Ultrafine Mineral Associations in Superhigh-Organic-Sulfur Kentucky Coals

Two high-organic-sulfur Kentucky coals, the eastern Kentucky River Gem coal and the western Kentucky Davis coal, are examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), both including elemental analysis by energy-dispersive spectroscopy (EDS). From the SEM–EDS analysis, it is observed that the western Kentucky coal had areas with Pb and Cd in addition to the expected Fe and S and the eastern Kentucky coal had individual Fe–S-rich areas with La and Ni and with Si, Al, Cr, Ni, and Ti. TEM and selected area electron diffraction (SAED) analyses demonstrate that anglesite with a rim of Pb-bearing amorphous Fe-oxide occurs in the western Kentucky coal. Melanterite, an Fe-sulfate, with minor Al, Si, and K EDS peaks, suggests that clay minerals may be in close association with the sulfate, is also detected in the coal. A polycrystalline metal in the eastern Kentucky sample with a composition similar to stainless steel is adjacent to an Al-rich shard. Euhedral pyrite grains surrounded by kaolinite and gibbsite are detected. Overall, it is noted that element associations should not be assumed to be organic just because minerals cannot be seen with optical microscopy or with standard bulk analytical techniques, such as X-ray diffraction (XRD)

An examination of campus climate for lesbian, gay, bisexual, and transgender (LGBT) students

Master of ScienceDepartment of Counseling & Student DevelopmentKenneth HugheyThe challenges facing lesbian, gay, bisexual, and transgender (LGBT) students on college and university campuses are many. For example, LGBT students face harassment and discrimination at significantly higher levels than their heterosexual peers, and are twice as likely to receive derogatory remarks (Rankin, Weber, Blumenfeld, & Frazer, 2010). As the visibility of LGBT college students and the adversity they face has increased, there is ever more pressure on college and universities to evaluate whether LGBT students’ needs are being met. A dependable method of determining this is to conduct an assessment of the campus climate for LGBT students. Campus climate can be consists of the mutually reinforcing relationship between the perceptions, attitudes, and expectations of both individuals and groups, as well as the actual patterns of interaction and behavior between individuals and groups (Cress, 2008). Thus, in order to assess a campus climate, one must determine the current perceptions, attitudes, and expectations that define the institution and its members. Campus climate has a significant impact upon students’ academic progress and achievement and their level of satisfaction with their university. Whether or not a student feels as though they matter on their campus is largely a result of the climate. Evaluations of campus climate for LGBT students allow administrations to uncover what inequalities may exist on their campus, which is the first step toward being able to correct them. There have been many methods of improving campus climate that have been effective at a variety of colleges and universities. Administrations that wish to provide LGBT students on their campus with a better experience should invest in as many of these practices as possible. The most important action in improving campus climate is to institute an LGBT resource center or office with a full-time staff member and significant office space. Other impactful strategies include establishing a Safe Zone or Allies program, encouraging LGBT students to form organizations for themselves and their allies, increasing the amount of interaction between LGBT students and faculty—especially LGBT faculty, and establishing a Queer Studies academic program

High Resolution Scanning Auger Microscopy of Mineral Surfaces

There are a number of cases where scanning Auger microscopy can be used to determine the near-surface composition of minerals with extremely high lateral resolution. This involves collecting Auger spectra with reasonable signal to noise ratios without encountering significant beam induced charging or surface degradation, even if the beam is impinging on a grain less than 1μm in diameter. We typically use a 3 keV beam with less than 10 nA beam current on a sample surface that is tilted (to increase backscattered and secondary electron emission efficiency) and relatively flat. To further minimize surface degradation, vacuum levels are kept high and the beam is rastered or defocused whenever possible. The Auger spectra of minerals can be used to study modification of surfaces due to geochemical influences or to identify submicron grains if the near-surface composition is representative of the bulk composition. Also, high lateral resolution step scans can be performed across sharp interfaces between two grains, allowing for short-range studies of solid-solid interactions in rocks at grain boundaries. We also report on preliminary attempts to chemically quantify Auger peak intensities for silicate minerals. Measurements of peak-to-peak heights for oxygen and silicon lines for eight silicate minerals of well-known composition indicate that Auger sensitivity factors can vary significantly with O/Si ratio

Cell adhesion of Shewanella oneidensis to iron oxide minerals: Effect of different single crystal faces

The results of experiments designed to test the hypothesis that near-surface molecular structure of iron oxide minerals influences adhesion of dissimilatory iron reducing bacteria are presented. These experiments involved the measurement, using atomic force microscopy, of interaction forces generated between Shewanella oneidensis MR-1 cells and single crystal growth faces of iron oxide minerals. Significantly different adhesive force was measured between cells and the (001) face of hematite, and the (100) and (111) faces of magnetite. A role for electrostatic interactions is apparent. The trend in relative forces of adhesion generated at the mineral surfaces is in agreement with predicted ferric site densities published previously. These results suggest that near-surface structure does indeed influence initial cell attachment to iron oxide surfaces; whether this is mediated via specific cell surface-mineral surface interactions or by more general interfacial phenomena remains untested

