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The behavior of trace elements during schwertmannite precipitation and subsequent transformation into goethite and jarosite 总被引：5，自引：0，他引：5
Patricia Acero Carlos Ayora José-Miguel Nieto 《Geochimica et cosmochimica acta》2006,70(16):4130-4139
Schwertmannite is a ubiquitous mineral formed from acid rock drainage (ARD), and plays a major role in controlling the water chemistry of many acid streams. The formation of schwertmannite was investigated in the acid discharge of the Monte Romero abandoned mine (Iberian Pyrite Belt, SW, Spain). Schwertmannite precipitated from supersaturated solutions mainly owing to the oxidation of Fe(II) to Fe(III) and transformed with time into goethite and jarosite. In a few hours, schwertmannite precipitation removed more than half of the arsenic load from solution, whereas the concentration of divalent trace metals (Zn, Cu, Pb, Cd, Ni, and Co) remained almost unchanged. In the laboratory, natural schwertmannite was kept in contact with its coexisting acid water in a flask with a solid-liquid mass ratio of 1:5 for 353 days. During this time, the pH of the solution dropped from 3.07 to 1.74 and the concentrations of sulfate and Fe increased. During the first 164 days, schwertmannite transformed into goethite plus H3O-jarosite but, subsequently, goethite was the only mineral to form. Some of the trace elements, such as Al, Cu, Pb, and As were depleted in solution during the first stage as schwertmannite transformed into goethite plus H3O-jarosite. On the contrary, the transformation of schwertmannite to goethite (with no jarosite) during the second stage released Al, Cu, and As to the solution. Despite the variation in their concentrations in solution, approximately 80% of the total Al and Cu inventories and more than 99% As and Pb remained in the solid phase throughout the entire aging process. 相似文献
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Environmental impact of heavy-metal dispersion in the Huerva River (Iberian Range,NE Spain) 总被引：1，自引：0，他引：1
P. Acero J. Mandado J. Gómez M. Gimeno L. Auqué F. Torrijo 《Environmental Geology》2003,43(8):950-956
In this study, the methodology of geochemical prospecting has been applied to the study of cadmium, lead, copper and zinc dispersion in the fine sediments of the upper course of the Huerva River (Iberian Range, NE Spain). The survey was organised in two stages: (1) general sampling along the river and its tributary channels, aimed at selecting the sections with the highest contents of the target elements, and (2) detailed study of those sections, aimed at an interpretation of possible positive geochemical anomalies and identification of their sources. The results of this study prove the existence of multiple and complex sources, with a significant influence of sources related to anthropogenic activity. However, the system shows a good ability to depurate itself under current conditions. 相似文献
3.
Acero Francisco Javier Fernández-Fernández María Isabel Carrasco Víctor Manuel Sánchez Parey Sylvie Hoang Thi Thu Huong Dacunha-Castelle Didier García José Agustín 《Theoretical and Applied Climatology》2018,133(1-2):605-617
Theoretical and Applied Climatology - Heat wave (HW) events are becoming more frequent, and they have important consequences because of the negative effects they can have not only on the human... 相似文献
4.
Andrade S. Daniel Almeida Stefanie Saltos Emilia Pacheco Daniel Hernandez Stephen Acero Wilson 《Landslides》2022,19(3):747-759
Debris flows are hazardous phenomena occurring at volcanoes, and monitoring them has proved as challenging as imperative in several cases. The use of seismic instruments to measure and study the physical properties of debris flows has witnessed significant progress in the last years, with the use of improved sensors, innovative methodologies and high-resolution analysis. However, the application of such studies to the practical task of providing early warnings remains limited by the significant amount of infrastructural and technological resources commonly required for their deployment. In Ecuador, debris flows at volcanoes are detected by means of seismic instruments which are usually part of broader monitoring networks, thus requiring calibration to provide quantitative information about the flows and feed early-warning systems. In the present work, a theoretical approach based on the Buckingham Π-theorem is used to determine an expression that linearly correlates the seismic signal produced by a transiting debris flow with its discharge rate, for instruments installed in different substrata and at variable distances from the drainage. The expression is experimentally tested with Acoustic Flow Monitors and Broad-band seismometers installed in the vicinity of drainages at Tungurahua and Cotopaxi volcanoes, where actual debris flows occurred in relation to eruptive activity. The experiments consist in comparing the measured peak amplitude values of the seismic signal envelopes with the estimated peak discharge rates of several events. The results confirm the validity of the theoretical expression with linear correlations observed between the seismic amplitudes and the discharge rates, thus defining calibration expressions that can be generally applied to varied environments and instruments. The seismic instruments calibrated through this methodology can provide instantaneous and reliable predictions of debris flow discharge rates within less than an order of magnitude and only requiring limited data processing and storage. Such level of prediction could help to improve early warning systems based on seismic instruments installed in locations where more developed instrumental arrays are unavailable or unpractical.
相似文献5.
