Mn(II)-oxidizing Bacteria are Abundant and Environmentally Relevant Members of Ferromanganese Deposits in Caves of the Upper Tennessee River Basin

The upper Tennessee River Basin contains the highest density of our nation's caves; yet, little is known regarding speleogenesis or Fe and Mn biomineralization in these predominantly epigenic systems. Mn:Fe ratios of Mn and Fe oxide-rich biofilms, coatings, and mineral crusts that were abundant in several different caves ranged from ca. 0.1 to 1.0 as measured using ICP-OES. At sites where the Mn:Fe ratio approached 1.0 this represented an order of magnitude increase above the bulk bedrock ratio, suggesting that biomineralization processes play an important role in the formation of these cave ferromanganese deposits. Estimates of total bacterial SSU rRNA genes in ferromanganese biofilms, coatings, and crusts measured approximately 7×107–9×109 cells/g wet weight sample. A SSU-rRNA based molecular survey of biofilm material revealed that 21% of the 34 recovered dominant (non-singleton) OTUs were closely related to known metal-oxidizing bacteria or clones isolated from oxidized metal deposits. Several different isolates that promote the oxidation of Mn(II) compounds were obtained in this study, some from high dilutions (10–8–10–10) of deposit material. In contrast to studies of caves in other regions, SSU rRNA sequences of Mn-oxidizing bacterial isolates in this study most closely matched those of Pseudomonas, Leptothrix, Flavobacterium, and Janthinobacterium. Combined data from geochemical analyses, molecular surveys, and culture-based experiments suggest that a unique consortia of Mn(II)-oxidizing bacteria are abundant and promoting biomineralization processes within the caves of the upper Tennessee River Basin

Sustained Anthropogenic Impact in Carter Saltpeter Cave, Carter County, Tennessee and the Potential Effects On Manganese Cycling

Anthropogenic impact is a pervasive problem in heavily trafficked cave systems and fecal contamination is equally problematic in many cave and karst waters worldwide. Carter Saltpeter Cave in Carter County, Tennessee exhibits Mn(III/IV) oxide coatings associated with groundwater seeps, as well as manganese oxide growth on litter. Culturing results revealed that Mn(III/IV) oxide production on litter was associated with Mn(II)-oxidizing fungi. Immediately prior to this study, a massive Mn(II)-oxidizing biofilm bloomed at a cave seep. During the course of this study from 2009–2011, the seep exhibited a dramatic visual reduction in Mn(III/IV) oxide production, which was hypothesized to correlate with a decrease in fecal nutrient input. Molecular methods (16S rRNA gene sequencing) confirmed the presence of Bacteroides-Prevotella human fecal indicators in this seep, and most probable number assays and ion chromatography of the associated seep water confirmed nutrient loading at the site. Further, phylogenetic analysis from clone sequences suggested a strong initial human-specific fecal signature (50% of the sequences clustering with human feces sequences) in July 2009, and a weaker human signature (20% clustering) by June 2011. Most Probable Number (MPN) analyses of heterotrophic bacteria at this site suggested that Mn(II) oxidation was correlated with heterotrophic activity, due to point source exogenous nutrient loading

Mn(II)-Oxidizing Bacteria Are Abundant And Environmentally Relevant Members Of Ferromanganese Deposits In Caves Of The Upper Tennessee River Basin

The upper Tennessee River Basin contains the highest density of our nation’s caves; yet, little is known regarding speleogenesis or Fe and Mn biomineralization in these predominantly epigenic systems. Mn:Fe ratios of Mn and Fe oxide-rich bio?lms, coatings, and mineral crusts that were abundant in several different caves ranged from ca. 0.1 to 1.0 as measured using ICP-OES. At sites where the Mn:Fe ratio approached 1.0 this represented an order of magnitude increase above the bulk bedrock ratio, suggesting that biomineralization processes play an important role in the formation of these cave ferromanganese deposits. Estimates of total bacterial SSU rRNA genes in ferromanganese bio?lms, coatings, and crusts measured approximately 7×107–9×109 cells/g wet weight sample. A SSU-rRNA based molecular survey of bio?lm material revealed that 21% of the 34 recovered dominant (non-singleton) OTUs were closely related to known metal-oxidizing bacteria or clones isolated from oxidized metal deposits. Several different isolates that promote the oxidation of Mn(II) compounds were obtained in this study, some from high dilutions (10–8–10–10) of deposit material. In contrast to studies of caves in other regions, SSU rRNA sequences of Mn-oxidizing bacterial isolates in this study most closely matched those of Pseudomonas, Leptothrix, Flavobacterium, and Janthinobacterium. Combined data from geochemical analyses, molecular surveys, and culture-based experiments suggest that a unique consortia of Mn(II)-oxidizing bacteria are abundant and promoting biomineralization processes within the caves of the upper Tennessee River Basin

