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Sample records for geochemical evolution perfil

  1. Geochemical Evolution of the Louisville Seamount Chain

    Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; Lonsdale, P. F.

    2007-12-01

    The Louisville seamount chain is a 4300 km long chain of submarine volcanoes in the southwestern Pacific that is commonly thought to represent a hotspot track. It spans an ~80 Myr age range, comparable to that of the Hawaiian-Emperor chain (Koppers et al., G-cubed, 5 (6), 2004). The few previously dredged igneous samples are dominantly basaltic and alkalic, and have been inferred to represent post-shield volcanism (Hawkins et al., AGU Monograph, 43, 235, 1987). Their isotope and trace element signatures suggest an unusually homogenous mantle source (Cheng et al., AGU Monograph, 43, 283, 1987). Dredging in 2006, during the AMAT02RR cruise of the R.V. Revelle, was carried out in the hope of recovering both shield and post-shield samples and of exploring the geochemical evolution of the chain. Igneous rocks were recovered from 33 stations on 23 seamounts covering some 47 Myr of the chain's history. Our study, focusing on the major and trace element and Sr, Nd and Pb isotopic characteristics of these samples, shows that all are alkalic basalts, basanites and tephrites containing normative nepheline. Variations in major and trace elements appear to be controlled predominantly by variable extents of melting and fractional crystallization, with little influence from mantle source heterogeneity. Indeed, age-corrected isotopic values define only a narrow range, in agreement with long-term source homogeneity relative to the scale of melting; e.g., ɛNd varies from +4.1 to +5.7, 206Pb/204Pb from 19.048 to 19.281, and 87Sr/86Sr from 0.70362 to 0.70398. These values broadly fall within the fields of the proposed "C" or "FOZO" mantle end-members. However, small variations are present, with less radiogenic Nd and Pb isotope ratios at the older, western end of the chain, defining a trend toward a broadly EM2-like composition. Although some workers have postulated that the Louisville hotspot was the source of the ~120 Myr Ontong Java Plateau, our samples are isotopically distinct

  2. Geochemical modelling of groundwater evolution using chemical equilibrium codes

    Pitkaenen, P.; Pirhonen, V.

    1991-01-01

    Geochemical equilibrium codes are a modern tool in studying interaction between groundwater and solid phases. The most common used programs and application subjects are shortly presented in this article. The main emphasis is laid on the approach method of using calculated results in evaluating groundwater evolution in hydrogeological system. At present in geochemical equilibrium modelling also kinetic as well as hydrologic constrains along a flow path are taken into consideration

  3. Adaptive Multiscale Modeling of Geochemical Impacts on Fracture Evolution

    Molins, S.; Trebotich, D.; Steefel, C. I.; Deng, H.

    2016-12-01

    Understanding fracture evolution is essential for many subsurface energy applications, including subsurface storage, shale gas production, fracking, CO2 sequestration, and geothermal energy extraction. Geochemical processes in particular play a significant role in the evolution of fractures through dissolution-driven widening, fines migration, and/or fracture sealing due to precipitation. One obstacle to understanding and exploiting geochemical fracture evolution is that it is a multiscale process. However, current geochemical modeling of fractures cannot capture this multi-scale nature of geochemical and mechanical impacts on fracture evolution, and is limited to either a continuum or pore-scale representation. Conventional continuum-scale models treat fractures as preferential flow paths, with their permeability evolving as a function (often, a cubic law) of the fracture aperture. This approach has the limitation that it oversimplifies flow within the fracture in its omission of pore scale effects while also assuming well-mixed conditions. More recently, pore-scale models along with advanced characterization techniques have allowed for accurate simulations of flow and reactive transport within the pore space (Molins et al., 2014, 2015). However, these models, even with high performance computing, are currently limited in their ability to treat tractable domain sizes (Steefel et al., 2013). Thus, there is a critical need to develop an adaptive modeling capability that can account for separate properties and processes, emergent and otherwise, in the fracture and the rock matrix at different spatial scales. Here we present an adaptive modeling capability that treats geochemical impacts on fracture evolution within a single multiscale framework. Model development makes use of the high performance simulation capability, Chombo-Crunch, leveraged by high resolution characterization and experiments. The modeling framework is based on the adaptive capability in Chombo

  4. Evolution of geochemical conditions in SFL 3-5

    Karlsson, Fred; Lindgren, M.; Skagius, K.; Wiborgh, M.; Engkvist, I.

    1999-12-01

    The evolution of geochemical conditions in the repository for long-lived low- and intermediate-level waste, SFL 3-5, and in the vicinity of the repository are important when predicting the retention of radionuclides and the long-term stability of engineered barriers. In this study the initial conditions at different repository sites at 300 - 400 m depth, the influence of repository construction and operation, the expected conditions after repository closure and saturation, and the evolution in a long-term perspective are discussed. Groundwaters that are found at these depths have near-neutral pH and are reducing in character, but the composition can vary from saline to non-saline water. The water chemistry in the near-field will mainly be influenced by the composition of the groundwater and by the large amounts of cementitious material that can be found in the repository. Disturbances caused during construction and operation are not expected to be permanent. Studies of old concrete indicate that leaching of concrete is a slow process. The geochemical conditions in the repository are therefore expected to be stable and prevail for hundreds of thousand years. However, the evolution of the surrounding environment may influence the conditions in long-term perspective

  5. Evolution of geochemical conditions in SFL 3-5

    Karlsson, Fred [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Lindgren, M.; Skagius, K.; Wiborgh, M. [Kemakta Konsult AB, Stockholm (Sweden); Engkvist, I. [Barsebaeck Kraft AB (Sweden)

    1999-12-01

    The evolution of geochemical conditions in the repository for long-lived low- and intermediate-level waste, SFL 3-5, and in the vicinity of the repository are important when predicting the retention of radionuclides and the long-term stability of engineered barriers. In this study the initial conditions at different repository sites at 300 - 400 m depth, the influence of repository construction and operation, the expected conditions after repository closure and saturation, and the evolution in a long-term perspective are discussed. Groundwaters that are found at these depths have near-neutral pH and are reducing in character, but the composition can vary from saline to non-saline water. The water chemistry in the near-field will mainly be influenced by the composition of the groundwater and by the large amounts of cementitious material that can be found in the repository. Disturbances caused during construction and operation are not expected to be permanent. Studies of old concrete indicate that leaching of concrete is a slow process. The geochemical conditions in the repository are therefore expected to be stable and prevail for hundreds of thousand years. However, the evolution of the surrounding environment may influence the conditions in long-term perspective.

  6. Geochemical evolution of the L/ILW near-field

    Kosakowski, G.; Berner, U.; Wieland, E.; Glaus, M.; Degueldre, C.

    2014-10-01

    The deep geological repository for low- and intermediate-level radioactive waste (L/ILW) contains large amounts of cement based materials used for waste conditioning, tunnel support and the backfill of cavities. The waste inventory is composed of a wide range of organic and inorganic materials. This study describes the spatial and temporal geochemical evolution of the cementitious near-field, and the interactions with the technical barriers and the surrounding host rock. This evolution is governed by several coupled processes, an important one being the development of saturation by groundwater ingress from the host rock. Saturation of the near-field is controlled by the inflow of water from the host rock, by the transport of dissolved gases from the near-field into the host rock and in the engineered gas transport system, and by the transport of humidity in the gas phase. The production of gas by anoxic corrosion of metals and by microbial degradation of organic wastes consumes water. The mineral reactions which give rise to concrete degradation, such as carbonation or alkali-silica-aggregate reactions may also consume or produce water. The first phase of cementitious near-field degradation, which persists only for a short period of time, is related to the hydration of cement minerals. The pore water has a pH of 13 or even higher because of the high content of dissolved alkali hydroxides. A constant pH of 12.5 determines the second phase of the cement degradation. The alkali concentration is reduced by mineral reactions and/or solute transport. This phase persists for a long time. In the third phase the portlandite is completely dissolved due to the reaction with silicates/aluminates present in the near-field and carbonate in the groundwater of the host rock or associated with reactive waste materials. The pore water is in equilibrium with calcium-silicate-hydrates (C-S-H) which gives rise to a pH value near 11 or lower. The Ca/Si ratio of C-S-H changes towards

  7. Geochemical evolution of the L/ILW near-field

    Kosakowski, G.; Berner, U.; Wieland, E.; Glaus, M.; Degueldre, C.

    2014-10-15

    The deep geological repository for low- and intermediate-level radioactive waste (L/ILW) contains large amounts of cement based materials used for waste conditioning, tunnel support and the backfill of cavities. The waste inventory is composed of a wide range of organic and inorganic materials. This study describes the spatial and temporal geochemical evolution of the cementitious near-field, and the interactions with the technical barriers and the surrounding host rock. This evolution is governed by several coupled processes, an important one being the development of saturation by groundwater ingress from the host rock. Saturation of the near-field is controlled by the inflow of water from the host rock, by the transport of dissolved gases from the near-field into the host rock and in the engineered gas transport system, and by the transport of humidity in the gas phase. The production of gas by anoxic corrosion of metals and by microbial degradation of organic wastes consumes water. The mineral reactions which give rise to concrete degradation, such as carbonation or alkali-silica-aggregate reactions may also consume or produce water. The first phase of cementitious near-field degradation, which persists only for a short period of time, is related to the hydration of cement minerals. The pore water has a pH of 13 or even higher because of the high content of dissolved alkali hydroxides. A constant pH of 12.5 determines the second phase of the cement degradation. The alkali concentration is reduced by mineral reactions and/or solute transport. This phase persists for a long time. In the third phase the portlandite is completely dissolved due to the reaction with silicates/aluminates present in the near-field and carbonate in the groundwater of the host rock or associated with reactive waste materials. The pore water is in equilibrium with calcium-silicate-hydrates (C-S-H) which gives rise to a pH value near 11 or lower. The Ca/Si ratio of C-S-H changes towards

  8. Geochemical evolution of the near field of a KBS-3 repository

    Arcos, David; Grandia, Fidel; Domenech, Cristina

    2006-09-01

    The Swedish concept developed by SKB for deep radioactive waste disposal, envisages an engineered multi-barrier system surrounding the nuclear waste (near field). In the present study we developed a numerical model to assess the geochemical evolution of the near field in the frame of the SKB's safety assessment SR-Can. These numerical models allow us to predict the long-term geochemical evolution of the near field system by means of reactive-transport codes and the information gathered in underground laboratory experiments and natural analogues. Two different scenarios have been defined to model this near field evolution, according to the pathway used by groundwater to contact the near field: a) through a fracture in the host rock intersecting the deposition hole; and b) through the material used to backfill the deposition tunnel. Moreover, we also modelled the effect of different groundwater compositions reaching the near field, as the up-rise of deep-seated brines and the intrusion of ice-melting derived groundwater. We also modelled the effect of the thermal stage due to the heat generated by spent fuel on the geochemical evolution of the bentonite barrier

  9. Geochemical evolution of the near field of a KBS-3 repository

    Arcos, David; Grandia, Fidel; Domenech, Cristina [Enviros Spain S.L., Barcelona (Spain)

    2006-09-15

    The Swedish concept developed by SKB for deep radioactive waste disposal, envisages an engineered multi-barrier system surrounding the nuclear waste (near field). In the present study we developed a numerical model to assess the geochemical evolution of the near field in the frame of the SKB's safety assessment SR-Can. These numerical models allow us to predict the long-term geochemical evolution of the near field system by means of reactive-transport codes and the information gathered in underground laboratory experiments and natural analogues. Two different scenarios have been defined to model this near field evolution, according to the pathway used by groundwater to contact the near field: a) through a fracture in the host rock intersecting the deposition hole; and b) through the material used to backfill the deposition tunnel. Moreover, we also modelled the effect of different groundwater compositions reaching the near field, as the up-rise of deep-seated brines and the intrusion of ice-melting derived groundwater. We also modelled the effect of the thermal stage due to the heat generated by spent fuel on the geochemical evolution of the bentonite barrier.

  10. Geochemical investigation of groundwater in the Tono area, Japan. Chemical characteristics and groundwater evolution

    Iwatsuki, Teruki; Hama, Katsuhiro; Yoshida, Hidekazu

    1997-01-01

    Geochemical investigations form an important part of the R and D program at the Tono study site, central Japan. Detailed geological structure and groundwater chemistry have been studied to understand the geochemical environment in the sedimentary and crystalline rocks distributed in this area. The chemical evolution of the groundwater in the sedimentary rocks is characterized with the variation in Na + , Ca 2+ and HCO 3 - concentrations, and ion exchange and dissolution of calcite are dominant reactions in the evolution of groundwater. Geological investigation shows that a fracture system of crystalline rock can be classified into:intact zone, moderately fractured zone and intensely fractured zone, according to the frequency and the width of fractures and fractured zones. The groundwater in the intact and fractured zones of crystalline rock are characterized by Na + -Ca 2+ -HCO 3 - or Na + -HCO 3 - dominated water, and Na + -Ca 2+ -Fe 2+ -HCO 3 - dominated water. The chemical evolution of groundwater is, generally, controlled by water-rock interaction between plagioclase, iron minerals and groundwater. The groundwater at depth of G.L.-186m in the crystalline rock at the Tono area is characterized by the mixture between the oxidized surface water and the reduced groundwater. The investigation based on correlation between geological structures and groundwater chemistry can be applied to understand the geochemical environment in deep crystalline rock, and will support the development of a realistic hydrogeochemical model. (author)

  11. A Watched Ocean World Never Boils: Inspecting the Geochemical Impact on Ocean Worlds from Their Thermal Evolution

    Spiers, E. M.; Schmidt, B. E.

    2018-05-01

    I aim to acquire better understanding of coupled thermal evolution and geochemical fluxes of an ocean world through a box model. A box model divides the system into plainer elements with realistically-solvable, dynamic equations.

  12. Geochemical analysis of Minho Estuary sedimentary record and its contribution to palaeoenvironmental evolution

    Ivarez-Iglesias, P. A.

    2009-01-01

    Two sediment cores (∼30 m long) were retrieved at the mouth of the Minho Estuary to assess its palaeoenvironmental evolution for the last millennia. Samples were characterized by Energy-Dispersive X-Ray Fluorescence Spectrometry and Instrumental Neutron Activation Analysis, complemented by sedimentological analyses. Provenance of major and trace element contents (lithogenic or biogenic, continental or marine) is assessed. The influence of grain size effect on total element concentration is discussed. Most of the samples present a negative Eu anomaly. Sedimentological and geochemical parameters allow differentiating four geological units - fluvial, marine, estuarine and sand barrier - which reflects the temporal evolution of the Minho Estuary. (author)

  13. Groundwater recharge, circulation and geochemical evolution in the source region of the Blue Nile River, Ethiopia

    Kebede, Seifu; Travi, Yves; Alemayehu, Tamiru; Ayenew, Tenalem

    2005-01-01

    Geochemical and environmental isotope data were used to gain the first regional picture of groundwater recharge, circulation and its hydrochemical evolution in the upper Blue Nile River basin of Ethiopia. Q-mode statistical cluster analysis (HCA) was used to classify water into objective groups and to conduct inverse geochemical modeling among the groups. Two major structurally deformed regions with distinct groundwater circulation and evolution history were identified. These are the Lake Tana Graben (LTG) and the Yerer Tullu Wellel Volcanic Lineament Zone (YTVL). Silicate hydrolysis accompanied by CO 2 influx from deeper sources plays a major role in groundwater chemical evolution of the high TDS Na-HCO 3 type thermal groundwaters of these two regions. In the basaltic plateau outside these two zones, groundwater recharge takes place rapidly through fractured basalts, groundwater flow paths are short and they are characterized by low TDS and are Ca-Mg-HCO 3 type waters. Despite the high altitude (mean altitude ∼2500 masl) and the relatively low mean annual air temperature (18 deg. C) of the region compared to Sahelian Africa, there is no commensurate depletion in δ 18 O compositions of groundwaters of the Ethiopian Plateau. Generally the highland areas north and east of the basin are characterized by relatively depleted δ 18 O groundwaters. Altitudinal depletion of δ 18 O is 0.1%o/100 m. The meteoric waters of the Blue Nile River basin have higher d-excess compared to the meteoric waters of the Ethiopian Rift and that of its White Nile sister basin which emerges from the equatorial lakes region. The geochemically evolved groundwaters of the YTVL and LTG are relatively isotopically depleted when compared to the present day meteoric waters reflecting recharge under colder climate and their high altitude

  14. Groundwater recharge, circulation and geochemical evolution in the source region of the Blue Nile River, Ethiopia

    Kebede, Seifu [Laboratory of Hydrogeology, University of Avignon, 33 Rue Louis Pasteur, 84000 Avignon (France) and Department of Geology and Geophysics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia)]. E-mail: seifu.kebede@univ-avignon.fr; Travi, Yves [Laboratory of Hydrogeology, University of Avignon, 33 Rue Louis Pasteur, 84000 Avignon (France); Alemayehu, Tamiru [Department of Geology and Geophysics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia); Ayenew, Tenalem [Department of Geology and Geophysics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia)

    2005-09-15

    Geochemical and environmental isotope data were used to gain the first regional picture of groundwater recharge, circulation and its hydrochemical evolution in the upper Blue Nile River basin of Ethiopia. Q-mode statistical cluster analysis (HCA) was used to classify water into objective groups and to conduct inverse geochemical modeling among the groups. Two major structurally deformed regions with distinct groundwater circulation and evolution history were identified. These are the Lake Tana Graben (LTG) and the Yerer Tullu Wellel Volcanic Lineament Zone (YTVL). Silicate hydrolysis accompanied by CO{sub 2} influx from deeper sources plays a major role in groundwater chemical evolution of the high TDS Na-HCO {sub 3} type thermal groundwaters of these two regions. In the basaltic plateau outside these two zones, groundwater recharge takes place rapidly through fractured basalts, groundwater flow paths are short and they are characterized by low TDS and are Ca-Mg-HCO {sub 3} type waters. Despite the high altitude (mean altitude {approx}2500 masl) and the relatively low mean annual air temperature (18 deg. C) of the region compared to Sahelian Africa, there is no commensurate depletion in {delta} {sup 18}O compositions of groundwaters of the Ethiopian Plateau. Generally the highland areas north and east of the basin are characterized by relatively depleted {delta} {sup 18}O groundwaters. Altitudinal depletion of {delta} {sup 18}O is 0.1%o/100 m. The meteoric waters of the Blue Nile River basin have higher d-excess compared to the meteoric waters of the Ethiopian Rift and that of its White Nile sister basin which emerges from the equatorial lakes region. The geochemically evolved groundwaters of the YTVL and LTG are relatively isotopically depleted when compared to the present day meteoric waters reflecting recharge under colder climate and their high altitude.

  15. Paleoclimates and geomorphological evolution of the Carajas region: geochemical and geochronological evidence

    Vasconcelos, P.M.

    1996-01-01

    Based on the geochronological results, on the petrographical and geochemical observations and considering the experimental evidences that suggests a great influence of the organic processes in the Manganese geochemistry it's possible to conclude that the dissolution and reprecipitation events of the Manganese oxides in the Carajas region, Para State, Brazil, represents humid and hot periods in the geological history of the region. The weathering dating furnishes information about the continental evolution in the Mesozoic/Cenozoic, difficult or impossible to determine by another methods

  16. Geochemical evolution of highly alkaline and saline tank waste plumes during seepage through vadose zone sediments

    Wan, Jiamin; Tokunaga, Tetsu K.; Larsen, Joern T.; Serne, R. JEFFREY

    2004-01-01

    Leakage of highly saline and alkaline radioactive waste from storage tanks into underlying sediments is a serious environmental problem at the Hanford Site in Washington State. This study focuses on geochemical evolution of tank waste plumes resulting from interactions between the waste solution and sediment. A synthetic tank waste solution was infused into unsaturated Hanford sediment columns (0.2, 0.6, and 2 m) maintained at 70C to simulate the field contamination process. Spatially and temporally resolved geochemical profiles of the waste plume were obtained. Thorough OH neutralization (from an initial pH 14 down to 6.3) was observed. Three broad zones of pore solutions were identified to categorize the dominant geochemical reactions: the silicate dissolution zone (pH > 10), pH-neutralized zone (pH 10 to 6.5), and displaced native sediment pore water (pH 6.5 to 8). Elevated concentrations of Si, Fe, and K in plume fluids and their depleted concentrations in plume sediments reflected dissolution of primary minerals within the silicate dissolution zone. The very high Na concentrations in the waste solution resulted in rapid and complete cation exchange, reflected in high concentrations of Ca and Mg at the plume front. The plume-sediment profiles also showed deposition of hydrated solids and carbonates. Fair correspondence was obtained between these results and analyses of field borehole samples from a waste plume at the Hanford Site. Results of this study provide a well-defined framework for understanding waste plumes in the more complex field setting and for understanding geochemical factors controlling transport of contaminant species carried in waste solutions that leaked from single-shell storage tanks in the past

  17. Trace elements at the intersection of marine biological and geochemical evolution

    Robbins, Leslie J.; Lalonde, Stefan V.; Planavsky, Noah J.; Partin, Camille A.; Reinhard, Christopher T.; Kendall, Brian; Scott, Clinton T.; Hardisty, Dalton S.; Gill, Benjamin C.; Alessi, Daniel S.; Dupont, Christopher L.; Saito, Mak A.; Crowe, Sean A.; Poulton, Simon W.; Bekker, Andrey; Lyons, Timothy W.; Konhauser, Kurt O.

    2016-01-01

    Life requires a wide variety of bioessential trace elements to act as structural components and reactive centers in metalloenzymes. These requirements differ between organisms and have evolved over geological time, likely guided in some part by environmental conditions. Until recently, most of what was understood regarding trace element concentrations in the Precambrian oceans was inferred by extrapolation, geochemical modeling, and/or genomic studies. However, in the past decade, the increasing availability of trace element and isotopic data for sedimentary rocks of all ages has yielded new, and potentially more direct, insights into secular changes in seawater composition – and ultimately the evolution of the marine biosphere. Compiled records of many bioessential trace elements (including Ni, Mo, P, Zn, Co, Cr, Se, and I) provide new insight into how trace element abundance in Earth's ancient oceans may have been linked to biological evolution. Several of these trace elements display redox-sensitive behavior, while others are redox-sensitive but not bioessential (e.g., Cr, U). Their temporal trends in sedimentary archives provide useful constraints on changes in atmosphere-ocean redox conditions that are linked to biological evolution, for example, the activity of oxygen-producing, photosynthetic cyanobacteria. In this review, we summarize available Precambrian trace element proxy data, and discuss how temporal trends in the seawater concentrations of specific trace elements may be linked to the evolution of both simple and complex life. We also examine several biologically relevant and/or redox-sensitive trace elements that have yet to be fully examined in the sedimentary rock record (e.g., Cu, Cd, W) and suggest several directions for future studies.

  18. Geochemical modelling of groundwater evolution and residence time at the Kivetty site

    Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy, Helsinki (Finland); Leino-Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

    1998-12-01

    An understanding of the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the final disposal of radioactive waste into the bedrock. The performance of technical barriers and migration of possibly released radionuclides depend on chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions which control chemical conditions in groundwater. The objective of this study is to interpret the processes and factors which control the hydrogeochemistry, such as pH and redox conditions. A model of the hydrogeochemical progress in different parts of the bedrock at Kivetty has been created and the significance of chemical reactions along different flowpaths calculated. Long term hydrodynamics have also been evaluated. The interpretation and modelling are based on groundwater samples (38 altogether) obtained from the soil layer, shallow wells in the bedrock, and five deep multi-packered boreholes (KRI-KR5) in the bedrock for which a comprehensive data set on dissolved chemical species and isotopes was available. Some analyses of dissolved gases and their isotopic measurements were also utilised. The data covers the bedrock at Kivetty to a depth of 850m. The results from groundwater chemistry, isotopes, petrography, hydrogeology of the site, geomicrobial studies, and PCA and speciation calculations were used in the evaluation of evolutionary processes at the site. The geochemical interpretation of water-rock interaction, isotope-chemical evolution and C-14 age calculations of groundwater was given a mass-balance approach (NETPATH). Reaction-path calculations (EQ3/6) were used to verify the thermodynamic feasibility of the reaction models obtained. The hydrogeochemistry of Kivetty is characterised by evolution from low-saline-carbonate-rich recharge water towards Na-Ca-Cl-type water. The salinity remains low. The most important changes in the chemistry of the

  19. Geochemical modelling of groundwater evolution and residence time at the Kivetty site

    Pitkaenen, P.; Luukkonen, A.; Ruotsalainen, P.; Leino-Forsman, H.; Vuorinen, U.