Shining Light on Black Rock Coatings in Smelter-Impacted Areas

Earth scientists have long known of the existence of black coatings on exposed rocks in smelter-impacted areas such as Sudbury, Ontario or Rouyn-Noranda, Québec. Black rock coatings in the Greater Sudbury area are remarkable geological records of atmospheric conditions, including mixing, scavenging, and oxidation processes, deposition rates, and the nature and source of anthropogenic releases to the atmosphere. The coatings are composed of an amorphous silica matrix that has trapped atmosphere-borne nanoparticles and has preserved their chemical and isotopic signature. These coatings are the product of high emissions of SO2 and subsequent non-stoichiometric dissolution of exposed siliceous rocks. The coatings contain spherical smelter-derived Cu–Ni-oxide particulate matter (micrometre and nanometre-sized) and metal-sulphate rich layers composed of nanometer aggregates of Fe–Cu sulphates. Lead, As, and Se-bearing nanoparticles emitted from smelters are incorporated in metal-sulphate-rich layers along the atmosphere-coating interface, presumably during coating formation. On a regional scale, ratios between different metal(loid)s in the coatings indicate that small diameter primary Pb, As and Se-bearing sulphate aerosols have been deposited at higher rates compared to larger, Ni-bearing particulate matter. High sulphur isotope values in coatings closer to smelting centres and their decrease with distance from the smelters is attributed to an increase in mixing of primary and secondary sulphates. SOMMAIRELes géoscientifiques connaissent depuis longtemps l’existence d’une couche noire sur les roches exposées aux abords des fonderies comme celles de Sudbury en Ontario ou Rouyn-Noranda au Québec.   Les couches noires des roches de la grande région de Sudbury constituent de remarquables enregistrements géologiques des phénomènes atmosphériques, notamment des processus de mélange, de piégeage, et d'oxydation, ainsi que des taux de sédimentation et de la nature et de l’origine des rejets anthropiques dans l'atmosphère.   Ces couches noires sont constituées d'une matrice de silice amorphe qui a piégé des nanoparticules atmosphériques et conservé leur signature chimique et isotopique.  Ces couches noires sont le produit de fortes émissions atmosphériques de SO2 et d’une dissolution non-stœchiométrique subséquente des roches siliceuses exposées.  Ces couches noires contiennent des sphérules de particules atmosphériques d’oxydes de Cu-Ni (de taille micrométrique et nanométrique) issues de la fonderie, et des couches riches en sulfate de métaux constituées d’agrégats nanométriques de sulfates de Fe-Cu.   Les nanoparticules de plomb, d’As et de Se émises par les fonderies sont incorporées dans les couches riches en sulfate de métal à l'interface de l’atmosphère et de cette couche, probablement lors de la formation de cette couche.  À l’échelle régionale, les rapports de concentration des différents métaux ou métalloïdes dans les couches noires indiquent que les aérosols de faible diamètre de sulfate de Pb, d’As et de Se primaires ont été déposés à des taux plus élevés que les particules nickélifères de plus grande dimension.  Les valeurs plus élevées des isotopes du soufre observées dans les couches à proximité des fonderies et leur diminution en fonction de l’éloignement des fonderies sont attribuées à une augmentation du mélange entre sulfates à l’émission et post-émission

Past, present and future global influence and technological applications of iron-bearing metastable nanominerals

Iron-bearing nanominerals such as ferrihydrite, schwertmannite, and green rust behave as metastable precursors leading to the formation of more thermodynamically stable iron mineral phases (e.g., jarosite, goethite, hematite, and magnetite). However, this transformation may last from days to tens or even hundreds of years, making them the most predominant iron-bearing minerals at environmental conditions and at the human time scale. The present review characterizes ferrihydrite, schwertmannite, and green rust nanominerals according to their main physical and chemical properties, and at both nano- and meso-scales. It also presents a comprehensive review of the multiple past and present Earth environments where these nanominerals have played, and still play, a pivotal role in the geochemistry, mineralogy and environmental nanogeosciences of these environments. Finally, the present and future technological applications of these nanominerals as well as their role in the generation of a more sustainable human-Earth relationship is discussed, with a special emphasis on their use in new circular economies and green based technologies

A review on Pb-bearing nanoparticles, particulate matter and colloids released from mining and smelting activities

