ALBERT

Beschreibung: Jarosite minerals (AB3(TO4)2(OH)6) are iron hydroxysulfate minerals that can readily incorporate trace metals into their mineral structure. A range of metals can be incorporated into the jarosite structure, including oxyanions such as selenate (SeO42−). Selenium is a micronutrient, but is toxic in relatively low doses. Selenium is present in aqueous systems in its two oxyanion forms: selenate and selenite (SeO32−). The tetrahedral sulfate coordination site can be completely substituted for selenate in jarosite minerals (NaFe3(SO4)x(SeO4)2-x(OH)6). Bacteria have been observed to reduce Se oxyanions to both more reduced forms and insoluble elemental Se. This is a pathway for selenium immobilization at contaminated sites. This experiment investigates the reductive dissolution of two Se-jarosites (solid substitution containing high and low selenium concentrations) in the presence of Shewanella putrefaciens CN32. It was observed that both Fe(III) and selenate were metabolically reduced and released into solution through jarosite dissolution . Selenate was also found to be incorporated intracellularly and reduced to particulate Se which was released upon cell lysis. Compared to the abiotic samples, enhanced dissolution was found with both the live and dead bacteria treatments.

Beschreibung: Applications of redox processes range over a number of scientific fields. This review article summarizes the theory behind the calculation of redox potentials in solution for species such as organic compounds, inorganic complexes, actinides, battery materials, and mineral surface-bound-species. Different computational approaches to predict and determine redox potentials of electron transitions are discussed along with their respective pros and cons for the prediction of redox potentials. Subsequently, recommendations are made for certain necessary computational settings required for accurate calculation of redox potentials. This article reviews the importance of computational parameters, such as basis sets, density functional theory (DFT) functionals, and relativistic approaches and the role that physicochemical processes play on the shift of redox potentials, such as hydration or spin orbit coupling, and will aid in finding suitable combinations of approaches for different chemical and geochemical applications. Identifying cost-effective and credible computational approaches is essential to benchmark redox potential calculations against experiments. Once a good theoretical approach is found to model the chemistry and thermodynamics of the redox and electron transfer process, this knowledge can be incorporated into models of more complex reaction mechanisms that include diffusion in the solute, surface diffusion, and dehydration, to name a few. This knowledge is important to fully understand the nature of redox processes be it a geochemical process that dictates natural redox reactions or one that is being used for the optimization of a chemical process in industry. In addition, it will help identify materials that will be useful to design catalytic redox agents, to come up with materials to be used for batteries and photovoltaic processes, and to identify new and improved remediation strategies in environmental engineering, for example the reduction of actinides and their subsequent immobilization. Highly under-investigated is the role of redox-active semiconducting mineral surfaces as catalysts for promoting natural redox processes. Such knowledge is crucial to derive process-oriented mechanisms, kinetics, and rate laws for inorganic and organic redox processes in nature. In addition, molecular-level details still need to be explored and understood to plan for safer disposal of hazardous materials. In light of this, we include new research on the effect of iron-sulfide mineral surfaces, such as pyrite and mackinawite, on the redox chemistry of actinyl aqua complexes in aqueous solution.

Beschreibung: Thermal desorption, by a rotary kiln of mercury contaminated soil and mine wastes, has been used in order to volatilize mercury from the contaminated medium. Solar thermal desorption is an innovative treatment that uses solar energy to increase the volatility of contaminants, which are removed from a solid matrix by a controlled air flow system. Samples of soils and mine wastes used in the experiments were collected in the abandoned Valle del Azogue mine (SE, Spain), where a complex ore, composed mainly of cinnabar, arsenic minerals (realgar and orpiment) and stibnite, was mined. The results showed that thermal treatment at temperatures >400 °C successfully lowered the Hg content (2070–116 ppm) to 〈15 mg kg−1. The lowest values of mercury in treated samples were obtained at a higher temperature and exposition time. The samples that showed a high removal efficiency (>99%) were associated with the presence of significant contents of cinnabar and an equivalent diameter above 0.8 mm.

Beschreibung: The editors of Minerals would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2013.

Beschreibung: Microbial populations and microbe-mineral interactions were examined in waste rock characterized by neutral rock drainage (NRD). Samples of three primary sulfide-bearing waste rock types (i.e., marble-hornfels, intrusive, exoskarn) were collected from field-scale experiments at the Antamina Cu–Zn–Mo mine, Peru. Microbial communities within all samples were dominated by neutrophilic thiosulfate oxidizing bacteria. However, acidophilic iron and sulfur oxidizers were present within intrusive waste rock characterized by bulk circumneutral pH drainage. The extensive development of microbially colonized porous Fe(III) (oxy)hydroxide and Fe(III) (oxy)hydroxysulfate precipitates was observed at sulfide-mineral surfaces during examination by field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDS). Linear combination fitting of bulk extended X-ray absorption fine structure (EXAFS) spectra for these precipitates indicated they were composed of schwertmannite [Fe8O8(OH)6–4.5(SO4)1–1.75], lepidocrocite [γ-FeO(OH)] and K-jarosite [KFe3(OH)6(SO4)2]. The presence of schwertmannite and K-jarosite is indicative of the development of localized acidic microenvironments at sulfide-mineral surfaces. Extensive bacterial colonization of this porous layer and pitting of underlying sulfide-mineral surfaces suggests that acidic microenvironments can play an important role in sulfide-mineral oxidation under bulk circumneutral pH conditions. These findings have important implications for water quality management in NRD settings.

Beschreibung: Globally, coal-fired power plants are the largest industrial source of carbon dioxide (CO2). CO2 emissions from flue gas have potential for direct mineralization with electrostatic precipitator fly ash particles in the field. Demonstration scale accelerated mineral carbonation (AMC) studies were conducted at the Jim Bridger Power Plant, a large coal fired power plant located in Wyoming, USA. AMC produces kinetically rapid conditions for increased rates of mineralization of CO2, sulfur dioxide (SO2) and mercury (Hg) on fly ash particles. Control and AMC reacted fly ash particles were investigated for: change in carbon (expressed as CaCO3), sulfur (expressed as SO42−), and mercury (Hg) contents; topology and surface chemical composition by scanning electron microscope/energy dispersive X-ray spectroscopy analysis; chemical distribution of trace elements; and aqueous mineral solubility by the toxicity characteristic leaching procedure. Results of the AMC process show an increase in C, S, and Hg on AMC fly ash particles suggesting that multiple pollutants from flue gas can be removed through this direct mineral carbonation process. Results also suggest that the AMC process shifts soluble trace elements in fly ash to less leachable mineral fractions. The results of this study can provide insight into potential successful field implementation of AMC.

Beschreibung: A review of the literature about calculating the adsorption properties of arsenic onto mineral models using density functional theory (DFT) is presented. Furthermore, this work presents DFT results that show the effect of model charge, hydration, oxidation state, and DFT method on the structures and adsorption energies for AsIII and AsV onto Fe3+-(oxyhydr)oxide cluster models. Calculated interatomic distances from periodic planewave and cluster-model DFT are compared with experimental data for AsIII and AsV adsorbed to Fe3+-(oxyhydr)oxide models. In addition, reaction rates for the adsorption of AsV on α-FeOOH (goethite) (010) and Fe3+ (oxyhydr)oxide cluster models were calculated using planewave and cluster-model DFT methods.

Beschreibung: Bulk magnetic properties of soils and sediments are often sensitive proxies for environmental change but commonly require interpretation in terms of the different sources of magnetic minerals (or components) that combine to generate them. Discrimination of different components in the bulk magnetic record is often attempted through endmember unmixing and/or high resolution measurements that can require intensive measurement plans, assume linear additivity, and sometimes have difficulty in discriminating a large number of sources. As an alternative, magnetic measurements can be made on isolated sediment fractions that constitute the bulk sample. When these types of measurements are taken, heterogeneity is frequently observed between the magnetic properties of different fractions, suggesting different magnetic components often associate with different physical grain sizes. Using a particle size-specific methodology, individual components can be isolated and studied and bulk magnetic properties can be linked to, and isolated from, sedimentological variations. Deconvolving sedimentary and magnetic variability in this way has strong potential for increased understanding of how magnetic fragments are carried in natural systems, how they vary with different source(s), and allows for a better assessment of the effect environmental variability has in driving bulk magnetic properties. However, despite these benefits, very few studies exploit the information they can provide. Here, I present an overview of the different sources of magnetic minerals, why they might associate with different sediment fractions, how bulk magnetic measurements have been used to understand the contribution of different components to the bulk magnetic record, and outline how particle size-specific magnetic measurements can assist in their better understanding. Advantages and disadvantages of this methodology, their role alongside bulk magnetic measurements, and potential future directions of research are also discussed.

Beschreibung: Molybdenite in the Aitik deposit and its southern extension was studied through mineralogical/chemical analysis and laboratory flotation tests. It is demonstrated that molybdenite varies considerably in grain size, ranging from coarse (>20 μm) to very fine (〈2 μm) and occurs predominantly as single grains in the groundmass of the rocks, as grain aggregates, and intergrown with chalcopyrite and pyrite. The dominating molybdenite-bearing rocks are the mica schists, the quartz-monzodiorite, and the Salmijärvi biotite-amphibole gneiss, the latter containing mostly medium-coarsegrained molybdenite. Later geological features, such as garnet-magnetite-anhydrite-K feldspar alteration and pegmatite dikes appear to be responsible for a significant part of the distribution pattern of molybdenite. Molybdenite grains contain up to 1587 ppm Re, with an average of 211 ± 10 ppm in Aitik molybdenite and 452 ± 33 ppm in Salmijärvi molybdenite. The higher Re concentrations are found in molybdenite associated with sericite- and quartz-amphibole-magnetite altered rocks, whereas low Re values occur in rocks in which potassic alteration is prominent. Molybdenite recovery is influenced by the mineralogy of the host rock and the alteration grade; hence both of these factors will have an impact on potential recoveries. The recovery of molybdenite was lower from flotation feeds with significant amounts of Mg-bearing clay-micas.

Beschreibung: Mogok gem corundum samples from twelve localities were analyzed for trace element signatures (LA-ICP-MS method) and oxygen isotope values (δ18O, by laser fluorination). The study augmented earlier findings on Mogok gem suites that suggested the Mogok tract forms a high vanadium gem corundum area and also identified rare alluvial ruby and sapphire grains characterised by unusually high silicon, calcium and gallium, presence of noticeable boron, tin and niobium and very low iron, titanium and magnesium contents. Oxygen isotope values (δ18O) for the ruby and high Si-Ca-Ga corundum (20‰–25‰) and for sapphire (10‰–20‰) indicate typical crustal values, with values >20‰ being typical of carbonate genesis. The high Si-Ca-Ga ruby has high chromium (up to 3.2 wt % Cr) and gallium (up to 0. 08 wt % Ga) compared to most Mogok ruby (〈2 wt % Cr; 〈0.02 wt % Ga). In trace element ratio plots the Si-Ca-Ga-rich corundum falls into separate fields from the typical Mogok metamorphic fields. The high Ga/Mg ratios (46–521) lie well within the magmatic range (>6), and with other features suggest a potential skarn-like, carbonate-related genesis with a high degree of magmatic fluid input The overall trace element results widen the range of different signatures identified within Mogok gem corundum suites and indicate complex genesis. The expanded geochemical platform, related to a variety of metamorphic, metasomatic and magmatic sources, now provides a wider base for geographic typing of Mogok gem corundum suites. It allows more detailed comparisons with suites from other deposits and will assist identification of Mogok gem corundum sources used in jewelry.

Beschreibung: The Oka complex is amongst the youngest carbonatite occurrences in North America and is associated with the Monteregian Igneous Province (MIP; Québec, Canada). The complex consists of both carbonatite and undersaturated silicate rocks (e.g., ijolite, alnöite), and their relative emplacement history is uncertain. The aim of this study is to decipher the petrogenetic history of Oka via the compositional, isotopic and geochronological investigation of accessory minerals, perovskite and apatite, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The new compositional data for individual perovskite and apatite grains from both carbonatite and associated alkaline silicate rocks are highly variable and indicative of open system behavior. In situ Sr and Nd isotopic compositions for these two minerals are also variable and support the involvement of several mantle sources. U-Pb ages for both perovskite and apatite define a bimodal distribution, and range between 113 and 135 Ma, which overlaps the range of ages reported previously for Oka and the entire MIP. The overall distribution of ages indicates that alnöite was intruded first, followed by okaite and carbonatite, whereas ijolite defines a bimodal emplacement history. The combined chemical, isotopic, and geochronological data is best explained by invoking the periodic generation of small volume, partial melts generated from heterogeneous mantle.