    1998-12-01

    An understanding of the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the final disposal of radioactive waste into the bedrock. The performance of technical barriers and migration of possibly released radionuclides depend on chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions which control chemical conditions in groundwater. The objective of this study is to interpret the processes and factors which control the hydrogeochemistry, such as pH and redox conditions. A model of the hydrogeochemical progress in different parts of the bedrock at Kivetty has been created and the significance of chemical reactions along different flowpaths calculated. Long term hydrodynamics have also been evaluated. The interpretation and modelling are based on groundwater samples (38 altogether) obtained from the soil layer, shallow wells in the bedrock, and five deep multi-packered boreholes (KRI-KR5) in the bedrock for which a comprehensive data set on dissolved chemical species and isotopes was available. Some analyses of dissolved gases and their isotopic measurements were also utilised. The data covers the bedrock at Kivetty to a depth of 850m. The results from groundwater chemistry, isotopes, petrography, hydrogeology of the site, geomicrobial studies, and PCA and speciation calculations were used in the evaluation of evolutionary processes at the site. The geochemical interpretation of water-rock interaction, isotope-chemical evolution and C-14 age calculations of groundwater was given a mass-balance approach (NETPATH). Reaction-path calculations (EQ3/6) were used to verify the thermodynamic feasibility of the reaction models obtained. The hydrogeochemistry of Kivetty is characterised by evolution from low-saline-carbonate-rich recharge water towards Na-Ca-Cl-type water. The salinity remains low. The most important changes in the chemistry of the

  20. Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

    DesMarais, David J.; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

  1. Geochemical modelling of groundwater evolution and residence time at the Haestholmen site

    Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy, Helsinki (Finland); Leino- Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

    2001-01-01

    An understanding of the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the geological final disposal of radioactive waste. The performance of technical barriers and migration of possibly released radionuclides depend on the geochemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions that control chemical conditions in groundwater. The objective of this study is to interpret the processes and factors that control the hydrogeochemistry, such as pH and redox conditions. A model of the hydrogeochemical progress in different parts of the crystalline bedrock at Haestholmen has been created and the significance of geochemical reactions and groundwater mixing along different flow paths calculated. Long term hydrodynamics have also been evaluated. The interpretation and modelling are based on water samples (64 altogether) obtained from precipitation, the Baltic Sea, the soil layer, shallow wells in the bedrock, and 14 deep boreholes in the bedrock for which a comprehensive data set on dissolved chemical species and isotopes was available. Some analyses of dissolved gases and their isotopic measurements were also utilised. The data covers the bedrock at Haestholmen to a depth of 1000 m. The results from groundwater chemistry, isotopes, petrography, hydrogeology of the site, geomicrobial studies, and PCA and speciation calculations were used to evaluate evolutionary processes at the site. The geochemical interpretation of water-rock interaction, isotope-chemical evolution ({delta}{sup 13}C and {delta}{sup 34}S) and mixing of palaeo-water types were approached by mass-balance calculations (NETPATH). Reaction-path calculations (EQ3/6) were used to verify the thermodynamic feasibility of the reaction models obtained. The interpretation and calculation of hydrochemical data from Haestholmen suggest that changes in external conditions, such as glaciation

  2. Geochemical evolution of groundwater in carbonate aquifers of southern Latium region, central Italy

    Giuseppe Sappa

    2013-03-01

    Full Text Available Spring and well water samples, from carbonate aquifers of Latium region, have been characterized to determine the hydrochemical processes governing the evolution of the groundwater. Most of the spring samples, issuing from Lepini, Ausoni and Aurunci Mts., are characterized as alkaline earth HCO3 waters, however, some samples show a composition of Cl--SO4 -- alkaline earth waters. Groundwater samples from Pontina Plain shows three different hydrochemical facies: alkaline earth HCO3 type, Cl-- SO4 -- alkaline earth type and Cl--SO4 -- alkaline type waters. Geochemical modeling and saturation index computation of the sampled waters show an interaction with calcareous and calcareous-dolomitic lithologies. Most of the springs and wells was kinetically saturated with respect to calcite and dolomite, and all the samples were below the equilibrium state with gypsum. This indicates that the groundwater has capacity to dissolve the gypsum along the flow paths. The electrical conductivity and Cl- concentrations of the sampled waters show a positive trend with the decrease in the distance from the coast, highlighting seawater intrusion in the coastal area. According to hydrochemistry results and geochemical modeling, the dominant factors in controlling the hydrochemical characteristics of groundwater are: (i water rock interaction with calcareous and calcareous-dolomitic lithologies; (ii seawater intrusion in the coastal area; (iii dissolution and/or precipitation of carbonate and (i.e. dolomite and calcite evaporate minerals (gypsum determined by saturation indexes; (iv mineral weathering process; (the high Mg/Ca ratio due to the weathering of Mg-rich dolomite.

  3. Vertical evolution of petrographic and organic geochemical parameters in Las Duenas mire (Cantabrian Coast, North Spain)

    Lopez-Dias, V.; Borrego, A.G.; Blanco, C.G. [Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

    2010-12-01

    Las Duenas mire has developed on a flat siliceous substrate over the Holocene. The sedimentary cover has a thickness of around 50 cm and the mire comprises a surface area of 27 ha. A core sample obtained using a manual probe was split into sub-samples of around 3-4 cm thickness for petrographic and organic geochemical analysis. The fen originated by minerogenesis and contains a high concentration of mineral matter throughout its profile which decreases towards the top. The present day vegetation is dominated by Sphagnum. A variety of transparent textinite with intense fluorescence is evidence of the low maturity of the profile, which is also confirmed by the presence of low reflecting huminite of the A variety (Hr {proportional_to} 0.15%). The fluorescence spectra of sporinite and cutinite are similar and, compared with those of transparent textinite, they have a lower intensity and are shifted to higher wavelengths. The low maturity of the organic matter is also confirmed by the presence of unstable {beta}{beta} hopane configurations, the abundance of hopene, and the presence of functionalized hopanoids, steroids and other triterpenoids. The evolution of the geochemical parameters in the peat profile indicates the presence of more humid conditions in the top 4 cm and at a depth of 11-15 cm. These periods are characterized by a high Sphagnum/higher plant contribution as deduced from the n-alkane ratios. The low reflectance of huminite at the depth of 11-15 cm could also support less oxidizing condition. The sediment at a depth of 22 cm where peaty matter starts to accumulate has been dated as 9603 cal BC, whereas the plant fraction at the same depth dates back to a maximum of 200 years. Sediment reworking derived from radiocarbon dates indicates that this fen is not suitable for palaeoenvironmental studies. (author)

  4. Lead Isotopes in Olivine-Phyric Shergottite Tissint: Implications for the Geochemical Evolution of the Shergottite Source Mantle

    Moriwaki, R.; Usui, T.; Simon, J. I.; Jones, J. H.; Yokoyama, T.

    2015-01-01

    Geochemically-depleted shergottites are basaltic rocks derived from a martian mantle source reservoir. Geochemical evolution of the martian mantle has been investigated mainly based on the Rb-Sr, Sm-Nd, and Lu-Hf isotope systematics of the shergottites [1]. Although potentially informative, U-Th- Pb isotope systematics have been limited because of difficulties in interpreting the analyses of depleted meteorite samples that are more susceptible to the effects of near-surface processes and terrestrial contamination. This study conducts a 5-step sequential acid leaching experiment of the first witnessed fall of the geochemically-depleted olivinephyric shergottite Tissint to minimize the effect of low temperature distrubence. Trace element analyses of the Tissint acid residue (mostly pyroxene) indicate that Pb isotope compositions of the residue do not contain either a martian surface or terrestrial component, but represent the Tissint magma source [2]. The residue has relatively unradiogenic initial Pb isotopic compositions (e.g., 206Pb/204Pb = 10.8136) that fall within the Pb isotope space of other geochemically-depleted shergottites. An initial µ-value (238U/204Pb = 1.5) of Tissint at the time of crystallization (472 Ma [3]) is similar to a time-integrated mu- value (1.72 at 472 Ma) of the Tissint source mantle calculated based on the two-stage mantle evolution model [1]. On the other hand, the other geochemically-depleted shergottites (e.g., QUE 94201 [4]) have initial µ-values of their parental magmas distinctly lower than those of their modeled source mantle. These results suggest that only Tissint potentially reflects the geochemical signature of the shergottite mantle source that originated from cumulates of the martian magma ocean

  5. Geochemical evolution of groundwater in the Western Delta region of River Godavari, Andhra Pradesh, India

    Nageswara Rao, P. V.; Appa Rao, S.; Subba Rao, N.

    2017-05-01

    The present study on geochemical evolution of groundwater is taken up to assess the controlling processes of water chemistry in the Western Delta region of the River Godavari (Andhra Pradesh), which is one of the major rice-producing centers in India. The study region is underlain by coarse sand with black clay (buried channels), black silty clay of recent origin (floodplain) and gray/white fine sand of modern beach sediment of marine source (coastal zone), including brown silty clay with fine sand (paleo-beach ridges). Groundwater is mostly brackish and very hard. It is characterized by Na+ > Mg2+ > Ca2+:HCO3 - > Cl- > SO4 2- > NO3 -, Na+ > Mg2+ > Ca2+:Cl- > HCO3 - > SO4 2-, and Mg2+ > Na+ > Ca2+ > or Cl- > or > SO4 2- facies. The ionic relations (Ca2+ + Mg2+:HCO3 -, Ca2+ + Mg2+:SO4 2- + HCO3 -, Na+ + K+:TC, Na+ + K+:Cl- + SO4 2-, HCO3 -:TC, HCO3 -:Ca2+ + Mg2+, Na+:Cl- and Na+:Ca2+) indicate that the rock weathering, mineral dissolution, evaporation and ion exchange are the processes to control the aquifer chemistry. Anthropogenic and marine sources are also the supplementary factors for brackish water quality. These observations are further supported by Gibbs mechanisms that control the water chemistry. Thus, the study suggests that the initial quality of groundwater of geogenic origin has been subsequently modified by the influences of anthropogenic and marine sources.

  6. The Role of Geochemical Modeling in Predicting Quality Evolution of Acid Mine Drainage

    Andrea Šlesárová

    2004-12-01

    Full Text Available In recent years the massive reduction of raw materials production brings a wide scale of problems. Among the most frequent exposes of mining activities belong besides old spoil heaps and sludge lagoons, also the drainage of acidic and highly mineralized mine waters known as “the Acid Mine Drainage” (thereinafter AMD from old mine workings. The acid mine drainage presents to the surrounding environment a massive problem. These waters are toxic to the plant and animal life, including fishes and aquatic insects. The primary control of the drainage pH and the metal content is the exposure of sulphide minerals to weathering, the availability of atmospheric oxygen, and the sensitivity of non-sulphide minerals to buffer acidity. A geochemical modeling software is increasingly used to solve evolution of the complex chemical systems such as the interaction of acid mine drainage with wall rocks, migration of AMD components. Beyond the better computer facilities it allows to study of thermodynamic properties substances and to enlarge thermodynamic databases. A model is a simplified version of reality based on its observation and experiments. A goal of the modeling process is the tendency to better understand processes taking place inside of the system, the attempt to assume the system’s behaviour in the future or to predict the effect of changed conditions in the system’s environment on the system itself.

  7. Petro-geochemical constraints on the source and evolution of magmas at El Misti volcano (Peru)

    Rivera, Marco; Martin, Hervé; Le Pennec, Jean-Luc; Thouret, Jean-Claude; Gourgaud, Alain; Gerbe, Marie-Christine

    2017-01-01

    El Misti volcano, a large and hazardous edifice of the Andean Central Volcanic Zone (CVZ) of southern Peru, consists of four main growth stages. Misti 1 (> 112 ka) is an old stratovolcano partly concealed by two younger stratocones (Misti 2, 112-40 ka; Misti 3, 38-11 ka), capped in turn by a recent summit cone (Misti 4, Peru. Geochemical evidence indicates that magmatic evolution is mostly controlled by Assimilation-Fractional Crystallisation (AFC) mechanisms. Modelling reveals a mass-assimilated/mass-fractionated ratio (ρ) ≤ 2.2, which suggests an assimilated crust fraction below 14 wt.% on average. Our isotopic data clearly identify the Proterozoic "Charcani gneiss" basement as the main contaminant. Both contamination and assimilation processes peaked at 30 wt.%, during the Misti 3 stage when rhyolites were generated. We ascribe the general depletion in HREE and Y and elevated La/Yb and Sr/Y ratios in El Misti samples to the enrichment of the mantle wedge source of the parental magmas by a felsic melt of adakitic composition and hydrous fluids. Our work highlights that El Misti's magmatic system has remained relatively homogeneous since at least 0.12 Ma, with a marked influence of the contaminating crust in the Late Pleistocene Misti 3 stage, which resulted in highly explosive eruptions. Andesitic-dacitic compositions are dominant in the Holocene and historical Misti 4 stage, and are expected for future volcanic events at El Misti.

  8. Controls on the geochemical evolution of Prairie Pothole Region lakes and wetlands over decadal time scales

    Goldhaber, Martin B.; Mills, Christopher T.; Mushet, David M.; McCleskey, R. Blaine; Rover, Jennifer

    2016-01-01

    One hundred sixty-seven Prairie Pothole lakes, ponds and wetlands (largely lakes) previously analyzed chemically during the late 1960’s and early to mid-1970’s were resampled and reanalyzed in 2011–2012. The two sampling periods differed climatically. The earlier sampling took place during normal to slightly dry conditions, whereas the latter occurred during and immediately following exceptionally wet conditions. As reported previously in Mushet et al. (2015), the dominant effect was expansion of the area of these lakes and dilution of their major ions. However, within that context, there were significant differences in the evolutionary pathways of major ions. To establish these pathways, we employed the inverse modeling computer code NetpathXL. This code takes the initial and final lake composition and, using mass balance constrained by the composition of diluting waters, and input and output of phases, calculates plausible geochemical evolution pathways. Despite the fact that in most cases major ions decreased, a subset of the lakes had an increase in SO42−. This distinction is significant because SO42− is the dominant anion in a majority of Prairie Pothole Region wetlands and lakes. For lakes with decreasing SO42−, the proportion of original lake water required for mass balance was subordinate to rainwater and/or overland flow. In contrast, lakes with increasing SO42− between the two sampling episodes tended to be dominated by original lake water. This suite of lakes tended to be smaller and have lower initial SO42−concentrations such that inputs of sulfur from dissolution of the minerals gypsum or pyrite had a significant impact on the final sulfur concentration given the lower dilution factors. Thus, our study provides context for how Prairie Pothole Region water bodies evolve geochemically as climate changes. Because wetland geochemistry in turn controls the ecology of these water bodies, this research contributes to the prediction of the

  9. Geochemical modelling of groundwater evolution and residence time at the Olkiluoto site

    Pitkaenen, P.; Luukkonen, A.; Ruotsalainen, P.; Leino-Forsman, H.; Vuorinen, U.

    1999-05-01

    An understanding of the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the final disposal of radioactive waste into the bedrock. The performance of technical barriers and migration of possibly released radionuclides depend on chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions which control chemical conditions in groundwater. The objective of this study is to interpret the processes and factors which control the hydrogeochemistry, such as pH and redox conditions. A model of the hydrogeochemical progress in different parts of the crystalline bedrock at Olkiluoto has been created and the significance of chemical reactions and groundwater mixing along different flowpaths calculated. Long term hydrodynamics have also been evaluated. The interpretation and modelling are based on water samples (63 altogether) obtained from precipitation, Baltic Sea, soil layer, shallow wells in the bedrock, and eight deep boreholes in the bedrock for which a comprehensive data set on dissolved chemical species and isotopes was available. Some analyses of dissolved gases and fracture calcite and their isotopic measurements were also utilised. The data covers the bedrock at Olkiluoto to a depth of 1000 m. The results from groundwater chemistry, isotopes, petrography, hydrogeology of the site, geomicrobial studies, and PCA and speciation calculations were used in the evaluation of evolutionary processes at the site. The geochemical interpretation of water-rock interaction, isotope-chemical evolution and mixing of palaeo water types were approached by mass-balance calculations (NETPATH). Reaction-path calculations (EQ3/6) were used to verify the thermodynamic feasibility of the reaction models obtained. The interpretation and calculation of hydrochemical data from Olkiluoto reveals the complex nature of hydrogeochemical evolution at the site. Changes in

  10. Geochemical modelling of groundwater evolution and residence time at the Olkiluoto site

    Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy (Finland); Leino-Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

    1999-05-01

    An understanding of the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the final disposal of radioactive waste into the bedrock. The performance of technical barriers and migration of possibly released radionuclides depend on chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions which control chemical conditions in groundwater. The objective of this study is to interpret the processes and factors which control the hydrogeochemistry, such as pH and redox conditions. A model of the hydrogeochemical progress in different parts of the crystalline bedrock at Olkiluoto has been created and the significance of chemical reactions and groundwater mixing along different flowpaths calculated. Long term hydrodynamics have also been evaluated. The interpretation and modelling are based on water samples (63 altogether) obtained from precipitation, Baltic Sea, soil layer, shallow wells in the bedrock, and eight deep boreholes in the bedrock for which a comprehensive data set on dissolved chemical species and isotopes was available. Some analyses of dissolved gases and fracture calcite and their isotopic measurements were also utilised. The data covers the bedrock at Olkiluoto to a depth of 1000 m. The results from groundwater chemistry, isotopes, petrography, hydrogeology of the site, geomicrobial studies, and PCA and speciation calculations were used in the evaluation of evolutionary processes at the site. The geochemical interpretation of water-rock interaction, isotope-chemical evolution and mixing of palaeo water types were approached by mass-balance calculations (NETPATH). Reaction-path calculations (EQ3/6) were used to verify the thermodynamic feasibility of the reaction models obtained. The interpretation and calculation of hydrochemical data from Olkiluoto reveals the complex nature of hydrogeochemical evolution at the site. Changes in

  11. The chemical evolution of a travertine-depositing stream: Geochemical processes and mass transfer reactions

    Lorah, Michelle M.; Herman, Janet S.

    1988-01-01

    This field study focuses on quantitatively defining the chemical changes occurring in Falling Spring Creek, a travertine-depositing stream located in Alleghany County, Virginia. The processes of CO2outgassing and calcite precipitation or dissolution control the chemical evolution of the stream. The observed chemical composition of the water was used with the computerized geochemical model WATEQF to calculate aqueous speciation, saturation indices, and CO2 partial pressure values. Mass balance calculations were performed to obtain mass transfers of CO2 and calcite. Reaction times, estimated from stream discharge, were used with the mass transfer results to calculate rates of CO2, outgassing and calcite precipitation between consecutive sampling points. The stream, which is fed by a carbonate spring, is supersaturated with respect to CO2 along the entire 5.2-km flow path. Outgassing of CO2 drives the solution to high degrees of supersaturation with respect to calcite. Metabolic uptake of CO2 by photosynthetic plants is insignificant, because the high supply rate of dissolved carbon dioxide and the extreme agitation of the stream at waterfalls and rapids causes a much greater amount of inorganic CO2 outgassing to occur. Calcite precipitation is kinetically inhibited until near the crest of a 20-m vertical waterfall. Calcite precipitation rates then reach a maximum at the waterfall where greater water turbulence allows the most rapid escape of CO2. Physical evidence for calcite precipitation exists in the travertine deposits which are first observed immediately above the waterfall and extend for at least 1.0 km below the falls. Net calcite precipitation occurs at all times of the year but is greatest during low-flow conditions in the summer and early fall.

  12. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

  13. Arsenic release and geochemical evolution of groundwater in an alluvial aquitard, West Bengal, India.

    Desbarats, A. J.; Pal, T.; Mukherjee, P. K.; Beckie, R. D.

    2017-12-01

    According to the World Health Organization, contamination of groundwater by geogenic arsenic (As) represents the largest mass poisoning in history. At a field site in West Bengal, India, the source of As affecting a shallow aquifer was traced to silty sediments filling an abandoned river meander. Along with As-bearing phases, these sediments also contain 0.46 % organic carbon. The release of As within the channel fill is investigated using a geochemical mass balance model supported by detailed field observations of aqueous chemistry, sequential extraction analyses of sediment chemistry, and analyses of sediment mineralogy. The model explores the evolution of groundwater chemistry along a flow path extending from its recharge point in an abandoned channel pond, through the channel-fill sequence, to the underlying aquifer. Variations in groundwater composition within the host sediments are explained in terms of mineral weathering driven by organic carbon decay. The model yields reaction coefficients expressing amounts of minerals (and gases) reacting or precipitating along the flow path. Arsenic and phosphorus cycles appear closely linked as these species are hosted by goethite, Fe-rich chlorite, and vivianite. Arsenic is released through the rapid reductive dissolution of goethite and the slower weathering of chlorite. Concomitantly, some As is sequestered in precipitating vivianite. These competing processes reach equilibrium deeper in the channel-fill sequence as groundwater As concentrations stabilize. Using groundwater residence time in channel fill obtained from a numerical flow model and the calculated reaction coefficients, rates of organic carbon oxidation, goethite dissolution, and net As release are estimated at 1.15 mmol C L-1 a-1, 0.18 mmol L-1 a-1, and 4.57 10-4 mmol L-1 a-1, respectively. Fine-grained yet slightly permeable deposits such as channel-fill silts containing reactive organic carbon and As-bearing goethite and phyllosilicates are localized

  14. Factors controlling the geochemical evolution of fumarolic encrustations, Valley of Ten Thousand Smokes, Alaska

    Kodosky, L.G.; Keith, T.E.C.

    1993-01-01

    Factor and canonical correlation analysis of geochemical data from eight fossil fumaroles suggest that six major factors controlled the formation and evolution of fumarolic encrustations on the 1912 ash-flow sheet in the Valley of Ten Thousand Smokes (VTTS). The six-factor solution model explains a large proportion (low of 74% for Ni to high of 99% for Si) of the individual element data variance. Although the primary fumarolic deposits have been degraded by secondary alteration reactions and up to 75 years of weathering, the relict encrustations still preserve a signature of vapor-phase element transport. This vapor-phase transport probably occurred as halide or oxyhalide species and was significant for As, Sb and Br. At least three, and possibly four, varied temperature leaching events affected the fumarolic deposits. High-temperature gases/liquids heavily altered the ejecta glass and mineral phases adjacent to the fumarolic conduit. As the fumaroles cooled. Fe-rich acidic condensate leached the ejecta and primary fumarolic deposits and resulted in the subsequent precipitation of Fe-hydroxides and/or Fe-oxides. Low- to ambient-temperature leaching and hydration reactions generated abundant hydrated amorphous phases. Up to 87% of the individual element data variance is apparently controlled by the chemistry of the ejecta on which the relict encrustations are found. This matrix chemistry factor illustrates that the primary fumarolic minerals surrounding the active VTTS vents observed by earlier workers have been effectively removed by the dissolution reactions. Element enrichment factors calculated for the VTTS relict encrustations support the statistical factor interpretations. On the average, the relict encrustations are enriched, relative to visibly unaltered matrix protolith, in As, Br, Cr, Sb, Cu, Ni, Pb, Fe, and LOI (an indirect measure of sample H2O content). ?? 1993.

  15. La evolución del perfil docente en un dispositivo de autoformación The evolution of the teaching profile in a device of autoformation

    María Laura Valcarce

    2007-12-01

    Full Text Available La autoformación requiere la evolución del perfil docente a un rol de acompañante. El desplazamiento que ello implica y el abandono de roles ya establecidos generan resistencias tanto en el docente como en el alumno. El propósito de este artículo es relevar algunas de las características más salientes de este perfil en el marco de un aprendizaje autónomo en tanto su evolución constituye uno de los aspectos esenciales en el proceso de enseñanza y de aprendizaje que posibilita el desarrollo de la autonomía en el alumno. Por otra parte, se intentará dar cuenta, desde una perspectiva psicoanalítica, de la relación con el saber como una de las variables intervinientes en el proceso de cambio y que dificultan la evolución hacia un rol de acompañante.The autoformation requires the evolution of the teacher profile to a role of companion. The movement that it implies and the abandonment of roles already established generate resistances both in the teacher and in the student. The purpose of this article is to asses some of the outstanding features of this profile in the framework of an autonomous learning since its evolution constitutes one of the essential aspects in the process of teaching and learning that enable the development of the autonomy in the student. On the other hand, an attempt will be made to give an account, from a psychoanalytical perspective, of the relation with the knowledge as one of the variables involved in the process of change that complicate the evolution towards the role of companion.

  16. Evolution of hillslope soils: The geomorphic theater and the geochemical play

    Yoo, Kyungsoo; Weinman, Beth; Mudd, Simon Marius; Hurst, Martin; Attal, Mikael; Maher, Kate

    2011-01-01

    Highlights: → We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. → Over wide range of denudation rates, soil thicknesses do not vary significantly. → Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. → In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. → Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of ∼700 m to the plateau at an elevation of ∼1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil erosion rates. From

  17. Evolution of hillslope soils: The geomorphic theater and the geochemical play

    Yoo, Kyungsoo, E-mail: kyoo@umn.edu [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Weinman, Beth [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Mudd, Simon Marius; Hurst, Martin; Attal, Mikael [School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, Scotland (United Kingdom); Maher, Kate [Dept. of Geological and Environmental Sciences, Braun Hall 118, 450 Serra Mall, Bldg. 320, Stanford, CA 94305-2115 (United States)

    2011-06-15

    Highlights: > We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. > Over wide range of denudation rates, soil thicknesses do not vary significantly. > Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. > In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. > Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of {approx}700 m to the plateau at an elevation of {approx}1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil

  18. Aspects of geochemical evolution of the SKB near field in the frame of SR-Site

    Sena, Clara; Salas, Joaquin; Arcos, David

    2010-09-01

    The concept for the final disposal of high level nuclear waste (HLNW) developed by the Swedish Nuclear Waste Management Company (SKB) entails a multi-barrier system that surrounds the HLNW, which is also known as the near-field. In the near-field, the buffer is initially subject to a high thermal gradient induced by the heat generated by the radioactive decay of the HLNW. During this period, the buffer is also subject to a hydrodynamic pressure induced by the surrounding water saturated rock massif which progressively leads to the saturation of the buffer. After saturation and cooling of the near-field, the interaction of groundwater with the bentonite buffer may result in an evolving distribution of some aqueous species in the bentonite porewater, as well as the redistribution of accessory minerals and the cation exchanger composition in the montmorillonite interlayer. The distribution of aqueous and solid species in the buffer can affect, directly or indirectly, some of the relevant safety function indicators defined by. In this context, the work developed by Arcos et al is revisited in the present work and, based on new data from SKB, additional models are developed for the SR-Site Safety Assessment. The work presented here represents an update of the model conducted within the SR-Can exercise and, therefore, similar simulation cases are developed. Three aspects must be considered regarding the geochemical evolution of the near field: (1) the effect of the thermal period; (2) the processes during the saturation of bentonite; and, (3) the interaction of the water-saturated bentonite with the local groundwater. In this numerical exercise, two types of bentonite are analysed: the MX-80 and the Deponit CA-N. The effect of the thermal period and the water saturation are analysed in a series of one-dimensional radial-symmetric simulations performed using TOUGHREACT which is a reactive transport code that accounts for variably saturated multi-phase flow under non

  19. Aspects of geochemical evolution of the SKB near field in the frame of SR-Site

    Sena, Clara; Salas, Joaquin; Arcos, David (Amphos 21, Barcelona (Spain))

    2010-09-15

    The concept for the final disposal of high level nuclear waste (HLNW) developed by the Swedish Nuclear Waste Management Company (SKB) entails a multi-barrier system that surrounds the HLNW, which is also known as the near-field. In the near-field, the buffer is initially subject to a high thermal gradient induced by the heat generated by the radioactive decay of the HLNW. During this period, the buffer is also subject to a hydrodynamic pressure induced by the surrounding water saturated rock massif which progressively leads to the saturation of the buffer. After saturation and cooling of the near-field, the interaction of groundwater with the bentonite buffer may result in an evolving distribution of some aqueous species in the bentonite porewater, as well as the redistribution of accessory minerals and the cation exchanger composition in the montmorillonite interlayer. The distribution of aqueous and solid species in the buffer can affect, directly or indirectly, some of the relevant safety function indicators defined by. In this context, the work developed by Arcos et al is revisited in the present work and, based on new data from SKB, additional models are developed for the SR-Site Safety Assessment. The work presented here represents an update of the model conducted within the SR-Can exercise and, therefore, similar simulation cases are developed. Three aspects must be considered regarding the geochemical evolution of the near field: (1) the effect of the thermal period; (2) the processes during the saturation of bentonite; and, (3) the interaction of the water-saturated bentonite with the local groundwater. In this numerical exercise, two types of bentonite are analysed: the MX-80 and the Deponit CA-N. The effect of the thermal period and the water saturation are analysed in a series of one-dimensional radial-symmetric simulations performed using TOUGHREACT which is a reactive transport code that accounts for variably saturated multi-phase flow under non

  20. Geochemical evolution of Ngorongoro Caldera, Northern Tanzania: Implications for crust magma interaction

    Mollel, Godwin F.; Swisher, Carl C.; Feigenson, Mark D.; Carr, Michael J.

