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Geochemistry of acid mine waters

Authors:
  • U.S. Geological Survey Emeritus - Natural Hazards Mission Area
... This reaction is exacerbated by mining activities, which fragment the parent rock into material that has an exponentially larger surface area available to oxidative conditions (INAP, 2009;Jamieson et al., 2015;McCarthy, 2011;Morin & Hutt, 2001). Iron sulfide minerals such as pyrite and pyrrhotite are often found in base and precious metal ores and because of their relative abundance they are typically recognised as the main acid forming minerals in mine wastes; however, all mineral sulfides are susceptible to oxidation (Nordstrom & Alpers, 1999;INAP, 2009). Carbonate (calcite, dolomite and magnesite) and some silicate minerals have the potential to consume the acid formed through sulfurbearing mineral oxidation, affecting both the pH and the ionic content of the drainage waters (Plumlee, 1999). ...
... Acid rock drainage (ARD) forms through a complex series of acid formation and neutralisation reactions at both active and abandoned mining sites. The naturally occurring phenomenon is associated with both waste rock and tailings primarily from the mining of coal, gold, copper, nickel, and lead-zinc (Nordstrom & Alpers, 1999;Akcil & Koldas, 2006). Accelerated by microbial effects, the oxidation of sulfur-bearing minerals in the waste material leads to acid formation, while acid neutralisation is a result of the dissolution of carbonate minerals, as well as some of the more reactive fast and intermediate weathering silicate minerals (Becker et al., 2015;INAP, 2009). ...
... A comprehensive summary of primary and secondary minerals involved in ARD generation may be found in Plumlee (1999), Morin & Hutt (2001) and Jamieson et al. (2015), with a summary of all minerals mentioned in this report being provided in alongside their respective chemical formulae in Supplementary Content, Table A-6. The geochemistry of ARD formation is inherently complex and has been reviewed in greater detail outside this report (Nordstrom and Alpers, 1999;Plumlee, 1999;Lottermoser, 2010). A brief overview of acid formation and neutralisation is however provided in sections 2.1.1 and 2.1.2. ...
... Oxygen does not have to diffuse to the pyrite surface all the time, and Fe 3+ can take its role. Complex chemical and microbiological processes occur on the surface layer of pyrite, which have thicknesses of up to several dozen nanometers [55]. The oxidation process of Fe 2+ in acidic environments is very slow and is independent of pH [55]. ...
... Complex chemical and microbiological processes occur on the surface layer of pyrite, which have thicknesses of up to several dozen nanometers [55]. The oxidation process of Fe 2+ in acidic environments is very slow and is independent of pH [55]. The lack of a correlation between pH and SO 4 2− could be explained by the complex processes of the interaction between water and sediment, the transformation of secondary minerals, sorption and desorption and the presence of unstable intermediate forms of sulfur in water [56]. ...
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Stone-building materials, despite their natural origin, must be tested for the concentration of trace elements necessary to assess their impact on the environment and humans. In addition to basic research determining their mineral composition and structural and textural features, it is important to analyze the geochemical interactions between the material matrix and the concentration of elements that have a negative impact on the surrounding natural environment and our health. In the presented study, mineralogical and geochemical studies were carried out on the Carpathian sandstones. It was shown that the studied sandstones are represented by lithic wackes and sublithic arenites. Rocks subject to the secondary process of sulfide mineralization were observed among sublithic arenites. Pyrite in the studied geomaterials took various forms. A detailed geochemical analysis was carried out in the material in which iron sulfides acted as a binder. The research was aimed at identifying possible variations in the concentration of elements, with a particular emphasis on the contact between the silica and mineralized phases. The assessment of the geochemical interaction of iron sulfides with silica at a successively enlarged measurement was carried out using the Mamdani–Assilian fuzzy inference model.
... Conductivity and SO4 2− are grouped together (sub-cluster on the right of the second cluster), as already referred above, especially for L1 because in acid-metal contaminated waters this anion is the main contributor to the high ionic content [5,37]. Fe and ORP go together also in this group. ...
... Conductivity and SO 4 2− are grouped together (sub-cluster on the right of the second cluster), as already referred above, especially for L1 because in acid-metal contaminated waters this anion is the main contributor to the high ionic content [5,37]. Fe and ORP go together also in this group. ...