Beschreibung: Incorporation reactions play an important role in dictating immobilization and release pathways for chemical species in low-temperature geologic environments. Quantum-mechanical investigations of incorporation seek to characterize the stability and geometry of incorporated structures, as well as the thermodynamics and kinetics of the reactions themselves. For a thermodynamic treatment of incorporation reactions, a source of the incorporated ion and a sink for the released ion is necessary. These sources/sinks in a real geochemical system can be solids, but more commonly, they are charged aqueous species. In this contribution, we review the current methods for ab initio calculations of incorporation reactions, many of which do not consider incorporation from aqueous species. We detail a recently-developed approach for the calculation of incorporation reactions and expand on the part that is modeling the interaction of periodic solids with aqueous source and sink phases and present new research using this approach. To model these interactions, a systematic series of calculations must be done to transform periodic solid source and sink phases to aqueous-phase clusters. Examples of this process are provided for three case studies: (1) neptunyl incorporation into studtite and boltwoodite: for the layered boltwoodite, the incorporation energies are smaller (more favorable) for reactions using environmentally relevant source and sink phases (i.e., ΔErxn(oxides) > ΔErxn(silicates) > ΔErxn(aqueous)). Estimates of the solid-solution behavior of Np5+/P5+- and U6+/Si4+-boltwoodite and Np5+/Ca2+- and U6+/K+-boltwoodite solid solutions are used to predict the limit of Np-incorporation into boltwoodite (172 and 768 ppm at 300 °C, respectively); (2) uranyl and neptunyl incorporation into carbonates and sulfates: for both carbonates and sulfates, it was found that actinyl incorporation into a defect site is more favorable than incorporation into defect-free periodic structures. In addition, actinyl incorporation into carbonates with aragonite structure is more favorable than into carbonates with calcite structure; and (3) uranium incorporation into magnetite: within the configurations tested that preserve charge neutrality (U6+ → 2Fe3+oct/tet or U4+ → Fe2+oct), uranium incorporation into magnetite is most favorable when U6+ replaces octahedral Fe3+ with charge balancing accomplished by an octahedral Fe3+ iron vacancy. At the end of this article, the limitations of this method and important sources of error inherent in these calculations (e.g., hydration energies) are discussed. Overall, this method and examples may serve as a guide for future studies of incorporation in a variety of contexts.

Beschreibung: The diagenetic evolution of the magnetic minerals during burial in sedimentary basins has been recently proposed. In this study, we provide new data from the Grès d’Annot basin, SE France. We analyze fine-grained clastic rocks that suffered a burial temperature from ~60 to >250 °C, i.e., covering oil and gas windows. Low temperature magnetic measurements (10–300 K), coupled with vitrinite reflectance data, aim at defining the magnetic mineral evolution through the burial history. Magnetite is documented throughout the entire studied transect. Goethite, probably occurring as nanoparticles, is found for a burial temperature 〈80 °C. Micron-sized pyrrhotite is highlighted for a burial temperature >200 °C below the Alpine nappes and the Penninic Front. A model of the evolution of the magnetic assemblage from 60 to >250 °C is proposed for clastic rocks, containing iron sulfides (pyrite) and organic matter. This work provides the grounds for a better understanding of the magnetic properties of petroleum plays.

Beschreibung: The reactivity of mineral surfaces in the fundamental processes of adsorption, dissolution or growth, and electron transfer is directly tied to their atomic structure. However, unraveling the relationship between the atomic surface structure and other physical and chemical properties of complex metal oxides is challenging due to the mixed ionic and covalent bonding that can occur in these minerals. Nonetheless, with the rapid increase in computer processing speed and memory, computer simulations using different theoretical techniques can now probe the nature of matter at both the atomic and sub-atomic levels and are rapidly becoming an effective and quantitatively accurate method for successfully predicting structures, properties and processes occurring at mineral surfaces. In this study, we have used Density Functional Theory calculations to study the adsorption of benzene on hematite (α-Fe2O3) surfaces. The strong electron correlation effects of the Fe 3d-electrons in α-Fe2O3 were described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach), which was found to provide an accurate description of the electronic and magnetic properties of hematite. For the adsorption of benzene on the hematite surfaces, we show that the adsorption geometries parallel to the surface are energetically more stable than the vertical ones. The benzene molecule interacts with the hematite surfaces through π-bonding in the parallel adsorption geometries and through weak hydrogen bonds in the vertical geometries. Van der Waals interactions are found to play a significant role in stabilizing the absorbed benzene molecule. Analyses of the electronic structures reveal that upon benzene adsorption, the conduction band edge of the surface atoms is shifted towards the valence bands, thereby considerably reducing the band gap and the magnetic moments of the surface Fe atoms.

Beschreibung: Ultramafic and mafic mine tailings are a valuable feedstock for carbon mineralization that should be used to offset carbon emissions generated by the mining industry. Although passive carbonation is occurring at the abandoned Clinton Creek asbestos mine, and the active Diavik diamond and Mount Keith nickel mines, there remains untapped potential for sequestering CO2 within these mine wastes. There is the potential to accelerate carbonation to create economically viable, large-scale CO2 fixation technologies that can operate at near-surface temperature and atmospheric pressure. We review several relevant acceleration strategies including: bioleaching of magnesium silicates; increasing the supply of CO2 via heterotrophic oxidation of waste organics; and biologically induced carbonate precipitation, as well as enhancing passive carbonation through tailings management practices and use of CO2 point sources. Scenarios for pilot scale projects are proposed with the aim of moving towards carbon-neutral mines. A financial incentive is necessary to encourage the development of these strategies. We recommend the use of a dynamic real options pricing approach, instead of traditional discounted cash-flow approaches, because it reflects the inherent value in managerial flexibility to adapt and capitalize on favorable future opportunities in the highly volatile carbon market.

Beschreibung: Since the second half of the 20th century, various devices have been developed in order to reduce the emissions of harmful substances at the exhaust pipe of combustion engines. In the automotive field, the most diffuse and best known device of this kind is the “three way” catalytic converter for engines using the Otto cycle designed to abate the emissions of carbon monoxide, nitrogen oxides and unburnt hydrocarbons. These catalytic converters can function only by means of precious metals (mainly platinum, rhodium and palladium) which exist in a limited supply in economically exploitable ores. The recent increase in prices of all mineral commodities is already making these converters significantly expensive and it is not impossible that the progressive depletion of precious metals will make them too expensive for the market of private cars. The present paper examines how this potential scarcity could affect the technology of road transportation worldwide. We argue that the supply of precious metals for automotive converters is not at risk in the short term, but that in the future it will not be possible to continue using this technology as a result of increasing prices generated by progressive depletion. Mitigation methods such as reducing the amounts of precious metals in catalysts, or recycling them can help but cannot be considered as a definitive solution. We argue that precious metal scarcity is a critical factor that may determine the future development of road transportation in the world. As the problem is basically unsolvable in the long run, we must explore new technologies for road transportation and we conclude that it is likely that the clean engine of the future will be electric and powered by batteries.

Beschreibung: Atmospheric levels of carbon dioxide (CO2) are rising at an accelerated rate resulting in changes in the pH and carbonate chemistry of the world’s oceans. However, there is uncertainty regarding the impact these changing environmental conditions have on carbonate-depositing microbial communities. Here, we examine the effects of elevated CO2, three times that of current atmospheric levels, on the microbial diversity associated with lithifying microbial mats. Lithifying microbial mats are complex ecosystems that facilitate the trapping and binding of sediments, and/or the precipitation of calcium carbonate into organosedimentary structures known as microbialites. To examine the impact of rising CO2 and resulting shifts in pH on lithifying microbial mats, we constructed growth chambers that could continually manipulate and monitor the mat environment. The microbial diversity of the various treatments was compared using 16S rRNA gene pyrosequencing. The results indicated that elevated CO2 levels during the six month exposure did not profoundly alter the microbial diversity, community structure, or carbonate precipitation in the microbial mats; however some key taxa, such as the sulfate-reducing bacteria Deltasulfobacterales, were enriched. These results suggest that some carbonate depositing ecosystems, such as the microbialites, may be more resilient to anthropogenic-induced environmental change than previously thought.

Beschreibung: The Mount Amiata mining district (southern Tuscany, Italy) was, for decades, one of the world’s largest mercury (Hg) producing regions, where mining activity lasted until the 1980s. The Paglia River drains the eastern part of the district and is also the main western tributary of the Tiber River. Recent studies show that, still today, high total Hg contents severely affect the downstream ecosystems of these rivers. In November 2012, a major flood event occurred in the Paglia River basin, which drastically changed the river morphology and, possibly, the Hg concentrations. In the present work, stream sediment was sampled before and after the flood to evaluate possible changes in sediment total Hg concentrations as a consequence of this event. The comparison between pre- and post-flood Hg concentrations shows that Hg content increased up to an order of magnitude after the flood, suggesting that this event triggered Hg mobilization in the basin rather than its dilution.

Beschreibung: Mining of metals and coals generates solid and liquid wastes that are potentially hazardous to the environment. Traditional methods to reduce the production of pollutants from mining and to treat impacted water courses are mostly physico-chemical in nature, though passive remediation of mine waters utilizes reactions that are catalysed by microorganisms. This paper reviews recent advances in biotechnologies that have been proposed both to secure reactive mine tailings and to remediate mine waters. Empirical management of tailings ponds to promote the growth of micro-algae that sustain populations of bacteria that essentially reverse the processes involved in the formation of acid mine drainage has been proposed. Elsewhere, targeted biomineralization has been demonstrated to produce solid products that allow metals present in mine waters to be recovered and recycled, rather than to be disposed of in landfill.

Beschreibung: Using alternative materials such as residual products from other industries to mitigate the negative effects of acid rock drainage would simultaneously solve two environmental problems. The main residual product still landfilled by sulphate paper mills is the alkaline material green liquor dregs (GLD). A physical, mineralogical and chemical characterization of four batches of GLD was carried out to evaluate the potential to use it as a sealing layer in the construction of dry covers on sulphide-bearing mine waste. GLD has relatively low hydraulic conductivity (10−8 to 10−9 m/s), a high water retention capacity (WRC) and small particle size. Whilst the chemical and mineralogical composition varied between the different batches, these variations were not reflected in properties such as hydraulic conductivity and WRC. Due to relatively low trace element concentrations, leaching of contaminants from the GLD is not a concern for the environment. However, GLD is a sticky material, difficult to apply on mine waste deposits and the shear strength is insufficient for engineering applications. Therefore, improving the mechanical properties is necessary. In addition, GLD has a high buffering capacity indicating that it could act as an alkaline barrier. Once engineering technicalities have been overcome, the long-term effectiveness of GLD should be studied, especially the effect of aging and how the sealing layer would be engineered in respect to topography and climatic conditions.

Beschreibung: A five-year, humidity-cell experiment was used to study the weathering evolution of a low-sulfide, granitic waste rock at 5 and 22 °C. Only the rock with the highest sulfide content (0.16 wt %) released sufficient acid to overcome a limited carbonate acid-neutralization capacity and produce a substantial decline in pH. Leached SO4 and Ca quickly increased then decreased during the first two years of weathering. Sulfide oxidation continued to release acid and SO4 after carbonate depletion, resulting in an increase in acid-soluble elements, including Cu and Zn. With the dissolution of Al-bearing minerals, the pH stabilized above 4, and sulfide oxidation continued to decline until the end of the experiment. The variation in activation energy of sulfide oxidation correlates with changes in sulfide availability, where the lowest activation energies occurred during the largest releases of SO4. A decrease in sulfide availability was attributed to consumption of sulfide and weathered rims on sulfide grains that reduced the oxidation rate. Varying element release rates due to changing carbonate and sulfide availability provide identifiable geochemical conditions that can be viewed as neutralization sequences and may be extrapolated to the field site for examining the evolution of mineral weathering of the waste rock.

Beschreibung: Shales are increasingly being exploited for oil and unconventional gas. Exploitation of sub-arctic oil shales requires the creation of gravel pads to elevate workings above the heaving effects of ground ice. These gravel pads can potentially generate acidic leachate, which can enhance the mobility of metals from the shale. To examine this potential, pyrite-bearing shale originating from sub-Arctic gravel pad sites were subjected to leaching tests for 600 days at initial pH values ranging from 2 to 5, to simulate potential real world conditions. At set times over the 600 day experiment, pH, oxidation reduction potential (ORP), dissolved oxygen and temperature were recorded and small liquid samples withdrawn and analysed for elemental concentrations using total reflection X-ray fluorescence spectrometry (TRXRF). Six of eight shale samples were found to be acid generating, with pH declining and ORP becoming increasingly positive after 100 days. Two of the eight shale samples produced increasingly alkaline leachate conditions with relatively low ORP after 100 days, indicating an inbuilt buffering capacity. By 600 days the buffering capacity of all samples had been consumed and all leachate samples were acidic. TRXRF analyses demonstrated significant potential for the leaching of S, Fe, Ni, Cu, Zn and Mn with greatest concentrations found in reaction vessels with most acidic pH and highest ORP.

