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Iván Morales-Arredondo Ramiro Rodríguez Maria Aurora Armienta Ruth Esther Villanueva-Estrada 《Hydrogeology Journal》2016,24(4):1029-1044
A groundwater sampling campaign was carried out in the summer of 2013 in a low-temperature geothermal system located in Juventino Rosas (JR) municipality, Guanajuato State, Mexico. This groundwater presents high concentrations of As and F? and high Rn counts, mainly in wells with relatively higher temperature. The chemistry of major elements was interpreted with different methods, like Piper and D’Amore diagrams. These diagrams allowed for classification of four groundwater types located in three hydrogeological environments. The aquifers are hosted mainly in alluvial-lacustrine sediments and volcanic rocks in interaction with fault and fracture systems. The subsidence, faults and fractures observed in the study area can act as preferential channels for recharge and also for the transport of deep fluids to the surface, especially in the basin plain. The formation of a piezometric dome and the observed hydrochemical behavior of groundwater suggest a possible origin of the As and F?. Geochemical processes occurring during water–rock interaction are related to high concentrations of As and F?. High temperatures and alteration processes (like rock weathering) induce dissolution of As and F?-bearing minerals, increasing the content of these elements in groundwater. 相似文献
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Iván A. Reyes Ister Mireles Francisco Patiño Thangarasu Pandiyan Mizraim U. Flores Elia G. Palacios Emmanuel J. Gutiérrez Martín Reyes 《Geochemical transactions》2016,17(1):3
Background
The presence of natural and industrial jarosite type-compounds in the environment could have important implications in the mobility of potentially toxic elements such as lead, mercury, arsenic, chromium, among others. Understanding the dissolution reactions of jarosite-type compounds is notably important for an environmental assessment (for water and soil), since some of these elements could either return to the environment or work as temporary deposits of these species, thus would reduce their immediate environmental impact.Results
This work reports the effects of temperature, pH, particle diameter and Cr(VI) content on the initial dissolution rates of K-Cr(VI)-jarosites (KFe3[(SO4)2 ? X(CrO4)X](OH)6). Temperature (T) was the variable with the strongest effect, followed by pH in acid/alkaline medium (H3O+/OH?). It was found that the substitution of CrO4 2?in Y-site and the substitution of H3O+ in M-site do not modify the dissolution rates. The model that describes the dissolution process is the unreacted core kinetic model, with the chemical reaction on the unreacted core surface. The dissolution in acid medium was congruent, while in alkaline media was incongruent. In both reaction media, there is a release of K+, SO4 2? and CrO4 2? from the KFe3[(SO4)2 ? X(CrO4)X](OH)6 structure, although the latter is rapidly absorbed by the solid residues of Fe(OH)3 in alkaline medium dissolutions. The dissolution of KFe3[(SO4)2 ? X(CrO4)X](OH)6 exhibited good stability in a wide range of pH and T conditions corresponding to the calculated parameters of reaction order n, activation energy E A and dissolution rate constants for each kinetic stages of induction and progressive conversion.Conclusions
The kinetic analysis related to the reaction orders and calculated activation energies confirmed that extreme pH and T conditions are necessary to obtain considerably high dissolution rates. Extreme pH conditions (acidic or alkaline) cause the preferential release of K+, SO4 2? and CrO4 2? from the KFe3[(SO4)2 ? X(CrO4)X](OH)6 structure, although CrO4 2? is quickly adsorbed by Fe(OH)3 solid residues. The precipitation of phases such as KFe3[(SO4)2 ? X(CrO4)X](OH)6, and the absorption of Cr(VI) after dissolution can play an important role as retention mechanisms of Cr(VI) in nature.24.