    2008-07-01

    Ngorongoro Caldera is the largest and best-preserved of nine Plio-Pleistocene volcanoes that make-up the Ngorongoro Volcanic Highlands (NVH) complex situated at the southern bifurcation of Gregory Rift, part of the East African Rift system of northern Tanzania. We report here, major and trace element abundances, Sr-Nd-Pb isotope analyses and 40Ar/ 39Ar laser incremental-heating and total fusion ages on lava and tephra sampled from stratigraphic sections exposed within the Ngorongoro Caldera. Major and trace elements measured on samples collected from the Ngorongoro Caldera wall indicate a stratified magma chamber whose silicic top and basaltic bottom was inverted by sequential eruptions. Samples from the lower part of the exposed Ngorongoro Caldera wall are high in silica, alkalis and HFSE (High Field Strength Elements). The Zr, Nb and Hf concentrations are highly correlated with each other and decrease up-section, indicative of the extent of magma evolution. Modeling of major, trace as well as Sr, Nd and Pb isotope data suggests that assimilation fractional crystallization processes were essential in producing the observed geochemical variations. The Sr and Nd isotope ratios from the Ngorongoro samples are widely dispersed ( 87Sr/ 86Sr = 0.70405 to 0.70801, 143Nd/ 144Nd = 0.512205 to 0.512623) and Pb isotope ratios are consistent with previous studies: 206Pb/ 204Pb = 18.73 to 19.37, 207Pb/ 204Pb = 15.64 to 15.69, 208Pb/ 204Pb = 39.52 to 39.55. Although Sr isotopic ratios are similar to Oceanic Island Basalt (OIB), the more radiogenic samples ( 87Sr/ 86Sr > 0.705) from the lower part of the section suggest crust-magma interaction; this is supported by Ce/Pb ratios (Ngorongoro Caldera wall section yield 40Ar/ 39Ar ages of 2.25 ± 0.02 Ma to 2.01 ± 0.02 Ma, constraining a duration of volcanism of the order of ~ 240 kyr. These ages suggest correlation of a normal to reverse geomagnetic polarity transition measured in the Ngorongoro Caldera wall section with the ~ 2

  1. On the dynamics and the geochemical mechanism of the evolution of the continental crust. 1

    Wetzel, K.

    1983-01-01

    An investigation of the isotopic composition of oxygen in the continental crust, in the oceans, in the oceanic crust and in the upper mantle shows the dynamics of plate tectonics and continental growthto be more or less constant during the last three or four aeons independent on the geochemical mechanism of continental growth. (author)

  2. Modeling coupled thermal, flow, transport and geochemical processes controlling near field long-term evolution

    Zhou, W.; Arthur, R.; Xu, T.; Pruess, K.

    2005-01-01

    precipitation/dissolution and solute transport. Preliminary results show that during the early heating phase, reactions strongly depend on the magnitude of the temperature gradient across the buffer. As the temperature gradient diminishes, reactions are increasingly dominated by groundwater solutes diffusing into the bentonite pore water from the host rock. Bentonite effective diffusion coefficient plays an important role to long-term solute transport. [1] Arthur, R., W. Zhou, and B. Stromberg, (2003), 'THC modeling of the non-isothermal phase of near-field evolution' in Proceedings of the 10. International High-Level Radioactive Waste Management Conference, March 30-April 2, 2003, Las Vegas, Nevada, USA. [2] Hoekmark, H. and B. Faelth, (2003), Thermal dimensioning of the deep repository, SKB TR-03- 09, Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden. [3] Bruno, J. D. Arcos, and L. Duro, (1999), Processes and features affecting the near field hydro-chemistry, SKB TR-99-29, Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden. [4] Xu, T., E. Sonnenthal, N. Spycher, and K. Pruess, (2003), TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive Geochemical Transport in Variably Saturated Geologic Media, LBNL-55460, Lawrence Berkeley National Laboratory, Berkeley, California, USA. (authors)

  3. Geochemical evolution of groundwater in the Mud Lake area, eastern Idaho, USA

    Rattray, Gordon W.

    2015-01-01

    Groundwater with elevated dissolved-solids concentrations—containing large concentrations of chloride, sodium, sulfate, and calcium—is present in the Mud Lake area of Eastern Idaho. The source of these solutes is unknown; however, an understanding of the geochemical sources and processes controlling their presence in groundwater in the Mud Lake area is needed to better understand the geochemical sources and processes controlling the water quality of groundwater at the Idaho National Laboratory. The geochemical sources and processes controlling the water quality of groundwater in the Mud Lake area were determined by investigating the geology, hydrology, land use, and groundwater geochemistry in the Mud Lake area, proposing sources for solutes, and testing the proposed sources through geochemical modeling with PHREEQC. Modeling indicated that sources of water to the eastern Snake River Plain aquifer were groundwater from the Beaverhead Mountains and the Camas Creek drainage basin; surface water from Medicine Lodge and Camas Creeks, Mud Lake, and irrigation water; and upward flow of geothermal water from beneath the aquifer. Mixing of groundwater with surface water or other groundwater occurred throughout the aquifer. Carbonate reactions, silicate weathering, and dissolution of evaporite minerals and fertilizer explain most of the changes in chemistry in the aquifer. Redox reactions, cation exchange, and evaporation were locally important. The source of large concentrations of chloride, sodium, sulfate, and calcium was evaporite deposits in the unsaturated zone associated with Pleistocene Lake Terreton. Large amounts of chloride, sodium, sulfate, and calcium are added to groundwater from irrigation water infiltrating through lake bed sediments containing evaporite deposits and the resultant dissolution of gypsum, halite, sylvite, and bischofite.

  4. Constraining Lateral Evolution of Magmatic Behavior in North Tanzania from Geophysical and Geochemical Analyses

    Gautier, S.; Tiberi, C.; Parat, F.; Baudouin, C.

    2016-12-01

    In the framework of CRAFTI and CoLiBrEA experiments in 2013, we proceeded to both seismic and geochemical studies along an EW profile through the North Tanzania Divergence. The data were collected along a line starting at the Ngorongoro volcanic area, ending at Kitumbeine edifice and crossing the rift valley. Recent seismological studies show lateral and depth variations for both velocity and Vp/Vs ratio within this area, particularly a change of Moho depth between the western and central parts of the rift. These two zones also exhibit diverse geochemical signatures that involve different magma storage (depth of reservoir, magma volume) and ascent as well as higher partial melts content for the western part. We take advantage of the recent and precise 3D lithospheric velocity models and receiver functions in this area to compare the structure and nature of Ngorongoro area and rift valley. We first compute ray path and establish regional coherency maps between piercing points, Vp/Vs ratio and tomographic images. Second, those results are compared with the composition of magma at depth obtained from a petrophysical and geochemical analysis of lava samples. We will discuss those results in terms of magmatic processes, and how they interact with the rifting in a cratonic lithosphere.

  5. Investigation of the geochemical evolution of groundwater under agricultural land: A case study in northeastern Mexico

    Ledesma-Ruiz, Rogelio; Pastén-Zapata, Ernesto; Parra, Roberto; Harter, Thomas; Mahlknecht, Jürgen

    2015-02-01

    Zona Citrícola is an important area for Mexico due to its citriculture activity. Situated in a sub-humid to humid climate adjacent to the Sierra Madre Oriental, this valley hosts an aquifer system that represents sequences of shales, marls, conglomerates, and alluvial deposits. Groundwater flows from mountainous recharge areas to the basin-fill deposits and provides base flows to supply drinking water to the adjacent metropolitan area of Monterrey. Recent studies examining the groundwater quality of the study area urge the mitigation of groundwater pollution. The objective of this study was to characterize the physical and chemical properties of the groundwater and to assess the processes controlling the groundwater's chemistry. Correlation was used to identify associations among various geochemical constituents. Factor analysis was applied to identify the water's chemical characteristics that were responsible for generating most of the variability within the dataset. Hierarchical cluster analysis was employed in combination with a post-hoc analysis of variance to partition the water samples into hydrochemical water groups: recharge waters (Ca-HCO3), transition zone waters (Ca-HCO3-SO4 to Ca-SO4-HCO3) and discharge waters (Ca-SO4). Inverse geochemical models of these groups were developed and constrained using PHREEQC to elucidate the chemical reactions controlling the water's chemistry between an initial (recharge) and final water. The primary reactions contributing to salinity were the following: (1) water-rock interactions, including the weathering of evaporitic rocks and dedolomitization; (2) dissolution of soil gas carbon dioxide; and (3) input from animal/human wastewater and manure in combination with by denitrification processes. Contributions from silicate weathering to salinity ranged from less important to insignificant. The findings suggest that it may not be cost-effective to regulate manure application to mitigate groundwater pollution.

  6. Modelling of long term geochemical evolution and study of mechanical perturbation of bentonite buffer of a KBS-3 repository

    Marsal, Francois; Pellegrini, Delphine; Deleruyelle, Frederic; Serres, Christophe (French Institute for Radiological Protection and Nuclear Safety (IRSN) (FR)); Windt, Laurent de (Paris School of Mines (ENSMP) (FR))

    2008-03-15

    The Swedish Nuclear Fuel and Waste Management Co. (SKB) has recently completed a safety assessment project named SR-Can, related to the KBS-3 disposal concept. In this concept, the waste packages are surrounded by a buffer made of either MX-80 or Deponit CA-N bentonite. Interactions between the buffer and groundwater may modify the buffer composition and thus its containment properties. The Swedish Radiation Protection Authorities (SSI) requested the French Institute for Radiological Protection and Nuclear Safety (IRSN) to perform the present study in support of SSI review of the SR-Can report. The purpose is to assess the geochemical evolution of both potential buffer materials due to the intrusion of different types of groundwater, with a similar modelling layout to that reported in SR-Can. Three main categories of water inflows via a fracture intersecting a deposition hole are considered: the Forsmark reference groundwater, a high-salinity groundwater to account for up-rise of deep-seated brines and a diluted water representing ice-melting derived groundwater. In addition to this, the redox buffering capacity of Deponit CA-N bentonite and the thermal effect on MX-80 bentonite geochemistry have been assessed. This modelling work has been performed using the reactive transport modelling code HYTEC. The main outcome of the present study is that the intrusion of the considered groundwaters should not affect drastically the geochemistry of neither the Deponit CA-N nor the MX-80 bentonite on the long-term (100,000 y). Bentonite pH may reach high values (up to 10.5) in some cases but does not reach SKB criterion value related to bentonite chemical stability. Dissolution-precipitation of accessory minerals is not significant enough to induce important porosity changes (rise by maximum 2 %). Globally, the montmorillonite exchanger undergoes Na by Ca partial replacement, which may decrease the swelling pressure of the bentonite. The simulated intrusion of oxidizing waters

  7. Modelling of long term geochemical evolution and study of mechanical perturbation of bentonite buffer of a KBS-3 repository

    Marsal, Francois; Pellegrini, Delphine; Deleruyelle, Frederic; Serres, Chris tophe; Windt, Laurent de

    2008-03-01

    The Swedish Nuclear Fuel and Waste Management Co. (SKB) has recently completed a safety assessment project named SR-Can, related to the KBS-3 disposal concept. In this concept, the waste packages are surrounded by a buffer made of either MX-80 or Deponit CA-N bentonite. Interactions between the buffer and groundwater may modify the buffer composition and thus its containment properties. The Swedish Radiation Protection Authorities (SSI) requested the French Institute for Radiological Protection and Nuclear Safety (IRSN) to perform the present study in support of SSI review of the SR-Can report. The purpose is to assess the geochemical evolution of both potential buffer materials due to the intrusion of different types of groundwater, with a similar modelling layout to that reported in SR-Can. Three main categories of water inflows via a fracture intersecting a deposition hole are considered: the Forsmark reference groundwater, a high-salinity groundwater to account for up-rise of deep-seated brines and a diluted water representing ice-melting derived groundwater. In addition to this, the redox buffering capacity of Deponit CA-N bentonite and the thermal effect on MX-80 bentonite geochemistry have been assessed. This modelling work has been performed using the reactive transport modelling code HYTEC. The main outcome of the present study is that the intrusion of the considered groundwaters should not affect drastically the geochemistry of neither the Deponit CA-N nor the MX-80 bentonite on the long-term (100,000 y). Bentonite pH may reach high values (up to 10.5) in some cases but does not reach SKB criterion value related to bentonite chemical stability. Dissolution-precipitation of accessory minerals is not significant enough to induce important porosity changes (rise by maximum 2 %). Globally, the montmorillonite exchanger undergoes Na by Ca partial replacement, which may decrease the swelling pressure of the bentonite. The simulated intrusion of oxidizing waters

  8. New chronological and geochemical constraints on the genesis and geological evolution of Ponza and Palmarola Volcanic Islands (Tyrrhenian Sea, Italy)

    Cadoux, Anita; Pinti, Daniele L.; Aznar, Cyril; Chiesa, Sergio; Gillot, Pierre-Yves

    2005-04-01

    . Palmarola volcanics represent a transitional magmatism: although a preserved collisional geochemical imprint, they show geochemical features approaching those of anorogenic lavas erupted in a within-plate context. The change of magmatism evidenced in this study can be related to the tectonic evolution of the area. Indeed, Hf, Ta and Rb contents suggest that the oldest Pliocene rhyolites of Ponza would emplace in a syn- to late-collisional setting, while the younger Pleistocene rhyolites of Palmarola would be emplaced in a post-collisional setting in which the orogenic character (Th/Ta) decreases and mantle influence (Nb/Ta) increases. Geochemical modeling strongly suggests that the Palmarola rhyolites represent the waning stages of a subduction-related magmatism. The K-Ar datings allow us to estimate precisely the transition of magmatism to last less than 1.3 Ma. The transitional magmas may be the result of the upwelling of asthenospheric mantle inducing melting of a metasomatized lithospheric mantle and the mixing between these two sources. This upwelling could occur during the extension of the Tyrrhenian basin, caused by the slab retreat and steepening, or during a process of slab break-off starting in the Pliocene.

  9. The evolution of the magmatic arc of Southern Peru (200-60 Ma), Arequipa area: insight from geochemical modeling

    Demouy, S.; Benoit, M.; De Saint Blanquat, M.; Brunet, P.

    2012-12-01

    Cordilleran-type batholiths are built by prolonged arc activity along continental margins and may provide detailed magmatic records of the subduction system evolution. The magmas produced in subduction context involve both mantellic and crustal end members and are subject to various petrological processes. The MASH zones (Hildreth and Moorbath, 1988), at the basis of the continental crust, are the best places for the genesis of such hybrid magmas. The various geochemical signatures observed in the plutonic rocks, may also be attributed to source heterogeneities or generated by subsequent petrological processes. This study has focused in the Arequipa section of the Coastal Batholith of Southern Peru (200-60 Ma), in an area extending over 80x40 km. Major and trace elements as well as Sr and Nd isotopic analyses were performed in a set of 100 samples ranging from gabbro to granite. The obtained data highlight the wide heterogeneity of the geochemical signatures that is not related to the classification of the rocks. In first step, Rb/Sr systematic was used to isolate a set of samples plotting along a Paleocene isochron and defining a cogenetic suite. This suite appears to have evolved by simple fractional crystallization. By using reverse modeling, the parameters controlling the fractional crystallization process were defined, as partition coefficients, initial concentrations and amount of fractional crystallization. The other magmatic suites display a wide range of isotopic and geochemical signatures. To explain this heterogeneity, a model involving competition between fractional crystallization and magma mixing into MASH zones was proposed. A large range of hybrid magma types is potentially generated during the maturation of the system, but this range tends to disappear as fractionation and mixing occurs. Finally the model predicts the genesis of a homogeneous reservoir created at depth, from which magmas may evolve only by fractional crystallization. Therefore

  10. Genesis and evolution of the fumaroles of vulcano (Aeolian Islands, Italy): a geochemical model

    Carapezza, M.; Nuccio, P. M.; Valenza, M.

    1981-09-01

    A geochemical model explaining the presence of fumaroles having different gas composition and temperature at the top of the crater and along the northeastern coast of Vulcano island is proposed. A pressurized biphase (liquid-vapor) reservoir at the depth of about 2 km is hypothesized. Energy and mass balance sheets control P-T conditions in the system. P-T must vary along a boiling curve of brine as liquid is present. The CO2 content in the steam is governed by the thermodynamic properties of the fluids in the H2-NaCl-CO2 system. On the assumption that oxygen fugacity in the system is between the HM-FMQ oxygen buffers, observed SO2/H2S, CO2/CO, CO/CH4 ratios in the fumarolic gases at the Fossa crater appear in equilibrium with a temperature higher than that observed, such as may exist at depth. The more reduced gas phases present on the sea-side may result from re-equilibrium processes in shallower aquifers. The suggested model would help in monitoring changes in volcanic activity by analyzing fumarolic gases.

  11. Hydro-geochemical and isotopic fluid evolution of the Los Azufres caldera geothermal field, Central Mexico

    Gonzalez-Partida, E [Centro de Geociencias, Campus Juriquilla-UNAM, Queretaro (Mexico); Viggiano-Guerra, J C [Subgerencia de Estudios C.F.E., Morelia. Michocan (Mexico); Perez, R J [Universidad de Calgary (Canada)], E-mail: egp@geociencias.unam.mx, E-mail: cesar.viggiano@cfe.gob.mx, E-mail: rene@geochemicalengineering.com

    2008-10-01

    Hydrothermal alteration at Los Azufres geothermal held is mostly propylitic showing progressive dehydration with depth, and temperature increase. The evolution of this system is inferred to be related to deep liquid water, boiling when ascending through fractures connected to the surface.

  12. Hydro-geochemical and isotopic fluid evolution of the Los Azufres caldera geothermal field, Central Mexico

    Gonzalez-Partida, E; Viggiano-Guerra, J C; Perez, R J

    2008-01-01

    Hydrothermal alteration at Los Azufres geothermal held is mostly propylitic showing progressive dehydration with depth, and temperature increase. The evolution of this system is inferred to be related to deep liquid water, boiling when ascending through fractures connected to the surface.

  13. Catahoula formation of the Texas coastal plain: origin, geochemical evolution, and characteristics of uranium deposits

    Galloway, W.E.; Kaiser, W.R.

    1979-01-01

    Uranium was released from volcanic glass deposited within the Catahoula through early pedogenic and diagenetic processes. Pedogenesis was the most efficient process for mobilizing uranium. Original uranium content in fresh Catahoula glass is estimated to have averaged at least 10 ppM; about 5 ppM was mobilized after deposition and made available for migration. Uranium was transported predominantly as uranyl dicarbonate ion. Chlorinity mapping reveals modern ground-water flow patterns. Six utranium deposits representative of the ores were studied. Uranium-bearing meteoric waters were reduced by pre-ore stage pyrite formed by extrinsically introduced fault-leaked sulfide or intrinsically by organic matter. Uranium was concentrated in part by adsorption on Ca-montmorillonite cutans, amorphous TiO 2 , and/or organic matter followed by uranyl reduction to U 4+ in amorphous uranous silicates. Clinoptilolite is not correlative with mineralization. Calcite is pervasive throughout host sands but shows no relationship to uranium mineralization. Presence of marcasite and uranium together at the alteration front strongly supports an acid pH during Catahoula mineralization. Maximum adsorption and minimum solubility of uranium occur at pH 6 in carbonate-rich waters. Log activity ratios of individual waters supersaturated with respect to montmorillonite, taken from montmorillonite-clinoptilolite activity diagrams, show positive correlation with uranium mineralization. High Ca 2+ , Mg 2+ , Al(OH) 4 - , and H + activities promote the formation of montmorillonite relative to clinoptilolite. High saturation ratios for montmorillonite show fair correlation with mineralization. The mineral-solution equilibria approach is a potential method of geochemical exploration. 56 figures, 8 tables

  14. Adding geochemical and isotope tracers to models of hillslope evolution: valuable constraints or monumental headache?

    Mudd, S. M.; Yoo, K.; Hurst, M. D.; Weinman, B. A.; Maher, K.

    2011-12-01

    Landscapes evolve through time, both in terms of their geomorphology and their geochemistry. Past studies have highlighted that topography suffers from the problem of equifinality: the topographic configuration of landscapes can be the result of many different, yet equally plausible, erosion histories. In hillslope soils the properties and chemistry of the soils themselves could provide additional constraints on landscape evolution. Here we present results from a combination of modelling and field studies that seek to quantify the co-evolution of hillslope morphology and the solid state chemistry of hillslope soils. The models follow large numbers of individual particles as they are entrained into a physically mobile soil layer, weathered, and accumulate isotopes such as 10Be and 21Ne. We demonstrate that multiple hillslope properties mitigate (but do not eliminate) the problem of equifinality and demonstrate the importance of accounting for individual particle residence times and ages in interpretation of both isotope and weathering data.

  15. Geochemical modelling study on the age and evolution of the groundwater at the Romuvaara site

    Pitkaenen, P; Vuorinen, U; Leino-Forsman, H [Technical Research Centre of Finland, Espoo (Finland); Snellman, M [Imatran Voima Oy, Helsinki (Finland)

    1996-09-01

    The objective of the study was to interpret the processes and factors which control the hydrogeochemistry (e.g. pH and redox conditions) in the radioactive waste disposal environment. A model of the hydrogeochemical evolution and the chemical flowpaths in different parts of the bedrock at the Romuvaara (in Finland) site has been created. The significance of chemical reactions along different flowpaths is calculated. Furthermore, the consistency of the hydrogeochemical model and the hydrogeological model is examined. (107 refs.).

  16. Geochemical modelling study on the age and evolution of the groundwater at the Romuvaara site

    Pitkaenen, P.; Vuorinen, U.; Leino-Forsman, H.; Snellman, M.

    1996-09-01

    The objective of the study was to interpret the processes and factors which control the hydrogeochemistry (e.g. pH and redox conditions) in the radioactive waste disposal environment. A model of the hydrogeochemical evolution and the chemical flowpaths in different parts of the bedrock at the Romuvaara (in Finland) site has been created. The significance of chemical reactions along different flowpaths is calculated. Furthermore, the consistency of the hydrogeochemical model and the hydrogeological model is examined. (107 refs.)

  17. Geochemical evolution of acidic ground water at a reclaimed surface coal mine in western Pennsylvania

    Cravotta,, Charles A.

    1991-01-01

    Concentrations of dissolved sulfate and acidity in ground water increase downflow in mine spoil and underlying bedrock at a reclaimed surface coal mine in the bituminous field of western Pennsylvania. Elevated dissolved sulfate and negligible oxygen in ground water from bedrock about 100 feet below the water table suggest that pyritic sulfur is oxidized below the water table, in a system closed to oxygen. Geochemical models for the oxidation of pyrite (FeS2) and production of sulfate (SO42-) and acid (H+) are presented to explain the potential role of oxygen (O2) and ferric iron (Fe3+) as oxidants. Oxidation of pyrite by O2 and Fe3+ can occur under oxic conditions above the water table, whereas oxidation by Fe3+ also can occur under anoxic conditions below the water table. The hydrated ferric-sulfate minerals roemerite [Fe2+Fe43+(SO4)4·14H2O], copiapite [Fe2+Fe43+(SO4)6(OH)2·20H20], and coquimbite [Fe2(SO4)3·9H2O] were identified with FeS2 in coal samples, and form on the oxidizing surface of pyrite in an oxic system above the water table. These soluble ferric-sulfate 11 salts11 can dissolve with recharge waters or a rising water table releasing Fe3+, SO42-. and H+, which can be transported along closed-system ground-water flow paths to pyrite reaction sites where O2 may be absent. The Fe3+ transported to these sites can oxidize pyritic sulfur. The computer programs WATEQ4F and NEWBAL were used to compute chemical speciation and mass transfer, respectively, considering mineral dissolution and precipitation reactions plus mixing of waters from different upflow zones. Alternative mass-balance models indicate that (a) extremely large quantities of O2, over 100 times its aqueous solubility, can generate the observed concentrations of dissolved SO42- from FeS2, or (b) under anoxic conditions, Fe3+ from dissolved ferric-sulfate minerals can oxidize FeS2 along closed-system ground-water flow paths. In a system open to O2, such as in the unsaturated zone, the aqueous

  18. Solid phase evolution in the Biosphere 2 hillslope experiment as predicted by modeling of hydrologic and geochemical fluxes

    K. Dontsova

    2009-12-01

    Full Text Available A reactive transport geochemical modeling study was conducted to help predict the mineral transformations occurring over a ten year time-scale that are expected to impact soil hydraulic properties in the Biosphere 2 (B2 synthetic hillslope experiment. The modeling sought to predict the rate and extent of weathering of a granular basalt (selected for hillslope construction as a function of climatic drivers, and to assess the feedback effects of such weathering processes on the hydraulic properties of the hillslope. Flow vectors were imported from HYDRUS into a reactive transport code, CrunchFlow2007, which was then used to model mineral weathering coupled to reactive solute transport. Associated particle size evolution was translated into changes in saturated hydraulic conductivity using Rosetta software. We found that flow characteristics, including velocity and saturation, strongly influenced the predicted extent of incongruent mineral weathering and neo-phase precipitation on the hillslope. Results were also highly sensitive to specific surface areas of the soil media, consistent with surface reaction controls on dissolution. Effects of fluid flow on weathering resulted in significant differences in the prediction of soil particle size distributions, which should feedback to alter hillslope hydraulic conductivities.