Beschreibung: Hyperspectral high spatial resolution HyMap data are used to map mine waste from massive sulfide ore deposits, mostly abandoned, on the Iberian Pyrite Belt (southwest Spain). Mine dams, mill tailings and mine dumps in variable states of pyrite oxidation are recognizable. The interpretation of hyperspectral remote sensing requires specific algorithms able to manage high dimensional data compared to multispectral data. The routine of image processing methods used to extract information from hyperspectral data to map geological features is explained, as well as the sequence of algorithms used to produce maps of the mine sites. The mineralogical identification capability of algorithms to produce maps based on archive spectral libraries is discussed. Trends of mineral growth differ spectrally over time according to the geological setting and the recovery state of the mine site. Subtle mineralogical changes are enhanced using the spectral response as indicators of pyrite oxidation intensity of the mine waste piles and pyrite mud tailings. The changes in the surface of the mill tailings deserve a detailed description, as the surfaces are inaccessible to direct observation. Such mineralogical changes respond faithfully to industrial activities or the influence of climate when undisturbed by human influence.

Beschreibung: Consistently classified among the references for calcite simple prisms, the microstructural units that form the outer layer of the Pinctada margaritifera have been investigated through a series of morphological, crystallographical and biochemical characterizations. It is often said that the polygonal transverse shape of the prisms result from the competition for space between adjacent crystals. In contrast to this classical scheme the Pinctada prisms appear to be composed of four successive developmental stages from the concentrically growing disks on the internal side of the periostracum to the morphological, structural and compositional changes in both envelopes and mineral components at the end of the prisms. These latest structural and compositional changes predate nacre deposition, so that the end of prism growth is not caused by occurrence of nacre, but by metabolic changes in the secretory epithelium. This sequence makes obvious the permanent biological control exerted by the outer cell layer of the mantle in both organic envelopes and mineralizing organic phases.

Beschreibung: A two-fold objective is proposed for this research: removing hazardous and unpleasant wastes and mitigating the emissions of green house gasses in the atmosphere. Thus, the first aim of this work is to identify, characterize and recycle industrial wastes with high contents of calcium or sodium. This involves synthesizing materials with the ability for CO2 sequestration as preliminary work for designing industrial processes, which involve a reduction of CO2 emissions. In this regard, phosphogypsum from the fertilizer industry and liquid wastes from the green olive and bauxite industries have been considered as precursors. Following a very simple procedure, Ca-bearing phosphogypsum wastes are mixed with Na-bearing liquid wastes in order to obtain a harmless liquid phase and an active solid phase, which may act as a carbon sequestration agent. In this way, wastes, which are unable to fix CO2 by themselves, can be successfully turned into effective CO2 sinks. The CO2 sequestration efficiency and the CO2 fixation power of the procedure based on these wastes are assessed.

Beschreibung: Bioleaching of olivine, a natural nickel-containing magnesium-iron-silicate, was conducted by applying chemoorganotrophic bacteria and fungi. The tested fungus, Aspergillus niger, leached substantially more nickel from olivine than the tested bacterium, Paenibacillus mucilaginosus. Aspergillus niger also outperformed two other fungal species: Humicola grisae and Penicillium chrysogenum. Contrary to traditional acid leaching, the microorganisms leached nickel preferentially over magnesium and iron. An average selectivity factor of 2.2 was achieved for nickel compared to iron. The impact of ultrasonic conditioning on bioleaching was also tested, and it was found to substantially increase nickel extraction by A. niger. This is credited to an enhancement in the fungal growth rate, to the promotion of particle degradation, and to the detachment of the stagnant biofilm around the particles. Furthermore, ultrasonic conditioning enhanced the selectivity of A. niger for nickel over iron to a value of 3.5. Pre-carbonating the olivine mineral, to enhance mineral liberation and change metal speciation, was also attempted, but did not result in improvement as a consequence of the mild pH of chemoorganotrophic bioleaching.

Beschreibung: Zircon (ZrSiO4) is the most commonly used mineral in U–Pb geochronology. Although it has proven to be a robust chronometer, it can suffer from Pb-loss or elevated common Pb, both of which impede precision and accuracy of age determinations. Chemical abrasion of zircon involves thermal annealing followed by relatively low temperature partial dissolution in HF acid. It was specifically developed to minimize or eliminate the effects of Pb-loss prior to analysis using Thermal Ionization Mass Spectrometry (TIMS). Here we test the application of chemical abrasion to Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) by analyzing zircons from both untreated and chemically abraded samples. Rates of ablation for high alpha-dose non-treated zircons are up to 25% faster than chemically abraded equivalents. Ablation of 91500 zircon reference material demonstrates a ca. 3% greater down-hole fractionation of 206Pb/238U for non-treated zircons. These disparities necessitate using chemical abrasion for both primary reference material and unknowns to avoid applying an incorrect laser induced fractionation correction. All treated samples display a marked increase in the degree of concordance and/or lowering of common Pb, thereby illustrating the effectiveness of chemical abrasion to LA-ICP-MS U–Pb zircon geochronology.

Beschreibung: As analytical and microanalytical applications employing uranium isotope ratios increase, so does the need for reliable reference materials, particularly in the fields of geochemistry, geochronology, and nuclear forensics. We present working values for uranium isotopic data of NIST 610/611 glass, collected by multicollector inductively-coupled plasma mass spectrometry (MC-ICP-MS), multicollector thermal ionization mass spectrometry (MC-TIMS), and secondary ion mass spectrometry (SIMS). The presence of depleted U, and, in this case, measureable 236U, makes NIST 610/611 an ideal candidate for a uranium isotopic reference material for nuclear materials. We analyzed multiple chips of three different NIST 611 wafers and found no heterogeneity in 234U/238U, 235U/238U, and 236U/238U within or between the wafers, within analytical uncertainty. We determined working values and uncertainties (using a coverage factor of two) using data from this study and the literature for the following U isotope ratios: 234U/238U = 9.45 × 10−6 ± 5.0 × 10−8; 235U/238U = 2.38555 × 10−3 ± 4.7 × 10−7; and 236U/238U = 4.314 × 10−5 ± 4.0 × 10−8. SIMS data show 235U/238U is reproducible to within 1% (within analytical uncertainty) in a single wafer, at a scale of 25 μm. Multiple studies have demonstrated homogeneity between wafers of NIST 610 and NIST 611, thus the data reported here can be considered representative of NIST 610 as well.

Beschreibung: Secondary jarosite and water-soluble iron-sulfate minerals control the composition of acid mine waters formed by the oxidation of sulfide in tailings impoundments at the (Zn-Pb-Ag) Pan de Azúcar mine located in the Pozuelos Lagoon Basin (semi-arid climate) in Northwest (NW) Argentina. In the primary zone of the tailings (9.5 wt % pyrite-marcasite) precipitation of anglesite (PbSO4), wupatkite ((Co,Mg,Ni)Al2(SO4)4) and gypsum retain Pb, Co and Ca, while mainly Fe2+, Zn2+, Al3+, Mg2+, As3+/5+ and Cd2+ migrate downwards, forming a sulfate and metal-rich plume. In the oxidation zone, jarosite (MFe3(TO4)2(OH)6) is the main secondary Fe3+ phase; its most suitable composition is M = K+, Na+, and Pb2+and TO4 = SO42−; AsO42−. During the dry season, iron-sulfate salts precipitate by capillary transport on the tailings and at the foot of DC2 (tailings impoundment DC2) tailings dam where an acid, Fe2+ rich plume outcrops. The most abundant compounds in the acid mine drainage (AMD) are SO42−, Fe2+, Fe3+, Zn2+, Al3+, Mg2+, Cu2+, As3+/5+, Cd2+. These show peak concentrations at the beginning of the wet season, when the soluble salts and jarosite dissolve. The formation of soluble sulfate salts during the dry season and dilution during the wet season conform an annual cycle of rapid metals and acidity transference from the tailings to the downstream environment.

Beschreibung: The role of mineral surfaces in the adsorption, transport, formation, and degradation of natural organic matter (NOM) in the biosphere remains an active research area owing to the difficulties in identifying proper working models of both NOM and mineral phases present in the environment. The variety of aqueous chemistries encountered in the subsurface (e.g., oxic vs. anoxic, variable pH) further complicate this field of study. Recently, the advent of nanoscale probes such as X-ray adsorption spectroscopy and surface vibrational spectroscopy applied to study such complicated interfacial systems have enabled new insight into NOM-mineral interfaces. Additionally, due to increasing capabilities in computational chemistry, it is now possible to simulate molecular processes of NOM at multiple scales, from quantum methods for electron transfer to classical methods for folding and adsorption of macroparticles. In this review, we present recent developments in interfacial properties of NOM adsorbed on mineral surfaces from a computational point of view that is informed by recent experiments.

Beschreibung: Among the diverse research fields and wide range of studies encompassed by environmental magnetism, the present work elaborates on critical aspects of the geochemistry of trace metals that emerged through years of original research in a variety of environmental compartments. This review aims at sharing the insights gained on (a) tracing metal pollution sources; and (b) identifying processes and transport pathways from sources to depositional environments. Case studies on the Elefsis Gulf (Greece) and the Gulf of Lions (France) demonstrate the potential of combined magnetic measurements and chemical analysis to trace pollution signals resulting from land-based sources and atmospheric deposition. Case studies on estuarine environments, namely the Louros, Acheloos, and Asopos Estuaries (Greece), address modes of trace metal behavior under the influence of different hydrological regimes and elucidate in situ processes within the transitional estuarine zone, that define their ultimate fate. As sources, transport pathways, and processes of trace metals are fundamental in environmental management assessments, the involvement of magnetic measurements in the policy cycle could facilitate the development and implementation of appropriate regulatory measures for the integrated management of river basins, coastal, and marine areas.

Beschreibung: This study aimed to manipulate the texture and elemental composition of the novel sheaths produced by the iron-oxidizing bacterium Leptothrix in culture by altering components of the medium. When previously isolated strain OUMS1 was cultured in media (pH 7.0 throughout incubation) containing various levels of Si on a rotary shaker at 20 °C and 70 rpm for 14 days, the strain was able to reproduce in media with up to 300 ppm Si, and the hollow microtubular architecture of the sheath was maintained even at 300 ppm Si. The constitutional iron oxide phase changed from poorly crystalline lepidocrocite at 0 ppm Si to X-ray diffraction (XRD)-amorphous 2-line ferrihydrite at 100–300 ppm via their mixture phase with intermediate Si content (Si-30 and -50 ppm). The results strongly indicate that the chemical character and crystallinity of the sheath texture can be regulated by culture conditions, especially components of the medium.

Beschreibung: Sulphidic mine tailings are among the largest mining wastes on Earth and are prone to produce acid mine drainage (AMD). The formation of AMD is a sequence of complex biogeochemical and mineral dissolution processes. It can be classified in three main steps occurring from the operational phase of a tailings impoundment until the final appearance of AMD after operations ceased: (1) During the operational phase of a tailings impoundment the pH-Eh regime is normally alkaline to neutral and reducing (water-saturated). Associated environmental problems include the presence of high sulphate concentrations due to dissolution of gypsum-anhydrite, and/or effluents enriched in elements such as Mo and As, which desorbed from primary ferric hydroxides during the alkaline flotation process. (2) Once mining-related operations of the tailings impoundment has ceased, sulphide oxidation starts, resulting in the formation of an acidic oxidation zone and a ferrous iron-rich plume below the oxidation front, that re-oxidises once it surfaces, producing the first visible sign of AMD, i.e., the precipitation of ferrihydrite and concomitant acidification. (3) Consumption of the (reactive) neutralization potential of the gangue minerals and subsequent outflow of acidic, heavy metal-rich leachates from the tailings is the final step in the evolution of an AMD system. The formation of multi-colour efflorescent salts can be a visible sign of this stage.

Beschreibung: Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, and goethite in sea water (common secondary minerals in coastal tailings) was investigated. The aim of the investigation was to establish As retention and transport under a marine flood scenario, which may occur due to climate change. Natural and synthetic minerals with co-precipitated and adsorbed As were contacted with seawater for 25 days. During this period As, Fe, Cl, SO4, and pH levels were constantly measured. The larger retention capability of samples with co-precipitated As, in relation with adsorbed As samples, reflects the different kinetics between diffusion, dissolution, and surface exchange processes. Ferrihydrite and schwertmannite showed good results in retaining arsenic, although schwertmannite holding capacity was enhanced due its buffering capacity, which prevented reductive dissolution throughout the experiment. Arsenic desorption from goethite could be understood in terms of ion exchange between oxides and electrolytes, due to the charge difference generated by a low point-of-zero-charge and the change in stability of surface complexes between synthesis conditions and natural media.

