Happy Jack Uraninite: A New Reference Material for High Spatial Resolution Analysis of U‐Rich Matrices     

Corinne Dorais  Antonio Simonetti  Loretta Corcoran  Tyler L. Spano  Peter C. Burns 《Geostandards and Geoanalytical Research》2020,44(1):125-132

There is currently a lack of well‐characterised matrix‐matched reference materials (RMs) for forensic analysis of U‐rich materials at high spatial resolution. This study reports a detailed characterisation of uraninite (nominally UO_2+x) from the Happy Jack Mine (UT, USA). The Happy Jack uraninite can be used as a RM for the determination of rare earth element (REE) mass fractions in nuclear materials, which provide critical information for source attribution purposes. This investigation includes powder X‐ray diffraction (pXRD) data, as well as major, minor and trace element abundances determined using a variety of micro‐analytical techniques. The chemical signature of the uraninite was investigated at the macro (cm)‐scale with micro‐X‐ray fluorescence (µXRF) mapping and at high spatial resolution (tens of micrometre scale) using electron probe microanalysis (EPMA) and laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analyses. Based on EPMA results, the uraninite is characterised by homogeneous UO₂ and CaO contents of 91.57 ± 1.49% m/m (2s uncertainty) and 2.70 ± 0.38% m/m (2s), respectively. Therefore, CaO abundances were used as the internal standard when conducting LA‐ICP‐MS analyses. Overall, the major element and REE compositions are homogeneous at both the centimetre and micrometre scales, allowing this material to be used as a RM for high spatial resolution analysis of U‐rich samples.  相似文献   

Rough evaluation of the water-inflow discharge in abandoned mining tunnels using a simplified water balance model: the case of the Cogne iron mine (Aosta Valley, NW Italy)     

Stefano Lo Russo  Loretta Gnavi  Daniele Peila  Enrico Suozzi 《Environmental Earth Sciences》2013,70(6):2753-2765

One of the most complex hydrogeological problems in the design and maintenance of drainage systems in abandoned mining sites is quantifying the maximum water infiltration and, therefore, the amount that is potentially drainable by the tunnels. This problem is compounded when water-inflow data are limited or lacking. The aim of the study was to present a single but reliable model for making this evaluation; this model was applied to the case history of the abandoned Cogne iron ore mining complex (Western Alps, Aosta Valley Region, NW Italy). The study focused on quantifying the amount of water infiltrating into the mine drifts, using a water balance model in a Geographic Information System (GIS) environment. In the model, five different infiltration scenarios were calculated, including a detailed analysis of rainfall data, snow density and thickness (Snow Water Equivalent calculation), and melting periods. The maximum water discharge that could affect the mine tunnels was, therefore, determined under several scenarios of normal precipitation conditions and during heavy rainfall, including the case of the Cogne valley flood in October 2000, used as a reference for the limit conditions. Taking into account the various approximations considered, the results can be considered a good indication of the magnitude of the total amount of water that should be drained out through abandoned mine drifts and in the drainage network during implementation of final closure of the mine.  相似文献   

Mobility Patterns of Overseas Human Capital in Australia: the role of a ‘new’ graduate visa scheme and rural development policy     

Francisco Rowe  Jonathan Corcoran  Alessandra Faggian 《The Australian geographer》2013,44(2):177-195

In 2007, the Australian federal government introduced a ‘new’ graduate visa scheme, the 485 visa sub-class. This visa facilitates the transition from student to worker for overseas graduates from Australian higher education institutions, with the potential to significantly increase their numbers in the country. At the same time, local governments have introduced various policies designed to attract and retain human capital in rural areas to address the shortfall of highly skilled individuals. This paper redresses the current lack of research into the spatial dynamics of overseas human capital in Australia and their relation to the new visa scheme in combination with shifts in rural development policies. Drawing on survey data of graduates describing the ‘before’ (2005) and ‘after’ (2008) periods of the introduction of the 485 visa scheme, this paper shows that the propensity of overseas graduates to move between Australia's regions has increased substantially. In particular, there have been an increasing proportion of overseas graduates moving to major cities despite rural development policy efforts to attract human capital to rural areas. However, these policy efforts appear to have attracted overseas graduates with particular qualifications (education and health) to work in such locales.  相似文献   

Optical spectroscopy of X-Mega targets – I. CPD −59° 2635: a new double-lined O-type binary in the Carina Nebula     