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Aljustrel, Lousal and S. Domingos mines are located in the Iberian Pyrite Belt (IPB), one of the greatest massive sulfide ore deposits worldwide. These mines’ surrounding streams are affected by Acid Mine Drainage (AMD). The main purpose of this study was to understand AMD influence in the water quality and diatom behavior. Thus, waters and diatoms were sampled in 6 sites from the 3 selected mines on winter and summer of 2016. The highest concentrations were found in acidic sites: A3 (Aljustrel—Al, Cd, Cu, Fe and Zn (and lowest pH)) and L1 (Lousal—As, Mn, Ca, Mg, SO42− and conductivity). The most abundant diatom species was Pinnularia aljustrelica with 100% of dominance in A3 and S1 acidic sites, which puts in evidence this species adaptation to AMD harsh conditions. Multivariate cluster analysis allowed us to reinforce results from previous studies, where spatial differences were more relevant than seasonal ones. In 12 years (2004–2016), and with many transformations undertaken (re-opening and rehabilitation), there is a conserva-tive behavior in the biological species (diatoms) and physicochemical concentrations (metals, pH and sulfates) from these three mining sites. This type of biogeochemical diagnosis is necessary for the sustainable use of these waters and the prevention of the polluting process, aimed to protect the water ecosystem and its biodiversity.
... Surface runoff and seepage from disturbed areas of mines in PAF regions can be a major source of AMD and adversely affect the receiving environment around these mines (Eary 1999;Nordstrom & Alpers 1999;Ezpana et al. 2005). For opencast mines, the disturbed areas are usually large and include mine pits, exposed coal seams, mine facilities, disturbed waste-rock material, coal stockpiles, access roads and ditches. ...
... Aluminium is a much less problematic metal than Fe in the treatment of AMD. It precipitates out of solution as an amorphous white slime composed of aluminium oxyhydroxide and hydroxysulphate at around a pH of 5 (Bigham 1994;Nordstrom & Alpers 1999), and it does not coat or armour limestone to the same extent as Fe (Hammarstrom et al. 2003;. Aluminium concentration will influence treatment selection when Fe concentrations are low (<10 mg/L, Figure 27). ...
... There has been a growing acceptance and use of the same techniques of geometallurgy (such as mineralogy and diagnostic leaching) to mine wastes to explain observations from geochemical testwork or predict potential environmental issues [1][2][3]. The weathering and gradual oxidation of sulfides, and in particular pyrite, has the potential to result in acid-rock drainage and metal(loid) leaching (ARDML) [4][5][6]. This process is accelerated during mining due to the increased likelihood of sulfide exposure, effectively accelerating the natural weathering process. ...
... This process is accelerated during mining due to the increased likelihood of sulfide exposure, effectively accelerating the natural weathering process. For ARDML the main deleterious minerals are the sulfides, and of these, due to its greater natural abundance the main contributor to ARDML is pyrite [5]. ...
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This study presents an evaluation of arsenic and other trace metals in the Hrazdan Iron-Ore project in Armenia using a methodology typically associated with Geometallurgical characterization. The principal host of the trace elements is pyrite and oxidized equivalents. Pyrite is a mineral of elemental concern as it has the potential to generate acidic pH in water that it contacts and thus mobilize metals of concern. In the Hrazdan deposit, there is a general excess of neutralizing carbonate minerals that result in adequate buffering of generated acid and limiting the mobility of metal cations in solution. However, metalloids that form oxyanions species such as those of arsenic or chromium tend to be more mobile in neutral to alkaline mine drainage. From the geometallurgi-cal assessment of the mine waste, the results of the geochemical testwork can be explained and the information used to assess potential issues with mine waste storage, timing of metal release and provide a baseline for mitigation strategies.
... 2). Indirectly this further lowers metal concentration through adsorption and/or precipitation processes (Nordstrom and Alpers, 1999;. In the case of large (up to several hm 3 of contaminated water), acidic metalliferous water bodies such as APL, triggering in-situ biosulfidogenesis can be a low-maintenance, passive bioremediation strategy, using the APL as large-scale natural reactors (Tuttle et al., 1969;Christensen et al., 1996). ...
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Microbial sulfate (SO42-) reduction in Acid Mine Drainage (AMD) environments can ameliorate the acidity and extreme metal concentrations by consumption of protons via the reduction of SO42- to hydrogen sulfide (H2S) and the concomitant precipitation of metals as metal sulfides. The activity of sulfate-reducing bacteria can be stimulated by the amendment of suitable organic carbon sources in these generally oligotrophic environments. Here, we used incubation columns (IC) as model systems to investigate the effect of glycerol amendment on the microbial community composition and its effect on the geochemistry of sediment and waters in AMD environments. The ICs were built with natural water and sediments from four distinct AMD-affected sites with different nutrient regimes: the oligotrophic Filón Centro and Guadiana acidic pit lakes, the Tintillo river (Huelva, Spain) and the eutrophic Brunita pit lake (Murcia, Spain). Physicochemical parameters were monitored during 18 months, and the microbial community composition was determined at the end of incubation through 16S rRNA gene amplicon sequencing. SEM-EDX analysis of sediments and suspended particulate matter was performed to investigate the microbially-induced mineral (neo)formation. Glycerol amendment strongly triggered biosulfidogenesis in all ICs, with pH increase and metal sulfide formation, but the effect was much more pronounced in the ICs from oligotrophic systems. Analysis of the microbial community composition at the end of the incubations showed that the SRB Desulfosporosinus was among the dominant taxa observed in all sulfidogenic columns, whereas the SRB Desulfurispora, Desulfovibrio and Acididesulfobacillus appeared to be more site-specific. Formation of Fe3+ and Al3+ (oxy)hydroxysulfates was observed during the initial phase of incubation together with increasing pH while formation of metal sulfides (predominantly, Zn, Fe and Cu sulfides) was observed after 1-5 months of incubation. Chemical analysis of the aqueous phase at the end of incubation showed almost complete removal of dissolved metals (Cu, Zn, Cd) in the amended ICs, while Fe and SO42- increased towards the water-sediment interface, likely as a result of the reductive dissolution of Fe(III) minerals enhanced by Fe-reducing bacteria. The combined geochemical and microbiological analyses further establish the link between biosulfidogenesis and natural attenuation through metal sulfide formation and proton consumption.