  19. A case study of long-term geochemical evolution of coal waste rock drainage and its remediation

    Jarvis, A.P.; Gandy, C.J.

    2010-01-01

    The geochemical evolution of drainage from an 35 hectare orphan waste rock pile over a 15-year period was described. Spoil material at the site was generated during coal mining at 2 collieries between 1922 and 1970, and was comprised of grey and black shale, ash, coal, and coal dust. The heap was founded on an impermeable clay layer. Located in northern England, drainage from the rock heap was intercepted by a small compost wetland system installed in 1997. The waste rock heap was selectively capped in 1998. Water samples were collected and analyzed. Anion concentrations were determined using an ion chromatograph. The samples were filtered periodically. Acidity concentrations and flow rates were determined. Results of the study showed measurable improvements in water quality as a result of capping the heap. The study demonstrated that a combination of selective spoil capping and wetland treatment can serve as a low-cost solution to acid mine drainage at some abandoned mine sites. 9 refs., 1 tab., 1 fig.

  20. A case study of long-term geochemical evolution of coal waste rock drainage and its remediation

    Jarvis, A.P.; Gandy, C.J. [Newcastle Univ. (United Kingdom). School of Civil Engineering and Geosciences, Hydrogeochemical Engineering Research and Outreach Group

    2010-07-01

    The geochemical evolution of drainage from an 35 hectare orphan waste rock pile over a 15-year period was described. Spoil material at the site was generated during coal mining at 2 collieries between 1922 and 1970, and was comprised of grey and black shale, ash, coal, and coal dust. The heap was founded on an impermeable clay layer. Located in northern England, drainage from the rock heap was intercepted by a small compost wetland system installed in 1997. The waste rock heap was selectively capped in 1998. Water samples were collected and analyzed. Anion concentrations were determined using an ion chromatograph. The samples were filtered periodically. Acidity concentrations and flow rates were determined. Results of the study showed measurable improvements in water quality as a result of capping the heap. The study demonstrated that a combination of selective spoil capping and wetland treatment can serve as a low-cost solution to acid mine drainage at some abandoned mine sites. 9 refs., 1 tab., 1 fig.

  1. New constraints on the textural and geochemical evolution of the upper mantle beneath the Styrian basin

    Aradi, Laszlo; Hidas, Károly; Zanetti, Alberto; János Kovács, István; Patkó, Levente; Szabó, Csaba

    2016-04-01

    Plio-Pleistocene alkali basaltic volcanism sampled sporadically the upper mantle beneath the Carpathian-Pannonian Region (CPR, e.g. [1]). Lavas and pyroclasts often contain mantle derived xenoliths, and the majority of them have been extensively studied [1], except the westernmost Styrian Basin Volcanic Field (SBVF, Eastern Austria and Slovenia). In the SBVF only a few volcanic centers have been studied in details (e.g. Kapfenstein & Tobaj). Based on these studies, the upper mantle beneath the SBVF is consists of dominantly high temperature, texturally and geochemically homogeneous protogranular spinel lherzolite. New major and trace element data from rock-forming minerals of ultramafic xenoliths, coupled with texture and deformation analysis from 12 volcanic outcrops across the SBVF, suggest that the lithospheric roots of the region are more heterogeneous than described previously. The studied xenoliths are predominantly lherzolite, amphibole is a common phase that replaces pyroxenes and spinels and proves modal metasomatism. Phlogopite coupled with apatite is also present in amphibole-rich samples. The texture of the xenoliths is usually coarse-grained and annealed with low abundance of subgrain boundaries in both olivine and pyroxenes. Olivine crystal preferred orientation (CPO) varies between the three most abundant one: [010]-fiber, orthogonal and [100]-fiber symmetry [2]. The CPO of pyroxenes is usually coherent with coeval deformation with olivine, however the CPO of amphibole is suggesting postkinematic epitaxial overgrowth on the precursor pyroxenes. According to equilibrium temperatures, the studied xenolith suite samples a broader temperature range (850-1100 °C) than the literature data, corresponding to mantle depths between 30 and 60 km, which indicates that the xenolith suite only represents the shallower part of the recent 100 km thick lithospheric mantle beneath the SBVF. The equilibrium temperatures show correlation with the varying CPO symmetries

  2. Status of geochemical modeling of groundwater evolution at the Tono in-situ tests site, Japan

    Sasamoto, Hiroshi; Yui, Mikazu; Arthur, R.C.

    1999-12-01

    Hydrochemical investigation of Tertiary sedimentary rocks at JNC's Tono in-situ tests site indicate the groundwaters are: meteoric in origin, chemically reducing at depths greater than a few tens of meters in the sedimentary rock, relatively old [carbon-14 ages of groundwaters collected from the lower part of the sedimentary sequence range from 13,000 to 15,000 years BP (before present)]. Ca-Na-HCO 3 type solutions near the surface, changing to Na-HCO 3 type groundwaters with increasing depth. The chemical evolution of the groundwaters is modeled assuming local equilibrium for selected mineral-fluid reactions, taking into account the rainwater origin of these solutions. Results suggest it is possible to interpret approximately the 'real' groundwater chemistry (i.e., pH, Eh, total dissolved concentrations of Si, Na, Ca, K, Al, carbonate and sulfate) if the following assumptions are adopted: CO 2 concentration in the gas phase contacting pore solutions in the overlying soil zone=10 -1 bar, minerals in the rock zone that control the solubility of respective elements in the groundwater include; chalcedony (Si), albite (Na), kaolinite (Al), calcite (Ca and carbonate), muscovite (K) and pyrite (Eh and sulfate). It is noted, however, that the available field data may not be sufficient to adequately constrain parameters in the groundwater evolution model. In particular, more detailed information characterizing certain site properties (e.g., the actual mineralogy of 'plagioclase', 'clay' and 'zeolite') are needed to improve the model. Alternative conceptual models of key reactions may also be necessary. For this reason, a model that accounts for ion-exchange reactions among clay minerals, and which is based on the results of laboratory experiments, has also been evaluated in the present study. Further improvements of model considering ion-exchange reactions are needed in future, however. (author)

  3. Modelling of long term geochemical evolution and study of mechanical perturbation of bentonite buffer of a KBS-3 repository

    Marsal, Francois; Pellegrini, Delphine; Deleruyelle, Frederic; Serres, Christophe (French Inst. for Radiological Protection and Nuclear Safety (IRSN), Fontenay-aux-Roses (FR)); Windt, Laurent de (Ecole des Mines de Paris, Paris (FR))

    2008-03-15

    PART I: The Swedish Nuclear Fuel and Waste Management Co. (SKB) has recently completed a safety assessment project named SR-Can, related to the KBS-3 disposal concept. In this concept, the waste packages are surrounded by a buffer made of either MX-80 or Deponit CA-N bentonite. Interactions between the buffer and groundwater may modify the buffer composition and thus its containment properties. The Swedish Radiation Protection Authorities (SSI) requested the French Institute for Radiological Protection and Nuclear Safety (IRSN) to perform the present study in support of SSI review of the SR-Can report. The purpose is to assess the geochemical evolution of both potential buffer materials due to the intrusion of different types of groundwater, with a similar modelling layout to that reported in SR-Can and detailed in Arcos et al. Three main categories of water inflows via a fracture intersecting a deposition hole are considered: the Forsmark reference groundwater, a high-salinity groundwater to account for up-rise of deep-seated brines and a diluted water representing ice-melting derived-groundwater. In addition to this, the redox buffering capacity of Deponit CA-N bentonite and the thermal effect on MX-80 bentonite geochemistry have been assessed. This modelling work has been performed using the reactive transport modelling code HYTEC. The main outcome of the present study is that the intrusion of the considered groundwaters should not affect drastically the geochemistry of neither the Deponit CA-N nor the MX-80 bentonite on the longterm (100,000 y). Bentonite pH may reach high values (up to 10.5) in some cases but does not reach SKB criterion value related to bentonite chemical stability. Dissolution-precipitation of accessory minerals is not significant enough to induce important porosity changes (rise by maximum 2 %). Globally, the montmorillonite exchanger undergoes Na by Ca partial replacement, which may decrease the swelling pressure of the bentonite. The

  4. The long term geochemical evolution of the nearfield of the HLW repository

    Bradbury, M. H.; Berner, U.; Curti, E.; Hummel, W.; Kosakowski, G.; Thoenen, T.

    2014-11-15

    The work presented in this report focuses on the spatial and temporal evolution of the near-field of the high level radioactive waste repository situated in the Opalinus Clay formation. The major components of the near-field of such a repository are spent fuel, vitrified high-level waste, canisters (assumed for the purposes of the present report to be made of carbon steel), compacted bentonite and a concrete liner. Over the one million year time period considered in safety analysis, these components will chemically interact with one another and potentially change their retention characteristics. As a starting reference point the 'initial' (unreacted) states of the Opalinus Clay, bentonite, concrete liner (mineralogies and water chemistries) and the canister are briefly described. The main processes considered to influence the evolution of the repository in time and space, and which often operate over different time scales, are: interactions of the concrete tunnel liner with compacted bentonite and Opalinus Clay, temperature gradients caused by the heat generating high level waste, mineralogical changes to the compacted bentonite through interactions with the corrosion products of the iron canisters, and finally, the dissolution of the spent fuel and vitrified high-level waste. The consequences of these processes (as a function of time) on the long term barrier performance of the near-field have been estimated, particularly with respect to radionuclide solubilities and the sorption, diffusion and swelling characteristics of the bentonite. The main conclusions drawn are as follows: The alteration depth into the bentonite due to the interaction with the concrete liner (assumed to be 15 cm thick) is likely to be much less than 13 cm over a one million year time scale, with the main reaction products being clays (illite), hydroxides, carbonates, calcium silicate hydrates, and aluminosilicates. The swelling pressure and the sorption capacity of the bentonite in

  5. The long term geochemical evolution of the nearfield of the HLW repository

    Bradbury, M. H.; Berner, U.; Curti, E.; Hummel, W.; Kosakowski, G.; Thoenen, T.

    2014-11-01

    The work presented in this report focuses on the spatial and temporal evolution of the near-field of the high level radioactive waste repository situated in the Opalinus Clay formation. The major components of the near-field of such a repository are spent fuel, vitrified high-level waste, canisters (assumed for the purposes of the present report to be made of carbon steel), compacted bentonite and a concrete liner. Over the one million year time period considered in safety analysis, these components will chemically interact with one another and potentially change their retention characteristics. As a starting reference point the 'initial' (unreacted) states of the Opalinus Clay, bentonite, concrete liner (mineralogies and water chemistries) and the canister are briefly described. The main processes considered to influence the evolution of the repository in time and space, and which often operate over different time scales, are: interactions of the concrete tunnel liner with compacted bentonite and Opalinus Clay, temperature gradients caused by the heat generating high level waste, mineralogical changes to the compacted bentonite through interactions with the corrosion products of the iron canisters, and finally, the dissolution of the spent fuel and vitrified high-level waste. The consequences of these processes (as a function of time) on the long term barrier performance of the near-field have been estimated, particularly with respect to radionuclide solubilities and the sorption, diffusion and swelling characteristics of the bentonite. The main conclusions drawn are as follows: The alteration depth into the bentonite due to the interaction with the concrete liner (assumed to be 15 cm thick) is likely to be much less than 13 cm over a one million year time scale, with the main reaction products being clays (illite), hydroxides, carbonates, calcium silicate hydrates, and aluminosilicates. The swelling pressure and the sorption capacity of the bentonite in this

  6. Evolution of the 2015 Cotopaxi eruption revealed by combined geochemical & seismic observations

    Hidalgo, Silvana; Battaglia, Jean; Arellano, Santiago; Sierra, Daniel; Bernard, Benjamin; Parra, Rene; Kelly, Peter; Dinger, Florian; Barrington, Charlotte; Samaniego, Pablo

    2018-01-01

    Through integration of multiple data streams to monitor volcanic unrest scientists are able to make more robust eruption forecast and to obtain a more holistic interpretation of volcanic systems. We examined gas emission and gas geochemistry, seismic and petrologic data recorded during the 2015 unrest of Cotopaxi (Ecuador) in order to decipher the origin and temporal evolution of this eruption. Identification of families of similar seismic events and the use of seismic amplitude ratios reveals temporal changes in volcanic processes. SO2 (300 to 24000 t/d), BrO/SO2 (5-10 x10-5), SO2/HCl (5.8 ± 4.8 and 6.6 ± 3.0) and CO2/SO2 (0.6 to 2.1) measured throughout the eruption indicate a shallow magmatic source. Bulk ash and glass chemistry indicate a homogenous andesitic (SiO2 wt%=56.94 ± 0.25) magma having undergone extensive S-exsolution and degassing during ascent. These data lead us to interpret this eruption as a magma intrusion and ascend to shallow levels. The intrusion progressively interacted with the hydrothermal system, boiled off water, and produced hydromagmatic explosions. A small volume of this intrusion continued to fragment and produced episodic ash emissions until it was sufficiently degassed and rheologically stiff. Based on the 470 kt of measured SO2 we estimate that ~ 65.3 x106 m3 of magma were required to supply the emitted gases. This volume exceeds the volume of erupted juvenile material by a factor of 50. This result emphasizes the importance of careful monitoring of Cotopaxi to identify the intrusion of a new batch of magma, which could rejuvenate the non-erupted material.

  7. The evolution of the Cappadocia Geothermal Province, Anatolia (Turkey): geochemical and geochronological evidence

    Şener, M. Furkan; Şener, Mehmet; Uysal, I. Tonguç

    2017-12-01

    Cappadocia Geothermal Province (CGP), central Turkey, consists of nine individual geothermal regions controlled by active regional fault systems. This paper examines the age dating of alteration minerals and the geochemistry (trace elements and isotopes) of the alteration minerals and geothermal waters, to assess the evolution of CGP in relation to regional tectonics. Ar-Ar age data of jarosite and alunite show that the host rocks were exposed to oxidizing conditions near the Earth's surface at about 5.30 Ma. Based on the δ18O-δD relationhip, water samples had a high altitude meteoric origin. The δ34S values of jarosite and alunite indicate that water samples from the southern part of the study area reached the surface after circulation through volcanic rocks, while northern samples had traveled to the surface after interacting with evaporates at greater depths. REY (rare earth elements and yttrium) diagrams of alteration minerals (especially illite, jarosite and alunite) from rock samples, taken from the same locations as the water samples, display a similar REY pattern to water samples. This suggests that thermal fluids, which reached the surface along a fault zone and caused the mineral alteration in the past, had similar chemical composition to the current geothermal water. The geothermal conceptual model, which defines a volcanically heated reservoir and cap rocks, suggests there are no structural drawbacks to the use of the CGP geothermal system as a resource. However, fluid is insufficient to drive the geothermal system as a result of scanty supply of meteoric water due to evaporation significantly exceeding rainfall.

  8. Hydro-geochemical and isotopic fluid evolution of the Los Azufres geothermal field, Central Mexico

    Gonzalez-Partida, E.; Carrillo-Chavez, A.; Levresse, G.; Tello-Hinojosa, E.; Venegas-Salgado, S.; Ramirez-Silva, G.; Pal-Verma, M.; Tritlla, J.; Camprubi, A.

    2005-01-01

    Hydrothermal alteration at Los Azufres geothermal field is mostly propylitic with a progressive dehydration with depth and temperature increase. Argillic and advanced argillic zones overlie the propylitic zone owing to the activity of gases in the system. The deepest fluid inclusions (proto-fluid) are liquid-rich with low salinity, with NaCl dominant fluid type and ice melting temperatures (T mi ) near zero (0 deg C), and salinities of 0.8 wt% NaCl equivalent. The homogenization temperature (T h ) = 325 ± 5 deg C. The boiling zone shows T h = ±300 deg C and apparent salinities between 1 and 4.9 wt% NaCl equivalent, implying a vaporization process and a very important participation of non-condensable gases (NCGs), mostly CO 2 . Positive clathrate melting temperatures (fusion) with T h = 150 deg C are observed in the upper part of the geothermal reservoir (from 0 to 700 m depth). These could well be the evidence of a high gas concentration. The current water produced at the geothermal wells is NaCl rich (geothermal brine) and is fully equilibrated with the host rock at temperatures between T = 300 and 340 deg C. The hot spring waters are acid-sulfate, indicating that they are derived from meteoric water heated by geothermal steam. The NCGs related to the steam dominant zone are composed mostly of CO 2 (80-98% of all the gases). The gases represent between 2 and 9 wt% of the total mass of the fluid of the reservoir. The authors interpret the evolution of this system as deep liquid water boiling when ascending through fractures connected to the surface. Boiling is caused by a drop of pressure, which favors an increase in the steam phase within the brine ascending towards the surface. During this ascent, the fluid becomes steam-dominant in the shallowest zone, and mixes with meteoric water in perched aquifers. Stable isotope compositions (δ 18 O-δD) of the geothermal brine indicate mixing between meteoric water and a minor magmatic component. The enrichment in δ 18

  9. Hydro-geochemical and isotopic fluid evolution of the Los Azufres geothermal field, Central Mexico

    Gonzalez-Partida, E. [Centro de Geociencias, UNAM, Campus Juriquilla, A.P. 15, Juriquilla, Qro., 76230 (Mexico)]. E-mail: egp@geociencias.unam.mx; Carrillo-Chavez, A. [Centro de Geociencias, UNAM, Campus Juriquilla, A.P. 15, Juriquilla, Qro., 76230 (Mexico); Levresse, G. [Centro de Geociencias, UNAM, Campus Juriquilla, A.P. 15, Juriquilla, Qro., 76230 (Mexico); Tello-Hinojosa, E. [Comision Federal de Electricidad, A.P. 31-7, C.P. 58090 Morelia, Mich. (Mexico); Venegas-Salgado, S. [Comision Federal de Electricidad, A.P. 31-7, C.P. 58090 Morelia, Mich. (Mexico); Ramirez-Silva, G. [Comision Federal de Electricidad, A.P. 31-7, C.P. 58090 Morelia, Mich. (Mexico); Pal-Verma, M. [Instituto de Investigaciones Electricas, A.P. 1-475, C.P. 62001 Cuernavaca, Morelos (Mexico); Tritlla, J. [Centro de Geociencias, UNAM, Campus Juriquilla, A.P. 15, Juriquilla, Qro., 76230 (Mexico); Camprubi, A. [Centro de Geociencias, UNAM, Campus Juriquilla, A.P. 15, Juriquilla, Qro., 76230 (Mexico)

    2005-01-01

    Hydrothermal alteration at Los Azufres geothermal field is mostly propylitic with a progressive dehydration with depth and temperature increase. Argillic and advanced argillic zones overlie the propylitic zone owing to the activity of gases in the system. The deepest fluid inclusions (proto-fluid) are liquid-rich with low salinity, with NaCl dominant fluid type and ice melting temperatures (T{sub mi}) near zero (0 deg C), and salinities of 0.8 wt% NaCl equivalent. The homogenization temperature (T{sub h}) = 325 {+-} 5 deg C. The boiling zone shows T{sub h} = {+-}300 deg C and apparent salinities between 1 and 4.9 wt% NaCl equivalent, implying a vaporization process and a very important participation of non-condensable gases (NCGs), mostly CO{sub 2}. Positive clathrate melting temperatures (fusion) with T{sub h} = 150 deg C are observed in the upper part of the geothermal reservoir (from 0 to 700 m depth). These could well be the evidence of a high gas concentration. The current water produced at the geothermal wells is NaCl rich (geothermal brine) and is fully equilibrated with the host rock at temperatures between T = 300 and 340 deg C. The hot spring waters are acid-sulfate, indicating that they are derived from meteoric water heated by geothermal steam. The NCGs related to the steam dominant zone are composed mostly of CO{sub 2} (80-98% of all the gases). The gases represent between 2 and 9 wt% of the total mass of the fluid of the reservoir. The authors interpret the evolution of this system as deep liquid water boiling when ascending through fractures connected to the surface. Boiling is caused by a drop of pressure, which favors an increase in the steam phase within the brine ascending towards the surface. During this ascent, the fluid becomes steam-dominant in the shallowest zone, and mixes with meteoric water in perched aquifers. Stable isotope compositions ({delta}{sup 18}O-{delta}D) of the geothermal brine indicate mixing between meteoric water and a

  10. Post-Eocene volcanics of the Abazar district, Qazvin, Iran: Mineralogical and geochemical evidence for a complex magmatic evolution

    Asiabanha, A.; Bardintzeff, J. M.; Kananian, A.; Rahimi, G.

    2012-02-01

    The style of volcanism of post-Eocene volcanism in the Alborz zone of northern Iran is different to that of Eocene volcanism (Karaj Formation). Indeed, the volcanic succession of the Abazar district, located in a narrow volcanic strip within the Alborz magmatic assemblage, is characterized by distinct mineralogical and chemical compositions linked to a complex magmatic evolution. The succession was produced by explosive eruptions followed by effusive eruptions. Two main volcanic events are recognized: (1) a thin rhyolitic ignimbritic sheet underlain by a thicker lithic breccia, and (2) lava flows including shoshonite, latite, and andesite that overlie the first event across a reddish soil horizon. Plagioclase in shoshonite (An 48-92) shows normal zoning, whereas plagioclase in latite and andesite (An 48-75) has a similar composition but shows reverse and oscillatory zoning. QUILF temperature calculations for shoshonites and andesites yield temperatures of 1035 °C and 1029 °C, respectively. The geothermometers proposed by Ridolfi et al. (2010) and Holland and Blundy (1994) yield temperatures of 960 °C and 944 °C for latitic lava, respectively. The samples of volcanic rock show a typical geochemical signature of the continental arc regime, but the andesites clearly differ from the shoshonites, the latites and the rhyolites. The mineralogical and chemical characteristics of these rocks are explained by the following petrogenesis: (1) intrusion of a hot, mantle-depth mafic (shoshonitic) magma, which differentiated in the magma chamber to produce a latitic and then a rhyolitic liquid; (2) rhyolitic ignimbritic eruptions from the top of the magma chamber, following by shoshonitic and then latitic extrusions; (3) magma mingling between the latitic and andesitic magmas, as indicated by the occurrence of andesite clasts within the latite; and (4) andesitic effusions. The youngest volcanic events in the Alborz zone show a close chemical relationship with continental arc

  11. The geochemical evolution of syncollisional magmatism and the implications for significant magmatic-hydrothermal lead-zinc mineralization (Gangdese, Tibet)

    Zhou, Jinsheng; Yang, Zhusen; Hou, Zengqian; Liu, Yingchao; Zhao, Xiaoyan; Zhang, Xiong; Zhao, Miao; Ma, Wang

    2017-09-01

    In addition to well-known subduction processes, the collision of two continents also generates abundant ore deposits, as in the case of the Tibetan Plateau, which is the youngest and most spectacular collisional belt on Earth. During the building history of the Gangdese magmatic belt, several magmatic flare-up events developed, however, significant magmatic-hydrothermal lead-zinc mineralization dominantly accompanied the magmatism during the syncollisional period ( 65-41 Ma). Based on integrated geochemical and isotopic data, we provide insights into the genesis and evolution of syncollisional magmas, and their implications for significant magmatic-hydrothermal lead-zinc mineralization. The Sr-Nd isotopic compositions of most syncollisional igneous rocks (87Sr/86Sr = 0.7034-0.7123; εNd(t) = - 9.0 to + 1.8) indicate a mixing origin between mantle-derived basaltic magmas and ancient crustal melts, and fractional crystallization is a fundamental mechanism by which syncollisional magmas evolve towards intermediate to silicic compositions. Most lead-zinc mineralization-related plutons are high silica (76.14% wt.% SiO2 on average), high oxygen fugacity (average ΔFMQ + 2.5) granites with highly evolved chemical signatures [average Eun/Eun* = 0.33, high Rb/Sr (average = 3.9)], and they represent the final products from primary magmas. Due to the contribution of ancient crustal melts to the genesis of mineralization-related parent magmas, the spatial distribution of Pb-Zn deposits within the northern Gangdese magmatic belt is controlled by the lithospheric architecture. In compressional environments, magmas have low evacuation efficiency and long magma chamber lifespan, which is favorable for basaltic parents evolved to high silica granites through sufficient fractional crystallization. This scenario contributes to our understanding of the significant magmatic-hydrothermal lead-zinc mineralization that occurred in the syncollisional period.

