Arsenic attenuation in tailings at a former Cu–W–As mine,SW Finland     

Annika Parviainen  Matthew B.J. Lindsay  Rafael Pérez-López  Blair D. Gibson  Carol J. Ptacek  David W. Blowes  Kirsti Loukola-Ruskeeniemi 《Applied Geochemistry》2012

Nearly half a century after mine closure, release of As from the Ylöjärvi Cu–W–As mine tailings in groundwater and surface water run-off was observed. Investigations by scanning electron microscopy (SEM), electron microprobe analysis (EMPA), synchrotron-based micro-X-ray diffraction (μ-XRD), micro-X-ray absorption near edge structure (μ-XANES) and micro-extended X-ray absorption fine structure (μ-EXAFS) spectroscopy, and a sequential extraction procedure were performed to assess As attenuation mechanisms in the vadose zone of this tailings deposit. Results of SEM, EMPA, and sequential extractions indicated that the precipitation of As bearing Fe(III) (oxy)hydroxides (up to 18.4 wt.% As₂O₅) and Fe(III) arsenates were important secondary controls on As mobility. The μ-XRD, μ-XANES and μ-EXAFS analyses suggested that these phases correspond to poorly crystalline and disordered As-bearing precipitates, including arsenical ferrihydrite, scorodite, kaňkite, and hydrous ferric arsenate (HFA). The pH within 200 cm of the tailings surface averaged 5.7, conditions which favor the precipitation of ferrihydrite. Poorly crystalline Fe(III) arsenates are potentially unstable over time, and their transformation to ferrihydrite, which contributes to As uptake, has potential to increase the As adsorption capacity of the tailings. Arsenic mobility in tailings pore water at the Ylöjärvi mine will depend on continued arsenopyrite oxidation, dissolution or transformation of secondary Fe(III) arsenates, and the As adsorption capacity of Fe(III) (oxy)hydroxides within this tailings deposit.  相似文献   

Preface: clay mineral diagenesis and very low-grade metamorphic processes. Proceedings of the 2011 Frey–Kübler symposium     

Rafael Ferreiro M?hlmann  Fernando Nieto  ?mer Bozkaya  Sébastien Potel  Asuman Günal Türkmeno?lu 《Swiss Journal of Geoscience》2012,105(2):117-120

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Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain     

Pérez-López R  Nieto JM  López-Cascajosa MJ  Díaz-Blanco MJ  Sarmiento AM  Oliveira V  Sánchez-Rodas D 《Marine pollution bulletin》2011,62(2):405-411

This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11 t y⁻¹), Zn (3.4 t y⁻¹) and Mo (0.88 t y⁻¹). There were other metals with high pollutant charge, such as Ti (232 kg y⁻¹), As (228 kg y⁻¹), Ni (195 kg y⁻¹), Pb (100 kg y⁻¹), Cr (39 kg y⁻¹) and Cd (33 kg y⁻¹). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary.  相似文献   

A new global alignment approach for underwater optical mapping   总被引：1，自引：0，他引：1  

Armagan Elibol  Rafael Garcia 《Ocean Engineering》2011,38(10):1207-1219

Lately, underwater vehicles have become important tools for exploration, monitoring and creation of maps of the seabed. Within mapping applications, the maps obtained from optical data are becoming essential in different study areas such as biological, geological and archaeological surveys, or in detection of benthic temporal changes. However, the underwater medium is very challenging for optical sensors and does not allow the area of interest to be imaged in a single image. Therefore, image mosaicing methods are necessary. Although recent advances in detection of correspondences between images have resulted in highly effective image registration methods, global alignment methods are still needed to obtain a globally coherent mosaic. In this paper, we propose a new global alignment method which works on the mosaic frame and does not require non-linear optimisation. Additionally, a simple image rectifying method is presented to reduce the down-scaling effect which might occur when minimising errors defined in the mosaic frame. Moreover, this rectifying method can also be seen as an alternative and straightforward way of incorporating different sensor information if available. The proposed framework has been tested with underwater image sequences. The resulting method is faster than its counterparts while providing the same level of registration quality.  相似文献   

Web-GIS tool for the management of rural land markets     

Juan Porta  Jorge Parapar  Paula García  Gracia Fernández  Juan Touriño  Ramón Doallo  Francisco Ónega  Inés Santé  Pablo Díaz  David Miranda  Rafael Crecente 《Earth Science Informatics》2013,6(4):209-226