Beschreibung: We present data of the time-evolution of a remediation approach on a marine shore tailings deposit by the implementation of an artificial wetland. Two remediation cells were constructed: one in the northern area at sea-level and one in the central delta area (above sea-level) of the tailings. At the beginning, the “sea-level” remediation cell had a low pH (3.1), with high concentrations of dissolved metals and sulfate and chloride ions and showed sandy grain size. After wetland implementation, the “sea-level” remediation cell was rapidly water-saturated, the acidity was consumed, and after four months the efficiency of metal removal from solution was up to 79.5%–99.4% for Fe, 94.6%–99.9% for Mn, and 96.1%–99.6% for Zn. Al and Cu concentrations decreased below detection limit. The “above sea-level” remediation cell was characterized by the same pH (3.1) and finer grain size (clayey–silty), and with some lower element concentrations than in the “sea-level” cell. Even after one year of flooding, the “above sea-level” cell was not completely flooded, showing on-going sulfide oxidation in between the wetland cover and the groundwater level; the pH increased only to 4.4 and metal concentrations decreased only by 96% for Fe, 88% for Al, 51% for Cu, 97% for Mn, and 95% for Zn. During a dry period, the water level dropped in the “sea-level” cell, resulting in a seawater ingression, which triggered the desorption of As into solution. These data show that the applied remediation approach for this tailings deposit is successful, if the system is maintained water-saturated. Metal removal from solution was possible in both systems: first, as a result of sorption on Fe(III) hydroxide/and/or clay minerals and/or co-precipitation processes after rise of pH; and then, with more reducing conditions, due to metal sulfides precipitation.

Beschreibung: The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the waste/metal production ratio. Mine wastes deposited on-land in so-called tailings dams, impoundments or waste-dumps have several associated environmental issues that need to be addressed (e.g., acid mine drainage formation due to sulphide oxidation, geotechnical stability, among others), and social concerns due to land use during mining. The mining industry recognizes these concerns and is searching for waste management alternatives for the future. One option used in the past was the marine shore or shallow submarine deposition of this waste material in some parts of the world. After the occurrence of some severe environmental pollution, today the deposition in the deep sea (under constant reducing conditions) is seen as a new, more secure option, due to the general thought that sulphide minerals are geochemically stable under the reduced conditions prevailing in the deep marine environment. This review highlights the mineralogical and geochemical issues (e.g., solubility of sulphides in seawater; reductive dissolution of oxide minerals under reducing conditions), which have to be considered when evaluating whether submarine tailings disposal is a suitable alternative for mine waste.

Beschreibung: Diffuse metal pollution from mining impacted sediment is widely recognised as a potential source of contamination to river systems and may significantly hinder the achievement of European Union Water Framework Directive objectives. Redox-transitional zones that form along metal contaminated river banks as a result of flood and drought cycles could cause biogeochemical changes that alter the behaviour of polyvalent metals iron and manganese and anions such as sulphur. Trace metals are often partitioned with iron, manganese and sulphur minerals in mining-contaminated sediment, therefore the dissolution and precipitation of these minerals may influence the mobility of potentially toxic trace metals. Research indicates that freshly precipitated metal oxides and sulphides may be more “reactive” (more adsorbent and prone to dissolution when conditions change) than older crystalline forms. Fluctuations at the oxic-anoxic interface brought about through changes in the frequency and duration of flood and drought episodes may therefore influence the reactivity of secondary minerals that form in the sediment and the flux of dissolved trace metal release. UK climate change models predict longer dry periods for some regions, interspersed with higher magnitude flood events. If we are to fully comprehend the future environmental risk these climate change events pose to mining impacted river systems it is recommended that research efforts focus on identifying the primary controls on trace metal release at the oxic-anoxic interface for flood and drought cycles of different duration and frequency. This paper critically reviews the literature regarding biogeochemical processes that occur at different temporal scales during oxic, reducing and dry periods and focuses on how iron and sulphur based minerals may alter in form and reactivity and influence the mobility of trace metal contaminants. It is clear that changes in redox potential can alter the composition of secondary iron and sulphur minerals and influence the sorption of toxic trace metals and susceptibility to dissolution when further redox potential changes occur. However further work is needed to determine: (i) The extent to which different duration and frequency of wet and dry cycles influences the dissolution and precipitation of iron and sulphur minerals in mining contaminated river bank sediment; (ii) The temporal effects on mineral reactivity (sorption capacity and susceptibility to dissolution); (iii) The key biogeochemical processes that control the mobility of contaminant trace metals under these dynamic redox potential conditions.

Beschreibung: Surface encrustation by minerals, which impedes cellular metabolism, is a potential hazard for microbes. The reduction of U(VI) to U(IV) by Shewanella oneidensis strain MR-1 leads to the precipitation of the mineral uraninite, as well as a non-crystalline U(IV) product. The wild-type (WT) strain can produce extracellular polymeric substances (EPS), prompting precipitation of U some distance from the cells and precluding encrustation. Using cryo-transmission electron microscopy and scanning transmission X-ray microscopy we show that, in the biofilm-deficient mutant ∆mxdA, as well as in the WT strain to a lesser extent, we observe the formation of membrane vesicles (MVs) as an additional means to lessen encrustation. Additionally, under conditions in which the WT does not produce EPS, formation of MVs was the only observed mechanism to mitigate cell encrustation. Viability studies comparing U-free controls to cells exposed to U showed a decrease in the number of viable cells in conditions where MVs alone are detected, yet no loss of viability when cells produce both EPS and MVs. We conclude that MV formation is a microbial strategy to shed encrusted cell surfaces but is less effective at maintaining cell viability than the precipitation of U on EPS.

Beschreibung: Intermolecular chemical networks defined by the hydrogen bonds formed at the α-quartz|water interface have been data-mined using graph theoretical methods so as to identify and quantify structural patterns and dynamic behavior. Using molecular-dynamics simulations data, the hydrogen bond (H-bond) distributions for the water-water and water-silanol H-bond networks have been determined followed by the calculation of the persistence of the H-bond, the dipole-angle oscillations that water makes with the surface silanol groups over time, and the contiguous H-bonded chains formed at the interface. Changes in these properties have been monitored as a function of surface coverage. Using the H-bond distribution between water and the surface silanol groups, the actual number of waters adsorbed to the surface is found to be 0.6 H2O/10 Å2, irrespective of the total concentration of waters within the system. The unbroken H-bond network of interfacial waters extends farther than in the bulk liquid; however, it is more fluxional at low surface coverages (i.e., the H-bond persistence in a monolayer of water is shorter than in the bulk) Concentrations of H2O at previously determined water adsorption sites have also been quantified. This work demonstrates the complementary information that can be obtained through graph theoretical analysis of the intermolecular H-bond networks relative to standard analyses of molecular simulation data.

Beschreibung: The future availability of helium has been raised as an issue in the literature. However, a disaggregated projection of helium production has not been attempted, presumably due to the difficult nature of accessing disaggregated historic production data to test the accuracy of this issue. This paper presents collated and estimated historic helium production statistics from 1921 to 2012 for each helium producing country in the world and by U.S. state. A high and regular growth projection of helium has been created. It is found that helium resources are sufficient for the near future, with the projected production plateauing in 2060–2075 and 2090–2100 for the high and regular growth scenarios, respectively. As long as natural gas deposits with helium are appropriately managed, there is little likelihood for helium shortages to occur in the short term due to geologic constraints.

Beschreibung: This review has as its underlying premise the need to become proficient in delivering a suite of element or metal products from polymetallic ores to avoid the predicted exhaustion of key metals in demand in technological societies. Many technologies, proven or still to be developed, will assist in meeting the demands of the next generation for trace and rare metals, potentially including the broader application of biohydrometallurgy for the extraction of multiple metals from low-grade and complex ores. Developed biotechnologies that could be applied are briefly reviewed and some of the difficulties to be overcome highlighted. Examples of the bioleaching of polymetallic mineral resources using different combinations of those technologies are described for polymetallic sulfide concentrates, low-grade sulfide and oxidised ores. Three areas for further research are: (i) the development of sophisticated continuous vat bioreactors with additional controls; (ii) in situ and in stope bioleaching and the need to solve problems associated with microbial activity in that scenario; and (iii) the exploitation of sulfur-oxidising microorganisms that, under specific anaerobic leaching conditions, reduce and solubilise refractory iron(III) or manganese(IV) compounds containing multiple elements. Finally, with the successful applications of stirred tank bioleaching to a polymetallic tailings dump and heap bioleaching to a polymetallic black schist ore, there is no reason why those proven technologies should not be more widely applied.

Beschreibung: Dissimilatory metal-reducing bacteria are ubiquitous in soils worldwide, possess the ability to transfer electrons outside of their cell membranes, and are capable of respiring with various metal oxides. Reduction of iron oxides is one of the more energetically favorable forms of anaerobic respiration, with a higher energy yield than both sulfate reduction and methanogenesis. As such, this process has significant implications for soil carbon balances, especially in the saturated, carbon-rich soils of the northern latitudes. However, the dynamics of these microbial processes within the context of the greater soil microbiome remain largely unstudied. Previously, we have demonstrated the capability of potentiostatically poised electrodes to mimic the redox potential of iron(III)- and humic acid-compounds and obtain a measure of metal-reducing respiration. Here, we extend this work by utilizing poised electrodes to provide an inexaustable electron acceptor for iron- and humic acid-reducing microbes, and by measuring the effects on both microbial community structure and greenhouse gas emissions. The application of both nonpoised and poised graphite electrodes in peat soils stimulated methane emissions by 15%–43% compared to soils without electrodes. Poised electrodes resulted in higher (13%–24%) methane emissions than the nonpoised electrodes. The stimulation of methane emissions for both nonpoised and poised electrodes correlated with the enrichment of proteobacteria, verrucomicrobia, and bacteroidetes. Here, we demonstrate a tool for precisely manipulating localized redox conditions in situ (via poised electrodes) and for connecting microbial community dynamics with larger ecosystem processes. This work provides a foundation for further studies examining the role of dissimilatory metal-reducing bacteria in global biogeochemical cycles.

Beschreibung: Tungsten mineralization in hydrothermal quartz veins from the Nyakabingo,Gifurwe and Bugarama deposits in central Rwanda occurs as the iron-rich endmember ofthe wolframite solid solution series (ferberite) and in the particular form of reinite, whichrepresents a pseudomorph of ferberite after scheelite. Primary ferberite, reinite and latesecondary ferberite are characterized by their trace element chemistry and rare earthelement patterns. The replacement of scheelite by ferberite is also documented in the traceelement composition. Primary ferberite shows high Mg, Zn, Sc, V, Nb, In and Snconcentrations, but very low Ca, Pb, Sr and Ba contents. Reinite and late secondaryferberite display an uncommon trace element composition containing high concentrationsof Ca, Pb, Sr, Ba, As and Ga, but very low levels in Sn, Zr, Hf, In, Ti, Sc, Nb, Ta, Mg andZn. Late secondary ferberite replacing primary ferberite is characterized by additionalenrichments in Bi, Pb, As and Sb. The rare earth element patterns of reinite and secondaryferberite are also similar to hydrothermal scheelite. The formation of the tungsten depositsin central Rwanda is interpreted to be epigenetic in origin, and the hydrothermalmineralizing fluids are related to the intrusion of the G4-granites.

Beschreibung: Rare Earths (RE) have been the focus of much attention in recent years as a consequence of a number of converging factors, prominent among which are: centralization of supply (in China), unique applications in high-end technologies particularly in the low-carbon energy industry, and global demand outstripping availability. Despite this focus, RE supply chain sustainability has not been examined in depth or in any systematic manner. This paper provides an initial review of RE sustainability considerations at present, including current initiatives to understand the research and development needs. The analysis highlights a broad range of areas needing consolidation with future research and calls for collaboration between industry and academia to understand the sustainability considerations of these critical elements in more depth.

Beschreibung: Early stages of sheath formation by Leptothrix sp. strain OUMS1 and its derivative sheathless mutant grown in media with or without Fe were examined by light and electron microscopy. Results showed that the initial parallel arrangement of fibrils excreted from the cells holds a key for subsequent construction of the sheath frame and that aqueous-phase Fe interacts with excreted fibrils whether fibrils are parallel-arranged or simply-intermingled.

Beschreibung: A Safety Maturity Model was developed for use in UK coal mining operations in order to assess the level of compliance and effectiveness with a recently introduced standards based safety management system. The developed model allowed for a “self-assessment” of the maturity to be undertaken by teams from the individual sites. Assessments were undertaken at all sites (surface and underground) and in some cases within each site (e.g., underground operations, surface coal preparation plant). Once the level of maturity was established, improvement plans were developed to improve the maturity of individual standards that were weaker than the average and/or improve the maturity as a whole. The model was likened to a journey as there was a strong focus on continual improvement and effectiveness of the standards, rather than pure compliance. The model has been found to be a practical and useful tool by sites as a means of identifying strengths and weaknesses within their systems, and as a means of assurance with the safety management system standards.

Beschreibung: The toxic element arsenic (As) occurs widely in solid and liquid mine wastes. Aqueous forms of arsenic are taken up in As-bearing sulfides, arsenides, sulfosalts, oxides, oxyhydroxides, Fe-oxides, -hydroxides, -oxyhydroxides and -sulfates, and Fe-, Ca-Fe- and other arsenates. Although a considerable body of research has demonstrated that microbes play a significant role in the precipitation and dissolution of these As-bearing minerals, and in the alteration of the redox state of As, in natural and simulated mining environments, the molecular-scale mechanisms of these interactions are still not well understood. Further research is required using traditional and novel mineralogical, spectroscopic and microbiological techniques to further advance this field, and to help design remediation schemes.

Beschreibung: Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn- and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented.