  12. Geochemical studies, magmatic evolution, microstructures and replacement mechanisms in Jebale-Barez granitoid Complex (East and Southeast Jiroft

    Jamal Rasouli

    2017-08-01

    -related arc magmatism. The systematic variation for the major elements implies involvement of fractional crystallization in the evolution of JBPC. The trends are consistent with the fractionation of plagioclase feldspar and ferromagnesian minerals as indicated by decreasing MgO, CaO, FeOt and TiO2 with increasing SiO2 despie the content of (K2O+Na2O. It generally increases with increasing SiO2 for intermediate compositions (67 wt% SiO2 ≤ and then decreases for more felsic granitic rocks, indicating that sodic feldspar was a major fractionating phase for alkali-granite and granite suit (Rasouli, 2015. Overall REE abundances slightly decrease with increasing SiO2 consistent with plagioclase fractionation. The distribution of voluminous volcanic rocks in the studied area implies that the JBPC could be a part of the mature magmatic arc. The field petrography and geochemical studies indicated that the JPBC originated from both crustal and mantle derived magmas: The increase in temperature and excess fluid pressure caused by subduction trigged melting of mantle edge and formation of basaltic magma and its ascending and introducing into the crust was followed by partial melting (Rasouli, 2015. The juxtaposed series of mafic-felsic pulses formed a mixed magma. Finally this magma is emplaced at broad, shallow magma chamber (9-12 km, where the differentiation took place by fractional crystallization and produced a wide variety of rocks form quartz-diorite to alkali granite. In such shallow magma reservoirs, the emplacement of magma took place as sill (Fridrich et al, 1991. Combining field observations and petrofabric studies displayed a deep caldera as a feeder zone for Eocene volcanic rocks (Rasouli, 2015. The JBPC is located in a shear zone and multiple magmatic pulses were injected as sills. The magmatic fabrics show active tectonic controls on magmatism during and after magma emplacement. The transpressional tectonic regime is well compatible with our data. References Fridrich, C

  13. Geochemical characterisation of Taal volcano-hydrothermal system and temporal evolution during continued phases of unrest (1991-2017)

    Maussen, Katharine; Villacorte, Edgardo; Rebadulla, Ryan R.; Maximo, Raymond Patrick; Debaille, Vinciane; Bornas, Ma. Antonia; Bernard, Alain

    2018-02-01

    Taal volcano (Luzon Island, Philippines) has last erupted in 1977 but has known some periods of increased activity, characterised by seismic swarms, ground deformation, increased carbon dioxide flux and in some cases temperature anomalies and the opening of fissures. We studied major, trace element and sulphur and strontium isotopic composition of Taal lake waters and hot springs over a period of 25 years to investigate the geochemical evolution of Taal volcano's hydrothermal system and its response to volcanic unrest. Long-term evolution of Main Crater Lake (MCL) composition shows a slow but consistent decrease of acidity, SO4, Mg, Fe and Al concentrations and a trend from light to heavy sulphate, consistent with a general decrease of volcanic gases dissolving in the hydrothermal system. Na, K and Cl concentrations remain constant indicating a non-volcanic origin for these elements. Sulphate and strontium isotopic data suggest this neutral chloride-rich component represents input of geothermal water into Taal hydrothermal system. A significant deviation from the long-term baseline can be seen in two samples from 1995. That year, pH dropped from 2.6 to 2.2, F, Si and Fe concentrations increased and Na, K and Cl concentrations decreased. Sulphate was depleted in 34S and temperature was 4 °C above baseline level at the time of sampling. We attribute these changes to the shallow intrusion of a degassing magma body during the unrest in 1991-1994. More recent unrest periods have not caused significant changes in the geochemistry of Taal hydrothermal waters and are therefore unlikely to have been triggered by shallow magma intrusion. A more likely cause for these events is thus pressurisation of the hydrothermal reservoir by increasing degassing from a stagnant magma reservoir. Our study indicates that new magmatic intrusions that might lead to the next eruption of Taal volcano are expected to change the geochemistry of MCL in the same way as in 1994-1995, with the most

  14. Intercomparison of Cement Solid-Solution Models. Issues Affecting the Geochemical Evolution of Repositories for Radioactive Waste

    Benbow, Steven; Savage, David; Walker, Colin

    2007-05-01

    Many concepts for the geological storage of radioactive waste incorporate cement based materials, which act to provide a chemical barrier, impede groundwater flow or provide structural integrity of the underground structures. Thus, it is important to understand the long-term behaviour of these materials when modelling scenarios for the potential release and migration of radionuclides. In the presence of invasive groundwater, the chemical and physical properties of cement, such as its pH buffering capacity, resistance to flow, and its mechanical properties, are expected to evolve with time. Modelling the degradation of cement is complicated by the fact that the long term pH buffer is controlled by the incongruent dissolution behaviour of calcium-silicate-hydrate (C-S-H) gel. It has been previously shown (SKI Report 2005:64) that it is possible to simulate the long term evolution of both the physical and chemical properties of cement based materials in an invasive groundwater using a fully coupled geochemical transport model. The description of the incongruent dissolution of C-S-H gel was based on a binary solid solution aqueous solution (SSAS) between end-member components portlandite (Ca(OH) 2 ) and a C-S-H gel composition expressed by its component oxides (CaH 2 SiO 4 ). The models considered a range of uncertainties including different groundwater compositions, parameterised couplings between the evolution of porosity with permeability and diffusivity and alternative secondary mineral assemblages. The results of the modelling suggested that alternative evolutions were possible under these different conditions. The focus of this report is to address the uncertainty regarding the choice of model for the C-S-H gel dissolution. We compare two alternative C-S-H SSAS models with the one that was used in the previous report, with an emphasis on a direct comparison of the model predictions. Thus we have chosen one simple simulated experimental model based on those in the

  15. The geodynamic evolution of the eastern Sierras Pampeanas based on geochemical, Sm-Nd, Pb-Pb and SHRIMP data

    Drobe, M; Lopez de Luchi, M; Steenken, A

    2011-01-01

    , have been carried out to unravel the provenance and the geodynamic history of the Eastern Sierras Pampeanas, Central Argentina. The geochemical and the Sm–Nd data point to a slightly stronger mafic and less-fractionated material in the provenance area of the Sierras de Co´rdoba when compared...

  16. The impacts of a linear wastewater reservoir on groundwater recharge and geochemical evolution in a semi-arid area of the Lake Baiyangdian watershed, North China Plain

    Wang, Shiqin [Faculty of Horticulture, Chiba University, Matsudo-City 271-8510 (Japan); Tang, Changyuan, E-mail: cytang@faculty.chiba-u.jp [Faculty of Horticulture, Chiba University, Matsudo-City 271-8510 (Japan); Song, Xianfang [Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); Wang, Qinxue [National Institute for Environmental Studies, Tsukuba 305-8506 (Japan); Zhang, Yinghua [Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); Yuan, Ruiqiang [College of Environment and Resources, Shanxi University (China)

    2014-06-01

    Sewage leakage has become an important source of groundwater recharge in urban areas. Large linear wastewater ponds that lack anti-seepage measures can act as river channels that cause the deterioration of groundwater quality. This study investigated the groundwater recharge by leakage of the Tanghe Wastewater Reservoir, which is the largest industrial wastewater channel on the North China Plain. Additionally, water quality evolution was investigated using a combination of multivariate statistical methods, multi-tracers and geochemical methods. Stable isotopes of hydrogen and oxygen indicated high levels of wastewater evaporation. Based on the assumption that the wastewater was under an open system and fully mixed, an evaporation model was established to estimate the evaporation of the wastewater based on isotope enrichments of the Rayleigh distillation theory using the average isotope values for dry and rainy seasons. Using an average evaporation loss of 26.5% for the input wastewater, the estimated recharge fraction of wastewater leakage and irrigation was 73.5% of the total input of wastewater. The lateral regional groundwater inflow was considered to be another recharge source. Combing the two end-members mix model and cluster analysis revealed that the mixture percentage of the wastewater decreased from the Highly Affected Zone (76%) to the Transition Zone (5%). Ion exchange and redox reaction were the dominant geochemical processes when wastewater entered the aquifer. Carbonate precipitation was also a major process affecting evolution of groundwater quality along groundwater flow paths. - Highlights: • An unlined wastewater reservoir caused the deterioration of groundwater quality. • An evaporation fraction was estimated by Rayleigh distillation theory of isotopes. • 73.5% of wastewater recharge to groundwater by leakage and irrigation infiltration. • The region influenced by wastewater was divided into four subzones. • Mixing, ion exchange, and

  17. Geochemical and Geophysical Characteristics of the Balud Ophiolitic Complex (BOC, Masbate Island, Philippines: Implications for its Generation, Evolution and Emplacement

    Pearlyn C. Manalo

    2015-01-01

    Full Text Available This paper presents the first field, geochemical and geophysical information on the recently recognized Early Cretaceous Balud Ophiolitic Complex (BOC in the island of Masbate in the Central Philippines. Mapping of the western limb of the island revealed that only the upper crustal section of the BOC is exposed in this area. Geochemically, the pillow basalts are characterized by transitional mid-oceanic ridge basalt-island arc tholeiitic compositions. Gravity surveys yielded low Bouguer anomaly values that are consistent with the highly dismembered nature of the BOC. Short wavelength, high amplitude magnetic anomalies registered across the study area are attributed to shallow magnetic sources. This is taken to support the model that the ophiolitic complex occurs as thin crustal slivers that are not deeply-rooted in the mantle. Comparing BOC with other ophiolites in the Central Philippines, such as those in the islands of Sibuyan, Leyte and Bohol, suggests the possibility of a common or contiguous source for similarly-aged and geochemically composed crust-mantle sequences in the region.

  18. Geochemical and stable isotopic evolution of the Guarani Aquifer System in the state of São Paulo, Brazil

    Sracek, Ondra; Hirata, Ricardo

    2002-09-01

    The purpose of this report is to explain geochemical and stable isotopes trends in the Brazilian unit of the Guarani Aquifer System (Botucatu and Piramboia aquifers) in São Paulo State, Brazil. Trends of dissolved species concentrations and geochemical modeling indicated a significant role of cation exchange and dissolution of carbonates in downgradient evolution of groundwater chemistry. Loss of calcium by the exchange for sodium drives dissolution of carbonates and results in Na-HCO3 type of groundwater. The cation-exchange front moves downgradient at probably much slower rate compared to the velocity of groundwater flow and at present is located near to the cities of Sertãozinho and Águas de Santa Barbara (wells PZ-34 and PZ-148, respectively) in a shallow confined area, 50-70 km from the recharge zone. Part of the sodium probably enters the Guarani Aquifer System. together with chloride and sulfate from the underlying Piramboia Formation by diffusion related to the dissolution of evaporates like halite and gypsum. High concentrations of fluorine (up to 13.3 mg/L) can be explained by dissolution of mineral fluoride also driven by cation exchange. However, it is unclear if the dissolution takes place directly in the Guarani Aquifer System or in the overlying basaltic Serra Geral Formation. There is depletion in δ2H and δ18O values in groundwater downgradient. Values of δ13C(DIC) are enriched downgradient, indicating dissolution of calcite under closed system conditions. Values of δ13C(DIC) in deep geothermal wells are very high (>-6.0‰) and probably indicate isotopic exchange with carbonates with δ13C about -3.0‰. Future work should be based on evaluation of vertical fluxes and potential for penetration of contamination to the Guarani Aquifer System. Résumé. Cet article a pour objet d'expliquer l'évolution de la géochimie et des isotopes stables dans l'unité brésilienne du système aquifère du Guarani (aquifères de Botucatu et Piramboia), dans

  19. Reassessment of the origin of the Dun Mountain Ophiolite, New Zealand : Nd-isotopic and geochemical evolution of magma suites

    Sivell, W.J.; McCulloch, M.T.

    2000-01-01

    Magmatic suites with contrasting isotopic and geochemical compositions, sequentially emplaced in different tectonic regimes, comprise the Dun Mountain Ophiolite Belt (DMOB), New Zealand. At D'Urville Island, the northernmost exposure of the DMOB, earliest erupted (stage 1) pillow basalts ε Nd (T) = +6.3 to +7.5, and are incompatible element enriched, like basalts from geochemically anomalous ridge segments. Overlying stage 2 basalts (sheeted flows) show a narrow range of ε Nd (T) = +8.3 + or -0.2, with chemical characteristics of depleted backarc basin basalts. These rocks are intruded by mafic to silicic stage 3 magmas, which have high uniform initial 143 Nd/ 144 Nd ratios (ε Nd (T) = +9.3 + or -0.2) over a wide range of 147 Sm/ 144 Nd values (yielding a precise Early Permian Nd-isotope age of 278 ± 4 Ma (MSWD = 0.48)). Stage 3 magmas show pronounced subduction-related geochemical signatures similar to island arc tholeiites (IAT) from immature arcs. They are closely analogous to some (boninite)-IAT magmas which characterise 'infant arc' eruptive activity in forearc basins of present-day Western Pacific island arc systems. A wide variety of stage 3 magma compositions, ranging from near-primary basaltic dikes (Mg = 74) to extremely fractionated silicic plagiogranites with uniformly very depleted isotopic ratios, is consistent with slow spreading rates which gave rise to polybaric, closed-system fractionation of magmas and periodic chamber abandonment. Some stage 3 rocks with SiO 2 levels in the andesite range have low-TiO 2 contents and high Mg, and may be fractionated equivalents of boninites. High ε Nd (T) values of stage 3 magmas indicate a lack of subducted sediment with inherited crustal residence signatures, and reflect the extent of supra-subduction zone (SSZ) mantle wedge depletion. DMOB stage 3 magmas may represent foreac magmatism that was the precursor to normal subduction-related volcanism established by c. 265 Ma in the Brook Street Arc and derived

  20. Integrative Modeling of cap-rock Integrity in the Context of CO2 Storage: Evolution of Transport and Geochemical Properties and Impact on Performance and Safety Assessment

    Bildstein, O.; Credoz, A.; Jullien, M.; Kervevan, C.; Audigane, P.; Jacquemet, N.; Lagneau, V.; Delaplace, P.; Perfetti, E.

    2010-01-01

    The objective of the 'Geocarbone-INTEGRITE' project (2005-2008) was to develop a methodology to assess the integrity of the cap-rock involved in the geological storage of CO 2 . A specific work package of the project (WP5) was dedicated to the integration of (1) the phenomenology describing the evolution of the storage system with a focus on the mechanisms occurring in the cap-rock and at the interface with the cap-rock, and (2) the data obtained from the investigation of petrographical, geomechanical, and geochemical properties, before and after reaction with CO 2 -rich solutions, performed in the other work packages (WP1 to WP4). This knowledge was introduced in numerical models and specific safety scenarios were defined in order to assess the performance of the CO 2 storage system. The results of the modeling show that the injection of CO 2 can potentially have a significant effect on the cap-rock by changing the porosity due to the dissolution and precipitation of minerals, but that the impact is limited to a zone from several decimeters to several meters of the cap-rock close to the interface with the reservoir depending on whether the supercritical carbon dioxide (SC-CO 2 ) plume enters into the cap-rock and if fractures are present at this location. The methodology used in this project can be applied to a pilot site for the injection of CO 2 in the Paris Basin. A key aspect of the safety of such a facility will be to look at the coupling of geochemical alteration and the evolution of geomechanical properties in the short and medium terms (several hundreds of years). The challenge for the future will be to structure and apply the safety assessment methodology with an operational finality, in order to support the robustness of the transition step to CGS projects at the industrial scale. (authors)

  1. A conceptual model for groundwater flow and geochemical evolution in the southern Outaouais Region, Québec, Canada

    Montcoudiol, N.; Molson, J.; Lemieux, J.-M.; Cloutier, V.

    2015-01-01

    Highlights: • Geochemical and isotope data help constrain the 2D conceptual flow model. • Stable isotopes indicate recharge occurring under conditions similar to current climate. • Mixing was found between younger ( 3 H) and older ( 14 C and 4 He) groundwater. • Mixing occurred under natural flow conditions and/or was induced during sampling. • The new conceptual model shows dominant local and intermediate flow systems. - Abstract: A conceptual model was developed for a hydrogeological flow system in the southern Outaouais Region, Quebec, Canada, where the local population relies heavily on groundwater pumped from shallow overburden aquifers and from deeper fractured crystalline bedrock. The model is based on the interpretation of aqueous inorganic geochemical data from 14 wells along a cross-section following the general flow direction, of which 9 were also analysed for isotopes (δ 18 O, δ 2 H, 3 H, δ 13 C, 14 C) and 4 for noble gases (He, Ne, Ar, Xe, Kr). Three major water types were identified: (1) Ca–HCO 3 in the unconfined aquifer as a result of silicate (Ca-feldspar) weathering, (2) Na–Cl as a remnant of the post-glacial Champlain Sea in stagnant confined zones of the aquifer, and (3) Na–HCO 3 , resulting from freshening of the confined aquifer due to Ca–Na cation exchange. Chemical data also allowed the identification of significant mixing zones. Isotope and noble gas data confirm the hypothesis of remnant water from the Champlain Sea and also support the hypothesis of mixing processes between a young tritium-rich component with an older component containing high 4 He concentrations. It is still unclear if the mixing occurs under natural flow conditions or if it is induced by pumping during the sampling, most wells being open boreholes in the bedrock. It is clear, however, that the hydrogeochemical system is dynamic and still evolving from induced changes since the last glaciation. As a next step, the conceptual model will serve as a

  2. Long-term Geochemical Evolution of Lithogenic Versus Anthropogenic Distribution of Macro and Trace Elements in Household Attic Dust.

    Balabanova, Biljana; Stafilov, Trajče; Šajn, Robert; Tănăselia, Claudiu

    2017-01-01

    Attic dusts were examined as historical archives of anthropogenic emissions, with the goal of elucidating the enrichment pathways associated with hydrothermal exploitation of Cu, Pb, and Zn minerals in the Bregalnica River basin in the eastern part of the Republic of Macedonia. Dust samples were collected from 84 settlements. Atomic emission spectrometry and mass spectrometry with inductively coupled plasma were applied as analytical techniques for the determination of 69 element contents. Multivariate analysis was applied for the extraction of dominant geochemical markers. The lithogenic distribution was simplified to six dominant geochemical markers: F1: Ga-Nb-Ta-Y-(La-Gd)-(Eu-Lu); F2: Be-Cr-Li-Mg-Ni; F3: Ag-Bi-Cd-Cu-In-Mn-Pb-Sb-Te-W-Zn; F4: Ba-Cs-Hf-Pd-Rb-Sr-Tl-Zr; F5: As-Co-Ge-V; and F6: К-Na-Sc-Ti. The anthropogenic effects on the air pollution were marked by a dominance of F3 and secondary dominance of F5. The fifth factor also was determined as a lithogenic marker for the occurrence of the very old Rifeous shales. The first factor also presents a very unique association that despite the heterogeneity relays on natural phenomena of tracking the deposition in areas of Proterosoic gneisses; related to the distribution of fine particles was associated with carbonate-silicate volcanic rocks. Intensive poly-metallic dust depositions were recorded only in the surroundings of localities where the hydrothermal extractions are implemented. Long-term deposition can be considered as pollution indexes for these hot spots. This mainly affects the Cd, Pb, and Zn deposition that is as high as 25, 3900, and 3200 mg/kg, respectively.

  3. PERFIL PROFESIONAL Y PERFIL LABORAL EN LOS DOCENTES DEL INSTITUTO SUPERIOR PEDAGÓGICO PÚBLICO AREQUIPA AREQUIPA, 2012

    MONTESINOS CHÁVEZ, MARÍA ELENA

    2014-01-01

    GESTIÓN SOCIAL Y RECURSOS HUMANOS EL PERFIL PROFESIONAL CARACTERÍSTICAS DEL PERFIL PROFESIONAL DIMENSIONES DEL PERFIL PROFESIONAL DOCENTE NIVELES DE ESPECIFICACIÓN DEL PERFIL PROFESIONAL GESTIÓN EDUCATIVA Y PERFILES PROFESIONAL Y DOCENTE PERFIL PROFESIONAL DOCENTE ASPECTOS FUNDAMENTALES ANÁLISIS DEL PERFIL DOCENTE EVALUACIÓN DEL PERFIL DOCENTE LAS UNIVERSIDADES Y EL PERFIL PROFESIONAL DE DOCENTES EL PERFIL LABORAL DOCENTE DEFINICIÓN COMPONENTES DEL PERFIL LABORAL OBJETIVOS DE LA ELABORACIÓN D...

  4. The evolution of crop cultivation and paleoenvironment in the Longji Terraces, southern China: Organic geochemical evidence from paleosols.

    Jiang, Yongjian; Li, Shijie; Chen, Wei; Cai, Desuo; Liu, Yan

    2017-11-01

    The Longji ancient agricultural terraces in the Longji Mountain area (Guilin, southern China), which still remain in use, are famous for their magnificent terraced landscape with a mix of ecosystem and human inhabitation. Previous research has revealed the genesis and preliminary paleoenvironmental record of the agricultural terraces, but little is known about variations in crop cultivation over time. In this study, organic geochemical analyses and radiocarbon dating of an aggradational cultivated soil from a terrace profile were used to explore crop type variation and relevant paleoenvironmental change during the period of cultivation on the Longji Terraces. Hydroponic farming with rice (C 3 ) planting has been the dominant cultivation mode since the initial construction of the terraces. Warm-dry climate contributed to the growth of drought-tolerant crop (C 4 ) cultivation in the late 15th century. Temperature deterioration during the Little Ice Age had a negative impact on dry and hydroponic farming activities from the late 15th century to the late 19th century, while climate warming after the Little Ice Age promoted the redevelopment of hydroponic farming. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Geochemical evolution of the acid crater lake of Poas volcano (Costa Rica): Insights into volcanic-hydrothermal processes

    Martínez Cruz, María

    2008-01-01

    This thesis describes the evolution of Laguna Caliente, an acid crater lake at the summit of Po:is, a persistently active volcano in central Costa Rica. The appearance, volume, temperature and chemical composition of the lake have continuously changed over the entire known period of its

  6. Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence

    Piochi, M.; Ayuso, R.A.; de Vivo, B.; Somma, R.

    2006-01-01

    New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma-Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal abundance, as well as by wide ranges of trace element contents and a wide span of initial Sr-isotopic compositions. Both the degree of undersaturation in silica and the crystal content increase through time, being higher in rocks produced after the eruption at 472 AD (Pollena eruption). Compositional variations have been generally thought to reflect contributions from diverse types of mantle and crust. Magma mixing is commonly invoked as a fundamental process affecting the magmas, in addition to crystal fractionation. Our assessment of geochemical and Sr-isotopic data indicates that compositional variability also reflects the influence of crustal contamination during magma evolution during upward migration to shallow crustal levels and/or by entrapment of crystal mush generated during previous magma storage in the crust. Using a variant of the assimilation fractional crystallization model (Energy Conservation-Assimilation Fractional Crystallization; [Spera and Bohrson, 2001. Energy-constrained open-system magmatic processes I: General model and energy-constrained assimilation and fractional crystallization (EC-AFC) formulation. J. Petrol. 999-1018]; [Bohrson, W.A. and Spera, F.J., 2001. Energy-constrained open-system magmatic process II: application of energy-constrained assimilation-fractional crystallization (EC-AFC) model to magmatic systems. J. Petrol. 1019-1041]) we estimated the contributions from the crust and suggest that contamination by carbonate rocks that underlie the volcano (2 km down to 9-10 km) is a fundamental process controlling magma compositions at Mt. Somma

  7. Geochemical characterisation of kerogen from the Boom Clay Formation (Mol, Belgium) and evolution under different thermal stress

    Deniau, I.

    2002-12-01

    The Boom clay formation in Belgium has been chosen as test site for the disposal of high level radioactive wastes. The organic matter present in the clay (kerogen) is sensible to the thermal stress and can generate a huge number of gaseous and liquid compounds leading to local pH changes and to fracturing processes. In particular, some polar compounds can complex radionuclides. The samples analyzed in this work were taken in the underground laboratory of Mol at a 223 m depth. They have been analyzed in detail using geochemical methods (Rock-Eval pyrolysis, element analysis, transmission and scanning electron microscopy), spectroscopic methods (Fourier transformation infrared spectroscopy, solid state 13 C NMR, Raman) and pyrolytic methods (off-line, on-line and in sealed tubes combined with coupled CG/SM analyses). The study of a representative sample of this formation has permitted to characterize the organic matter at the molecular scale, to determine its fossilization mechanisms and the nature of the organic compounds trapped inside the kerogen. The organic matter of the Boom clays comes mainly from phyto-planktonic matter with an important contribution of terrestrial and bacterial matter. The degradation-recondensation played an important role in its preservation but the presence of numerous oxygenated molecules implies that oxidative incorporation also participated to this preservation. Finally, various products (hydrocarbons, oxygenated and nitrogenous polar compounds) trapped in significant amount inside the macro-molecular structure are released under a relatively weak thermal stress. Moreover several small polar organic molecules are released and can play a significant role in the retention or migration of radionuclides inside the geologic barrier. A sample submitted to a in-situ thermal stress of 80 deg. C during 5 years (Cerberus experiment) do not show any significant change in its kerogen structure with respect to the non-heated reference sample

  8. Recharge sources and geochemical evolution of groundwater in the Quaternary aquifer at Atfih area, the northeastern Nile Valley, Egypt

    El-Sayed, Salah Abdelwahab; Morsy, Samah M.; Zakaria, Khalid M.

    2018-06-01

    This study addresses the topic of recharge sources and evolution of groundwater in the Atfih area situated in the northeastern part of the Nile Valley, Egypt. Inventory of water wells and collection of groundwater and surface water samples have been achieved. Water samples are analyzed for major ions according to the American Society for Testing and Materials and for the environmental isotopes analysis (oxygen-18 and deuterium) by using a Triple Liquid Isotopic Water Analyzer (Los Gatos). The groundwater is available from the Quaternary aquifer formed mainly of graded sand and gravel interbedded with clay lenses. The hydrogeologic, hydrogeochemical and isotopic investigations indicate the hydrodynamic nature of the aquifer, where different flow paths, recharge sources and evolution mechanisms are distinguished. The directions of groundwater flow are from E, W and S directions suggesting the contribution from Nile River, the Eocene aquifer and the Nile basin, respectively. The groundwater altitudes range from 13 m (MSL) to 44 m (MSL). The hydraulic gradient varies between 0.025 and 0.0015. The groundwater is alkaline (pH > 7) and has salinity ranging from fresh to brackish water (TDS between 528 mg/l and 6070 mg/l). The observed wide range in the ionic composition and water types reflects the effect of different environmental and geological conditions through which the water has flowed. The isotopic compositions of groundwater samples vary between -14.13‰ and +23.56 for δD and between - 2.91‰ and +3.10 for δ18O. The isotopic data indicates that the Quaternary aquifer receive recharge from different sources including the Recent Nile water, surplus irrigation water, old Nile water before the construction of Aswan High Dam, surface runoff of local rains and Eocene aquifer. Evaporation, water rock interaction and mixing between different types of waters are the main processes in the groundwater evolution. Major suggestions are presented to develop the aquifer

  9. A geochemical and Pb, Sr isotopic study of the evolution of granite-gneisses from the Bastar craton, Central India

    Sarkar, G.; Paul, D.K.; Misra, V.P.; de Laeter, J.R.; Mc Naughton, N.J.