J.F. Albacete Colombo †‡  N.I. Morrell †§¶  V.S. Niemela †&#;  M.F. Corcoran 《Monthly notices of the Royal Astronomical Society》2001,326(1):78-84

Optical spectroscopy of CPD −59° 2635, one of the O-type stars in the open cluster Trumpler 16 in the Carina Nebula, reveals this star to be a double-lined binary system. We have obtained the first radial velocity orbit for this system, consisting of a circular solution with a period of 2.2999 d and semi-amplitudes of 208 and 273 km s⁻¹. This results in minimum masses of 15 and 11 M_⊙ for the binary components of CPD −59° 2635, which we classified as O8V and O9.5V, although spectral type variations of the order of 1 subclass, which we identify as the Struve–Sahade effect , seem to be present in both components. From ROSAT HRI observations of CPD −59° 2635 we determine a luminosity ratio log( L _x/ L _bol)≈−7 , which is similar to that observed for other O-type stars in the Carina Nebula region. No evidence of light variations is present in the available optical or X-ray data sets.  相似文献   

Rain water-aerosol trace metal relationships at cap ferrat: A coastal site in the Western Mediterranean   总被引：1，自引：0，他引：1  

R. Chester  M. Nimmo  P. A. Corcoran 《Marine Chemistry》1997,58(3-4)

The factors controlling the distributions of the trace metals Al, Co, Ni, Cu and Pb in a series of 25 individual rain water samples collected at Cap Ferrat, a site on the Western Mediterranean coast, are interpreted in relation to aerosols taken simultaneously at the same site. The trace metal chemistry and pH of the rain waters are constrained by the scavenged aerosols, which are composed of a mixture of urban-dominated (European) and crust-dominated (Saharan) components. Thus, the pH values of the rain waters, which range between 3.95 to 6.77, reflect the type of aerosol scavenged from the air; urban-dominated aerosol components giving rise to acidic rains, and crust-dominated aerosol resulting in neutral to basic rains. The average solubilities of the trace metals in the rain waters increase in the order Al (17%), Co (36%), Ni (53%), Pb (65%) and Cu (76%). The paniculate ↔ dissolved speciation of the non-crust-dominated metals Cu and Pb varies with pH, being more soluble at lower pH values, and exhibits the classical pH ‘adsorption edge’. However, the pH of rain can vary during an individual rain event in response to the sequential scavenging of crust-dominated and urban-dominated aerosol components. As a result, the solubility of non-crust-dominated trace metals, such as Pb, can also vary sequentially during an individual rain event; the maximum solubility being related to a ‘dip’ in pH associated with the scavenging of urban-rich aerosol components, followed by a return to the initial pH as the pH-influencing components are exhausted. Data from the present study therefore indicate that the pH-controlled trace metal solubility relationship reported for individual rain events can also occur sequentially in the same event. The particulate material in the rain waters does not contain the relatively high concentrations of Ni, Cu and Pb found in the parent aerosols, and its composition approaches that of crust-dominated aerosols transported to the Mediterranean. Data from the present study, together with those for other Western European coastal locations, indicate that there is a Pb-Cu fractionation between aerosols and rainwaters which results in a significantly greater fraction of the aerosol Pb, relative to Cu, escaping precipitation scavenging in the coastal zone and so becoming available for long-range atmospheric transport.  相似文献   

Interdecadal variability in the Gulf of Maine zooplankton community, with potential impacts on fish recruitment   总被引：4，自引：1，他引：4  

Pershing  Andrew J.; Greene  Charles H.; Jossi  Jack W.; O'Brien  Loretta; Brodziak  Jon K.T.; Bailey  Barbara A. 《ICES Journal of Marine Science》2005,62(7):1511-1523

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Quantitative measures of textural anisotropy resulting from magmatic compaction illustrated by a sample from the Palisades sill, New Jersey     

Norman H. Gray  Anthony R. Philpotts  Loretta D. Dickson 《Journal of Volcanology and Geothermal Research》2003,121(3-4):293-312