Formation of Replacement Dolomite in the Latemar Carbonate Buildup, Dolomites, Northern Italy: Part 1. Field Relations, Mineralogy, and Geochemistry

Replacement dolomite in the Latemar carbonate buildup, northern Italy, formed when limestone was infiltrated by and reacted with Mg-rich fluid. It occurs in discrete bodies in sharp contact with unreacted limestone. The dolomite developed in a nearly orthogonal lattice of vertical columns (replacement of limestone breccia pipes) and sheets (replacement along fractures and limestone-dike contacts) and of nearly horizontal bedding-parallel sheets and tubes. Mapped patterns of replacement dolomite directly image that part of the plumbing system in which the amount of fluid flow was sufficient to form dolomite. Decreases in the proportion of dolomite relative to limestone and in the proportion of vertical relative to horizontal dolomite-limestone contacts with increasing elevation indicate that the overall direction of fluid flow was upward and then outward along more permeable bedding horizons. Dolomite is significantly enriched in Fe, Mn, and Zn, as well as in Mg, relative to calcite in precursor limestone but not in Cu, Ni, Co, Cr, Ba, or Pb. The Fe, Mn, and Zn content of dolomite varies spatially within outcrops from the scale of meters down to the micron scale of oscillatory growth zoning in individual dolomite crystals. The variation is interpreted in terms of a dolomitizing fluid that, unlike unmodified seawater, contained significant amounts of Fe, Mn, and Zn, as well as of Mg, and whose composition varied in space at a range of scales and in time at the site of growth of individual dolomite crystals... [See article for complete abstract]]]> 2008 English http://libres.uncg.edu/ir/asu/f/Carmichael_Sarah_2008_Formation_Pt1.pdf oai:libres.uncg.edu/4532 2014-02-15T06:02:02Z UNCG Information Systems Management Issues: Reporting and Relevance NC DOCKS at The University of North Carolina at Greensboro Palvia, Prashant <![CDATA[Reports of key information systems issues have been published over the last two decades in many journals. Leading IS journals (e.g., MIS Quarterly, Information &amp; Management, among others) have published key IS management issue reports every three or four years over the last 15 years, and will probably continue to provide such reports in the future. Although these reports claim to provide decisional guidance to practitioners, researchers, consultants, etc., the authors in their experience have noted concerns about their usefulness. While not questioning the validity of the methods and analysis conducted in these studies, we address two important questions in this article: the manner of reporting of the key issue results (which might be misleading), and the relevance of the results (are they providing what they intended to?). We hope that our discussion will provide new perspectives in making resource allocation decisions to both readers and authors of key issue articles

Paleogeography And Paleoenvironments Of The Late Devonian Kellwasser Event: A Review Of Its Sedimentological And Geochemical Expression

The Late Devonian (383-359 Ma) was a time of prolonged climate instability with catastrophic perturbation of global marine ecosystems at the Frasnian-Famennian (F-F) and the Devonian-Carboniferous (D-C) boundaries. The causes and mechanisms of anoxia and extinction at the F-F interval are not clearly delineated, and alternative explanations for virtually every aspect of this interval are still intensely debated. In many (but not all) locations, the F-F interval is characterized by two dark, organic-rich lithologies: the Lower and Upper Kellwasser beds (as originally described in Germany) that represent a stepwise ocean anoxia and extinction sequence. The Upper and Lower Kellwasser anoxia event beds are often collectively termed the Kellwasser Event, and the termination of this sequence is within the Upper Kellwasser Event at the F-F boundary. Current knowledge is limited by significant sampling bias, as most previous studies sampled epicontinental seaways or passive continental shelves, primarily from localities across Europe and North America. Together these formed a single equatorial continent with a rising mountain chain during the Late Devonian. Our understanding of the Kellwasser Event is thus based on data and observations from a restricted set of paleoenvironments that may not represent the complete range of Late Devonian environments and oceanic conditions. In the last decade, new methodologies and research in additional paleoenvironments around the world confirm that the Kellwasser Event was global in scope, but also that its expression varies with both paleoenvironment and paleogeography. Studying the many differing geochemical and lithological expressions of the Kellwasser Event using a) a wide variety of paleoenvironments, b) a multiproxy approach, and c) placement of results into the broader context of Late Devonian marine biodiversity patterns is vital for understanding the true scope of ocean anoxia, and determining the causes of the marine biodiversity crisis at the F-F boundary

New Insight Into The Origin Of Manganese Oxide Ore Deposits In The Appalachian Valley And Ridge Of Northeastern Tennessee And Northern Virginia, USA