    1990-01-01

    Preliminary Pb-Pb and Rb-Sr geochronology of granitic and gneissic rocks from the Sukma area of the Bastar craton, Central India, provides important constraints on crustal evolution. Much of the craton is made up of felsic orthogneisses and younger granitic intrusives, compositionally ranging from tonalite to granite. Pb-Pb isotopic data suggest the presence of ca. 3.0 Ga old gneisses. Younger granitic intrusives have been dated at ca. 2.6 Ga which represents a widespread resetting and/or emplacement event. Comparison of the Pb-Pb and Rb-Sr whole rock ages suggests that the latter were more perturbed after the gneiss-forming or emplacement events. All rock suites show significant geological scatter of isotopic data probably because of sampling on a regional scale, and reflect multi-stage isotopic evolution in a complex terrain. The present isotopic data indicate the presence of Archaean rock in the Bastar craton and suggest temporal similarity with the oldest crustal rocks in the Singhbhum and Dharwar cratons. (author). 18 refs., 4 tabs., 8 figs

  10. Hydrochemical investigation and status of geochemical modeling of groundwater evolution at the Kamaishi in-situ tests site, Japan

    Sasamoto, Hiroshi; Yui, Mikazu; Arthur, Randolph C.

    1999-07-01

    The results of hydrochemical investigations of groundwaters in the Kurihashi granodiorite at JNC's Kamaishi in-situ tests site indicate that these solutions are: meteoric in origin, chemically reducing (at depths greater than a few hundreds meters), relatively young [residence times in the Kurihashi granodiorite generally less than about 40 years, but groundwaters older than several thousand years BP (before present) are also indicated by preliminary carbon-14 dating of samples obtained from the KH-1 borehole], Ca-HCO 3 type solutions near the surface, changing to Na-HCO 3 type groundwaters with increasing depth. The evolution of groundwater compositions in the Kurihashi granodiorite is modeled assuming local equilibrium for selected mineral-fluid reactions, taking into account the rainwater origin of these solutions. Results suggest it is possible to interpret approximately the 'real' groundwater chemistry (i.e., pH, Eh, total dissolved concentrations of Si, Na, Ca, K, Al, carbonate and sulfate) in the Kurihashi granodiorite if the following assumptions are adopted: CO 2 concentration in the gas phase contacting pore solutions in the overlying soil zone=10 -2 bar, minerals in the rock zone that control the solubility of respective elements in the groundwater include; chalcedony (Si), albite (Na), kaolinite (Al), calcite (Ca and carbonate), microcline (K) and pyrite (Eh and sulfate). Discussions with international experts suggest a systematic approach utilizing reaction-path models of irreversible water-rock interactions in open systems may be needed to more realistically model groundwater evolution at the Kamaishi test site. Detailed information characterizing certain site properties (e.g., fracture mineralogy) may be required to adequately constrain such models, however. (author)

  11. Hydrocarbons dating by Re-Os method: experimental study of the Re-Os couple geochemical behaviour in oils during the evolution of a petroleum system

    Mahdaoui, Fatima

    2013-01-01

    The Re-Os radiogenic system is well adapted to the dating of oils and bitumen. However the meaning of the obtained age is ambiguous. This is mainly due to gaps in our knowledge of the geochemical behavior and the speciation of Re and Os in oils. Specifically, use of the Re-Os geo-chronometer requires an understanding of how Re-Os behavior can lead to the fulfillment of the conditions necessary for the development of an isochron. These conditions are: i) the isotopic homogenization of oils at the scale of a petroleum field ii) the fractionation of Re from Os so as to obtain samples with various Re/Os ratios iii) the closure of the system during the period of radiogenic ingrowth of the daughter isotope, that is, from the time of the event of interest to the present day. Experimental investigation of the organic geochemical behavior of Re and Os in oils under various conditions, designed as analogs of the different stages of petroleum generation and evolution, were performed in order to evaluate the use of the Re-Os system as a geo-chronometer in the context of a direct use on petroleum. The possibility of Re-Os fractionation resulting from asphaltene loss during oil evolution was investigated by sequential asphaltene precipitation in the laboratory. This study determined that Re and Os are mainly located in the most polar asphaltene fractions, that is, in the first to precipitate. This study also demonstrated that Re/Os ratios are not disturbed by asphaltene loss during the evolution of oils, unless this loss is unrealistically large. Thus asphaltene precipitation during migration and emplacement is not responsible for the Re/Os fractionation required for the use of the geo-chronometer. The possibility of metal transfer from formation waters to petroleum was studied by performing contact experiments between oils and aqueous solutions of Re and Os of various concentrations over a wide range of temperatures and for varying periods of time. This study demonstrated a

  12. Geochemical modelling of the evolution of a granite-concrete-water system around a repository for spent nuclear fuel

    Fritz, B.; Made, B.; Tardy, Y.

    1988-04-01

    The interactions between a granitic rock and concrete due to the natural solutions circulating around a repository for spent nuclear fuel has been simulated considering the dissolution of Ca(OH) 2 as the major source of alkalinity due to the concrete. This study follows a previous one considering the same interaction without concrete at 25, 60 and 100 deg C. The temperature range has been extended to 150 deg C. The results of the modelling are considered as following: - evolution of the water chemistry due to detected pssible chemical reactions. - minerals produced and dissolved. The calculations give mass transfers and volumic consequences (opening or closing tendencies). The conclusions of this yearly report are mainly the following: (1) the extent of the temperature range for the storage (up to 150 deg C) does not change the tendencies previously detected in the same conditions without any particular alkaline effect due to concrete dissolution, the reactions occurring tend to decrease the porosity of the rock by a sealing effect due to calcite precipitation and clays formation. (2) The effect of an alkaline concrete dissolution is clearly important, pH may reach very high values in closed system, and the volumic consequence is found in favour of an opening of the porosity, at the stage of saturation of the portlandite. This is probably an important point considering the security of natural barriers around such a repository. (authors)

  13. The role of anthropogenic and natural factors in shaping the geochemical evolution of groundwater in the Subei Lake basin, Ordos energy base, Northwestern China.

    Liu, Fei; Song, Xianfang; Yang, Lihu; Han, Dongmei; Zhang, Yinghua; Ma, Ying; Bu, Hongmei

    2015-12-15

    Groundwater resources are increasingly exploited for industrial and agricultural purposes in many arid regions globally, it is urgent to gain the impact of the enhanced anthropogenic pressure on the groundwater chemistry. The aim of this study was to acquire a comprehensive understanding of the evolution of groundwater chemistry and to identify the impact of natural and anthropogenic factors on the groundwater chemistry in the Subei Lake basin, Northwestern China. A total of 153 groundwater samples were collected and major ions were measured during the three campaigns (August and December 2013, May 2014). At present, the major hydrochemical facies in unconfined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Na-HCO3, Ca-Mg-SO4 and Na-SO4-Cl types, while the main hydrochemical facies in confined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Ca-HCO3 and Na-HCO3 types. Relatively greater seasonal variation can be observed in the chemical constituents of confined groundwater than that of unconfined groundwater. Rock weathering predominates the evolution of groundwater chemistry in conjunction with the cation exchange, and the dissolution/precipitation of gypsum, halite, feldspar, calcite and dolomite are responsible for the chemical constituents of groundwater. Anthropogenic activities can be classified as: (1) groundwater overexploitation; (2) excessive application of fertilizers in agricultural areas. Due to intensive groundwater pumping, the accelerated groundwater mineralization resulted in the local changes in hydrochemical facies of unconfined groundwater, while the strong mixture, especially a large influx of downward leakage from the unconfined aquifer into the confined aquifer, played a vital role in the fundamental variation of hydrochemical facies in confined aquifer. The nitrate contamination is mainly controlled by the local hydrogeological settings coupled with the traditional flood irrigation. The deeper insight into geochemical evolution of

  14. A geochemical modelling study of the evolution of the chemical composition of seawater linked to a "snowball" glaciation

    G. Le Hir

    2008-02-01

    Full Text Available The Snowball Earth theory initially proposed by Kirschvink (1992 to explain the Neoproterozoic glacial episodes, suggested that the Earth was fully ice-covered at 720 Ma (Sturtian episode and 640 Ma (Marinoan episode. This succession of extreme climatic crises induced environmental perturbations which are considered as a strong selective pressure on the evolution of life (Hoffman et al., 1998. Using a numerical model of carbon-alkalinity global cycles, we quantify environmental stresses caused by a global glaciation. According to our results, we suggest that during global glaciations, the ocean becomes acidic (pH~6, and undersaturated with respect to carbonate minerals. Moreover the quick transition from ice-house to greenhouse conditions implies an abrupt and large shift of the oceanic surface temperature which causes an extended hypoxia. The intense continental weathering, in the aftermath of the glaciation, deeply affects the seawater composition inducing rapid changes in terms of pH and alkalinity. We also propose a new timing for post glacial perturbations and for the cap carbonates deposition, ~2 Myr instead of 200 kyr as suggested in a previous modelling study. In terms of Precambrian life sustainability, seawater pH modifications appear drastic all along the glaciation, but we suggest that the buffering action of the oceanic crust dissolution avoids a total collapse of biological productivity. But short-lived and large post-glacial perturbations are more critical and may have played the role of an environmental filter proposed in the classic snowball Earth theory. Although the link between environmental changes and life sustainability cannot be modelled accurately, we suggest that only a permissive life (Knoll, 2003 may explain the relative continuity in microfossils diversity observed before, during and after Neoproterozoic glaciation events.

  15. Geochemical evolution of a high arsenic, alkaline pit-lake in the Mother Lode Gold District, California

    Savage, Kaye S.; Ashley, Roger P.; Bird, Dennis K.

    2009-01-01

    The Harvard orebody at the Jamestown gold mine, located along the Melones fault zone in the southern Mother Lode gold district, California, was mined in an open-pit operation from 1987 to 1994. Dewatering during mining produced a hydrologic cone of depression; recovery toward the premining ground-water configuration produced a monomictic pit lake with alkaline Ca-Mg-HCO3-SO4–type pit water, concentrations of As up to 1,200 μg/L, and total dissolved solids (TDS) up to 2,000 mg/L. In this study, pit-wall rocks were mapped and chemically analyzed to provide a context for evaluating observed variability in the composition of the pit-lake waters in relationship to seasonal weather patterns. An integrated hydrogeochemical model of pit-lake evolution based on observations of pit-lake volume, water composition (samples collected between 1998–2000, 2004), and processes occurring on pit walls was developed in three stages using the computer code PHREEQC. Stage 1 takes account of seasonally variable water fluxes from precipitation, evaporation, springs, and ground water, as well as lake stratification and mixing processes. Stage 2 adds CO2fluxes and wall-rock interactions, and stage 3 assesses the predictive capability of the model.Two major geologic units in fault contact comprise the pit walls. The hanging wall is composed of interlayered slate, metavolcanic and metavolcaniclastic rocks, and schists; the footwall rocks are chlorite-actinolite and talc-tremolite schists generated by metasomatism of greenschist-facies mafic and ultramafic igneous rocks. Alteration in the ore zone provides evidence for mineralizing fluids that introduced CO2, S, and K2O, and redistributed SiO2. Arsenian pyrite associated with the alteration weathers to produce goethite and jarosite on pit walls and in joints, as well as copiapite and hexahydrite efflorescences that accumulate on wall-rock faces during dry California summers. All of these pyrite weathering products incorporate arsenic at

  16. Evolution of Metallic Trace Elements in Contaminated River Sediments: Geochemical Variation Along River Linear and Vertical Profile

    Kanbar, Hussein; Montarges-Pelletier, Emmanuelle; Mansuy-Huault, Laurence; Losson, Benoit; Manceau, Luc; Bauer, Allan; Bihannic, Isabelle; Gley, Renaud; El Samrani, Antoine; Kobaissi, Ahmad; Kazpard, Veronique; Villieras, Frédéric

    2015-04-01

    Metal pollution in riverine systems poses a serious threat that jeopardizes water and sediment quality, and hence river dwelling biota. Since those metallic pollutants can be transported for long distances via river flow, river management has become a great necessity, especially in times where industrial activities and global climate change are causing metal release and spreading (by flooding events). These changes are able to modify river hydrodynamics, and as a consequence natural physico-chemical status of different aquatic system compartments, which in turn alter metal mobility, availability and speciation. Vertical profiles of sediments hold the archive of what has been deposited for several tenths of years, thus they are used as a tool to study what had been deposited in rivers beds. The studied area lies in the Orne river, northeastern France. This river had been strongly modified physically and affected by steelmaking industrial activities that had boosted in the middle of the last century. This study focuses on several sites along the linear of the Orne river, as well as vertical profiles of sediments. Sediment cores were collected at sites where sedimentation is favoured, and in particular upstream two dams, built in the second half of the XXth century for industrial purposes. Sediment cores were sliced into 2-5cm layers, according to suitability, and analysed for physical and physico-chemical properties, elemental content and mineralogy. Data of the vertical profile in a sediment core is important to show the evolution of sediments as a function of depth, and hence age, in terms of nature, size and constituents. The physical properties include particle size distribution (PSD) and water content. In addition, the physico-chemical properties, such as pH and oxido-reduction potential (ORP) of interstitial water from undisturbed cores were also detected. Total elemental content of sediment and available ones of extracted interstitial waters was detected using

  17. The Marbat metamorphic core-complex (Southern Arabian Peninsula) : reassessment of the evolution of a Neoproterozoic island-arc from petrological, geochemical and U-Pb zircon data

    Barbey, P.; Denele, Y.; Paquette, J. L.; Berger, J.; Ganne, Jérôme; Roques, D.

    2018-01-01

    The Marbat basement (Sultanate of Oman) belongs to the Neoproterozoic accretion domain of the Arabian-Nubian shield. We present new geochronological, petrological and geochemical data as an extension of our previous study (Denele et al., 2017) re-interpreting this basement as a metamorphic core complex (MCC). We showed that this MCC consists of a metamorphic unit (Juffa complex) separated by an extensional detachment from a plutonic unit (Sadh complex and Tonalite plutons). Geochemical data s...

  18. The 2014-15 eruption and the short-term geochemical evolution of the Fogo volcano (Cape Verde): Evidence for small-scale mantle heterogeneity

    Mata, J.; Martins, S.; Mattielli, N.; Madeira, J.; Faria, B.; Ramalho, R. S.; Silva, P.; Moreira, M.; Caldeira, R.; Moreira, M.; Rodrigues, J.; Martins, L.

    2017-09-01

    Recurrent eruptions at very active ocean island volcanoes provide the ideal means to gain insight on the scale of spatial variations at the mantle source and on temporal changes of magma genesis and evolution processes. In 2014, after 19 years of quiescence, Fogo volcano (Cape Verde Archipelago) experienced a new eruption, with the vents located 200 m from those of the 1995 eruption, and less than 2000 m from those of the 1951 event. This offered a unique opportunity to investigate the existence of small-scale mantle heterogeneities and the short-term compositional evolution of magmas erupted by a very active oceanic volcano like Fogo. Here we present petrological and geochemical data from the early stages of the Fogo's most recent eruption - started on November 23, 2014 - and compare them with the signature of previous eruptions (particularly those of 1995 and 1951). The magmas erupted in 2014 are alkaline (up to 23.4% and 0.94% of normative ne and lc, respectively) with somewhat evolved compositions (Mg # < 56), ranging from tephrites to phonotephrites. The eruption of phonotephritic lavas preceded the effusion of tephritic ones. Lavas carried to the surface clinopyroxene and kaersutite phenocrysts and cognate megacrysts, which indicate that the main stages of magma evolution occurred in magma chambers most probably located at mantle depths (25.6 ± 5.5 km below sea level). This was followed by a shallower (< 1.5 km below sea level) and shorter (≈ 50 days) magma stagnation before the eruption. 2014 magmas have more unradiogenic Sr and more radiogenic Nd compositions than those of the previous 1951 and 1995 eruptions, which generally have less radiogenic Pb ratios. These isotopic differences - coming from quasi-coeval materials erupted almost in the same place - are remarkable and reflect the small-scale heterogeneity of the underlying mantle source. Moreover, they reflect the limited isotopic averaging of the source composition during partial melting events as

  19. Evolução do perfil neuromotor e capacidade funcional de mulheres fisicamente ativas de acordo com a idade cronológica Evolución del perfil neuromotor y la capacidad funcional de mujeres fisicamente activas de acuerdo con la edad cronológica Evolution of neuromotor profile and functional capacity of physically active women according to chronological age

    Sandra Mahecha Matsudo

    2003-11-01

    é comparar la evolución del perfil neuromotor y la capacidad funcional de mujeres activas en el período de un año de acuerdo con la edad cronológica. MÉTODOS: La muestra estuvo compuesta por 117 mujeres de 50 a 79 años de edad (: 65 ± 6,6 años participantes de un programa de ejercicios aeróbicos, dos veces por semana, 50 minutos por sesión durante 5,4 ± 3,0 años y divididas por la edad: 50-59 (n: 23; 60-69 (n: 60; 70-79 (n: 34. Los tests neuromotores y de movilidad incluyeron: fuerza muscular de los miembros inferiores y superiores, agilidad, flexibilidad de tronco, velocidad de levantarse de la silla, equilíbrio estático, velocidad normal de andar y velocidad máxima de andar. Los resultados iniciales de las dos evaluaciones siguientes, realizadas intérvalos de 6 meses, fueron comparados usando ANOVA two way, con post-hoc Bonferroni. RESULTADOS: En un ano no hubo ninguna alteración del desempeño neuromotor, ya que la velocidad de levantar de la silla y la velocidad de andar no evidenciaron diferencias significativas en los grupos de 50-59 e 60-69 años, presentando resultados un 10-20% mejores; en cuanto a la velocidad máxima de andar hubo una mejora (8% en los grupos de 60 a 79 años. CONCLUSIÓN: La evolución de la aptitud física y la capacidad funcional tuvo un comportamiento similar, en mujeres físicamente activas independientemente de la edad cronológica. Esta evolución fortalece la hipótesis de un efecto favorable de la actividad física regular en la promoción de la salud, estrategia fundamental del envejecimiento saludable.BACKGROUND AND PURPOSE: There are few longitudinal studies to determine the effect of aging on physical fitness and functional capacity of physically active women. The purpose of this study was to compare the evolution of neuromotor profile and functional capacity in active elderly women in one-year period as related to chronological age at the base line. METHODS: Sample consisted of 117 women from 50 to 79 years of age

  20. Late Cenozoic Magmatic and Tectonic Evolution of the Ancestral Cascade Arc in the Bodie Hills, California and Nevada: Insights from Integrated Geologic, Geophysical, Geochemical and Geochronologic Studies

    John, D. A.; du Bray, E. A.; Box, S. E.; Blakely, R. J.; Fleck, R. J.; Vikre, P. G.; Cousens, B.; Moring, B. C.

    2012-12-01

    Geologic mapping integrated with new geophysical, geochemical, and geochronologic data characterize the evolution of Bodie Hills volcanic field (BHVF), a long-lived eruptive center in the southern part of the ancestral Cascade arc. The ~700 km2 field was a locus of magmatic activity from ~15 to 8 Ma. It includes >25 basaltic andesite to trachyandesite stratovolcanoes and silicic trachyandesite to rhyolite dome complexes. The southeastern part of the BHVF is overlain by the ~3.9 to 0.1 Ma, post-arc Aurora Volcanic Field. Long-lived BHVF magmatism was localized by crustal-scale tectonic features, including the Precambrian continental margin, the Walker Lane, the Basin and Range Province, and the Mina deflection. BHVF eruptive activity occurred primarily during 3 stages: 1) dominantly trachyandesite stratovolcanoes (~15.0 to 12.9 Ma), 2) coalesced trachydacite and rhyolite lava domes and trachyandesite stratovolcanoes (~11.6 to 9.7 Ma), and 3) dominantly silicic trachyandesite to dacite lava dome complexes (~9.2 to 8.0 Ma). Small rhyolite domes were emplaced at ~6 Ma. Relatively mafic stratovolcanoes surrounded by debris flow aprons lie on the margins of the BHVF, whereas more silicic dome fields occupy its center. Detailed gravity and aeromagnetic data suggest the presence of unexposed cogenetic granitic plutons beneath the center of the BHVF. Isotopic compositions of BHVF rocks are generally more radiogenic with decreasing age (e.g., initial Sr isotope values increase from ~0.7049 to 0.7061), which suggests progressively greater magma contamination by crustal components during evolution of the BHVF. Approximately circular, polygenetic volcanoes and scarcity of dikes suggest a low differential horizontal stress field during BHVF formation. Extensive alluvial gravel deposits that grade laterally into fluvial gravels and finer grained lacustrine sediments and the westerly sourced Eureka Valley Tuff (EVT; ~9.4 Ma) blanket large parts of the BHVF. The earliest sediments

  1. Geological evolution of the center-southern portion of the Guyana shield based on the geochemical, geochronological and isotopic studies of paleoproterozoic granitoids from southeastern Roraima, Brazil

    Almeida, Marcelo Esteves

    2006-01-01

    This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of Cd (1.96-1.93 Ga). Regional mapping, petrography, geochemistry and zircon geochronology carried out in the Urad have showed widespread Paleoproterozoic calc-alkaline granitic magmatism. These granitoid rocks are distributed into several magmatic associations with different Paleoproterozoic (1.97-1.89 Ga) ages, structural and geochemical affinities. Detailed mapping, petrographic and geochronological studies have distinguished two main sub domains in the UAD. In the northern UAD, the high-K calc-alkaline Martins Pereira (1.97 Ga) and Serra Dourada S-type granites (1.96 Ga) are affected by NE-SW and E-W ductile dextral shear-zones, showing coexistence of magmatic and deformational fabrics related to heterogeneous deformation. Inliers of basement (2.03 Ga) crop out northeast of this area, and are formed by meta volcano-sedimentary sequence (Cauarane Group) and TTG-like calc-alkaline association (Anaua Complex). Xenoliths of meta diorites (Anaua Complex) and para gneisses (Cauarane Group) reinforce the intrusive character of Martins Pereira

  2. Late Paleozoic-Early Mesozoic tectonic evolution of the Paleo-Asian Ocean: geochronological and geochemical evidence from granitoids in the northern margin of Alxa, Western China

    Sha, Xin; Wang, Jinrong; Chen, Wanfeng; Liu, Zheng; Zhai, Xinwei; Ma, Jinlong; Wang, Shuhua

    2018-03-01

    The Paleo-Asian Ocean (Southern Mongolian Ocean) ophiolitic belts and massive granitoids are exposed in the Alxa block, in response to oceanic subduction processes. In this work, we report petrographic, geochemical, and zircon U-Pb age data of some granitoid intrusions from the northern Alxa. Zircon U-Pb dating for the quartz diorite, tonalite, monzogranite, and biotite granite yielded weighted mean 206Pb/238U ages of 302±9.2 Ma, 246.5±4.6 Ma, 235±4.4 Ma, and 229.5±5.6 Ma, respectively. The quartz diorites ( 302 Ma) exhibit geochemical similarities to adakites, likely derived from partial melting of the initially subducted Chaganchulu back-arc oceanic slab. The tonalites ( 246.5 Ma) display geochemical affinities of I-type granites. They were probably derived by fractional crystallization of the modified lithospheric mantle-derived basaltic magmas in a volcanic arc setting. The monzogranites ( 235 Ma) are characterized by low Al2O3, but high Y and Yb with notably negative Eu anomalies. In contrast, the biotite granites ( 229.5 Ma) show high Al2O3 but low Y and Yb with steep HREE patterns and the absence of negative Eu anomalies. Elemental data suggested that the biotite granites were likely derived from a thickened lower crust, but the monzogranites originated from a thin crust. Our data suggested that the initial subduction of the Chaganchulu oceanic slab towards the Alxa block occurred at 302 Ma. This subduction process continued to the Early Triassic ( 246 Ma) and the basin was finally closed before the Middle Triassic ( 235 Ma). Subsequently, the break-off of the subducted slab triggered asthenosphere upwelling (240-230 Ma).

  3. Geochemical evolution processes and water-quality observations based on results of the National Water-Quality Assessment Program in the San Antonio segment of the Edwards aquifer, 1996-2006

    Musgrove, MaryLynn; Fahlquist, Lynne; Houston, Natalie A.; Lindgren, Richard J.; Ging, Patricia B.

    2010-01-01

    As part of the National Water-Quality Assessment Program, the U.S. Geological Survey collected and analyzed groundwater samples during 1996-2006 from the San Antonio segment of the Edwards aquifer of central Texas, a productive karst aquifer developed in Cretaceous-age carbonate rocks. These National Water-Quality Assessment Program studies provide an extensive dataset of groundwater geochemistry and water quality, consisting of 249 groundwater samples collected from 136 sites (wells and springs), including (1) wells completed in the shallow, unconfined, and urbanized part of the aquifer in the vicinity of San Antonio (shallow/urban unconfined category), (2) wells completed in the unconfined (outcrop area) part of the regional aquifer (unconfined category), and (3) wells completed in and springs discharging from the confined part of the regional aquifer (confined category). This report evaluates these data to assess geochemical evolution processes, including local- and regional-scale processes controlling groundwater geochemistry, and to make water-quality observations pertaining to sources and distribution of natural constituents and anthropogenic contaminants, the relation between geochemistry and hydrologic conditions, and groundwater age tracers and travel time. Implications for monitoring water-quality trends in karst are also discussed. Geochemical and isotopic data are useful tracers of recharge, groundwater flow, fluid mixing, and water-rock interaction processes that affect water quality. Sources of dissolved constituents to Edwards aquifer groundwater include dissolution of and geochemical interaction with overlying soils and calcite and dolomite minerals that compose the aquifer. Geochemical tracers such as magnesium to calcium and strontium to calcium ratios and strontium isotope compositions are used to evaluate and constrain progressive fluid-evolution processes. Molar ratios of magnesium to calcium and strontium to calcium in groundwater typically

  4. PERFILES MOTIVACIONALES EN SALVAMENTO DEPORTIVO

    J.A. Moreno

    2010-09-01

    Full Text Available

     

    RESUMEN

    El objetivo de este trabajo fue establecer diferentes perfiles motivacionales en una muestra compuesta por 283 deportistas federados de salvamento deportivo (141 hombres y 142 mujeres, de edades comprendidas entre los 14 y los 38 años. Las variables analizadas fueron la percepción del clima motivacional, la motivación intrínseca, la motivación extrínseca, la desmotivación y el flow disposicional. El análisis cluster reveló tres perfiles motivacionales. El “perfil no autodeterminado” obtuvo puntuaciones altas en la percepción de un clima ego y en desmotivación, moderadas en motivación intrínseca, extrínseca y flow disposicional, y bajas en la percepción de un clima tarea. El “perfil autodeterminado” mostró puntuaciones altas en la percepción de un clima tarea y en motivación intrínseca, revelando los valores más altos de flow disposicional. También obtuvo puntuaciones moderadas en motivación extrínseca y bajas en desmotivación y en la percepción de un clima ego. El “perfil pobremente motivado” reflejó una puntuación moderada en la percepción de un clima ego y baja en el resto de variables de estudio. La puntuación más alta que obtuvo fue en desmotivación. Además, los resultados mostraron que en niveles de competición más elevados los perfiles motivacionales parecían ser más negativos.
    Palabras Clave: motivación, autodeterminación, clima motivacional, flow, salvamento deportivo.