Francisco Javier Acero María Cruz Gallego José Agustín García 《Theoretical and Applied Climatology》2012,108(3-4):411-423
In order to analyze the effects of the duration of precipitation events, trends in extreme rainfall over the Iberian Peninsula (IP) for multi-day extreme precipitation events (1 to 7?days) were evaluated from records of 52 observatories regularly distributed over Iberia with no missing data for the common period 1958–2004. Two approaches were used: first, the nonparametric Mann–Kendall test together with the Sen method, and second, a parametric test based on the statistical theory of extreme values, involving time-dependent parameters to account for possible temporal changes in the frequency distribution. It was found that, in winter, there were significant negative trends for a great part of the Iberian Peninsula, but significant positive trends for the southeast over areas that shrank as the number of days considered for the precipitation event increased. Spring also showed negative trends for a great part of the IP but with a major area of positive trend over the northeast that remained unchanged when considering the maxima of from 1 to 7?days of rainfall. Autumn showed a bipolar spatial pattern, with the west being positive and the east negative. 相似文献
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Patricia Acero Luis F. Auqué María J. Gimeno Javier B. Gómez 《Environmental Earth Sciences》2010,59(8):1613-1628
In this study, the potential for mineral precipitation reactions to occur during the excavation, disposal, backfilling and
closure of a deep geological repository for the final disposal of spent nuclear fuel was evaluated with the assistance of
hydrogeochemical modelling. Four modelling exercises, corresponding to the main expectable geochemical scenarios in the Excavation
Damaged Zone (EDZ) throughout repository evolution, were carried out and the times for sealing of the discontinuities owing
to mineral precipitation in each of them were evaluated and discussed. The simulations show that mineral precipitation reactions
are thermodynamically feasible in most of the studied cases. The main mineral phases potentially responsible for the hydraulic
sealing of the EDZ are calcite and ferric oxyhydroxides, being the estimated volumes occupied by the precipitation of calcite
between one and three orders of magnitude larger than the volume of precipitating ferric phases. The estimated times for complete
sealing of the EDZ may vary between several hundreds to more than 1 million years. The shortest sealing times (less than 3,000 years)
are obtained for the mixture of groundwaters from the repository depth with dilute infiltration waters. 相似文献
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Patricia Acero Carlos Ayora Jesús Carrera Maarten W. Saaltink Sebastiá Olivella 《Applied Geochemistry》2009
Weathering processes affecting pyritic wastes may generate huge amounts of acid waters with high concentrations of potentially toxic contaminants (acid mine drainage). Acid mine drainage is mainly produced in the vadose zone. In the present study, a coupled non-isothermal multiphase flow and reactive transport model of the vadose zone of sulfide mine tailings was developed. The geochemical model included kinetically controlled reactions for Fe(II)-oxidation and for the dissolution of sulfide and aluminosilicate phases and the Pitzer ion-interaction model to describe the behavior of the pore-water solutions. Model results were compared with experimental observations in unsaturated column experiments under strongly evaporative conditions similar to arid or semiarid climates. Evolution trends for temperature, water saturation, evaporation rates, pore-water hydrochemistry and mineral phases observed during the drying experiment were adequately reproduced. The coupled model reproduced the increase of solute concentrations in the column top and the precipitation of a crust of secondary mineral phases. This crust became a barrier for water vapour diffusion to the atmosphere and modified the thermohydraulic behavior of the tailings. Enhanced downward migration of water vapour and its condensation in this colder end of the column were correctly taken into account by the model, which reproduced the dilution observed in the lower part of the column during the experiments. 相似文献
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Juan A. Acero Jon Arrizabalaga Sebastian Kupski Lutz Katzschner 《Theoretical and Applied Climatology》2013,113(1-2):137-154
This work examines the characteristics of the urban heat island (UHI) in a medium-sized city in northern Spain (Bilbao) using 5-year climate data (2005–2009) and the results of three specific measurement campaigns (2009–2010). Urban climate variables are not only compared with those in rural sites but also local climatic differences occurring inside the city are analysed. The findings presented in this paper show the influence of complex topography and sea/land breeze in the urban climate. Spatial characteristics and temporal evolution of UHI is presented. Hourly maximum temperature anomaly (ΔT u–r, max) occurs just after sunrise and an urban cold island (UCI) is developed after midday. Along the year, mean UHI intensity is highest in autumn and the UCI effect increases in spring and summer in relation with sea breeze cooling potential. Diurnal and seasonal variation of air flow patterns appear to influence significantly on UHI intensity. 相似文献
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Francisco Javier Acero Sylvie Parey Thi Thu Huong Hoang Didier Dacunha-Castelle José Agustín García María Cruz Gallego 《水文科学杂志》2017,62(9):1394-1411
Based on a previous study for temperature, a new method for the calculation of non-stationary return levels for extreme rainfall is described and applied to Extremadura, a region of southwestern Spain, using the peaks-over-threshold approach. Both all-days and rainy-days-only datasets were considered and the 20-year return levels expected in 2020 were estimated taking different trends into account: first, for all days, considering a time-dependent threshold and the trend in the scale parameter of the generalized Pareto distribution; and second, for rainy days only, considering how the mean, variance, and number of rainy days evolve. Generally, the changes in mean, variance and number of rainy days can explain the observed trends in extremes, and their extrapolation gives more robust estimations. The results point to a decrease of future return levels in 2020 for spring and winter, but an increase for autumn. 相似文献
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