Beschreibung: Extremely Re-rich molybdenite occurs with pyrite in sodic–calcic, sodic–sericitic and sericitic-altered porphyritic stocks of granodioritic–tonalitic and granitic composition in the Sapes–Kirki–Esymi, Melitena and Maronia areas, northeastern Greece. Molybdenite in the Pagoni Rachi and Sapes deposits is spatially associated with rheniite, as well as with intermediate (Mo,Re)S2 and (Re,Mo)S2 phases, with up to 46 wt % Re. Nanodomains and/or microinclusions of rheniite may produce the observed Re enrichment in the intermediate molybdenite–rheniite phases. The extreme Re content in molybdenite and the unique presence of rheniite in porphyry-type mineralization, combined with preliminary geochemical data (Cu/Mo ratio, Au grades) may indicate that these deposits have affinities with Cu–Au deposits, and should be considered potential targets for gold mineralization in the porphyry environment. In the post-subduction tectonic regime of northern Greece, the extreme Re and Te enrichments in the magmatic-hydrothermal systems over a large areal extent are attributed to an anomalous source (e.g., chemical inhomogenities in the mantle-wedge triggered magmatism), although local scale processes cannot be underestimated.

Beschreibung: Documentation of contaminant source and dispersal pathways in riverine environments is essential to mitigate the potentially harmful effects of contaminants on human and ecosystem health, and is required from a legal perspective (particularly where the polluter pays principle is in effect) in assessing site liability. Where multiple natural and/or anthropogenic sources exist, identification of contaminant provenance has proven problematic, and estimated contributions from a specific source are often the subject of judicial debate. The past, current, and future use of geochemical and isotopic tracers in environmental forensic investigations of contaminant provenance, transport, and fate are analyzed herein for sediment-associated trace metals in riverine environments, particularly trace metals derived from mining and refining operations. The utilized methods have evolved significantly over the past four decades. Of primary significance has been the growing integration of geomorphic and stratigraphic techniques with the use of an increasing number of geochemical tracers including stable isotopes. The isotopes of Pb have been particularly well studied, and have been applied to a wide range of environmental media. Advances in analytical chemistry since the early 1990s have allowed for the precise characterization of other non-traditional stable isotopic systems within geological materials. The potential for using these non-traditional isotopes as tracers in river systems has yet to be adequately explored, but a number of these isotopes (e.g., Cd, Cu, Cr, Hg, Sb, and Zn) show considerable promise. Moreover, some of these isotopes (e.g., those of Cu, Cr, and Hg) may provide important insights into biogeochemical cycling processes within aquatic environments. This review suggests that future environmental forensic investigations will be characterized by an interdisciplinary approach that combines the use of multiple geochemical tracers with detailed stratigraphic, geomorphic, and hydrologic data, thereby yielding results that are likely to withstand the scrutiny of judicial review.

Beschreibung: The aquatic, Fe-oxidizing bacteria Leptothrix spp. produce uniquely shaped extracellular sheaths composed of organic bacterial polymers encrusted with inorganic elements from its aquatic environments. At the initial stage of sheath formation, bacterial cells were aligned in the sheath, but later most sheaths became empty. Here, we studied the mechanism of sheath hollowing by examining an isolate of Leptothrix sp. strain OUMS1 cultured in either artificial medium or natural groundwater. After 3 days in the medium, most sheaths at the initial stage surrounded a line of live cells, while some cells in the line were dead regardless of their position in a sheath. In sheaths where cells and/or their remnants were barely distinguishable by differential interference contrast microscopy (DIC), a vital stain and a stain specific for nucleic acids occasionally revealed dead cells and/or nucleic acid remnants, while sheaths that lacked a positive response to these reagents looked transparent when viewed with DIC. In specimens cultured in the medium for 7 days, dead cells increased in number regardless of their position in the sheath. Almost the same phenomena occurred in specimens cultured in natural groundwater until day 7. Transmission electron microscopy (TEM) showed that cells degenerated, leading to autolysis of bacterial cells in the sheath. These observations led us to conclude that autolysis of bacterial cells could be a major cause of sheath hollowing.

Beschreibung: The iron mining regions of Brazil contain thousands of “iron ore caves” (IOCs) that form within Fe(III)-rich deposits. The mechanisms by which these IOCs form remain unclear, but the reductive dissolution of Fe(III) (hydr)oxides by Fe(III) reducing bacteria (FeRB) could provide a microbiological mechanism for their formation. We evaluated the susceptibility of Fe(III) deposits associated with these caves to reduction by the FeRB Shewanella oneidensis MR-1 to test this hypothesis. Canga, an Fe(III)-rich duricrust, contained poorly crystalline Fe(III) phases that were more susceptible to reduction than the Fe(III) (predominantly hematite) associated with banded iron formation (BIF), iron ore, and mine spoil. In all cases, the addition of a humic acid analogue enhanced Fe(III) reduction, presumably by shuttling electrons from S. oneidensis to Fe(III) phases. The particle size and quartz-Si content of the solids appeared to exert control on the rate and extent of Fe(III) reduction by S. oneidensis, with more bioreduction of Fe(III) associated with solid phases containing more quartz. Our results provide evidence that IOCs may be formed by the activities of Fe(III) reducing bacteria (FeRB), and the rate of this formation is dependent on the physicochemical and mineralogical characteristics of the Fe(III) phases of the surrounding rock.

Beschreibung: Double difference seismic tomography was performed using travel time data from a carbon sequestration site at the Aneth oil field in southeast Utah as part of a Department of Energy initiative on monitoring, verification, and accounting (MVA) of sequestered CO2. A total of 1211 seismic events were recorded from a borehole array consisting of 23 geophones. Artificial velocity models were created to determine the likelihood of detecting a CO2 plume with an unfavorable event and receiver arrangement. In tests involving artificially modeled ray paths through a velocity model, ideal event and receiver arrangements clearly show velocity reductions. When incorporating the unfavorable event and station locations from the Aneth Unit into synthetic models, the ability to detect velocity reductions is greatly diminished. Using the actual, recorded travel times, the Aneth Unit results show differences between a synthetic baseline model and the travel times obtained in the field, but the differences do not clearly indicate a region of injected CO2. MVA accuracy and precision may be improved through the use of a receiver array that provides more comprehensive ray path coverage, and a more detailed baseline velocity model.

Beschreibung: Albitite-type uranium deposits are widely distributed, usually of low grade (〈1% U3O8), but are often large and collectively contain over 1 million tonnes of U3O8. Uranium is hosted in a wide range of metamorphic lithologies, whose only common characteristic is that they have been extensively mylonitised. Ore minerals are disseminated and rarely in megascopic veins, within and adjacent to albitised mylonites. Grain size is uniformly fine, generally less than 50 microns. Scanning electron microscopy reveals that spatial association between uranium and various Ti-bearing phases is common. Gangue minerals include albite, carbonates (calcite and dolomite), and sodic pyroxene and amphibole. The ore rarely contains economic metals apart from uranium, phosphorous at Itataia being an exception. There is widespread evidence of hydrothermal zirconium mobility and hydrothermal zircon and other Zr phases are frequent and in some cases abundant gangue minerals. Positive correlations are noted between uranium and various high field strength elements. The group remains poorly described and understood, but a link to iron-oxide copper-gold (IOCG) deposits and/or carbonatite and/or alkaline magmatism is plausible.

Beschreibung: Biomining, the biotechnology that uses microorganisms to extract metals from ores and concentrates, is currently used exclusively for processing reduced ores and mine wastes. Metals of economic value also occur extensively in oxidized ores, such as nickel laterites. While these are not amenable to oxidative dissolution, the ferric iron minerals they contain can, in theory, be disrupted by iron reduction, causing associated metals to be released. We have harnessed the ability of the facultatively anaerobic, acidophilic bacterium Acidithiobacillus ferroooxidans to couple the oxidation of elemental sulphur to the reduction of ferric iron in the goethite fraction of a limonitic nickel ore at 30 °C. Nickel and other metals (Co, Cr and Mn) were effectively solubilised and maintained in solution due to the low pH (1.8) of the leach liquor. The results highlight the potential for the bioprocessing of oxidized, iron-rich ores using an approach that is energy-saving and environmentally-benign compared with metallurgical processes currently applied to the extraction of Ni from lateritic ores.

Beschreibung: It is more common than not, for mineral processing studies to proceed via the examination of model flotation systems with the resulting data often lacking statistical verification. The resultant concentrates and tails may then be subjected to a restricted range of analyses, for diagnosis of the flotation behavior variations observed, that themselves bias the outcomes. For instance surface analysis may be undertaken without reference to solution speciation, or liberation may be studied but surface speciation may not be taken into account. We propose an integrated approach whereby firstly the flotation data are vigorously scrutinized and the mineralogy, liberation, surface and solution speciation are examined in parallel to establish a chemical over view of the system. It is proposed that to make progress in the understanding of flotation systems, in terms of the minerals chemistry, that a multi-dimensional analytical approach is utilized and that the focus shifts towards the analysis of real ores and industrial flotation systems.

Beschreibung: The purpose of this study was to evaluate health risks to operators of large and small load-haul-dump (LHD) vehicles exposed to whole-body vibration (WBV), based on criteria established in ISO 2631-1, ISO 2631-5, and EU Directive 2002/44 EC. Studies simultaneously evaluating health risks based on all three standards are limited. Operator WBV exposure was measured in accordance with ISO 2631-1 using a tri-axial seat pad accelerometer. According to ISO 2631-1, four of the seven large LHD vehicle operators and three of six small LHD vehicle operators were exposed to WBV above the 8-hour vibration dose value (VDV) health guidance caution zone (HGCZ). According to the EU Directive 2002/44/EC criteria one of the seven large LHD vehicle operators and one of the six small LHD vehicle operators were exposed to WBV above the VDV daily exposure limit. However, health risks predicted by ISO 2631-5 criteria only placed one of seven large LHD vehicle operators and one of the six small LHD vehicle operators in the high probability of an adverse health effect category. Thus, the probability of adverse health effects, associated with WBV exposure during LHD vehicle operation, is suggested to be greatest based on the ISO 2631-1 8-hour VDV HGCZ and lowest based on ISO 2631-5 Sed criterion values.

Beschreibung: New geological, bulk chemical and mineralogical (QEMSCAN and FEG-EPMA) data are presented for albitite-type uranium deposits of the Mount Isa region of Queensland, Australia. Early albitisation of interbedded metabasalt and metasiltstone predated intense deformation along D2 high strain (mylonite) zones. The early sodic alteration paragenetic stage includes albite, riebeckite, aegirine, apatite, zircon and magnetite. This paragenetic stage was overprinted by potassic microveins, containing K-feldspar, biotite, coffinite, brannerite, rare uraninite, ilmenite and rutile. An unusual U-Zr phase has also been identified which exhibits continuous solid solution with a uranium silicate possibly coffinite or nenadkevite. Calcite, epidote and sulphide veinlets represent the latest stage of mineralisation. This transition from ductile deformation and sodic alteration to vein-controlled uranium is mirrored in other examples of the deposit type. The association of uranium with F-rich minerals and a suite of high field strength elements; phosphorous and zirconium is interpreted to be indicative of a magmatic rather than metamorphic or basinal fluid source. No large intrusions of appropriate age outcrop near the deposits; but we suggest a relationship with B- and Be-rich pegmatites and quartz-tourmaline veins.

Beschreibung: Microbial communities mediating gold cycling occur on gold grains from (sub)-tropical, (semi)-arid, temperate and subarctic environments. The majority of identified species comprising these biofilms are β-Proteobacteria. Some bacteria, e.g., Cupriavidus metallidurans, Delftia acidovorans and Salmonella typhimurium, have developed biochemical responses to deal with highly toxic gold complexes. These include gold specific sensing and efflux, co-utilization of resistance mechanisms for other metals, and excretion of gold-complex-reducing siderophores that ultimately catalyze the biomineralization of nano-particulate, spheroidal and/or bacteriomorphic gold. In turn, the toxicity of gold complexes fosters the development of specialized biofilms on gold grains, and hence the cycling of gold in surface environments. This was not reported on isoferroplatinum grains under most near-surface environments, due to the lower toxicity of mobile platinum complexes. The discovery of gold-specific microbial responses can now drive the development of geobiological exploration tools, e.g., gold bioindicators and biosensors. Bioindicators employ genetic markers from soils and groundwaters to provide information about gold mineralization processes, while biosensors will allow in-field analyses of gold concentrations in complex sampling media.

Beschreibung: Two-phase (water and air) flow in the forced-air mechanically-stirred Dorr-Oliver machine has been investigated using computational fluid dynamics (CFD). A 6 m3 model is considered. The flow is modeled by the Euler-Euler approach, and transport equations are solved using software ANSYS-CFX5. Unsteady simulations are conducted in a 180-degree sector with periodic boundary conditions. Air is injected into the rotor at the rate of 2.63 m3/min, and a uniform bubble diameter is specified. The effects of bubble diameter on velocity field and air volume fraction are determined by conducting simulations for three diameters of 0.5, 1.0, and 2.0 mm. Air volume fraction contours, velocity profiles, and turbulent kinetic energy profiles in different parts of the machine are presented and discussed. Results have been compared to experimental data, and good agreement is obtained for the mean velocity and turbulent kinetic energy profiles in the rotor-stator gap and in the jet region outside stator blades.