     

    ABSTRACT

    The main purpose of this article has been to analyze the motivational profiles in a group of 283 lifesavers (141 male and 142 female, of ages 14 to 38 years. There were several variables that were analyzed: perception

  5. Perfil. María Rodilla

    Rodilla, María

    2017-01-01

    [ES] Perfil sobre María Rodilla, ilustradora valenciana que centra su trabajo en el feminismo Rodilla, M. (2017). Perfil. María Rodilla. EME Experimental Illustration, Art & Design. (5):52-53. doi:10.4995/eme.2017.7616. 52 53 5

  6. Neoproterozoic-Early Paleozoic Peri-Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U-Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

    Jiang, Y. D.; Schulmann, K.; Kröner, A.; Sun, M.; Lexa, O.; Janoušek, V.; Buriánek, D.; Yuan, C.; Hanžl, P.

    2017-11-01

    Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an integrated geological, geochemical, and zircon U-Pb geochronological study on a giant Ordovician metasedimentary succession of the Mongolian Altai Mountains. This succession is characterized by dominant terrigenous components mixed with volcanogenic material. It is chemically immature, compositionally analogous to graywacke, and marked by significant input of felsic to intermediate arc components, pointing to an active continental margin depositional setting. Detrital zircon U-Pb ages suggest a source dominated by products of early Paleozoic magmatism prevailing during the Cambrian-Ordovician and culminating at circa 500 Ma. We propose that the Ordovician succession forms an "Altai sedimentary wedge," the evolution of which can be linked to the geodynamics of the margins of the Mongolian Precambrian Zavhan-Baydrag blocks. This involved subduction reversal from southward subduction of a passive continental margin (Early Cambrian) to the development of the "Ikh-Mongol Magmatic Arc System" and the giant Altai sedimentary wedge above a north dipping subduction zone (Late Cambrian-Ordovician). Such a dynamic process resembles the tectonic evolution of the peri-Pacific accretionary Terra Australis Orogen. A new model reconciling the Baikalian metamorphic belt along the southern Siberian Craton with peri-Pacific Altai accretionary systems fringing the Mongolian microcontinents is proposed to explain the Cambro-Ordovician geodynamic evolution of the Mongolian collage system.

  7. Integration of remote sensing, geochemical and field data in the Qena-Safaga shear zone: Implications for structural evolution of the Eastern Desert, Egypt

    El-Din, Gamal Kamal; Abdelkareem, Mohamed

    2018-05-01

    The Qena-Safaga shear zone (QSSZ) represents a significant structural characteristic in the Eastern Desert of Egypt. Remote Sensing, field and geochemical data were utilized in the present study. The results revealed that the QSSZ dominated by metamorphic complex (MC) that intruded by syn-tectonic granitoids. The low angle thrust fault brings calc-alkaline metavolcanics to overlie MC and its association. Subsequently, the area is dissected by strike-slip faults and the small elongated basins of Hammamat sediments of Precambrian were accumulated. The MC intruded by late-to post-tectonic granites (LPG) and Dokhan Volcanics which comprise felsic varieties forming distinctive columnar joints. Remote sensing analysis and field data revealed that major sub-vertical conspicuous strike-slip faults (SSF) including sinistral NW-SE and dextral ca. E-W shaped the study area. Various shear zones that accompanying the SSF are running NW-SE, NE-SW, E-W, N-S and ENE-WSW. The obtained shear sense presented a multiphase of deformation on each trend. i.e., the predominant NW-SE strike-slip fault trend started with sinistral displacement and is reactivated during later events to be right (dextral) strike slip cutting with dextral displacement the E-W trending faults; while NE-SW movements are cut by both the N-S and NNW - SSE trends. Remote sensing data revealed that the NW-SE direction that dominated the area is associated with hydrothermal alteration processes. This allowed modifying the major and trace elements of the highly deformed rocks that showed depletion in SiO2 and enrichments in Fe2O3, MnO, Al2O3, TiO2, Na2O, K2O, Cu, Zn and Pb contents. The geochemical signatures of major and trace elements revealed two types of granites including I-type calc-alkaline granites (late-to post-tectonic) that formed during an extensional regime. However, syn-tectonic granitoids are related to subduction-related environment.

  8. Geochemical Constraints for Mercury's PCA-Derived Geochemical Terranes

    Stockstill-Cahill, K. R.; Peplowski, P. N.

    2018-05-01

    PCA-derived geochemical terranes provide a robust, analytical means of defining these terranes using strictly geochemical inputs. Using the end members derived in this way, we are able to assess the geochemical implications for Mercury.

  9. Geochemical exploration for uranium

    1988-01-01

    This Technical Report is designed mainly to introduce the methods and techniques of uranium geochemical exploration to exploration geologists who may not have had experience with geochemical exploration methods in their uranium programmes. The methods presented have been widely used in the uranium exploration industry for more than two decades. The intention has not been to produce an exhaustive, detailed manual, although detailed instructions are given for a field and laboratory data recording scheme and a satisfactory analytical method for the geochemical determination of uranium. Rather, the intention has been to introduce the concepts and methods of uranium exploration geochemistry in sufficient detail to guide the user in their effective use. Readers are advised to consult general references on geochemical exploration to increase their understanding of geochemical techniques for uranium

  10. New geochemical, geochronological and structural constraints on the Ediacaran evolution of the south Sirwa, Agadir-Melloul and Iguerda inliers, Anti-Atlas, Morocco

    Blein, O.; Baudin, T.; Soulaimani, A.; Cocherie, A.; Chèvremont, P.; Admou, H.; Ouanaimi, H.; Hafid, A.; Razin, P.; Bouabdelli, M.; Roger, J.

    2014-10-01

    Paleoproterozoic metamorphic and igneous rocks, Tonian (?)-lower Cryogenian passive margin sedimentary rocks, Neoproterozoic dolerites, and Upper Ediacaran volcaniclastic, volcanic and pyroclastic rocks are exposed in the Agadir Melloul, Iguerda and the southern edge of the Sirwa inliers. A recent field mapping program of the Ediacaran Ouarzazate Group in these areas allow to distinguish three principal volcanic sequences. The first sequence (Adrar-n-Takoucht Formation) outcrops mainly south of the Sirwa inlier, and is composed of felsic pyroclastic deposits and local basaltic lavas with ages ranging between 572 and 570 Ma. The second sequence (Anammar and Tadoughast formations) occurs primarily in the Agadir Melloul-Jbel Iguiguil inlier. The Anammar Formation contains essentially volcano-detrital sediments, with fine airfall pyroclastic deposits. The Tadoughast Formation is composed of felsic pyroclastic deposits and rhyolitic domes with ages ranging between 567 and 564 Ma. The third sequence (Fajjoud Formation) contains felsic pyroclastic deposits, with an age of 556 Ma, associated with porphyritic basalts. The magmatism of the Ouarzazate Group was not continuous between 572 and 556 Ma, but related to distinct pyroclastic pulses. Geochemical data indicate that the pyroclastic rocks of the Ouarzazate Group have a highly potassic calc-alkaline to shoshonitic affinity. However, the basaltic facies associated with the Adrar-n-Takoucht Formation demonstrate a calc-alkaline affinity whereas those associated with the Fajjoud Formation have a tholeiitic affinity. Rhyolitic domes were derived from hyperaluminous leucogranites. In sum, the typology of zircons defines three poles: (i) subalkaline granites; (ii) calc-alkaline monzogranites and granodiorites frequently associated with basic rocks; and (iii) aluminous leucogranites. In addition, the volcaniclastic deposits of the Ouarzazate Group are submitted to a syn-sedimentary tectonic. The Adrar-n-Takoucht Formation is

  11. Geochemical modelling baseline compositions of groundwater

    Postma, Diederik Jan; Kjøller, Claus; Andersen, Martin Søgaard

    2008-01-01

    and variations in water chemistry that are caused by large scale geochemical processes taking place at the timescale of thousands of years. The most important geochemical processes are ion exchange (Valreas and Aveiro) where freshwater solutes are displacing marine ions from the sediment surface, and carbonate......Reactive transport models, were developed to explore the evolution in groundwater chemistry along the flow path in three aquifers; the Triassic East Midland aquifer (UK), the Miocene aquifer at Valreas (F) and the Cretaceous aquifer near Aveiro (P). All three aquifers contain very old groundwaters...... dissolution (East Midlands, Valreas and Aveiro). Reactive transport models, employing the code PHREEQC, which included these geochemical processes and one-dimensional solute transport were able to duplicate the observed patterns in water quality. These models may provide a quantitative understanding...

  12. Reconnaissance Geochemical Study

    distribution patterns. The geochemical distribution maps of the elements reveal that Cu, Pb, Zn, Co, Sc, Ni, Cr, .... After filtration, the leached solutions were diluted with ultra ...... some other rare earth elements in the study area. The occurrence ...

  13. Using environmental isotopes along with major hydro-geochemical compositions to assess deep groundwater formation and evolution in eastern coastal China

    Xu, Naizheng; Gong, Jianshi; Yang, Guoqiang

    2018-01-01

    Hydrochemical analysis and environmental isotopic tracing are successfully applied to study groundwater evolution processes. Located in eastern China, the Jiangsu Coastal Plain is characterized by an extensively exploited deep groundwater system, and groundwater salinization has become the primary water environmental problem. This paper provides a case study on the use of a hydrochemical and environmental isotopic approach to assess possible mixing and evolution processes at Yoco Port, Jiangsu Province, China. Hydrochemical and isotopic patterns of deep groundwater allow one to distinguish different origins in deep water systems. HCO3- is the dominant anion in the freshwater samples, whereas Na+ and Cl- are the dominant major ions in the saline samples. According to δ18O, δ2H and 14C dating, the fresh water is derived from precipitation under a colder climate during the Glacial Maximum (Dali Glacial), while the saline groundwater is influenced by glacial-interglacial cycles during the Holocene Hypsithermal. The δ18O, δ2H and 3H data confirm that deep groundwater in some boreholes is mixed with overlying saline water. The deep groundwater reservoir can be divided into a saline water sector and a fresh water sector, and each show distinct hydrochemical and isotopic compositions. The saline groundwater found in the deep aquifer cannot be associated with present seawater intrusion. Since the Last Glacial Maximum in the Late Pleistocene, the deep groundwater flow system has evolved to its current status with the decrease in ice cover and the rising of sea level. However, the hydraulic connection is strengthened by continuous overexploitation, and deep groundwater is mixed with shallow groundwater at some points.

  14. Isotopic and geochemical evolution of ground and surface waters in a karst dominated geological setting: a case study from Belize, Central America

    Marfia, A.M.; Krishnamurthy, R.V.; Atekwana, E.A.; Panton, W.F.

    2004-01-01

    Analysis of stable isotopes and major ions in groundwater and surface waters in Belize, Central America was carried out to identify processes that may affect drinking water quality. Belize has a subtropical rainforest/savannah climate with a varied landscape composed predominantly of carbonate rocks and clastic sediments. Stable oxygen (δ 18 O) and hydrogen (δD) isotope ratios for surface and groundwater have a similar range and show high d-excess (10-40.8%o). The high d-excess in water samples suggest secondary continental vapor flux mixing with incoming vapor from the Caribbean Sea. Model calculations indicate that moisture derived from continental evaporation contributes 13% to overhead vapor load. In surface and groundwater, concentrations of dissolved inorganic carbon (DIC) ranged from 5.4 to 112.9 mg C/l and δ 13 C DIC ranged from -7.4 to -17.4%o. SO 4 2 , Ca 2+ and Mg 2+ in the water samples ranged from 2-163, 2-6593 and 2-90 mg/l, respectively. The DIC and δ 13 C DIC indicate both open and closed system carbonate evolution. Combined δ 13 C DIC and Ca 2+ , Mg 2+ , and SO 4 2- suggest additional groundwater evolution by gypsum dissolution and calcite precipitation. The high SO 4 2- content of some water samples indicates regional geologic control on water quality. Similarity in the range of δ 18 O, δD and δ 13 C DIC for surface waters and groundwater used for drinking water supply is probably due to high hydraulic conductivities of the karstic aquifers. The results of this study indicate rapid recharge of groundwater aquifers, groundwater influence on surface water chemistry and the potential of surface water to impact groundwater quality and vise versa

  15. Sedimentary evolution of the Mesozoic continental redbeds using geochemical and mineralogical tools: the case of Upper Triassic to Lowermost Jurassic Monte di Gioiosa mudrocks (Sicily, southern Italy)

    Perri, Francesco; Critelli, Salvatore; Mongelli, Giovanni; Cullers, Robert L.

    2011-10-01

    The continental redbeds from the Internal Domains of the central-western Mediterranean Chains have an important role in the palaeogeographic and palaeotectonic reconstructions of the Alpine circum-Mediterranean orogen evolution since these redbeds mark the Triassic-Jurassic rift-valley stage of Tethyan rifting. The composition and the sedimentary evolution of the Middle Triassic to Lowermost Jurassic continental redbeds of the San Marco d'Alunzio Unit (Peloritani Mountains, Southern Italy), based on mineralogical and chemical analyses, suggests that the studied mudrock sediments share common features with continental redbeds that constitute the Internal Domains of the Alpine Mediterranean Chains. Phyllosilicates are the main components in the mudrocks. The 10 Å-minerals (illite and micas), the I-S mixed layers, and kaolinite are the most abundant phyllosilicates. The amount of illitic layers in I-S mixed layers coupled with the illite crystallinity values (IC) are typical of high degree of diagenesis, corresponding to a lithostatic/tectonic loading of about 4-5 km. The mineralogical assemblage coupled with the A-CN-K plot suggest post-depositional K-enrichments. Palaeoweathering proxies (PIA and CIW) record intense weathering at the source area. Further, the studied sediments are affected by reworking and recycling processes and, as consequence, it is likely these proxies monitor cumulative effect of weathering. The climate in the early Jurassic favoured recycling and weathering occurred under hot, episodically humid climate with a prolonged dry season. The source-area is the low-grade Paleozoic metasedimentary basement. Mafic supply is minor but not negligible as suggested by provenance proxies.

  16. Perfil do pesquisador fisioterapeuta brasileiro

    HJCG Coury

    Full Text Available OBJETIVO: Traçar um perfil do pesquisador fisioterapeuta quanto a sua formação, produção científica e fomento e bolsas obtidos pela área do Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq. MÉTODOS: Foram consultados os curricula vitae de cada pesquisador fisioterapeuta com doutorado disponíveis na Plataforma Lattes do CNPq, que é uma agência do MCT dedicada à promoção da pesquisa científica e à formação de recursos humanos para a pesquisa. A escolha dessa fonte pública de informação ocorreu porque cada pesquisador interessado em auxílios de pesquisa ou envolvidos com a pós-graduação deve preencher eletronicamente um curriculum vitae com informações sobre formação e produção científica. O sistema requer uma senha pessoal e uma declaração do pesquisador atestando a veracidade das informações fornecidas, o que assegura precisão no preenchimento. Estatísticas sobre fomento e bolsas disponíveis foram também consultadas. Uma análise de regressão binária foi rodada para explicar a ocorrência de publicações ISI/JCR. RESULTADOS: Houve um crescimento extraordinário (900% no número de doutores com graduação em Fisioterapia, na última década, em áreas tradicionais ou novos campos de atuação e crescimento expressivo em número de artigos publicados, dissertações e teses orientadas. Os fatores analisados pela regressão conseguiram explicar 49,8% da ocorrência de artigos indexados. Dados de fomento e bolsas mostram um investimento pequeno do CNPq na Fisioterapia comparativamente às demais áreas da Saúde. CONCLUSÕES: O perfil do pesquisador traçado aqui poderá prover à comunidade acadêmica uma perpectiva de sua identidade e auxiliar no estabelecimento de prioridades futuras para o aprimoramento do conhecimento e prática profissional.

  17. Water-Rock Interactions in the Peridotite Aquifer of the Oman-UAE Ophiolite: Strontium Isotopic Ratio and Geochemical Evolution of Groundwater

    Bompard, Nicolas; Matter, Juerg; Teagle, Damon

    2016-04-01

    The peridotite aquifer in Wadi Tayin, Sultanate of Oman, is a perfect example of natural carbonation of ultramafic rocks. In situ mineral carbonation is considered the most safest and permanent option of CO2 Capture and Sequestration (CCS). However, the process itself is yet to be characterised and a better understanding of the mechanisms involved in natural mineral carbonation is needed before geo-engineering it. We used the 87Sr/86Sr system to follow the water-rock interactions along the groundwater flowpath in the peridotite aquifer and to determine the sources of divalent cations (Mg2+, Ca2+) required for mineral carbonation. The Sr-isotope data of groundwater show that the aquifer rocks are the main source for divalent cations (Mg2+, Ca2+ and Sr2+) and secondary carbonates are their main sink. The groundwater 87Sr/86Sr ratio evolves with its pH: from 87Sr/86Sr = 0.7087 (n=3) to 0.7082 (n=8) between pH 7 and 8, and from 0.7086 (n=6) at pH 9 to 0.07075 (n=9) at pH 11. This evolution seems to support a two-step model for the water-rock interactions in the peridotite aquifer. From pH 7 to 8, secondary Ca-carbonate precipitation buffers the pH rise resulting from peridotite serpentinisation. From pH 9 to 11, peridotite serpentinisation drives the pH to alkaline condition. The change from a Mg-rich to a Ca-rich groundwater at pH 9 seems to confirm the two-step model.

  18. A geochemical study of Nea-Kameni hyalodacites (Santorini Volcano, Aegean island arc). Inferences concerning the origin and effects of solfataras and magmatic evolution

    Briqueu, Louis; Lancelot, Joël R.

    1984-03-01

    Since the Santorini Volcano (Aegean arc, eastern Mediterranean Sea) collapsed, volcanic activity has been located at the center of the flooded caldera. Over the past 800 years, five lava flows have formed one of the central islets (Nea-Kameni). Since 1951, when the last eruption occurred, a permanent fumarolic activity has remained. We present chemical analyses (major elements, trace-elements and Sr isotopic ratios) of ten samples from the five hyalodacitic lava flows, showing different stages of alteration, from a completely fresh lava up to one bearing native sulfur and other sublimates. Only the macroscopic aspect of these hyalodacites is affected by fumarolic activity. The elements that are mobile as a result of hydrothermal processes, such as the alkaline (K, Rb) or the chalcophile elements (Zn, Pb), show great homogeneity; the same can be said for the Sr isotopic compositions which range from 0.7046 to 0.7049. None of the analyzed samples has an Sr isotopic composition as high as those reported by Puchelt and Hoefs (1971) for rock samples collected in the same lava flows. If we take into account the marine surroundings of Nea-Kameni islet, these observations put severe restraints on the different hypotheses regarding the origin of the halogens (seawater or meteoric water). The contamination processes of these dacitic lavas are clearly less important than assumed by other authors according to previous Sr isotopic data. Finally, the homogeneity of the elements with low partition coefficients is sufficient to show that the magma has not undergone any perceptible evolution during the last 300 years.

  19. Geochemical simulation of the evolution of granitic rocks and clay minerals submitted to a temperature increase in the vicinity of a repository for spent nuclear fuel

    Fritz, B.; Kam, M.; Tardy, Y.

    1984-07-01

    The alteration of a granitic rock around a repository for spent nuclear fuel has been simulated considering the effect of an increase of temperature due to this kind of induced geothermal system. The results of the simulation have been interpreted in terms of mass transfer and volumic consequences. The alteration proceeds by dissolution of minerals (with an increase of the volumes of fissures and cracks) and precipitation of secondary miminerals as calcite and clay minerals particularly (with a decrease of the porosity). The increase of the temperature from 10 degrees C to about 100 degrees C will favour the alteration of the granitic rock around the repository by the solution filling the porosity. The rock is characterized by a very low fissure porosity and a consequent very low water velocity. This too, favours intense water rock interactions and production of secondary clays and the total possible mass transfer will decrease the porosity. A combination of these thermodynamic mass balance calculations with a kinetic approach of mineral dissolutions gives a first attempt to calibrate the modelling in the time scale: the decrease of porosity can be roughly estimated between 2 and 20% for 100,000 years. The particular problem of Na-bentonites behaviour in the proximate vicinity of the repository has been studied too. One must distinguish between two types of clay-water interactions: -within the rock around the repository, Na-bentonites should evolute with illitization in slighltly open system with low clay/water ratios, -within the repository itself, the clay reacts in a closed system for a long time with high clay/water ratios and a self-buffering effect should maintain the bentonite type. This chemical buffering effect is a positive point for the use of this clay as chemical barrier. (Author)

  20. Geochemical Investigations of Groundwater Stability

    Bath, Adrian

    2006-05-01

    groundwaters, and also by stable isotopes and uranium isotopes in secondary minerals. Information on timing of water and solute movements is important because it indicates any correlation with the timing of external events that might have perturbed and destabilised the groundwater system in the past, and allows a timescale to be estimated for the persistence of stable conditions. Data from a number of published site investigation projects and research programmes are reviewed to illustrate the patterns of geochemical data and the relationships between them, and how these are interpreted in terms of hydrodynamic stability. Data from Aespoe and Stripa and from exploratory boreholes at Finnsjoen and other sites in Sweden are compiled and discussed. Preliminary data from SKB's ongoing site investigations at Simpevarp/Laxemar and Forsmark are not considered in detail but their general similarities with Aespoe and Finnsjoen/SFR respectively are introduced into the discussion of geochemical evidence for groundwater stability in inland and coastal areas. Relevant data from Finnish sites including Olkiluoto, from the Whiteshell URL area in Canada, from Sellafield in the UK, and from the Tono area and URL in Japan are also summarised in appendices and discussed because they add further insights into the interpretation of geochemical indicators for a range of geological environments. The compiled data provide only limited scope for comparison of groundwater evolution and stability between inland and coastal areas in Sweden, because of the patchiness of representative data especially from early site studies. The external changes that might have perturbed stable groundwater conditions in the past are glaciation (i.e. melt water, mechanical loading/unloading and permafrost) and varying sea water infiltration at coastal sites due to changes in palaeo-Baltic and isostatic conditions. The present distributions of palaeo-Baltic sea water in groundwaters at coastal sites vary, reflecting local

  1. Geochemical Investigations of Groundwater Stability

    Bath, Adrian [Intellisci Ltd., Loughborough (United Kingdom)

    2006-05-15

    groundwaters, and also by stable isotopes and uranium isotopes in secondary minerals. Information on timing of water and solute movements is important because it indicates any correlation with the timing of external events that might have perturbed and destabilised the groundwater system in the past, and allows a timescale to be estimated for the persistence of stable conditions. Data from a number of published site investigation projects and research programmes are reviewed to illustrate the patterns of geochemical data and the relationships between them, and how these are interpreted in terms of hydrodynamic stability. Data from Aespoe and Stripa and from exploratory boreholes at Finnsjoen and other sites in Sweden are compiled and discussed. Preliminary data from SKB's ongoing site investigations at Simpevarp/Laxemar and Forsmark are not considered in detail but their general similarities with Aespoe and Finnsjoen/SFR respectively are introduced into the discussion of geochemical evidence for groundwater stability in inland and coastal areas. Relevant data from Finnish sites including Olkiluoto, from the Whiteshell URL area in Canada, from Sellafield in the UK, and from the Tono area and URL in Japan are also summarised in appendices and discussed because they add further insights into the interpretation of geochemical indicators for a range of geological environments. The compiled data provide only limited scope for comparison of groundwater evolution and stability between inland and coastal areas in Sweden, because of the patchiness of representative data especially from early site studies. The external changes that might have perturbed stable groundwater conditions in the past are glaciation (i.e. melt water, mechanical loading/unloading and permafrost) and varying sea water infiltration at coastal sites due to changes in palaeo-Baltic and isostatic conditions. The present distributions of palaeo-Baltic sea water in groundwaters at coastal sites vary, reflecting

  2. High-precision U-Pb zircon geochronological constraints on the End-Triassic Mass Extinction, the late Triassic Astronomical Time Scale and geochemical evolution of CAMP magmatism

    Blackburn, T. J.; Olsen, P. E.; Bowring, S. A.; McLean, N. M.; Kent, D. V.; Puffer, J. H.; McHone, G.; Rasbury, T.

    2012-12-01

    Mass extinction events that punctuate Earth's history have had a large influence on the evolution, diversity and composition of our planet's biosphere. The approximate temporal coincidence between the five major extinction events over the last 542 million years and the eruption of Large Igneous Provinces (LIPs) has led to the speculation that climate and environmental perturbations generated by the emplacement of a large volume of magma in a short period of time triggered each global biologic crisis. Establishing a causal link between extinction and the onset and tempo of LIP eruption has proved difficult because of the geographic separation between LIP volcanic deposits and stratigraphic sequences preserving evidence of the extinction. In most cases, the uncertainties on available radioisotopic dates used to correlate between geographically separated study areas often exceed the duration of both the extinction interval and LIP volcanism by an order of magnitude. The "end-Triassic extinction" (ETE) is one of the "big five" and is characterized by the disappearance of several terrestrial and marine species and dominance of Dinosaurs for the next 134 million years. Speculation on the cause has centered on massive climate perturbations thought to accompany the eruption of flood basalts related to the Central Atlantic Magmatic Province (CAMP), the most aerially extensive and volumetrically one of the largest LIPs on Earth. Despite an approximate temporal coincidence between extinction and volcanism, there lacks evidence placing the eruption of CAMP prior to or at the initiation of the extinction. Estimates of the timing and/or duration of CAMP volcanism provided by astrochronology and Ar-Ar geochronology differ by an order of magnitude, precluding high-precision tests of the relationship between LIP volcanism and the mass extinction, the causes of which are dependent upon the rate of magma eruption. Here we present high precision zircon U-Pb ID-TIMS geochronologic data

  3. Methods for geochemical analysis

    Baedecker, Philip A.

