Abstract: 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.
Abstract: 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.
Abstract: 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.
Abstract: 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.
Abstract: 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.
Abstract: 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.