... Once released in the drainage, Fe 3+ and SO 4 2− may precipitate as secondary minerals. The formation of an iron oxyhydroxide and/or hydroxysulfate layer (e.g., jarosite for a pH comprised between 1 and 2 and goethite for a pH above 2) may particularly affect the mobility of these ions as well as other dissolved species because this so-called "indurated layer" tends to cement the tailings' pores, thereby limiting the oxidation of the reactive particles and the diffusion of oxygen passing through the tailings [16,17]. ...
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Increasing variability in precipitation patterns is expected to result from climate change in Canada. This effect has the potential to affect the performances of saturated covers in inhibiting acid rock drainage (ARD) and metal leaching (ML) processes. Because ARD and ML may cause the release of deleterious chemical species into the environment, such climate-change-driven impact was investigated using trickle leach columns. The physical, chemical, and mineralogical characteristics of the tailings as well as chemical composition of the leachate were measured before and after the column study. Results from the experiment showed that higher variability in precipitation regimes could enhance leaching of uranium. Leaching ranged from 67.1 to 90.1% of the total amount of U, with greater values associated with higher variability in precipitation patterns. Lower water levels and prolonged drought periods led to higher oxygen fluxes to the U tailings and dissolution of carbonate-bearing minerals. The release of carbonates could have enhanced uranium leaching through the formation of stable uranium-carbonate complexes in solution. Overall, this study shows that water level variation caused by varying precipitation patterns can significantly affect the drainage chemistry of saturated cover systems for which the level fluctuates freely near the tailings–cover interface.
... Only several pyrite layers with 2-3 mm thick or some framboid pyrites with several millimeters in diameter can be seen under SEM. The pyrite is not easily preserved in outcrop conditions and tends to be oxidized to sulfate (Nordstrom and Alpers, 1999). The Mingyue and Zhaiziyan outcrops are all newly excavated sections, which make sure that the pyrite samples are fresh and not oxidized. ...
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Several commercial Precambrian petroleum systems have been discovered worldwide. The microorganisms found in the Precambrian successions play a significant role in the development of high-quality hydrocarbon source rocks and microbialites with a high reservoir porosity. Yet, it remains unclear regarding issue of environments in which microbial activities can lead to the development of organic-rich hydrocarbon source rocks or reservoirs, and how the microbial source rock and reservoir constitute an effective hydrocarbon source-reservoir assemblage system. During the Edicaran Doushantuo Formation period, high-quality black shale source rocks were widely developed, and the organic matter in the source rocks was mainly derived from microbes including bacteria and algae. The thickness of the source rocks is up to 200 m, and the total organic carbon (TOC) value is ∼ 17.9%. During the Dengying Formation period, thick-layered microbialites, including microbial stromatolite, thrombolite, and botryoidal dolomite were developed extensively, with the abundant primary framework and secondary dissolution pores. During the Precambrian evolution, the transition of the seawater environment controlled the development of microbial source rocks or microbialite reservoirs. In a deep, euxinic reducing seawater condition, microbial organic matter was well preserved and accumulated in fine-grain sediments, thus forming the high-quality microbial source rocks. Meanwhile, under such a reducing condition, a large amount of layered, nodular, granular, and strawberry pyrites were precipitated due to the effect of BSR reaction with extremely positive δ³⁴S values (up to 39.0‰). Meanwhile, in a shallow turbulent high-energy oxidized seawater condition, especially in the intermittent “Dolomite Sea” environment, microbial dolomitization promoted the massive development of microbial dolomite mound/shoal frameworks, constituting the matrix for the development of large-scale microbialite reservoirs. During the later burial evolution processes, the oil and gas generated from the Doushantuo Formation source rocks migrated and accumulated into the overlying Dengying Formation microbialite reservoirs, which constituted an effective hydrocarbon source-reservoir assemblage system. Overall, the areas surrounding the Mianyang, west side of the Chengkou, and northwest side of the western Hubei troughs are considered to be the potentially favorable areas with microbial source rock-reservoir assemblage system. The microbial source-reservoir assemblages in these Precambrian strata worldwide are worth further exploring.