Land abandonment and stagnation of rural markets in the last few years have become one of the main concerns of rural administrations. The use of Web and GIS (Geographic Information System) technologies can help to mitigate the effects of these problems. This paper pro-poses a novel Web-GIS tool with spatial capabilities for the dynamization of rural land markets by encouraging the transfer of land from owners to farmers through the leasing of plots. The system, based on open source software, offers information about the properties, their environment and their owners. It uses standards for handling the geographic information and for communicating with external data sources. This system was used as the basis for the development of SITEGAL, the tool for the management of the Land Bank of Galicia (www.bantegal.com/sitegal). SITEGAL has been operational since 2007 obtaining benefits for both administration and users (farmers and land owners), and promoting the e-Government.  相似文献   

Interactive effects of environmental variability and human impacts on the long-term dynamics of an Amazonian floodplain lake and a South Atlantic coastal lagoon   总被引：2，自引：1，他引：1  

Reinaldo L. Bozelli  Adriano Caliman  Rafael D. Guariento  Luciana S. Carneiro  Jayme M. Santangelo  Marcos P. Figueiredo-Barros  Joo J.F. Leal  Adriana M. Rocha  Letícia B. Quesado  Paloma M. Lopes  Vinicius F. Farjalla  Claudio C. Marinho  Fabio Roland  Francisco A. Esteves 《Limnologica》2009,39(4):306-313

Human activities are exposing freshwater ecosystems to a wide range of stressors, whose direct and indirect effects can be alleviated or exacerbated through interactive effects with dynamic environmental drivers. This study used long-term data from two Neotropical lacustrine freshwater systems (Batata Lake, an Amazonian floodplain lake and Imboassica lagoon, an Atlantic coastal lagoon) subjected to different kinds of environmental fluctuations (i.e., flood pulse and sandbar opening) and anthropogenic impacts (i.e., siltation and eutrophication). Our objective was to determine whether the effects of human perturbations are contingent on modifications of important biotic and abiotic characteristics through environmental variability. For both ecosystems, environmental variability consistently interacted with anthropogenic perturbations to alter most of the variables analyzed, such as nutrient dynamics, chlorophyll-a concentration, zooplankton and benthic invertebrate species richness, and temporal community stability, which indicates that interactive effects between environmental variability and anthropogenic perturbations may impact a myriad of ecosystem properties. Furthermore, the nature of these interactive effects was highly dependent on the variable considered and on the ecosystem analyzed. For example, at Imboassica lagoon, sandbar openings interacted synergistically with trophic state to increase the phosphorus concentration in the water column. At Batata Lake, flooding generally alleviated the negative effects of siltation on species richness by both diluting inorganic suspended material concentration and by promoting local recruitment from the regional species pool. Such results indicate that our ability to understand and predict the outcome of anthropogenic impacts on inland aquatic systems can be hampered if we consider human stressors as “static” phenomena disconnected from dynamic interactions with major local environmental drivers.  相似文献   

Very Small Array observations of the Sunyaev–Zel'dovich effect in nearby galaxy clusters     

Katy Lancaster †  Ricardo Genova-Santos  Nelson Falcòn  Keith Grainge  Carlos Gutièrrez  Rüdiger Kneissl  Phil Marshall  Guy Pooley  Rafael Rebolo  Jose-Alberto Rubiño-Martin  Richard D. E. Saunders  Elizabeth Waldram  Robert A. Watson 《Monthly notices of the Royal Astronomical Society》2005,359(1):16-30

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Dust particles in the atmospheres of terrestrial planets and their roles for prebiotic chemistry: An overview     

Vladimir A. Basiuk  Rafael Navarro-Gonzalez 《Astrophysics and Space Science》1996,236(1):61-75