Lead (Pb) is one of the most paradoxical elements, both having diverse practical uses, as well as being extremely toxic to humans, and especially to children. The use of Pb records a steady growth with annual production currently exceeding 10 million metric tons. In spite of the environmental awareness of modern society, humans are still exposed to Pb through its emission by smelting and mining activities, and also by Pb-bearing mine wastes and soils. Here, we review the chemical and mineralogical forms of Pb generated from smelting and mining processes and subsequently altered in tailings, slag piles, and soils. In smelter plumes, Pb is emitted to the atmosphere either in the form of smaller nano-size particulate matter (PM) often associated with S, or larger micrometer Pb-bearing PM matter accompanied by oxide-silicate matrices. Pb-bearing phases in mine tailings and impacted soils depict a greater mineralogical and chemical complexity than those emitted from smelters and the larger particle size of this PM also leads to a lower Pb bioavailability. High resolution observations in aquatic system, soils and rock coatings impacted by smelting and mining activities show the presence of Pb-bearing phosphates, sulfides, sulfates, carbonates, and oxide nanoparticles. Larger micrometer size particles of Pb-bearing minerals form often through the aggregation of Pb-bearing nanoparticles, a process commonly referred to as crystallization through particle attachment. Mobilization of Pb within soil columns is strongly affected by the transport of colloids, especially those composed of organic matter and Fe-hydroxides because Pb is taken up efficiently by these two soil components. The extraordinary variability and complexities of all of these processes suggest that future reduction of Pb contamination in the environment and its impact on human health mainly depends on eliminating or greatly reducing Pb-release from smelting operations and tailings impoundments

Nanoparticles in fossil and mineral fuel sectors and their impact on environment and human health: A review and perspective

Nanoscience and technology have enabled better insights into the environmental and health impacts arising from the mining, production and use of fossil and mineral fuels. Here we provide an overview of the nanoscience-based applications and discoveries concerning coal and mineral fuel (i.e., uranium-containing minerals) mining, refining/production, use, and disposal of wastes. These processes result in massive nanoparticle release and secondary nanoparticle generation which have highly significant environmental implications and human health consequences on local, regional, and even global levels. Until recently, very little was known about nanoparticle fractions. Recent advancements and sophistications enable us to detect, collect and study these materials which are roughly 1 nm (0.001 µm) up to several tens of nanometers in size. These materials are known to behave differently (chemically, electrically, and mechanically), relative to their macroscopic equivalents. This is what makes nanoscience fascinating and difficult to predict, underscoring the importance of this emerging new field. For example, nanoparticles associated with coal and mineral fuel influence the release, uptake, and transportation of hazardous elements associated with mining, processing, and waste storage in the surrounding areas. This includes long distance transport down streams, rivers, and eventually to oceans such as from coal and uranium mine drainages. In terms of human health, in all phases of mining, production/refining, use, and waste disposal, the associated nanoparticles can be acquired through oral ingestion, inhalation, and dermal absorption. Inhalation has been shown to be particularly damaging, where lung, heart, kidney, and brain diseases are prevalent. Relative to all other fields of science and engineering associated with coal and mineral fuel mining, production, use, and clean-up efforts, nanoscience, although a much newer field then the rest by comparison, is still greatly under-represented and under-utilized. There is also a continuing gap between what we so far know about the behavior of nanoparticles, and what remains to be discovered

Nanoscale Processes in the Environment: Nanobiogeochemistry of Microbe/Mineral Interactions

This project involves the application of nanoscience to the fields of fundamental and applied environmental geochemistry and biogeochemistry [1] Probing ligand-mineral interactions at the nanoscale: We have developed a chemical force microscopy (CFM) technique that probes the forces of interaction in aqueous solution between complex organic molecules and mineral surfaces in both distance and force nanospace. Using this method, previously unknown interactions between microbially produced siderophores and iron oxide mineral surfaces have been revealed Iron is a required nutrient for all organisms including bacteria, fungi and plants. The insoluble nature of iron in oxidizing, circumneutral aqueous environments, however, limits concentrations to levels well below the 10 -7 -10 -8 M required for bacterial growth. A response to this limitation is the extracellular release of low molecular weight biomolecules known as siderophores. With formation constants (K f ) on the order of 10 20-10 5 0 , the siderophore-Fe(III) complex is highly stable and thermodynamically favorable under environmental conditions. Indeed, much is known about siderophore interaction with soluble sources of iron; however, the largest source of iron in soils are solid forms, specifically, oxide minerals. Siderophores are known to release ferric iron from minerals, but the nature of the interaction of siderophores with the surface and the associated dissolution mechanism has been unknown. The CFM techniques used in this study have allowed us to directly measure the forces of interaction between siderophores and mineral surfaces for the first time A protein coupling technique was employed to covalently attach the siderophore azotobactin to a hydrazide terminated AFM tip. The activated tip was probed against two minerals: goethite (aFeOOH) and its isostructural Al-equivalent diaspore (a-AlOOH). Upon contact with each mineral surface, the adhesion force between azotobactin and the iron containing goethite was two to three times the value observed for the isostructural Al-equivalent diaspore. The relative force affinity for the iron containing mineral (versus aluminum) correlates with the difference between the aqueous complex formation constants estimated for azotobactin and Fe(III) (aq) (K f =10 2 8 ) and Al(III) (aq) (K f~1 0 1 6 ). Further, the adhesion force between azotobactin and goethite significantly decreases (4 nN to 2 nN) when small amounts of soluble iron (0.1 mM FeCl 3 ·6H 2 O) are added to the system at pH 3.5 suggesting a significant specific interaction between azotobactin's chelating groups and the mineral surface. Specifically, plateau features in the force data generated upon tip retraction fro