... Such acidic solutions, generally known as acid mine drainage (AMD), mainly derive from the dissolutive oxidation of the Fe sulphides pyrite and pyrrhotite, which are the most common and widespread sulphides present in ore deposits [1]. AMD is characterized by very low pH values (usually in the range between 2-3) and high concentrations of dissolved elements [2,3]. The oxidation of Fe sulphides is a complex phenomenon involving chemical, biological, and electrochemical reactions. ...
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Acid mine drainage (AMD) is a common environmental problem in many sulphide mines worldwide, and it is widely accepted that the microbial community plays a major role in keeping the process of acid generation active. The aim of this work is to describe, for the first time, the microbial community thriving in goethite and jarosite Fe precipitates from the AMD of the Libiola mine. The observed association is dominated by Proteobacteria (>50%), followed by Bacteroidetes (22.75%), Actinobacteria (7.13%), Acidobacteria (5.79%), Firmicutes (2.56%), and Nitrospirae (1.88%). Primary producers seem to be limited to macroalgae, with chemiolithotrophic strains being almost absent. A phylogenetic analysis of bacterial sequences highlighted the presence of heterotrophic bacteria, including genera actively involved in the AMD Fe cycle and genera (such as Cytophaga and Flavobacterium) that are able to reduce cellulose. The Fe precipitates constitute a microaerobic and complex environment in which many ecological niches are present, as proved by the wide range of bacterial species observed. This study is the first attempt to quantitatively characterize the microbial community of the studied area and constitutes a starting point to learn more about the microorganisms thriving in the AMD of the Libiola mine, as well as their potential applications.
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Due to the high solubility of uranyl sulfate and selenite minerals, the investigation involving the determination of the crystal structures and physical properties of these minerals is essential in actinide environmental chemistry for the simulation of uranium migration from uraninite deposits and nuclear waste repositories. However, the determination of the complete crystal structures of the uranyl sulfate minerals johannite (Cu(UO) (SO) (OH) · 8H O) and pseudojohannite (Cu (UO) (SO) O (OH) · 12H O) and the uranyl selenite mineral derriksite (Cu [((UO)(SeO) (OH) ]) has not been feasible so far. In this work, the crystal structures of these minerals, including the positions of the hydrogen atoms, are determined using first principles solid-state methods based on periodic density functional theory using plane wave basis sets and pseudo-potentials. The lattice parameters and associated geometrical variables as well as the corresponding X-ray diffraction patterns derived from the computed crystal structures are in excellent agreement with their experimental counterparts, derived from the corresponding experimental structures lacking the hydrogen atom positions. The complete crystal structure of derriksite is also determined by refinement from X-ray diffraction data, the resulting structure being consistent with the computed one. The knowledge of the positions of H atoms is of fundamental importance not only because they define the corresponding hydrogen bond networks holding together the atoms in the structures, but also because it allows for the efficient, inexpensive and safe determination of the physical properties using first principles methods. This feature is particularly important in the case of uranium-containing minerals due to their radiotoxicity, complicating the handling of the samples and experimental measurements. In this work, from the computed crystal structures, the elasticity tensors of these minerals are computed using the finite displacement method and a rich set of elastic properties including the bulk, Young's and shear moduli, the Poisson's ratio, ductility, anisotropy and hardness indices and bulk modulus derivatives with respect to pressure derivatives are determined.
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Applicability of the manometric method for studying the oxidation of pyritic material in the presence of bacteria has been demonstrated. Resting cells of Ferrobacillus ferrooxidans accelerated the oxidation of coal pyrites and coarsely crystalline marcasite, but were inactive on coarsely crystalline pyrite. Resting cells of Thiobacillus thiooxidans were inactive on all pyrites tested. Oxidation rates in the presence of Ferrobacillus were increased by reducing the particle size of pyritic samples, and, in one case, by removing the CaCO3 from a calcite-containing sample.
Chapter
In general, the involvement of biological systems in acid mine drainage can be arbitrarily divided into three categories: (1) the influence of acid drainage on biological systems, (2) the influence of organisms on formation of acid drainage, and, (3) biological means of abatement and treatment. Distinction between two categories of microbes is made on the basis of nutritional requirements. Both types have been discussed extensively in the literature (Dugan and Randles, 1968; Ivanov, 1964; Kelly, 1967; Silverman and Ehrlich, 1964).