Beschreibung: Whole-body vibration is a significant health risk for between 4% and 7% of the work force in North America. In addition, many factors compound the health risks of heavy machinery operators. For example, twisted trunk and neck postures stiffen the spine and increase the transmission of vibration to the head. Similarly, workers adopt awkward postures in order to gain appropriate lines of sight for machine operations. Although the relative contribution of these various issues can be evaluated in field studies and models, we propose that virtual reality is a powerful medium for investigating issues related to health and safety in mining machine operators. We have collected field data of posture and vibration, as well as visual environment, for a forklift operating in a warehouse. This paper describes the process and outcome of this field data collection, and provides a discussion on the next steps to develop and test the virtual reality model to enable laboratory testing. Our ongoing studies will evaluate the interplay between posture and vibration under conditions replicating routine heavy machinery operations, such as underground mining.

Beschreibung: Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS) deposits of Corchia ophiolite (Parma province, Italy) in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and sedimentary rocks. The Pozzo mineralization is hosted by a serpentinite. Concentrations of gold up to 3070 ppb have been reported for the Cantiere Donnini and up to 6295 ppb in the Pozzo mine. According to the field relationships, gold composition, mineralogical assemblage and sulfur isotope data, we can conclude that two different types of gold mineralization have been recognized in the Corchia ophiolite: (1) formed at low temperature in submarine environment (Cantiere Donnini and Speranza) and (2) formed at high temperature in the oceanic mantle (Pozzo) by segregation of an immiscible sulfide liquid.

Beschreibung: Major companies in the minerals industry are increasingly recognizing that their operations have an impact in the wider community. Regarding transportation issues, this impact extends beyond purely the safety of company vehicle fleets to consideration of Community Road Safety (CRS) concerns, which address the driving, walking, and riding practices of community members in a locale with increased heavy vehicle traffic. Our assessment here of national and international trends in approaches to road safety awareness and associated road safety strategies is meant to inform companies in the minerals industry of developments that can influence the design of their road safety initiatives. The review begins by considering the overall road safety context and the dominant “safe systems” framework employed internationally. Thereafter, it considers what is typically included in CRS initiatives for the minerals industry. Three case studies are then presented to highlight approaches that feature exemplary collaboration, design, implementation, or impact. Thereafter, we analyze lessons learnt by key researchers and practitioners in the CRS field. Finally, we conclude that best CRS practices for the minerals industry rely on eleven factors, including for example collaboration with local entities and stepwise implementation.

Beschreibung: Artisanal metallurgical slag produced more than 50 years ago at a mine site in southwest Japan is rich in toxic metals and metalloids. Some of the slag remains on a waste dump and could contaminate the surrounding area through the dissolution of heavy metals and metalloids during weathering. To assess this risk, this study has investigated the behavior of the toxic elements in the smelting slag during weathering. Most of the potentially toxic elements are contained in willemite and/or matte drops. Maximum metal and metalloid concentrations in the slag are 28.1 wt % Fe, 22.7 wt % Zn, 1.63 wt % Cu, 3450 mg/kg Sn, 826 mg/kg Pb, 780 mg/kg As, and 116 mg/kg Cd. Zn is mainly contained in willemite, whereas other metals and metalloids are mainly concentrated in matte drops. The willemite and matte drops are converted to Fe-hydroxides during weathering, indicating that potentially toxic metals and metalloids contained in these phases are released by weathering processes. Therefore, weathering of the artisanal metallurgical slag, containing large amounts of willemite and matte drops, may pollute the surrounding environment.

Beschreibung: Mineralogical characterization by X-ray diffraction (XRD) and a high throughput automated quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) was conducted on samples from a sulphate-reducing biochemical reactor (BCR) treating high concentrations of metals (As, Zn, Cu) in smelter waste landfill seepage. The samples were also subjected to energy dispersive X-ray (EDX) analysis of specific particles. The bulk analysis results revealed that the samples consisted mainly of silicate and carbonate minerals. More detailed phase analysis indicated four different classes: zinc-arsenic sulphosalts/sulphates, zinc-arsenic oxides, zinc phosphates and zinc-lead sulphosalts/sulphates. This suggests that sulphates and sulphides are the predominant types of Zn and As minerals formed in the BCR. Sphalerite (ZnS) was a common mineral observed in many of the samples. In addition, X-ray point analysis showed evidence of As and Zn coating around feldspar and amphibole particles. The presence of arsenic-zinc-iron, with or without cadmium particles, indicated arsenopyrite minerals. Copper-iron-sulphide particles suggested chalcopyrite (CuFeS2) and tennantite (Cu,Fe)12As4S13. Microbial communities found in each sample were correlated with metal content to describe taxonomic groups associated with high-metal samples. The research results highlight mineral grains that were present or formed at the site that might be the predominant forms of immobilized arsenic, zinc and copper.

Beschreibung: The feasibility of investigating the adsorption of n-octanohydroxamate collector on copper and iron oxide minerals with static secondary ion mass spectrometry has been assessed. Secondary ion mass spectra were determined for abraded surfaces of air-exposed copper metal, malachite, pseudomalachite and magnetite that had been conditioned in aqueous potassium hydrogen n-octanohydroxamate solution, as well as for the corresponding bulk CuII and FeIII complexes. In each case, the chemical species present at the solid/vacuum interface of a similarly prepared surface were established by X-ray photoelectron spectroscopy. The most abundant positive and negative metal-containing fragment ions identified for the bulk complexes were also found to be diagnostic secondary ions for the collector adsorbed on the oxide surfaces. The relative abundances of those diagnostic ions varied with, and could be rationalised by, the monolayer or multilayer coverage of the adsorbed collector. However, the precise mass values for the diagnostic ions were not able to corroborate the different bonding in the copper and iron hydroxamate systems that had been deduced from photoelectron and vibrational spectra. Parent secondary ions were able to provide supporting information on the co-adsorption of hydroxamic acid at each conditioned surface.

Beschreibung: Fifteen multi-national mining companies are currently members of the Earth Moving Equipment Safety Round Table (EMESRT). Formed in 2006, EMESRT engages with mining equipment manufacturers with the aim of accelerating improvements in the safe design of mining equipment. An initial stage in this process was to communicate industry understanding of the risks in the form of “design philosophies” that describe potential unwanted events in eight hazard categories. A technique for analysing risks associated with operation and maintenance tasks, the Operability and Maintainability Analysis Technique (OMAT), was subsequently developed and trialed. The next step is the EMESRT Design Evaluation for Equipment Procurement (EDEEP) process. The aims of requesting manufacturers to follow this process are to provide equipment purchasers with a common way of assessing how well the issues in the EMESRT Design Philosophies are addressed in the equipment design; and to provide manufacturers with additional information for use during equipment design. The process involves identifying priority tasks based on frequency and severity of the consequences of potential unwanted events identified in the EMESRT Design Philosophies; undertaking a task-based risk assessment of priority tasks in conjunction with site-based personnel; evaluating the effectiveness of control measures; and providing information about safe design features in a standardised format.

Beschreibung: The epigenetic Zn-Pb deposits in the Lycksele-Storuman ore district, northern Sweden, are hosted by Paleoproterozoic basement near the margin of the Caledonian mountains. A paleogeographic reconstruction suggests that platform sediments, including Cambrian shales, overlaid the mineralised basement. The mineralisation type, containing sphalerite, galena, calcite and fluorite, is confined to veins and breccias and interpreted to be of Mississippi Valley Type (MVT) style. There is no appreciable wall rock alteration. Fluid inclusion work reveals coexisting aqueous and hydrocarbon fluids. Ore deposition is interpreted to have occurred during mixing of two fluids; a cool (

Beschreibung: Nerita undata is a marine gastropod, the shell of which consists of an external layer composed of very fine, long and undulating calcite prisms, and of an internal aragonite crossed-lamellar layer. As for any Ca-carbonate shell, both layers are composite materials, resulting from the  sub-micrometric association of organic macromolecules with the mineral phase. But at the transition between the two layers, in situ synchrotron-based mapping using μ-XANES spectroscopy performed at the S K-edge and SR-FTIR spectroscopy reveals that biochemical compositions change correlatively with the mineral phase, such as displayed by the distribution of sulfur-containing organic compounds (S-polysaccharides or S-amino acids) and organic molecular groups (amide I and II bands). These results highlight the complex change of secretory activity operated by the mineralizing tissue (the mollusk mantle) between these two parts of the shell, which is suspected to minutely control the setting-up of the crossed-lamellar microstructural pattern over the calcite prisms—A not so straightforward feature.

Beschreibung: Objectives: In artisanal small-scale gold mining (ASGM) areas in many developing countries, mercury (Hg) is used to extract gold from ore. Data of 1250 participants from Indonesia, Mongolia, Philippines, Tanzania, and Zimbabwe were combined to analyze the relation between exposure in ASGM areas and body burden. Methods: Four groups were selected relating to their intensity of contact with mercury: (i) a non-exposed control group; (ii) a low exposed group with participants only living in mining areas, but not working as miners; (iii) a medium exposed group, miners living in exposed areas and working with mercury without smelting amalgam; and (iv) a high exposed group, miners living in exposed areas and smelting amalgam. Results: Compared to the non-exposed control group, participants living and/ or miners working in highly exposed areas have significantly higher concentration of total mercury in urine, hair and blood (p-value 〈 0.001). The median mercury value in urine in the control group is 〈 0.2 µg/L. In the high exposed group of amalgam smelters, the median in urine is 12.0 µg/L. The median in blood in the control group is 〈 0.93 µg/L. The median level in blood of the high exposed group is 7.56 µg/L. The median for mercury in hair samples from the control group is 0.21 µg/g. In the high exposed group the median hair concentration is 2.4 µg/g hair. Mercury levels also differ considerably between the countries, reflecting a diverse background burden due to different fish eating habits and different work place methods. Conclusions: A high percentage of exposed individuals had levels above threshold values. These high levels of mercury are likely to be related with serious health problems.

Beschreibung: The bulk minerals iron ore and bauxite cause significant greenhouse emissions in their processing to steel and aluminum respectively. The level of these emissions is highly dependent on the source of electrical and thermal energy. However, they also cause significant greenhouse gas emissions from their transportation across the globe for processing. This study examines these minerals from the perspective of greenhouse gas avoidance, examining the location of processing as an option for reducing transportation-based and process-based emissions. The analysis proposes a “radius of reduction” to define the potential for transporting ore to reduce emissions by offshore processing. Overall scenarios for localized steel production indicate potential for 85% reduction of transport emissions in the steel industry and 14% of overall industry emissions. Local high-carbon electricity grids and inefficient production mean that the benefit of reduced transportation is partially counteracted by increased processing emissions. The transportation of all global bauxite to Norway and other nations with low-emissions electricity for production of aluminum could result in an overall reduction of industry emissions of up to 44%.

Beschreibung: The recent definitive deuterium solid state NMR spectroscopic evidence for structural water in fluor- and hydroxylapatites has prompted our study of the conditions necessary for the removal and reincorporation of this important structural feature of apatites. Thermal gravimetric analysis of 20 synthetic carbonated calcium hydroxylapatite (CCaApOH) samples and nine carbonated calcium fluorapatite (CCaApF) samples has been used to determine the amount of structural and adsorbed water in each sample. No correlation between the weight percent and number of moles of structural water and the weight percent carbonate in CCaApOH and CCaApF has been found. In contrast, there appears to be a relationship between the amount of adsorbed water and the carbonate concentration in the fluorapatites prepared with a two hour digestion time, as well as in the hydroxylapatites prepared with one hour digestion periods, presumably due to the effect of carbonate on crystallite size. Structural water can be removed from the apatite lattice, primarily above 200 °C, but heating to over 550 °C is required for complete removal. This water can be partly reincorporated through an apparently kinetically-controlled process that is enhanced by an increase in time and/or temperature. We speculate that the incorporation of structural water occurs at the beginning of the formation of the apatite structure, approximately coincident with the incorporation of carbonate. We also speculate that water is both removed and reincorporated by proton transfers from water molecules to hydroxide ions.

Beschreibung: Same level falls continue to contribute to an alarming number of slip/trip/fall injuries in the mining workforce. The objective of this study was to investigate how walking on different surface types and transverse slopes influences gait parameters that may be associated with a trip event. Gait analysis was performed for ten subjects on two orientations (level and sloped) on smooth, hard surface (control) and irregular (gravel, larger rocks) surfaces. Walking on irregular surfaces significantly increased toe clearance compared to walking on the smooth surface. There was a significant (p 〈 0.05) decrease in cadence (steps/min), stride length (m), and speed (m/s) from control to gravel to larger rocks. Significant changes in external rotation and increased knee flexion while walking on irregular surfaces were observed. Toe and heel clearance requirements increased on irregular surfaces, which may provide an explanation for trip-induced falls; however, the gait alterations observed in the experienced workers used as subjects would likely improve stability and recovery from a trip.

