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Edmundo Placencia-Gómez Annika Parviainen Tero Hokkanen Kirsti Loukola-Ruskeeniemi 《Environmental Earth Sciences》2010,61(7):1435-1447
The Haveri tailings area contains 1.5 Mt of sulfide-bearing waste from the Au–Cu mine that operated during 1942–1961. Geophysical
and geochemical methods were used to evaluate and characterize the generation of acid mine drainage (AMD). Correlations were
examined among the electrical resistivity tomography (ERT) data, the total sulfide content and concentrations of sulfide-bound
metals (Cu, Co, Fe, Mn, Ni, Pb and Zn) of tailings samples, and the resistivity and geochemistry of surface water. The resulting
geophysical–geochemical model defines an area in the vadose tailings, where a low resistivity anomaly (<10 Ohm m) is correlated
with the highest sulfide content, extensive sulfide oxidation and low pH (average 3.1). The physical and geochemical conditions,
resulting from the oxidation of the sulfide minerals, suggest that the low resistivity anomaly is associated with acidic and
metal-rich porewater (i.e., AMD). The lower resistivity values in the saturated zone of the central impoundment suggest the
formation of a plume of AMD. The natural subsoil layer (silt and clay) and the bedrock surface below the tailings area were
well mapped from the ERT data. The detected fracture zones of the bedrock that could work as leakage pathways for AMD were
consistent with previous geological studies. The integrated methodology of the study offers a promising approach to fast and
reliable monitoring of areas of potential AMD generation and its subsurface movement over large areas (ca. 9 ha). This methodology
could be helpful in planning drill core sampling locations for geochemical and mineralogical analysis, groundwater sampling,
and choosing and monitoring remedial programs. 相似文献
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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
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Seasonal GCM-based temperature and precipitation projections for the end of the 21st century are presented for five European regions; projections are compared with corresponding estimates given by the PRUDENCE RCMs. For most of the six global GCMs studied, only responses to the SRES A2 and B2 forcing scenarios are available. To formulate projections for the A1FI and B1 forcing scenarios, a super-ensemble pattern-scaling technique has been developed. This method uses linear regression to represent the relationship between the local GCM-simulated response and the global mean temperature change simulated by a simple climate model. The method has several advantages: e.g., the noise caused by internal variability is reduced, and the information provided by GCM runs performed with various forcing scenarios is utilized effectively. The super-ensemble method proved especially useful when only one A2 and one B2 simulation is available for an individual GCM. Next, 95% probability intervals were constructed for regional temperature and precipitation change, separately for the four forcing scenarios, by fitting a normal distribution to the set of projections calculated by the GCMs. For the high-end of the A1FI uncertainty interval, temperature increases close to 10°C could be expected in the southern European summer and northern European winter. Conversely, the low-end warming estimates for the B1 scenario are ~ 1°C. The uncertainty intervals of precipitation change are quite broad, but the mean estimate is one of a marked increase in the north in winter and a drastic reduction in the south in summer. In the RCM simulations driven by a single global model, the spread of the temperature and precipitation projections tends to be smaller than that in the GCM simulations, but it is possible to reduce this disparity by employing several driving models for all RCMs. In the present suite of simulations, the difference between the mean GCM and RCM projections is fairly small, regardless of the number or driving models applied. 相似文献
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Andreï Lecomte Michel Cathelineau Etienne Deloule Marc Brouand Chantal Peiffert Kirsti Loukola-Ruskeeniemi Esa Pohjolainen Hannu Lahtinen 《Mineralium Deposita》2014,49(4):513-533
In the central part of the Fennoscandian Shield, the Talvivaara Ni–Zn–Cu–Co deposit, hosted by Palaeoproterozoic metamorphosed black schists, contains low uranium concentrations ranging from 10 to 30 ppm. The Talvivaara black schists were deposited 2.0–1.9 Ga ago and underwent subsequent metamorphism during the 1.9–1.79 Ga Svecofennian orogeny. Anhedral uraninite crystals rimmed by bitumen constitute the main host of uranium. U–Pb secondary ion mass spectrometry dating indicates that uraninite crystals were formed between 1,878?±?17 and 1,871?±?43 Ma, during peak metamorphism. Rare earth element patterns and high Th content (average 6.38 wt%) in disseminated uraninite crystals indicate that U was concentrated during high temperature metamorphism (>400 °C). The formation of bitumen rims around uraninite may be explained by two distinct scenarios: (a) a transport of U coincident with the migration of hydrocarbons or (b) post-metamorphic formation of bitumen rims, through radiolytic polymerization of gaseous hydrocarbons at the contact with uraninite. 相似文献
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K. Loukola-Ruskeeniemi 《Mineralium Deposita》1991,26(2):152-164
Metamorphosed black shale formations 120–150 m thick with median concentrations of 7% non-carbonate carbon and 6–8% sulphur are abundantly met in drill cores in the Kainuu and Outokumpu areas. Carbon isotope
3C values are comparable to the average isotopic composition of non-carbonate carbon in sedimentary rocks. The rare earth element patterns show cerium depletion, indicating a marine origin. Base metal concentrations in black shales are high in the Talvivaara mineralization (ore estimate: 300 Mt with 0.26% Ni, 0.14% Cu and 0.53% Zn) and in the vicinity of ophiolite complexes. In the Kainuu schist belt, the median value for gold is 35 ppb (max 170 ppb) in the western part and 16 ppb (max 180 ppb) in the east. Highest platinum and palladium concentrations encountered are 60–70 ppb. It is shown that in the Kainuu black shales, concentrations of sulphur, base metals and precious metals have been increased by hydrothermal processes, as indicated by positive europium anomalies, elevated mercury concentrations (max 7.5 ppm), high sulphur isotope
34S values and the enrichment of sulphur and base metals relative to carbon. The processes operative during the deposition of these shales find an analogy in recent processes in ocean ridge spreading axes. 相似文献
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Giorgiana De Franceschi Lucilla Alfonsi David Altadill Pal Bencze Alain Bourdillon Dalia Buresova Ljiljana R. Cander Benito de la Morena Lefteris Economou Miguel Herraiz Kirsti Kauristie Jan Lastovicka Silvia Pau Gracia Rodriguez Richard Stamper Iwona Stanislawska 《Earth, Moon, and Planets》2009,104(1-4):63-67
The objective of the COST296 Action MIERS (Mitigation of Ionospheric Effects on Radio Systems) is to develop an increased knowledge of the effects imposed by the ionosphere on practical radio systems, and for the development and implementation of techniques to mitigate the deleterious effects of the ionosphere on such systems (http://www.cost296.rl.ac.uk). The COST296 Community contributes to the international efforts of IHY with scientific and outreach activities as well. After the realization of a web site hosted by Istituto Nazionale di Geofisica e Vulcanologia (INGV), developed also to promote the ionospheric physics to the open public, the COST296 Community supported an initiative addressed to the pupils of the primary school of several European Countries: the realization of a school-calendar dedicated to the Sun and to the Sun-Earth connections. 相似文献