.. Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the Iron Mountain Superfund site, California. Proc Natl Acad Sci USA 96: 3455-3462

United States Geological Survey, 3215 Marine Street, Boulder, CO 80303-1066, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/1999; 96(7):3455-62. DOI: 10.1073/pnas.96.7.3455
Source: PubMed


The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as -3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal sulfate salts such as melanterite, chalcanthite, coquimbite, rhomboclase, voltaite, copiapite, and halotrichite have been identified, and some of these are forming from negative-pH mine waters. Geochemical calculations show that, under a mine-plugging remediation scenario, these salts would dissolve and the resultant 600,000-m3 mine pool would have a pH of 1 or less and contain several grams of dissolved metals per liter, much like the current portal effluent water. In the absence of plugging or other at-source control, current weathering rates indicate that the portal effluent will continue for approximately 3, 000 years. Other remedial actions have greatly reduced metal loads into downstream drainages and the Sacramento River, primarily by capturing the major acidic discharges and routing them to a lime neutralization plant. Incorporation of geochemical modeling and mineralogical expertise into the decision-making process for remediation can save time, save money, and reduce the likelihood of deleterious consequences.

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    • "Nordstrom and Alpers [1] describe the reactions involved in the origin of an AMD from pyrite oxidation through three steps: "

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    • "In these locations pH has a considerable effect on the availability and, as a consequence, the toxicity of heavy metals (Mason and Jenkins 1995). Acidic environments tend to contain unusually high concentrations of heavy metals, because their solubility increases markedly as the pH decreases (Nordstrom and Alpers 1999). Despite these extreme environmental conditions, a large number of prokaryotic and eukaryotic organisms have been identified living in the presence of high concentrations of heavy Abstract High concentrations of heavy metals are typical of acidic environments. "
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    ABSTRACT: High concentrations of heavy metals are typical of acidic environments. Therefore, studies on acidophilic organisms in their natural environments improve our understanding on the evolution of heavy metal tolerance and detoxification in plants. Here we sequenced the transcriptome of the extremophilic microalga Chlamydomonas acidophila cultivated in control conditions and with 500 μM of copper for 24 h. High-throughput 454 sequencing was followed by de novo transcriptome assembly. The reference transcriptome was annotated and genes related to heavy metal tolerance and abiotic stress were identified. Analyses of differentially expressed transcripts were used to detect genes involved in metabolic pathways related to abiotic stress tolerance, focusing on effects caused by increased levels of copper. Both transcriptomic data and observations from PAM fluorometry analysis suggested that the photosynthetic activity of C. acidophila is not adversely affected by addition of high amounts of copper. Up-regulated transcripts include several transcripts related to photosynthesis and carbohydrate metabolism, transcripts coding for general stress response, and a transcript annotated as homologous to the oil-body-associated protein HOGP coding gene. The first de novo assembly of C. acidophila significantly increases transcriptomic data available on extremophiles and green algae and thus provides an important reference for further molecular genetic studies. The differences between differentially expressed transcripts detected in our study suggest that the response to heavy metal exposure in C. acidophila is different from other studied green algae.
    Extremophiles 04/2015; 19(3). DOI:10.1007/s00792-015-0746-1 · 2.31 Impact Factor
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    • "related with both working and abandoned mining operations . Mineral extraction and beneficiation produce crushed, milled waste rock deposited in tailings causing a potential risk to the environment when exposed to weathering (Nordstrom and Alpers 1999; Dold and Fontboté 2001). They act as a major contributor to environmental pollution, providing sources of heavy metals that may lead to the contamination of the surrounding soils, agricultural areas and villages through weathering (wind erosion, water runoff, and leachates) (Conesa et al. 2006; Navarro Flores and Martínez Sola 2010; Navarro et al. 2008; Chaoyang et al. 2009; Vrhovnik et al. 2011; Bes et al. 2014; Mileusnić et al. 2014,, Kříbek et al. 2014). "
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    ABSTRACT: The present and past mining activity left several abandoned tailings and dams in the Panasqueira tin–tungsten mining area. Seasonal water samples and stream sediments were collected during two different periods (rainy and dry seasons) and analyzed for a wide range of major and trace elements, in order to define the present hydrochemical situation. Rain waters interact with the altered sulfides stored in the tailings which generate runoff waters with high metal concentrations. The waste material derived from the exploitation enhanced acidification and metal-releasing processes, due to the increase in the specific surface, which favors the oxidation of sulfide minerals. Acid drainage and high metal(loid)s (Cd, Fe, Mn, Zn, Cu, As) concentrations in solution were observed in waters leaching the Panasqueira tailing deposits. In dry season, generally the acidic waters, enriched in metals, evaporate progressively depositing sulfate efflorescences characteristic of acidic environments. The elements distribution in precipitated minerals helps in the interpretation of aqueous geochemical data. Aqueous concentrations may be attenuated by goethite, gibbsite, and/or ferrihydrite precipitation in the oxidation zone through adsorption processes. The use of these waters for human consumption and for irrigation represents a threat to humans as they have a potential carcinogenic risk, especially due to the As concentrations. The acid water precipitation is present on the stream sediments, with concentrations exceeding the toxicity limits. Stream sediments are good receptors of metals and metalloids transported by waters. The enrichment factor values, of heavy metal(loid)s from Casinhas stream and Zêzere river sediments, are extremely high in Ag, As, Cd, and Cu revealing enrichments for these potential toxic elements. I geo values shows that samples are strongly to very strongly polluted for Ag, As, Bi, Cd, and Cu. According to the consensus-based SQGs, 80 % of the samples were classified at the level of great concern and adverse biological effects are to be expected frequently in this area.
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