The available literature on sources, chemical composition, and importance of dust particles for the origins of life is analyzed. The most abundant sources of dust on the early terrestrial planets are sedimentation of interplanetary dust, meteoritic/cometary impacts, and volcanic eruptions. Interplanetary dust can originate directly from interstellar space, from evaporation of cometary bodies, from collisional destruction of asteroidal and meteoritic bodies, and nucleation in sunspots. Many rather complex organic species, including those of prebiotic interest, have been identified in the interstellar medium and cometary dust. Some of them are believed to formvia catalytic processes on the surfaces of dust particles. However, the mechanisms are not known, and even simulating experiments are difficult to perform due to insufficient knowledge of physical conditions in the space media and of chemical composition and properties of the dust. Besides the catalytic roles, cometary dust is believed to be the best delivery vehicle for organic matter of space origin to the atmospheres of terrestrial planets. Abundant sources of catalytically active fine dust can be volcanoes. Various organic and biological compounds have been found in terrestrial volcanic gases and ash, which are assumed to formvia the catalytic Fischer-Tropsch reactions. At present the eruptions on the Earth provide a unique opportunity to observein situ the formation of organic matter, and knowledge of the ash composition and local conditions allows to perform simulating experiments.  相似文献   

Influence of surface heterogeneities of building granite on its thermal response and its potential for the generation of thermoclasty     

Miguel Gómez-Heras  Bernard J. Smith  Rafael Fort 《Environmental Geology》2008,56(3-4):547-560

Surface properties, especially albedo, and aspect are widely accepted as strong influences on the surface thermal response of building stone to insolation. However, the influence that adjacent areas of stone with very different surface properties may have on the thermal response of a patch of stonework, and the ways in which spatial variation in thermal characteristics might enhance stone decay has received relatively little attention. This paper examines the differential thermal response of granite used in construction that results from the presence of dark coloured micro-granular enclaves within a leucocratic host. Surface temperatures and temperature differences between enclaves exhibiting mico-spalling, enclaves with no spalling and the surrounding stone were measured for different aspects and seasons on a 20th century building in Madrid. These data were used to calculate a number of “indices” related to short-term temperature cycling and temperature gradients that have the theoretical capability of generating irreversible deformation of the stone. These indices suggest that micro-spalling of enclaves, compared to a lack of similar decay on the host-rock, is related to their differential thermal response to insolation, most importantly the lower albedo and thermal conductivity values of the enclaves. However, these factors are not sufficient on their own to trigger spalling, and breakdown was only observed where enclaves also experienced repeated, short-term surface temperature cycling caused by, for example, temporary shading by adjacent vegetation. These rapid temperature reversals are identified as a key contributory factor to the thermally driven decay observed on some of the enclaves.  相似文献   

Very low grade metamorphism of the Taveyanne formation of western Switzerland   总被引：1，自引：1，他引：1  

David Schmidt  Susanne T. Schmidt  Joseph Mullis  Rafael Ferreiro Mählmann  Martin Frey 《Contributions to Mineralogy and Petrology》1997,129(4):385-403

The andesitic early Oligocene Taveyanne metagreywacke of the Helvetic nappes of western Switzerland shows an increase of metamorphic grade from zeolite facies through lower greenschist facies. Electron microprobe analysis, fluid inclusion thermometry, stable isotope analysis, coal rank, illite and chlorite crystallinity and thermodynamic calculations were carried out to determine metamorphic conditions. Evaluation of all techniques used in this study suggest that only combinations of different parameters yield reliable information to constrain very low-grade metamorphic conditions. Electron microprobe analyses are presented for actinolite, chlorite, epidote, phengite, laumontite, prehnite, pumpellyite, and titanite. With increasing metamorphic grade, chlorite is enriched in tetrahedral Al, pumpellyite becomes poorer in Fe_tot and more homogeneous in chemical composition, and titanite tends to incorporate Ti at the expense of Al and Fe³⁺. Metamorphic P-T conditions were determined by a combination of fluid inclusion microthermobarometry, stable isotope thermometry on quartz-calcite veins, chlorite “geothermometry” and thermodynamic calculations. Peak temperatures range from 210–250 °C for zeolite facies to 270–300 °C for prehnite-pumpellyite facies to 300–360 °C for pumpellyite-actinolite facies. An evaluation of 289 chlorite analyses indicates that the tetrahedral Al content is negatively correlated with the saponite component. Temperatures derived from chlorite “geothermometry” match maximum temperature conditions mentioned above. Illite crystallinity data for shales and slates intercalated with the Taveyanne metagreywacke indicate that the diagenetic zone correlates with the zeolite facies, the upper anchizone with the prehnite-pumpellyite facies, and the lower epizone with the pumpellyite-actinolite facies. A comparison of coal rank and illite crystallinity data (n=12,r=0.91) yielded R _max values of 2.9 and 5.5% for the lower and upper boundary of the anchizone, respectively. Received: 2 August 1996 / Accepted: 16 July 1997  相似文献