Víctor Hugo Durán Zuazo José Ramón Francia Martínez Iván García Tejero Carmen Rocío Rodríguez Pleguezuelo Armando Martínez Raya Simón Cuadros Tavira 《水文科学杂志》2013,58(8):1610-1625
Abstract This study presents an analysis of three hydrological years (2007/08, 2008/09 and 2009/10) of precipitation, runoff and sediment yield collected from a small (669.7 ha) semi-arid watershed in southeastern Spain (Lanjarón). At the watershed outlet the runoff, suspended sediment concentration, total solute concentrations and dissolved nutrients (N-NO3, N-NH4, H2PO4 and K) in streamflow were continuously monitored. The runoff was highly variable, ranging between 53.4 and 154.7 mm year?1, with an average of 97.6 mm year?1. In contrast, sediment yields were more regular, averaging 1.8 Mg ha?1 year?1. The hydrological response of the watershed depended mainly on rainfall intensity. Formerly, 32% of the watershed was forested and runoff was more regular, despite the typical Mediterranean rainfall cycle; however, due to forest area reduction to 17% and the increase in abandoned farmland area (18%) in recent decades, the runoff variability has increased. Greater amounts of solutes (32.7 Mg ha?1 year?1) were exported, so that this water is considered as poor for irrigation use. The temporal nutrient export was related to seasonal discharge fluctuations as well as daily concentrations. In addition, the nutrient concentrations of the water discharged were lower than threshold limits cited in water-quality standards for agricultural use and for potable water, with the exception of K (65.9 mg L?1), which may degrade surface waters as well as irrigated soils. Thus, hydrological and erosive processes depended on the watershed features, but also on prior conditions in combination with the characteristics of rainfall episodes. Citation Durán, Z.V.H., Francia, M.J.R., Garcia, T.I., Rodríguez, P.C.R., Martínez, R.A., and Cuadros, T.S., 2012. Runoff and sediment yield from a small watershed in southeastern Spain (Lanjarón): implications for water quality. Hydrological Sciences Journal, 57 (8), 1610–1625. 相似文献
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After treatment of the anion exchanger resins from several manufacturers with FeCl3 or CuSO4 their capacity to take up thiocyanate ions increases by the factor 2 … 3. By regeneration with diluted sulphuric acid or hydrochloric acid after precipitation of the ferric or cupric hydroxide a thiocyanate solution of 10 and 15 g/l, respectively, is obtained, which can be reused. The hydroxides dissolved in acid are used for the treatment of the ion exchanger. The process is proposed for the regenerating of wastewaters containing thiocyanate. 相似文献
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Iv. M. Varentsov 《Surveys in Geophysics》1983,6(1-2):55-78
The main results obtained during the last 5–8 yr in the solution of forward and inverse problems of 3D induction studies are summarized. The up-to-date status of 3D modelling is presented and prospective improvements in the formulation and numerical solution of forward problems are discussed. Approximate techniques and practical aspects of 3D modelling are specially considered. The general scheme of 3D interpretation of electromagnetic geophysical observations is outlined and realistic formalized approaches to solving 3D inverse problems, namely direct inversion and formalized model fitting, are studied. 相似文献
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Móga JNOS Kiss KLAUDIA Szabó MRIA Kériné Borsodi ANDREA Kéri ANDRS Mari LSZLó Knáb MóNIKA Iván VERONIKA 《山地科学学报》2013,10(1):16-28
In order to study the karstological processes within the karst ecological system,the geohazards and degradation of karst landscapes on the karst areas of the Bakony mountains(Hungary),we investigated the abiotic elements of the environment,soil and cover deposits,erosion soil decay;the changes in the quantity and quality of karst waters:contamination at swallow holes,contamination of karst springs;and the biogenic factors:surface vegetation coverage by the corine land cover method,plant-ecological examinations,qualification of surface waters with the help of biological water labeling.We recognized that the increasing human activities during the past few centuries have had significant impact on the investigated landscapes of karst areas because of their spatial sensitivity.In the scope of our research we concluded that the landscape changes due to natural and human effects can vary strongly on the different karst areas.These differences can arise from the climatic and geomorphologic situation,the coverlayer’s qualities,etc.,but primarily from the different utilization of the investigated karst areas(e.g.the intensity,characteristics and territorial extension of utilization).On the spot investigation we detected traces of new and fast geomorphological processes(gully formation,landslides,collapses,new sinkhole development) and landforms(sinkholes,gullies,swallow holes),which are clear evidences of the effect of climatic changes. 相似文献
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This paper analyses measured data from two small tropical watersheds: one in a semiarid (Aiuaba, Brazil, 12·0 km2, 5 years of measurements) and another in a humid environment (Jaruco, Cuba, 43·5 km2, 21 years of measurements). The watersheds are similar with respect to catchment area (tens of km2), potential evaporation (2·1–2·6 m year?1), temperature (22–30 °C) and relief (mild hillslope steepness); but show considerable hydrological discrepancies: average precipitation in the humid watershed is two times higher; average river discharge (mm year?1) is five times higher; and surface water availability (mm year?1) is 14 times higher than in the semiarid watershed. Long‐term operation of hypothetical surface reservoirs in both basins is simulated. The analysis shows that 73% of the average river discharge are available (with 90% annual reliability) in the humid watershed, against only 28% in the semiarid. The main cause of this difference is the excess evaporation, which consumes 55% of the stored water in the semiarid reservoir, but only 12% in the humid one. The research concludes that: (1) although precipitation indicators are higher in the humid area, they are of the same order of magnitude as in the semiarid; and (2) fluvial‐regime and water‐availability variables are more than one order of magnitude higher in the humid basin, which shows a multiplication effect of these hydrological processes. Such major hydrological differences, despite the similarities between the two tropical watersheds, show the importance of further investigations in the field of comparative hydrology. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Claudia Robbi Sluter Corné P. J. M. van Elzakker Ivana Ivánová 《The Cartographic journal》2017,54(1):77-90
Geo-information solutions can achieve a higher level of quality if they are developed in accordance with a user-centred design that requires definition of the user requirements in the first step of solution construction. We treat a geo-information solution as a system designed to support human-based activities in a specific context through which solutions to contextual problems can be achieved via geographic knowledge. Geographic knowledge is a result of geo-data exploration, analysis, interpretation and dissemination with a given geo-information system. Taking the characteristics of geo-information systems into account, existing methods and techniques of requirements engineering may be applied for the design and implementation of geo-information solutions. Based on these considerations, here we present a generic framework that can aid geo-information experts, geo-informaticians and cartographers in the design and construction of more efficient, effective and satisfactory solutions. 相似文献