Beschreibung: This review describes some of the literature pertaining to sleep deprivation, shift working, and heat exposure. Consequences of each on human cognitive function, particularly with respect to vigilance and attentional capacity are reviewed. Individually, each of these factors is known to impair human cognition; however, we propose the possibility that for miners working in hot underground environments and who are assigned to rotating shifts, the combination may leave miners with significant degrees of fatigue and decreased ability to focus on tasks. We suggest that such decreased capacity for vigilance is a source of concern in an occupational health and safety context.

Beschreibung: In recent decades, excellent progress has been made globally in finding mineral resources, extracting them efficiently and effectively, dramatically reducing environmental degradation, and preventing adverse health and safety impacts on workers and stakeholders. The industry has realized tremendous advances in technology and applied science; has met changing and more stringent environmental performance criteria; has made remarkable reductions in fatality, illness, and lost-time accident rates; and has connected better than ever before with the communities in which mining, milling, and smelting are housed. A new era focused on continuous improvement in tackling key sustainable development parameters has come and is intensifying [1].  In order to maintain the social licenses needed to enlist broad public support for mining businesses, continued progress must be visible to national, provincial, and local governments as well as the people who live in the areas blessed with the mineral resources that the global economy and growing population will demand. [...]

Beschreibung: The characterization, evaluation and remediation of polluted soils is one of the present environmental challenges to be addressed in the coming years. The origin of trace elements in soils can be either geogenic or anthropogenic, but only the latter is interesting from a legal point of view. The hazard of the pollutants in the soils not only depends on their total concentration, but particularly on their availability. The mobility of the trace elements depends on their speciation, and it is also affected by several soil parameters. Mining activity is one of the most important anthropogenic causes of soil pollution. As a case study, this work is focused in the Riotinto mining area (Iberian Pyrite Belt, IPB, SW Spain). The IPB is one of the most important metallogenic provinces in the world and it has been exploited for thousands of years. The disposal of mining residues has produced important sources of contamination by trace elements and acidic waters affecting soils and rivers. In addition to these problems, the closure of mines in the Pyrite Belt at the end of the 20th Century has led to a great loss of employment, which has caused the development of an intensive agriculture of citrus fruits as a new source of income. The intensive growing of citrus fruits and the traditional subsistence agriculture have been developed surrounding the mining areas and on floodplains near to mining sites. The level of soil pollution has not been taken into account in these cases, nor has its impact on the health of the inhabitants of these areas. Therefore, it is of great interest to study the current state of the cultivated soils and the sources and types of contaminants derived from mining activity in order to program its decontamination, where appropriate, according to legislation. In order to know the present and future hazard posed by the soils chemical and mineralogical speciation has been carried out, given that the availability of a metal depends on the phase in which it is found. The results showed that mining activity has caused high levels of As, Cu, Pb and Zn in several cultivated soils. Moreover, Cu, Pb and Zn showed a high bioavailability. This suggests that at least other studies are necessary to preserve health in the inhabitants of this area. The methodology carried out in this work allowed to select potentially polluted areas where agricultural activities are not recommended.

Beschreibung: Despite undeniable progress, the mining industry remains the scene of serious accidents revealing disregard for occupational health and safety (OHS) and leaving open the debate regarding the safety of its employees. The San José mine last collapse near Copiapó, Chile on 5 August 2010 and the 69-day rescue operation that followed in order to save 33 miners trapped underground show the serious consequences of neglecting worker health and safety. The aim of this study was to validate a new approach to integrating OHS into risk management in the context of a new open-pit mining project in Quebec, based on analysis of incident and accident reports, semi-structured interviews, questionnaires and collaborative field observations. We propose a new concept, called hazard concentration, based on the number of hazards and their influence. This concept represents the weighted fraction of each category of hazards related to an undesirable event. The weight of each category of hazards is calculated by AHP, a multicriteria method. The proposed approach included the creation of an OHS database for facilitating expert risk management. Reinforcing effects between hazard categories were identified and all potential risks were prioritized. The results provided the company with a rational basis for choosing a suitable accident prevention strategy for its operational activities.

Beschreibung: Mollusk shells, especially the nacre, are of commercial interest as well as palaeoenvironmental proxies. They are also investigated as biomaterials for medical purposes and biomimetics. Although the mineralogy is well-known and unique (aragonite tablets), the organic components are various. However, determination of the precise composition of the soluble organic matrix (SOM) of the nacreous layer is difficult. Among the range of possible techniques, 1D electrophoresis and High-performance liquid chromatography (HPLC) have previously been applied separately to differentiate pI and molecular weights. To date, no clear correlation has been established between the two parameters obtained in such conditions. Here, we report the use of preparative electrophoresis, coupled with HPLC, to determine the molecular weights of the pI fractions. The results are compared with 2D gel electrophoresis. It is shown that both methods have drawbacks and advantages, and are not redundant. The complexity of the composition of the nacreous tablet shown by scanning electron microscope (SEM) and Atomic Force Microscope (AFM) observations is also evidenced by electrophoresis and HPLC.

Beschreibung: The purpose of this study was to investigate the relationship between community-level exposure to changes in economic conditions and the incidence and prevalence of mental disorders and cardiovascular disease in 29 resource-based communities (with a focus on mining communities) in British Columbia (BC) during a period of time marked by an economic downturn (1991–2002) The investigation relied on Labour Force Survey (LFS) and Statistics Canada Census data, and health records from the British Columbia Ministry of Health (MoH). Age and sex adjusted prevalence and incidence rates were calculated for each community from 1991 to 2002 and the development of an economic change indicator defined using Census data and industry/government documents allowed for yearly assessment of community-level exposure to economic conditions. The relationship between exposure to economic change and rates of acute and chronic cardiovascular disease and mental disorders across the 29 study communities was investigated using a generalized linear model (stratified by type of community, and adjusted for the effect of the community). Findings indicate an impact on the prevalence rates for acute cardiovascular disease (CVD) during periods of economic decline (rate increased by 13.1 cases per 1,000 population, p 〈 0.0001 as compared with stable periods) and bust conditions (rate increased by 30.1 cases per 1,000 population, p 〈 0.0001 as compared with stable conditions) and mental disorders (rate increased by 13.2 cases per 1,000 population, p = 0.0001) in mining communities during declining economic conditions as compared to steady periods of mining employment. This is not observed in other resource-based communities. The paper concludes by highlighting implications for the mining industry to consider as they begin to recognize and commit to mining community health.

Beschreibung: This paper critically assesses if accessible lithium resources are sufficient for expanded demand due to lithium battery electric vehicles. The ultimately recoverable resources (URR) of lithium globally were estimated at between 19.3 (Case 1) and 55.0 (Case 3) Mt Li; Best Estimate (BE) was 23.6 Mt Li. The Mohr 2010 model was modified to project lithium supply. The Case 1 URR scenario indicates sufficient lithium for a 77% maximum penetration of lithium battery electric vehicles in 2080 whereas supply is adequate to beyond 2200 in the Case 3 URR scenario. Global lithium demand approached a maximum of 857 kt Li/y, with a 100% penetration of lithium vehicles, 3.5 people per car and 10 billion population.

Beschreibung: Nacre, or mother of pearl, is composed of aragonite tablets and is produced by some mollusks. Because of the highly organized internal structure, chemical complexity, mechanical properties and optical effects of nacre, its formation is among the best-studied examples of calcium carbonate biomineralization. The pearl oyster Pinctada margaritifera is harvested in French Polynesia for pearl farming. The quality of the pearl depends on the quality of the nacre on its surface and its iridescent colors are affected by the thickness of the layers. Here we report on an experimental study conducted to influence the shape and the thickness of nacre tablets by keeping pearl oysters at four different depths (7, 20, 30 and 39 m) for one week. Scanning electron microscopy was used to measure the thickness of the nacre tablets and to analyze their final shape. The shape of the tablets changed from hexagonal to rhomboid at a depth of 39 m. The change in shape led to a change in size. The thickness of the tablets was reduced by between 16 and 30% on average. We also measured the oxygen isotopic composition using Secondary Ion Mass Spectrometry. In this study, we demonstrated that depth can modify the size, shape and thickness of nacre tablets, but not the d18O. This environmental modification is important for the biomineralization of the shell of the pearl oyster Pinctada margaritifera.

Beschreibung: In several recent models of invertebrate skeletogenesis, Ca-carbonate crystallization occurs within a liquid-filled chamber. No explanation is given neither for the simultaneous occurrence of distinct polymorphs of Ca-carbonate within these liquid volumes, nor for the spatial arrangement of the mineral units which are always organized in species-specific structural sequences. Results of a series of physical characterizations applied to reference skeletal materials reveal the inadequacy of this liquid-filled chamber model to account for structural and chemical properties of the shell building units. Simultaneously, these data provide convergent pieces of evidence for a specific mode of crystallization developed throughout various invertebrate phyla, supporting the hypothesized “common strategy” based on a multi-scaled control exerted on formation of their calcareous hard parts.

Beschreibung: Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.

Beschreibung: In an aquatic environment, the genus Leptothrix produces an extracellular Fe- or Mn-encrusted tubular sheath composed of a complex hybrid of bacterial exopolymers and aqueous-phase inorganic elements. This ultrastructural study investigated initial assemblage of bacterial saccharic fibrils and subsequent deposition of aqueous-phase inorganic elements to form the immature sheath skeleton of cultured Leptothrix sp. strain OUMS1. After one day of culture, a globular and/or thread-like secretion was observed on the surface of the bacterial cell envelope, and secreted bodies were transported across the intervening space away from the cell to form an immature sheath skeleton comprising assembled and intermingled fibrils. Energy dispersive X-ray microanalysis and specific Bi-staining detected a distinguishable level of P, trace Si, and a notable amount of carbohydrates in the skeleton, but not Fe. By the second day, the skeleton was prominently thickened with an inner layer of almost parallel aligned fibrils, along with low level of Fe deposition, whereas an outer intermingled fibrous layer exhibited heavy deposition of Fe along with significant deposition of P and Si. These results indicate that basic sheath-construction proceeds in two steps under culture conditions: an initial assemblage of bacterial saccharic fibrils originated from the cell envelope and the subsequent deposition of aqueous-phase Fe, P, and Si.

Beschreibung: In recent decades, excellent progress has been made globally in finding mineral resources, extracting them efficiently and effectively, dramatically reducing environmental degradation, and preventing adverse health and safety impacts on workers and stakeholders. The industry has realized tremendous advances in technology and applied science; has met changing and more stringent environmental performance criteria; has made remarkable reductions in fatality, illness, and lost-time accident rates; and has connected better than ever before with the communities in which mining, milling, and smelting are housed. A new era focused on continuous improvement in tackling key sustainable development parameters has come and is intensifying [1].  In order to maintain the social licenses needed to enlist broad public support for mining businesses, continued progress must be visible to national, provincial, and local governments as well as the people who live in the areas blessed with the mineral resources that the global economy and growing population will demand. [...]

Beschreibung: In several recent models of invertebrate skeletogenesis, Ca-carbonate crystallization occurs within a liquid-filled chamber. No explanation is given neither for the simultaneous occurrence of distinct polymorphs of Ca-carbonate within these liquid volumes, nor for the spatial arrangement of the mineral units which are always organized in species-specific structural sequences. Results of a series of physical characterizations applied to reference skeletal materials reveal the inadequacy of this liquid-filled chamber model to account for structural and chemical properties of the shell building units. Simultaneously, these data provide convergent pieces of evidence for a specific mode of crystallization developed throughout various invertebrate phyla, supporting the hypothesized “common strategy” based on a multi-scaled control exerted on formation of their calcareous hard parts.

Beschreibung: In an aquatic environment, the genus Leptothrix produces an extracellular Fe- or Mn-encrusted tubular sheath composed of a complex hybrid of bacterial exopolymers and aqueous-phase inorganic elements. This ultrastructural study investigated initial assemblage of bacterial saccharic fibrils and subsequent deposition of aqueous-phase inorganic elements to form the immature sheath skeleton of cultured Leptothrix sp. strain OUMS1. After one day of culture, a globular and/or thread-like secretion was observed on the surface of the bacterial cell envelope, and secreted bodies were transported across the intervening space away from the cell to form an immature sheath skeleton comprising assembled and intermingled fibrils. Energy dispersive X-ray microanalysis and specific Bi-staining detected a distinguishable level of P, trace Si, and a notable amount of carbohydrates in the skeleton, but not Fe. By the second day, the skeleton was prominently thickened with an inner layer of almost parallel aligned fibrils, along with low level of Fe deposition, whereas an outer intermingled fibrous layer exhibited heavy deposition of Fe along with significant deposition of P and Si. These results indicate that basic sheath-construction proceeds in two steps under culture conditions: an initial assemblage of bacterial saccharic fibrils originated from the cell envelope and the subsequent deposition of aqueous-phase Fe, P, and Si.