Early in the crystallization of many tholeiitic basaltic magmas, plagioclase crystals cluster together into a 3-D cellular network, which forms a passive marker capable of recording the deformation that accompanies compaction of crystal mush. Although irregular in detail, the overall network is initially isotropic and only becomes anisotropic as a result of compaction. We have developed four independent methods to quantify the 3-D textural anisotropy of a basalt sample using at least three non-parallel thin sections. Three of the methods are based on the geometrical properties of digitized maps of the feldspar chain networks. One approach focuses on the angular variation of the mean intercept along parallel traverses through the network, another examines the orientation and size distribution of individual links, and the third considers the average shape of interstitial regions outlined by the plagioclase network. The fourth technique approximates the textural anisotropy by the variogram anisotropy of a scanned thin section image. We illustrate the methods using five oriented non-parallel thin sections from a sample of diabase 146 m above the base of the 300-m-thick Palisades sill of New Jersey. Compaction of crystal mush in this sill has previously been postulated on the basis of chemical evidence. The 3-D feldspar network anisotropy based on the first three approaches suggests nearly uniaxial compaction on the order of 8.6% in a direction within 3° of the intersection of the columnar joints at the sample site. A rigorous statistical test based on the statistics of elliptically contoured non-normal multivariate distributions documents that the link-vector distribution in vertical sections are statistically anisotropic at a 95% confidence level and that the overall compaction is 7.9±2.6%. The orientation and magnitude of the 3-D textural anisotropy determined by the image variogram of the non-opaque minerals is almost identical to the mean feldspar network anisotropy; 8.5% compaction in a direction 10° from the columnar joint intersections. The major silicate textural and feldspar network anisotropy axes both plunge almost directly down dip of the sill. On the other hand, the major axis of the variogram anisotropy of the opaque minerals is approximately parallel to the strike of the sill and to the major axis of the anisotropic magnetic susceptibility. The anisotropy of the silicate mineral fabric may reflect down-dip flow of a deformable melt-rich crystal mush, whereas the AMS and opaque textural anisotropy reflects the influence of gravitational stresses during the growth of magnetite in the final stages of melt crystallization. Evidently the Palisades sill was not originally horizontal but was intruded in an orientation close to its present attitude.  相似文献   

Evaluation of the Johnson and Ettinger Model for Prediction of Indoor Air Quality     

Ian Hers  Reidar Zapf-Gilje  Paul C. Johnson  Loretta Li 《Ground Water Monitoring & Remediation》2003,23(1):62-76

Screening level models are now commonly used to estimate vapor intrusion for subsurface volatile organic compounds (VOCs). Significant uncertainty is associated with processes and models and, to date, there has been only limited field-based evaluation of models for this pathway. To address these limitations, a comprehensive evaluation of the Johnson and Ettinger (J&E) model is provided through sensitivity analysis, comparisons of model-predicted to measured vapor intrusion for 11 petroleum hydrocarbon and chlorinated solvent sites, and review of radon and flux chamber studies. Significant intrusion was measured at five of 12 sites with measured vapor attenuation ratios (α_m's) (indoor air/source vapor) ranging from ∼1 × 10⁻⁶ to 1 × 10⁻⁴. Higher attenuation ratios were measured for studies using radon, inert tracers, and flux chambers; however, these ratios are conservative owing to boundary conditions and tracer properties that are different than those at most VOC-contaminated sites. Reasonable predictions were obtained using the J&E model with comparisons indicating that model-predicted vapor attenuation ratios (α_p's) were on the same order, or less than the α_m's. For several sites, the (m were approximately two orders of magnitude less than the a 's indicating that the J&E model is conservative in these cases. The model comparisons highlight the importance in using appropriate input parameters for the J&E model. The regulatory implications associated with use of the J&E model to derive screening criteria are also discussed.  相似文献   

The SCUBA Half Degree Extragalactic Survey – IV. Radio–mm–FIR photometric redshifts     

Itziar Aretxaga  David H. Hughes  Kristen Coppin  Angela M. J. Mortier  Jeff Wagg  James S. Dunlop  Edward L. Chapin  Stephen A. Eales  Enrique Gaztañaga  Mark Halpern  Rob J. Ivison  Eelco van Kampen  Douglas Scott  Stephen Serjeant  Ian Smail  Thomas Babbedge  rew J. Benson  Scott Chapman  David L. Clements  Loretta Dunne  Simon Dye  Duncan Farrah  Matt J. Jarvis  Robert G. Mann  Alexandra Pope  Robert Priddey  Steve Rawlings  Marc Seigar  Laura Silva  Chris Simpson  Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2007,379(4):1571-1588

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Coordinated monitoring of the eccentric O-star binary Iota Orionis: the X-ray analysis   总被引：1，自引：0，他引：1  

Julian M. Pittard  Ian R. Stevens  Michael F. Corcoran  Ken G. Gayley  Sergey V. Marchenko  Gregor Rauw † 《Monthly notices of the Royal Astronomical Society》2000,319(1):137-153

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