Manganese oxide deposits have long been observed in association with carbonates within the Appalachian Mountains, but their origin has remained enigmatic for well over a century. Ore deposits of Mn oxides from several productive sites located in eastern Tennessee and northern Virginia display morphologies that include botryoidal and branching forms, massive nodules, breccia matrix cements, and fracture fills. The primary ore minerals include hollandite, cryptomelane, and romanèchite. Samples of Mn oxides from multiple localities in these regions were analyzed using electron microscopy, X-ray analysis, Fourier transform infrared spectroscopy, and trace/rare earth element geochemistry. The samples from eastern Tennessee have biological morphologies, contain residual biopolymers, and exhibit REE signatures that suggest the ore formation was due to supergene enrichment (likely coupled with microbial activity). In contrast, several northern Virginia ores hosted within quartz-sandstone breccias exhibit petrographic relations, mineral morphologies, and REE signatures indicating inorganic precipitation, and a likely hydrothermal origin with supergene overprinting. Nodular accumulations of Mn oxides within weathered alluvial deposits that occur near to breccia-hosted Mn deposits in Virginia show geochemical signatures that are distinct from the breccia matrices, and appear to reflect remobilization of earlier-emplaced Mn and concentration within supergene traps. Based on the proximity of all of the productive ore deposits to mapped faults or other zones of deformation, we suggest that the primary source of all of the Mn may have been deep-seated, and that Mn oxides with supergene and/or biological characteristics result from the local remobilization and concentration of this primary Mn

The origin of replacement dolomite, Dolomites, northern Italy: Part 2

Conference Abstrac

A new model for the Kellwasser Anoxia Events (Late Devonian): Shallow water anoxia in an open oceanic setting in the Central Asian Orogenic Belt

The Frasnian–Famennian mass extinction event devastated tropical marine ecosystems and ranks in the top six in taxonomic and ecological severity. The close stratigraphic association between the extinction and the Kellwasser Anoxia Events support a link between oceanographic anoxia and extinction. The Upper and Lower Kellwasser horizons have been identified in epicontinental and basinal settings in Laurussia, Gondwana, Siberia, and South China. The Hongguleleng Formation (Late Devonian) in northwestern Xinjiang, China, contains both the Frasnian–Famennian boundary and the rebound from the Frasnian–Famennian extinction event in a highly fossiliferous shallow marine setting associated with a Devonian oceanic island arc complex (part of the Central Asian Orogenic Belt, or CAOB). Here we show that the Hongguleleng Formation also records the Upper Kellwasser Anoxia Event through analysis of multiple geochemical proxies. In contrast to previous studies asserting that the Kellwasser Events were restricted to epicontinental seaways and basins, our results indicate that it occurred not only along the shallow continental margins of the closing Rheic Ocean, but also in shallow water in the open oceanic part of Paleotethys. Previous explanations for the Kellwasser Events from epicontinental margins and basins call for the migration of deep anoxic bottom water into shallow water environments as a kill mechanism for shallow marine ecosystems or attribute it to sea level rise and subsequent stagnation. There is no evidence that the Devonian oceans completely overturned during the Kellwasser Events; similarly, many transgressive events in the Devonian are not associated with black shales. We therefore suggest an alternative mechanism for the Kellwasser Events based on new evidence from the CAOB, where anoxia is driven by episodic eutrophication of surface waters

The Devonian-Carboniferous Boundary In Vietnam: Sustained Ocean Anoxia With A Volcanic Trigger For The Hangenberg Crisis?

The Devonian-Carboniferous transition (359 Ma) was a time of extreme climate and faunal change and is associated with the end-Devonian biodiversity crisis. The transition is characterized by transgressive/regressive cycles, which culminated in the onset of widespread ocean anoxia (the Hangenberg Black Shale event) and a remarkable sea-level fall close to the Devonian-Carboniferous boundary (the Hangenberg Sandstone event); together these are known as the Hangenberg Crisis. The Hangenberg Crisis has been documented around the globe, but the trigger mechanisms for its onset remain unknown. The Pho Han Formation on Cat Ba Island in northeastern Vietnam preserves the Devonian-Carboniferous transition and Hangenberg Crisis in a sediment- starved basinal facies on the South China carbonate platform. Although the Hangenberg Black Shale event is generally preserved as a discrete anoxic interval in Devonian-Carboniferous boundary sections of North America and Europe, the Pho Han Formation records sustained dysoxic/anoxic conditions from the Famennian (Upper Devonian) through the Tournasian (early Carboniferous), with severe anoxia (approaching euxinia) throughout the Hangenberg Black Shale event interval (as determined by trace element proxies, increased total organic carbon, and framboidal pyrite distributions). There is also significant mercury enrichment corresponding to the Hangenberg Crisis in the Pho Han Formation. The isolated paleogeography of the region suggests that the mercury is most likely sourced from distal volcanic emissions. It is therefore possible that large-scale volcanic activity acted as a trigger mechanism for the Hangenberg Crisis and biodiversity drop at the Devonian- Carboniferous transition, similar to other major mass extinction events

Constraining reactions between MOR vent fluids and new oceanic crust: the hydrothermal upflow zone beneath M vent, 9°50'N EPR

Conference Abstrac