Beschreibung: Nacre, or mother of pearl, is composed of aragonite tablets and is produced by some mollusks. Because of the highly organized internal structure, chemical complexity, mechanical properties and optical effects of nacre, its formation is among the best-studied examples of calcium carbonate biomineralization. The pearl oyster Pinctada margaritifera is harvested in French Polynesia for pearl farming. The quality of the pearl depends on the quality of the nacre on its surface and its iridescent colors are affected by the thickness of the layers. Here we report on an experimental study conducted to influence the shape and the thickness of nacre tablets by keeping pearl oysters at four different depths (7, 20, 30 and 39 m) for one week. Scanning electron microscopy was used to measure the thickness of the nacre tablets and to analyze their final shape. The shape of the tablets changed from hexagonal to rhomboid at a depth of 39 m. The change in shape led to a change in size. The thickness of the tablets was reduced by between 16 and 30% on average. We also measured the oxygen isotopic composition using Secondary Ion Mass Spectrometry. In this study, we demonstrated that depth can modify the size, shape and thickness of nacre tablets, but not the d18O. This environmental modification is important for the biomineralization of the shell of the pearl oyster Pinctada margaritifera.

Beschreibung: Mollusk shells, especially the nacre, are of commercial interest as well as palaeoenvironmental proxies. They are also investigated as biomaterials for medical purposes and biomimetics. Although the mineralogy is well-known and unique (aragonite tablets), the organic components are various. However, determination of the precise composition of the soluble organic matrix (SOM) of the nacreous layer is difficult. Among the range of possible techniques, 1D electrophoresis and High-performance liquid chromatography (HPLC) have previously been applied separately to differentiate pI and molecular weights. To date, no clear correlation has been established between the two parameters obtained in such conditions. Here, we report the use of preparative electrophoresis, coupled with HPLC, to determine the molecular weights of the pI fractions. The results are compared with 2D gel electrophoresis. It is shown that both methods have drawbacks and advantages, and are not redundant. The complexity of the composition of the nacreous tablet shown by scanning electron microscope (SEM) and Atomic Force Microscope (AFM) observations is also evidenced by electrophoresis and HPLC.

Beschreibung: Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.

Beschreibung: The bulk minerals iron ore and bauxite cause significant greenhouse emissions in their processing to steel and aluminum respectively. The level of these emissions is highly dependent on the source of electrical and thermal energy. However, they also cause significant greenhouse gas emissions from their transportation across the globe for processing. This study examines these minerals from the perspective of greenhouse gas avoidance, examining the location of processing as an option for reducing transportation-based and process-based emissions. The analysis proposes a “radius of reduction” to define the potential for transporting ore to reduce emissions by offshore processing. Overall scenarios for localized steel production indicate potential for 85% reduction of transport emissions in the steel industry and 14% of overall industry emissions. Local high-carbon electricity grids and inefficient production mean that the benefit of reduced transportation is partially counteracted by increased processing emissions. The transportation of all global bauxite to Norway and other nations with low-emissions electricity for production of aluminum could result in an overall reduction of industry emissions of up to 44%.

Beschreibung: This review describes some of the literature pertaining to sleep deprivation, shift working, and heat exposure. Consequences of each on human cognitive function, particularly with respect to vigilance and attentional capacity are reviewed. Individually, each of these factors is known to impair human cognition; however, we propose the possibility that for miners working in hot underground environments and who are assigned to rotating shifts, the combination may leave miners with significant degrees of fatigue and decreased ability to focus on tasks. We suggest that such decreased capacity for vigilance is a source of concern in an occupational health and safety context.

Beschreibung: Despite undeniable progress, the mining industry remains the scene of serious accidents revealing disregard for occupational health and safety (OHS) and leaving open the debate regarding the safety of its employees. The San José mine last collapse near Copiapó, Chile on 5 August 2010 and the 69-day rescue operation that followed in order to save 33 miners trapped underground show the serious consequences of neglecting worker health and safety. The aim of this study was to validate a new approach to integrating OHS into risk management in the context of a new open-pit mining project in Quebec, based on analysis of incident and accident reports, semi-structured interviews, questionnaires and collaborative field observations. We propose a new concept, called hazard concentration, based on the number of hazards and their influence. This concept represents the weighted fraction of each category of hazards related to an undesirable event. The weight of each category of hazards is calculated by AHP, a multicriteria method. The proposed approach included the creation of an OHS database for facilitating expert risk management. Reinforcing effects between hazard categories were identified and all potential risks were prioritized. The results provided the company with a rational basis for choosing a suitable accident prevention strategy for its operational activities.

Beschreibung: Objectives: In artisanal small-scale gold mining (ASGM) areas in many developing countries, mercury (Hg) is used to extract gold from ore. Data of 1250 participants from Indonesia, Mongolia, Philippines, Tanzania, and Zimbabwe were combined to analyze the relation between exposure in ASGM areas and body burden. Methods: Four groups were selected relating to their intensity of contact with mercury: (i) a non-exposed control group; (ii) a low exposed group with participants only living in mining areas, but not working as miners; (iii) a medium exposed group, miners living in exposed areas and working with mercury without smelting amalgam; and (iv) a high exposed group, miners living in exposed areas and smelting amalgam. Results: Compared to the non-exposed control group, participants living and/ or miners working in highly exposed areas have significantly higher concentration of total mercury in urine, hair and blood (p-value 〈 0.001). The median mercury value in urine in the control group is 〈 0.2 µg/L. In the high exposed group of amalgam smelters, the median in urine is 12.0 µg/L. The median in blood in the control group is 〈 0.93 µg/L. The median level in blood of the high exposed group is 7.56 µg/L. The median for mercury in hair samples from the control group is 0.21 µg/g. In the high exposed group the median hair concentration is 2.4 µg/g hair. Mercury levels also differ considerably between the countries, reflecting a diverse background burden due to different fish eating habits and different work place methods. Conclusions: A high percentage of exposed individuals had levels above threshold values. These high levels of mercury are likely to be related with serious health problems.

Beschreibung: Same level falls continue to contribute to an alarming number of slip/trip/fall injuries in the mining workforce. The objective of this study was to investigate how walking on different surface types and transverse slopes influences gait parameters that may be associated with a trip event. Gait analysis was performed for ten subjects on two orientations (level and sloped) on smooth, hard surface (control) and irregular (gravel, larger rocks) surfaces. Walking on irregular surfaces significantly increased toe clearance compared to walking on the smooth surface. There was a significant (p 〈 0.05) decrease in cadence (steps/min), stride length (m), and speed (m/s) from control to gravel to larger rocks. Significant changes in external rotation and increased knee flexion while walking on irregular surfaces were observed. Toe and heel clearance requirements increased on irregular surfaces, which may provide an explanation for trip-induced falls; however, the gait alterations observed in the experienced workers used as subjects would likely improve stability and recovery from a trip.

Beschreibung: The purpose of this study was to investigate the relationship between community-level exposure to changes in economic conditions and the incidence and prevalence of mental disorders and cardiovascular disease in 29 resource-based communities (with a focus on mining communities) in British Columbia (BC) during a period of time marked by an economic downturn (1991–2002) The investigation relied on Labour Force Survey (LFS) and Statistics Canada Census data, and health records from the British Columbia Ministry of Health (MoH). Age and sex adjusted prevalence and incidence rates were calculated for each community from 1991 to 2002 and the development of an economic change indicator defined using Census data and industry/government documents allowed for yearly assessment of community-level exposure to economic conditions. The relationship between exposure to economic change and rates of acute and chronic cardiovascular disease and mental disorders across the 29 study communities was investigated using a generalized linear model (stratified by type of community, and adjusted for the effect of the community). Findings indicate an impact on the prevalence rates for acute cardiovascular disease (CVD) during periods of economic decline (rate increased by 13.1 cases per 1,000 population, p 〈 0.0001 as compared with stable periods) and bust conditions (rate increased by 30.1 cases per 1,000 population, p 〈 0.0001 as compared with stable conditions) and mental disorders (rate increased by 13.2 cases per 1,000 population, p = 0.0001) in mining communities during declining economic conditions as compared to steady periods of mining employment. This is not observed in other resource-based communities. The paper concludes by highlighting implications for the mining industry to consider as they begin to recognize and commit to mining community health.

Beschreibung: The characterization, evaluation and remediation of polluted soils is one of the present environmental challenges to be addressed in the coming years. The origin of trace elements in soils can be either geogenic or anthropogenic, but only the latter is interesting from a legal point of view. The hazard of the pollutants in the soils not only depends on their total concentration, but particularly on their availability. The mobility of the trace elements depends on their speciation, and it is also affected by several soil parameters. Mining activity is one of the most important anthropogenic causes of soil pollution. As a case study, this work is focused in the Riotinto mining area (Iberian Pyrite Belt, IPB, SW Spain). The IPB is one of the most important metallogenic provinces in the world and it has been exploited for thousands of years. The disposal of mining residues has produced important sources of contamination by trace elements and acidic waters affecting soils and rivers. In addition to these problems, the closure of mines in the Pyrite Belt at the end of the 20th Century has led to a great loss of employment, which has caused the development of an intensive agriculture of citrus fruits as a new source of income. The intensive growing of citrus fruits and the traditional subsistence agriculture have been developed surrounding the mining areas and on floodplains near to mining sites. The level of soil pollution has not been taken into account in these cases, nor has its impact on the health of the inhabitants of these areas. Therefore, it is of great interest to study the current state of the cultivated soils and the sources and types of contaminants derived from mining activity in order to program its decontamination, where appropriate, according to legislation. In order to know the present and future hazard posed by the soils chemical and mineralogical speciation has been carried out, given that the availability of a metal depends on the phase in which it is found. The results showed that mining activity has caused high levels of As, Cu, Pb and Zn in several cultivated soils. Moreover, Cu, Pb and Zn showed a high bioavailability. This suggests that at least other studies are necessary to preserve health in the inhabitants of this area. The methodology carried out in this work allowed to select potentially polluted areas where agricultural activities are not recommended.

Beschreibung: In this study, we compare the major- and trace-element compositions of olivine, garnet, and clinopyroxene that occur as single crystals (142 grains), with those derived from xenoliths (51 samples) from six kimberlites in the Lucapa area, northeastern Angola: Tchiuzo, Anomaly 116, Catoca, Alto Cuilo-4, Alto Cuilo-63 and Cucumbi-79. The samples were analyzed using electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results suggest different paragenetic associations for these kimberlites in the Lucapa area. Compositional overlap in some of the macrocryst and mantle xenolith samples indicates a xenocrystic origin for some of those macrocrysts. The presence of mantle xenocrysts suggests the possibility of finding diamond. Geothermobarometric calculations were carried out using EPMA data from xenoliths by applying the program PTEXL.XLT. Additional well calibrated single-clinopyroxene thermobarometric calculations were also applied. Results indicate the underlying mantle experienced different equilibration conditions. Subsequent metasomatic enrichment events also support a hypothesis of different sources for the kimberlites. These findings contribute to a better understanding of the petrogenetic evolution of the kimberlites in northeastern Angola and have important implications for diamond exploration.

Beschreibung: Microbial carbonate mineralization is widespread in nature and among microorganisms, and of vast ecological and geological importance. However, our understanding of the mechanisms that trigger and control processes such as calcification, i.e., mineralization of CO2 to calcium carbonate (CaCO3), is limited and literature on cyanobacterial calcification is oftentimes bewildering and occasionally controversial. In cyanobacteria, calcification may be intimately associated with the carbon dioxide-(CO2) concentrating mechanism (CCM), a biochemical system that allows the cells to raise the concentration of CO2 at the site of the carboxylating enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) up to 1000-fold over that in the surrounding medium. A comprehensive understanding of biologically induced carbonate mineralization is important for our ability to assess its role in past, present, and future carbon cycling, interpret paleontological data, and for evaluating the process as a means for biological carbon capture and storage (CCS). In this review we summarize and discuss the metabolic, physiological and structural features of cyanobacteria that may be involved in the reactions leading to mineral formation and precipitation, present a conceptual model of cyanobacterial calcification, and, finally, suggest practical applications for cyanobacterial carbonate mineralization.

Beschreibung: This paper draws on research conducted in the past two decades examining issues related to the human element in mine disasters. While much of the emergency response community employs a systems approach that takes into account psychosocial issues as they impact all aspects of an emergency, the mining industry has lagged behind in integrating this critical element. It is only within the past few years that behavioral interventions have begun to be seen as a part of disaster readiness and resiliency in the industry. The authors discuss the potential applications of psychosocial studies and suggest ways to improve mine emergency planning, psychological support, and decision-making during a response, as well as actions in the aftermath of incidents. Topics covered, among others, include an economic rationale for including such studies in planning a mine emergency response, sociological issues as they impact such things as leadership and rescue team dynamics, and psychological issues that have an effect on individual capacity to function under stress such as during escape, in refuge alternatives, and in body recovery. This information is intended to influence the mine emergency escape curriculum and impact actions and decision-making during and after a mine emergency. The ultimate goal is to mitigate the trauma experienced by individuals, the organization, and the community.