Prediction of the long-term performance of abandoned lead zinc mine tailings in a Welsh catchment     

Barbara Palumbo-Roe  Ben Klinck  Vanessa Banks  San Quigley 《Journal of Geochemical Exploration》2009,100(2-3):169-181

In this study we investigated the sulphidic mine tailings from Frongoch and Grogwynion, two abandoned lead zinc mines in mid-Wales, UK. Despite falling within the same ore field the mine waste characterisation has identified differences in the tailings from the two sites. Bulk concentrations range from 10 to 52 g kg^− 1 for Pb, 1.1 to 2.9 g kg^− 1 for Zn in Grogwynion and from 1.0 to 130 g kg^− 1 for Pb, 11 to 110 g kg^− 1 for Zn in Frongoch. An experimental (European standard leaching tests TS 14429 and TS 14405) and geochemical modelling approach was used to study the leaching composition as a function of pH and liquid/solid ratio. There was little correlation between the tailings bulk metal concentrations and the leachate composition, but variations in Pb and Zn concentrations were found to be consistent with control of dissolved Pb and Zn by secondary minerals and the mechanisms of dissolution/precipitation/sorption involving them. Specifically, the Grogwynion mine tailings with near-neutral pH have predominantly lead and zinc carbonates controlling Pb and Zn solubility in the leachates, whereas the Pb and Zn concentrations in Frongoch leachates are best modelled with a surface complexation model for metal sorption to oxyhydroxides. The different speciation results in a greater sensitivity of Grogwynion tailings to acidification with a potential release of Pb in solution up to 10 times higher than in Frongoch, despite similar bulk Pb concentrations. At acid pH, Zn is similarly dissolved to a greater extent in Grogwynion than in Frongoch tailings. There was no evidence of sulphide oxidation during the batch and column leaching tests and the suitability of using these European leaching standards for the characterisation of sulphidic mine waste materials for waste management purposes has been considered.  相似文献   

Petrology and geochemistry of REE-rich Mafé banded iron formations (Bafia group,Cameroon)     

Charles Nkoumbou  Fuh Calistus Gentry  Jacqueline Tchakounte Numbem  Yolande Vanessa Belle Ekwe Lobé  Christin Steve Nwagoum Keyamfé 《Comptes Rendus Geoscience》2017,349(4):165-174

Archaean–Paleoproterozoic foliated amphibole-gneisses and migmatites interstratified with amphibolites, pyroxeno-amphibolites and REE-rich banded-iron formations outcrop at Mafé, Ndikinimeki area. The foliation is nearly vertical due to tight folds. Flat-lying quartz-rich mica schists and quartzites, likely of Pan-African age, partly cover the formations. Among the Mafé BIFs, the oxide BIF facies shows white layers of quartz and black layers of magnetite and accessory hematite, whereas the silicate BIF facies is made up of thin discontinuous quartz layers alternating with larger garnet (almandine–spessartine) + chamosite + ilmenite ± Fe-talc layers. REE-rich oxide BIFs compositions are close to the East Pacific Rise (EPR) hydrothermal deposit; silicate BIFs plot midway between EPR and the associated amphibolite, accounting for a contamination by volcanic materials, in addition to the hydrothermal influence during their oceanic deposition. The association of an oceanic setting with alkaline and tholeiitic magmatism is typical of the Algoma-type BIF deposit. The REE-rich BIFs indices recorded at Mafé are interpreted as resulting from an Archaean–Paleoproterozoic mineralization.  相似文献   

Evaluation of stable iodine status of the areas affected by the Chernobyl accident in an epidemiological study in Belarus and the Russian Federation     

Elena Korobova  Yadviga Anoshko  Ausrele Kesminiene  Aleksander Kouvyline  Sergei Romanov  Vanessa Tenet  Eero Suonio  Elisabeth Cardis 《Journal of Geochemical Exploration》2010

Variation of the stable iodine supply was evaluated in the soils of around more than 700 settlements in the regions (oblasts) of Belarus and the Russian Federation contaminated after the Chernobyl accident. It involved the use of regional information on iodine content in different types of soil cover, biogeochemical criteria of iodine deficiency in food chains, and the available soil maps.  相似文献   

Boundary-Layer Stress Instabilities in Neutral,Rotating Turbulent Flows     

Enrico Ferrero  Luca Mortarini  Massimigliano Manfrin  Arnaldo Longhetto  Rita Genovese  Renato Forza 《Boundary-Layer Meteorology》2009,130(3):347-363

Boundary-layer instabilities are studied by analyzing the results of laboratory simulations of wall turbulence in a shear-driven rotating flow. The experiments were carried out in the Turin University Laboratory rotating water tank, where a circular flow was generated by either increasing (spin-up) or decreasing (spin-down) the rotation speed of the platform. The flow was measured using a Particle Image Velocimetry technique and the developed turbulence analyzed. Two cases were accounted for, in the former the measurements were performed over a smooth surface (bottom of the tank), while in the latter a rough-to-smooth transition was considered. The turbulent boundary layer developed inside the tank is analyzed by means of vertical profiles of mean and turbulent quantities and on the basis of drag coefficients. Then turbulent structures developed in the different cases are shown and discussed in terms of the vorticity fields. Finally, an analysis based on the concept of swirling strength was carried out to select among the vortex extremes those associated with a coherent structure.  相似文献   

Satellite-derived estimates of potential carbon sequestration through afforestation of agricultural lands in the United States     

Christopher Potter  Steven Klooster  Seth Hiatt  Matthew Fladeland  Vanessa Genovese  Peggy Gross 《Climatic change》2007,80(3-4):323-336

Afforestation of marginal agricultural lands represents a promising option for carbon sequestration in terrestrial ecosystems. An ecosystem carbon model was used to generate new national maps of annual net primary production (NPP), one each for continuous land covers of ‘forest’, ‘crop’, and ‘rangeland’ over the entire U. S. continental area. Direct inputs of satellite “greenness” data from the Advanced Very High Resolution Radiometer (AVHRR) sensor into the NASA-CASA carbon model at 8-km spatial resolution were used to estimate spatial variability in monthly NPP and potential biomass accumulation rates in a uniquely detailed manner. The model predictions of regrowth forest production lead to a conservative national projection of 0.3 Pg C as potential carbon stored each year on relatively low-production crop or rangeland areas. On a regional level, the top five states for total crop afforestation potential were: Texas, Minnesota, Iowa, Illinois, and Missouri, whereas the top five states for total rangeland afforestation potential are: Texas, California, Montana, New Mexico, and Colorado. Afforestation at this level of intensity has the capacity to offset at least one-fifth of annual fossil fuel emission of carbon in the United States. These projected afforestation carbon gains also match or exceed recent estimates of the annual sink for atmospheric CO₂ in currently forested area of the country.  相似文献   

Variability in terrestrial carbon sinks over two decades: Part 2 — Eurasia   总被引：1，自引：1，他引：0  

C. Potter  S. Klooster  P. Tan  M. Steinbach  V. Kumar  V. Genovese 《Global and Planetary Change》2005,49(3-4):177-186

We have analyzed 17 yr (1982–1998) of net carbon flux predictions from a simulation model based on satellite observations of monthly vegetation cover. The NASA-CASA model was driven by vegetation cover properties derived from the Advanced Very High Resolution Radiometer and radiative transfer algorithms that were developed for the Moderate Resolution Imaging Spectroradiometer (MODIS). We report that although the terrestrial ecosystem sink for atmospheric CO₂ for the Eurasian region has been fairly consistent at between 0.3 and 0.6 Pg C per year since 1988, high interannual variability in net ecosystem production (NEP) fluxes can be readily identified at locations across the continent. Ten major areas of highest variability in NEP were detected: eastern Europe, the Iberian Peninsula, the Balkan states, Scandinavia, northern and western Russia, eastern Siberia, Mongolia and western China, and central India. Analysis of climate anomalies over this 17-yr time period suggests that variability in precipitation and surface solar irradiance could be associated with trends in carbon sink fluxes within such regions of high NEP variability.  相似文献   

Turning Contention into Collaboration: Engaging Power,Trust, and Learning in Collaborative Networks     

Vanessa R. Levesque  Aram J. K. Calhoun  Kathleen P. Bell  Teresa R. Johnson 《社会与自然资源》2017,30(2):245-260

Given the complexity and multiplicity of goals in natural resource governance, it is not surprising that policy debates are often characterized by contention and competition. Yet at times adversaries join together to collaborate to find creative solutions not easily achieved in polarizing forums. We employed qualitative interviews and a quantitative network analysis to investigate a collaborative network that formed to develop a resolution to a challenging natural resource management problem, the conservation of vernal pools. We found that power had become distributed among members, trust had formed across core interests, and social learning had resulted in shared understanding and joint solutions. Furthermore, institutions such as who and when new members joined, norms of inclusion and openness, and the use of small working groups helped create the observed patterns of power, trust, and learning.  相似文献   

Temporal variability of diverse mountain permafrost slope movements derived from multi-year daily GPS data,Mattertal, Switzerland   总被引：1，自引：0，他引：1  

Vanessa Wirz  Marten Geertsema  Stephan Gruber  Ross S. Purves 《Landslides》2016,13(1):67-83

In this study, high resolution surface measurements of diverse slope movements are compared to environmental factors such as ground surface temperature (GST) and snow cover, in order to reveal and compare velocity fluctuations caused by changing environmental conditions. The data cover 2 years (2011–2013) of Global Positioning System (GPS) and GST measurements at 18 locations on various slope movement types within an alpine study site in permafrost (Mattertal, Switzerland). Velocities have been estimated based on accurate daily GPS solutions. The mean annual velocities (MAV) observed at all GPS stations varied between 0.006 and 6.3 ma^?1. MAV were higher in the period 2013 compared to 2012 at all stations. The acceleration in 2013 was accompanied by a longer duration of the snow cover and zero curtain and slightly lower GST. The amplitude (0–600 %) and the timing of the intra-annual variability were generally similar in both periods. At most stations, an annual cycle in the movement signal was observed, with a phase lag of 1–4 months to GST. Maximum velocity typically occurred in late summer and autumn, and minimum velocity in late winter and beginning of spring. The onset of acceleration always started in spring during the snowmelt period. At two stations located on steep rock glacier tongues, overprinted on the annual cycle, short-term peaks of velocity increase, occurred during the snowmelt period, indicating a strong influence of meltwater.  相似文献   

An investigation of future fuel load and fire weather in Australia     

Hamish Clarke  Andrew J. Pitman  Jatin Kala  Claire Carouge  Vanessa Haverd  Jason P. Evans 《Climatic change》2016,139(3-4):591-605

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The relationship between climate and rock glacier distribution in the Ben Ohau Range, New Zealand   总被引：2，自引：0，他引：2  

Vanessa Brazier  Martin P. Kirkbride  Ian F. Owens 《Geografiska Annaler: Series A, Physical Geography》1998,80(3-4):193-207

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