    1987-01-01

    The laboratories for analytical chemistry within the Geologic Division of the U.S. Geological Survey are administered by the Office of Mineral Resources. The laboratory analysts provide analytical support to those programs of the Geologic Division that require chemical information and conduct basic research in analytical and geochemical areas vital to the furtherance of Division program goals. Laboratories for research and geochemical analysis are maintained at the three major centers in Reston, Virginia, Denver, Colorado, and Menlo Park, California. The Division has an expertise in a broad spectrum of analytical techniques, and the analytical research is designed to advance the state of the art of existing techniques and to develop new methods of analysis in response to special problems in geochemical analysis. The geochemical research and analytical results are applied to the solution of fundamental geochemical problems relating to the origin of mineral deposits and fossil fuels, as well as to studies relating to the distribution of elements in varied geologic systems, the mechanisms by which they are transported, and their impact on the environment.

  4. Modelling the Interaction of Low pH Cements and Bentonite. Issues Affecting the Geochemical Evolution of Repositories for Radioactive Waste

    Watson, Claire; Benbow, Steven; Savage, David

    2007-05-01

    It is well known that in the hyperalkaline conditions (pH > 12) of standard cement pore fluids, there is potential for deleterious effects upon the host rock and other EBS materials, notably bentonite, in geological repositories for radioactive waste. Low pH cements are beginning to be considered as a potential alternative material that may address some of these concerns. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non pozzolanic silica flour. NUMO, Posiva and SKB have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. In this report we give the results of a preliminary modelling study to investigate the potential impacts of low pH cement water. We compare the evolution of a bentonite sample under the influence of several invading cement porewaters over a pH range from 10 to 13.2. The porewater compositions are taken from published CSH gel leaching experiments and published cement-bentonite modelling studies. The models suggest that the amount of degradation that is likely to be observed when low pH cement water interacts with bentonite is likely to be much less than when OPC water is the invading fluid. Below pH 11 there was not an observable Na montmorillonite dissolution front which would tend to support the pH ≤ 11 target suggested by NUMO, Posiva and SKB. The models used in this study could be improved upon by including a cement component to the model (rather than representing cement as a fixed boundary condition). Solid-solution models

  5. Geochemical modelling: what phenomena are missing

    Jacquier, P.

    1989-12-01

    In the framework of safety assessment of radioactive waste disposal, retention phenomena are usually taken into account by the Kd concept. It is well recognized that this concept is not enough for safety assessment models, because of the several and strong assumptions which are involved in this kind of representation. One way to have a better representation of the retention phenomena, is to substitute for this Kd concept an explicit description of geochemical phenomena and then couple transport codes with geochemical codes in a fully or a two-step procedure. We use currently such codes, but the scope of this paper is to display the limits today of the geochemical modelling in connection with sites analysis for deep disposal. In this paper, we intend to give an overview of phenomena which are missing in the geochemical models, or which are not completely introduced in the models. We can distinguish, on one hand phenomena for which modelling concepts exist such as adsorption/desorption and, on the other hand, phenomena for which modelling concepts do not exist for the moment such as colloids, and complexation by polyelectrolyte solutions (organics). Moreover we have to take care of very low concentrations of radionuclides, which can be expected from the leaching processes in the repository. Under those conditions, some reactions may not occur. After a critical review of the involved phenomena, we intend to stress the main directions of the wishful evolution of the geochemical modelling. This evolution should improve substantially the quality of the above-mentioned site assessments

  6. Facebook: personalidad y privacidad en los perfiles

    Casado Riera, Carla; Oberst, Ursula E.; Carbonell, Xavier

    2015-01-01

    El objetivo del presente estudio fue investigar la relación entre la configuración de la privacidad en los perfiles de Facebook y dos dimensiones de personalidad, extraversión y neuroticismo, en relación con el sexo. Se aplicó el Cuestionario de la Privacidad en Facebook y el cuestionario de personalidad EPI a una muestra de 92 mujeres y 70 hombres, usuarios de Facebook. No se encontró una relación significativa entre extraversión o neuroticismo y la privacidad en los perfiles de Facebook, pe...

  7. Competencias docentes digitales: propuesta de un perfil

    Adriana Rangel Baca

    2015-01-01

    En este artículo se presenta la propuesta de un perfil de competencias docentes digitales y se describen las dimensiones, competencias e indicadores que lo componen. Se analizan distintas fuentes para determinar el conjunto de recursos a movilizar por los docentes en materia digital y se elabora una versión preliminar del perfil, la cual es puesta a consideración de un grupo de expertos en el uso de las Tecnologías de la Información y la Comunicación (TIC) para su validación. Los resultados m...

  8. Geochemical prospecting in Guiana

    Coulomb, R.

    1957-01-01

    During the last few years geochemical prospecting techniques have become common usage in the field of mineral deposit prospecting. The real scope of these methods lies in their use in the prospecting of large areas. The most promising use of the geochemistry and hydro-geochemistry of uranium is in heavily forested tropical territories, with few outcrops, where radiometry is strongly handicapped. (author) [fr

  9. Perfil evolutivo das varizes esofágicas pós esplenectomia associada à ligadura da veia gástrica esquerda e escleroterapia na hipertensão portal esquistossomótica Evolutional profile of the esophageal varices after splenectomy associated with ligation of the left gastric vein and sclerotherapy in schistosomal portal hypertension

    João Batista-Neto

    2013-03-01

    Full Text Available RACIONAL: A esquistossomose mansônica afeta 200 milhões de pessoas em 70 países do mundo. Estima-se que 10% dos infectados evoluirão para a forma hepatoesplênica e, destes, 30% progredirão para hipertensão portal e varizes esofagogástricas, cuja expressão será através de hemorragia digestiva com mortalidade relevante no primeiro episódio hemorrágico. Múltiplas técnicas cirúrgicas foram desenvolvidas para prevenir o ressangramento. OBJETIVO: Avaliar o perfil evolutivo das varizes esofágicas após esplenectomia + ligadura da veia gástrica esquerda associada à escleroterapia endoscópica na hipertensão portal esquistossomótica. MÉTODO: Estudo prospectivo, observacional, de pacientes esquistossomóticos com antecedentes de hemorragia digestiva alta, submetidos à esplenectomia + ligadura da veia gástrica esquerda e escleroterapia. As variáveis estudadas foram perfil evolutivo das varizes esofágicas antes e após a operação e índice de recidiva hemorrágica. RESULTADOS: Amostra foi constituída por 30 pacientes distribuídos, quanto ao gênero, em 15 doentes para cada sexo. A idade variou de 19 a 74 anos (mediana=43 anos. Houve redução do grau, calibre e red spots em todos os pacientes (pBACKGROUND: The schistosomiasis affects 200 million people in 70 countries worldwide. It is estimated that 10% of those infected will develop hepatosplenic status and of these, 30% will progress to portal hypertension and esophagogastric varices, whose expression is through gastrointestinal bleeding with significant mortality in the first bleeding episode. Multiple surgical techniques have been developed to prevent re-bleeding. AIM: To evaluate the evolutional profile of esophageal varices after splenectomy + ligation of the left gastric vein associated with endoscopic sclerotherapy in schistosomal portal hypertension. METHODS: Prospective and observational study including schistosomiasis patients with previous history of upper digestive

  10. Perfiles de autor en repositorios institucionales

    Patricia Genovés

    2017-10-01

    Full Text Available Este trabajo describe las funciones y utilidades de la implementación de perfiles de autor en repositorios institucionales, como un servicio de valor agregado dirigido a acrecentar su uso entre los miembros de una institución y mejorar la visibilidad de la producción científica alojada en el repositorio. Incluye un relevamiento de servicios de perfiles de autor implementados en repositorios institucionales argentinos y extranjeros. Advierte que, ante el establecimiento de mandatos nacionales de depósito, la necesidad de contar con repositorios institucionales fuertes y sostenibles en el tiempo es aún mayor que antes. Integrar a los repositorios las funcionalidades de los sistemas curriculares y de gestión de información científica y tecnológica es un camino para lograr esa fortaleza, y los perfiles de autor son el resultado visible de dicha integración. Señala que el beneficio que representa para un autor contar con un perfil público en el repositorio de su institución es equivalente al beneficio que para una institución representa contar con un repositorio digital, en términos de ventaja competitiva, valor añadido, incremento de la visibilidad y facilidades de recuperación y acceso a la producción generada.

  11. Earlier history of the ≥70-Ma-old Canary hotspot based on the temporal and geochemical evolution of the Selvagen Archipelago and neighboring seamounts in the eastern North Atlantic

    Geldmacher, Jörg; Hoernle, Kaj; van den Bogaard, Paul; Zankl, Goor; Garbe-Schönberg, Dieter

    2001-11-01

    Major element, trace element and Sr-Nd-Pb isotope data, combined with 40Ar/39Ar age determinations, of volcanic rocks from the Selvagen Islands and neighboring seamounts in the eastern North Atlantic reveal the earlier history of the ≥70 Ma old Canary hotspot. A basanitic to phonolitic late shield stage intrusive complex (29 Ma) is exposed on Selvagem Pequena. The evolution of Selvagem Grande can be divided into three magmatic phases: a tephritic to phonolitic late shield stage intrusive complex (24-26 Ma) and two rejuvenated or post-erosional stages (8-12 and 3.4 Ma) consisting of alkali basalt, basanite and rare phonolite. During the early to mid-Miocene volcanic hiatus (12-24 Ma), the top of the volcano was beneath sea level as evidenced by marine carbonate sediments (13-24 Ma, dated through correlation of 87Sr/86Sr with the seawater Sr isotope curve). The geochemistry of the shield stage lavas indicates that they derive from plume sources, whereas the post-erosional lavas are derived from metasomatized lithospheric sources. Five sampled seamounts to the east and northeast of the islands range in composition from alkali basalt and basanite to phonolite. Samples from Dacia, Conception Bank and Lars were dated at 9, 17 and 68 Ma, respectively. Geochemical data suggest that the dredged samples come from the post-erosional stage of volcanism, and therefore, the dates represent minimum ages for the seamount volcanoes. The elevation of erosional platforms formed at wave base decrease from Selvagen Grande (∼100 m above sea level) to Lars seamount (∼900 m below sea level), suggesting a southwest to northwest age progression and that all of these seamounts are older than the Selvagen Islands. Trace element and Sr-Nd-Pb isotopic composition of the Selvagen Islands and neighboring seamounts are consistent with their origin from the Canary plume. Interaction of the weak Canary mantle plume with a slow moving plate appears to be responsible for generating a 450-km

  12. Alligator Rivers Analogue project. Geochemical Data Bases

    Bennett, D.G.; Read, D.

    1992-01-01

    The Koongarra uranium deposit in the Northern Territory of Australia is being studied to evaluate the processes involved in the geochemical alteration of the ore body and the formation of the uranium dispersion fan. A broad range of research is being undertaken into the geochemistry and hydrology of the site with the aim of understanding the transport of radionuclides through the system. During the project a range of geochemical and hydrogeochemical models have been developed to account for measured data from the site and with which to predict site evolution. The majority of these models are based on the premise of thermodynamic chemical equilibrium and employ fundamental thermodynamic data to characterise the chemistry of the system. From the differences which exist between the thermodynamic data bases (Appendices I and II) it is possible to gain a view of the level of uncertainty associated with thermodynamic data in each set of calculations. This report gives a brief introduction to the geochemical processes underlying the models, and details the equations used to quantify the more common of these processes (e.g. aqueous speciation and mineral solubility). A description is given of the computer codes (EQ3/6, PHREEQE, MINTEQ) most commonly used during the project for geochemical modelling. Their key features are highlighted and comparisons made. It is concluded that the degree of uncertainty in geochemical modelling studies arising as a result of using one code rather than another is relatively insignificant when compared to that related to differences in the underlying data bases. 73 refs., 3 figs

  13. Retention/sorption and geochemical modelling

    Arcos, D.; Grandia, F.; Domenech, C. [Enviros Spain, S.L., Barcelona (Spain); SCK-CEN, Mol (Belgium); Sellin, P. [SKB - Swedish Nuclear Fuel and Waste Management, SE, Stockholm (Sweden); Hunter, F.M.I.; Bate, F.; Heath, T.G.; Hoch, A. [Serco Assurance, Oxfordshire (United Kingdom); Werme, L.O. [SKB - Svensk Karnbranslehantering AB, Stockholm (Sweden); Bruggeman, C.; Maes, I.A.; Breynaert, E.; Vancluysen, J. [Leuven Katholieke Univ., Lab. for Colloid Chemistry (Belgium); Montavon, G.; Guo, Z. [Ecole des Mines, 44 - Nantes (France); Riebe, B.; Bunnenberg, C.; Meleshyn, A. [Leibniz Univ. Hannover, Zentrum fur Strahlenschutz und Radiookologie, Hannover (Germany); Dultz, S. [Leibniz Univ. Hannover, Institut fur Bodenkunde, Hannover (Germany)

    2007-07-01

    This session gathers 4 articles dealing with: the long-term geochemical evolution of the near field of a KBS-3 HLNW repository: insights from reactive transport modelling (D. Arcos, F. Grandia, C. Domenech, P. Sellin); the investigation of iron transport into bentonite from anaerobically corroding steel: a geochemical modelling study (F.M.I. Hunter, F. Bate, T.G. Heath, A. Hoch, L.O. Werme); SeO{sub 3}{sup 2-} adsorption on conditioned Na-illite: XAS spectroscopy, kinetics, surface complexation model and influence of compaction (C. Bruggeman, A. Maes, G. Montavon, E. Breynaert, Z. Guo, J. Vancluysen); the influence of temperature and gamma-irradiation on the anion sorption capacity of modified bentonites (B. Riebe, C. Bunnenberg, A. Meleshyn, S. Dultz)

  14. Geochemical modeling: a review

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted

  15. Geochemical modeling: a review

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted.

  16. Perfiles Latinoamericanos: Regional sociology, connected sociologies

    Nelson Arteaga Botello

    2017-07-01

    Full Text Available The landscape of sociology published in the 48 numbers of the Perfiles Latinoamericanos magazineis analyzed. The diversity of topics, perspectives, and methodologies of the articles define aseries of fields of reflection around civil society, collective action, subjectivities and social identities,cities, media, violence, and theory. The essay suggests how the sociology that is producedin Latin America is not isolated but connected with international debates. It converges forms ofdoing theory and research with resonances on a global scale.

  17. Evaluation quantitative des produits formés lors de l'évolution géochimique de la matière organique Quantitative Evaluation of Products Formed During the Geochemical Evolution of Organic Matter

    Pelet R.

    2006-11-01

    Full Text Available L'évaluation quantitative des produits mobiles formés lors de l'évolution géochimique de la matière organique est nécessaire parce qu'on ne peut jamais retrouver ces produits en place dans. la roche où ils ont pris naissance. Ils ont, en effet, pu migrer durant l'histoire géologique, et de toute manière une fraction, importante et non connue, se perd lors de la prise des échantillons puis de leur conservation avant analyse. La connaissance de l'analyse d'un état E et d'un état plus évolué E' ne suffit pas pour reconstituer les quantités de produits formés. La pyrolyse type Rock-Eval sur kérogènes, avec détermination du carbone résiduel, permet par contre, à partir d'une hypothèse raisonnable, de calculer les hydrocarbures produits. L'analyse élémentaire permet d'y ajouter CO2, H2O, H2S et N2 (considérés comme seuls produits à côté des hydrocarbures. Une analyse chromatographique sommaire supplémentaire permet d'estimer la composition globale des hydrocarbures. Dans le cas des roches, on propose des techniques de correction de l'effet de matrice pratiquement utilisables et qui permettent de retrouver les résultats précédents, au prix d'une incertitude accrue. The mobile products formed during the geochemical evolution of organic matter must be quantitatively evaluated because these products can never be found in place in the rock where they were formed. Indeed, they may have migrated during geological history, and in any case a large and unknown fraction gets lost when samples are taken and then stored before being analysed. Knowing the elemental analysis of a state E and of a more evolved state E' does not suffice for recreating the amounts of products formed. On the other hand Rock-Eval type pyrolysis of kerogens, including the determination of the residual carbon, can be used to compute the hydrocarbons produced, on the basis of a reasonable hypothesis. Elemental analysis then enables the evaluation of CO2, H2O

  18. Synthesizing Earth's geochemical data for hydrogeochemical analysis

    Brantley, S. L.; Kubicki, J.; Miller, D.; Richter, D.; Giles, L.; Mitra, P.

    2007-12-01

    For over 200 years, geochemical, microbiological, and chemical data have been collected to describe the evolution of the surface earth. Many of these measurements are data showing variations in time or in space. To forward predict hydrologic response to changing tectonic, climatic, or anthropogenic forcings requires synthesis of these data and utilization in hydrogeochemical models. Increasingly, scientists are attempting to synthesize such data in order to make predictions for new regions or for future time periods. However, to make such complex geochemical data accessible requires development of sophisticated cyberinfrastructures that both invite uploading as well as usage of data. Two such cyberinfrastructure (CI) initiatives are currently developing, one to invite and promote the use of environmental kinetics data (laboratory time course data) through ChemxSeer, and the other to invite and promote the use of spatially indexed geochemical data for the Earth's Critical Zone through CZEN.org. The vision of these CI initiatives is to provide cyber-enhanced portals that encourage domain scientists to upload their data before publication (in private cyberspace), and to make these data eventually publicly accessible (after an embargo period). If the CI can be made to provide services to the domain specialist - e.g. to provide data analysis services or data comparison services - we envision that scientists will upload data. In addition, the CI can promote the use and comparison of datasets across disciplines. For example, the CI can facilitate the use of spatially indexed geochemical data by scientists more accustomed to dealing with time-course data for hydrologic flow, and can provide user-friendly interfaces with CI established to facilitate the use of hydrologic data. Examples of the usage of synthesized data to predict soil development over the last 13ky and its effects on active hydrological flow boundaries in surficial systems will be discussed for i) a N

  19. Geochemical Survey of Pernambuco

    Horowitz, A.; Duarte, P.J.; Almeida, M.G. de; Medeiros, M.O.

    1988-01-01

    The area studied i this work is located in a triangle formed by the Sibiro and Boca da Mata Sugar-Mills and Serinhaem country. In the Cabo Formation the search determinated conglomerates, arcos and clays. Although the highest geochemical activity have been done in the decomposed crystalin, and the values from Cabo Formation don't be encourager, this formation has lithology compatible with uranium mineralization. The Cabo Formation's sediments presents lithologic variations very expressives, with conglomerates, arcoses and clay silts, which determinate the choise of the area. This area presented favorable to uranium prospecting and to others elements interesting to ragional geochemistry. The atomic absorption analysis, fluorimetry and spectrometry were done for the following elements: Zn, V, Ti, Ni, Pb, Mn, Ga, Cu, Co, Bi, Ag, B, Mo, and U. (C.D.G.) [pt

  20. O perfil do negociador nas empresas

    Marques, Eduardo de Oliveira

    2002-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. Comparativo entre os perfis negociador e cultural da população de negociadores em relação ao perfil cultural das empresas da primeira camada de fornecedores do grupo Fiat, objetivando -se determinar os tipos de negociadores mais adequados às organizações, aferindo-se o tipo de correlação existente entre as culturas e os estilos de negociação....

  1. Perfil psicosocial de la persona emprendedora

    Trejo López, Enrique Alberto

    2015-01-01

    El objeto de la tesis es estudiar el perfil psicosocial de la persona emprendedora y de la emprendedora que continúa a pesar de la crisis, constatando las diferencias respecto al resto de los grupos laborales. Se realiza un estudio multidimensional, psicosocial, de nivel descriptivo y analítico, con un carácter longitudinal, aplicando instrumentos y metodologías cualitativas y cuantitativas y aportando datos disgregado por sexo En el marco teórico recogemos los estudios e investigacion...

  2. PERFILES PROFESIONALES Y VALORES RELATIVOS AL TRABAJO

    Moreno, José Eduardo; Marcaccio, Antonela

    2014-01-01

    El objetivo del presente trabajo es evaluar la relación existente entre los valores relativos al trabajo y algunos perfiles profesionales (contabilidad y administración, marketing y ventas, y recepción). El instrumento utilizado es la Escala Argentina de Valores Relativos al Trabajo (Moreno & Marcaccio, 2012) que contiene cuatro subescalas de cinco ítems cada una, a saber: Realización Personal, Reconocimiento Social, Altruismo y Aspiraciones Económicas. La muestra incluye a 425 sujetos (40% v...

  3. Perfil logístico de Colombia

    Cardozo Maglioni, María Victoria; Lozano Suarez, María Goretty

    2012-01-01

    El presente documento ofrece un estudio del perfil logístico de Colombia con la finalidad de dar a conocer el estado de arte de las ciudades, puertos e infraestructura principal para facilitar la toma de decisiones de los empresarios. Para el desarrollo de este trabajo se determinaron a partir de un análisis competitivo del país; las principales ciudades y puertos; logrando establecer un inventario de maquinaria y equipo e infraestructura logística; enmarcados en retos ya establecidos en las ...

  4. Perfil das pacientes submetidas a gluteoplastia

    José Horácio Costa Aboudib Júnior

    2014-01-01

    Durante nossas frequentes apresentações em cursos, congressos e jornadas e mesmo em nossas publicações, existiam constantes perguntas sobre o perfil dessas pacientes. O crescente interesse da mídia e das pacientes a este respeito e também a crescente procura pela cirurgia nos estimulou a realizar este trabalho. Segundo dados da Sociedade Brasileira de Cirurgia Plástica (SBPC) e da American Society of Plastic Surgery (ASPS), referem que 20.000 pacientes foram submetidas a esta cirurgia. Em 201...

  5. Statistical interpretation of geochemical data

    Carambula, M.

    1990-01-01

    Statistical results have been obtained from a geochemical research from the following four aerial photographies Zapican, Carape, Las Canias, Alferez. They have been studied 3020 samples in total, to 22 chemical elements using plasma emission spectrometry methods.

  6. Late Eocene to present isotopic (Sr-Nd-Pb) and geochemical evolution of sediments from the Lomonosov Ridge, Arctic Ocean: Implications for continental sources and linkage with the North Atlantic Ocean

    Stevenson, Ross; Poirier, André; Véron, Alain; Carignan, Jean; Hillaire-Marcel, Claude

    2015-09-01

    New geochemical and isotopic (Sr, Nd, Pb) data are presented for a composite sedimentary record encompassing the past 50 Ma of history of sedimentation on the Lomonosov Ridge in the Arctic Ocean. The sampled sediments encompass the transition of the Arctic basin from an enclosed anoxic basin to an open and ventilated oxidized ocean basin. The transition from anoxic basin to open ventilated ocean is accompanied by at least three geochemical and isotopic shifts and an increase in elements (e.g., K/Al) controlled by detrital minerals highlighting significant changes in sediment types and sources. The isotopic compositions of the sediments prior to ventilation are more variable but indicate a predominance of older crustal contributions consistent with sources from the Canadian Shield. Following ventilation, the isotopic compositions are more stable and indicate an increased contribution from younger material consistent with Eurasian and Pan-African crustal sources. The waxing and waning of these sources in conjunction with the passage of water through Fram Strait underlines the importance of the exchange of water mass between the Arctic and North Atlantic Oceans.

  7. Orientation geochemical survey for uranium exploration using 230Th

    Xia Dingliang.

    1985-01-01

    The distribution of 230 Th in soils, rocks and ores and its relationship with respect to uranium ore formation are discussed for its possible use in geochemical exploration for U. 230 Th, U and Ra, being members of the same decay series, are different in their geochemical behavior upon which the study is orientated. Twenty uranium deposits and occurrences located in western and southern Hunan province are tested. Geochemical data obtained are comprehensively correlated. It is suggested that 230 Th is useful not only in U-Ra disequilibrium study but also in understanding the geochemical evolution of U ores. The data aid to interpret the genesis of uranium deposits and to assess the radioactive anomalies and uranium-bearing zones. Therefore, it can be adopted as a tool for searching in deep-buried uranium ores. The field procedure is rather simple and flexible to meet any geological environment. It is easy to read out and is less influnced by any kind of interference. In case of disequilibrium caused by oxidation and reduction during the period of ore formation it still gives good indication compared with that of radiometry, radonmetry and geochemical sampling for U

  8. Geochemical exploration for uranium

    Rose, A.W.

    1977-01-01

    The processes and types of dispersion that produce anomalies in stream water, stream sediment, and ground water, and the factors that must be considered in planning and interpreting geochemical surveys are reviewed. Examples of surveys near known deposits show the types of results to be expected. Background values depend mainly on the content of U in rocks of the drainage area. In igneous rocks, U tends to increase with potassium from ultramafic rocks (0.01 ppM) to granitic rocks (1 to 5 ppM). Some alkalic rocks have unusually high contents of U (15 to 100 ppM). Uranium-rich provinces marked by igneous rocks unusually rich in U are recognized in several areas and appear to have a deep crustal or mantle origin. In western U.S., many tertiary tuffaceous rocks have a high U content. Sandstones, limestones, and many shales approximate the crustal abundance at 0.5 to 4 ppM, but black shales, phosphates, and some organic materials are notably enriched in U. Uranium is very soluble in most oxidizing waters at the earth's surface, but is precipitated by reducing agents (organic matter, H 2 S) and adsorbed by organic material and some Fe oxides. In most surface and ground waters, U correlates approximately with the total dissolved solids, conductivity, and bicarbonate concentration of the water, and with the U content of rocks it comes into contact with. Most surveys of stream water near known districts show distinct anomalies extending a few km to tens of km downstream. A complication with water is the large variability with time, up to x 50, as a result of changes in the ratio of ground water to direct runoff, and changes in rate of oxidation and leaching. Collection and analysis of water samples also pose some difficulties

  9. Archean crust-mantle geochemical differentiation

    Tilton, G. R.

    Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

  10. Archean crust-mantle geochemical differentiation

    Tilton, G. R.

    1983-01-01

    Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

  11. EL PERFIL DEL EDITOR DE JUEGOS DE ROL

    Héctor Sevillano Pareja

    2010-11-01

    Full Text Available El presente trabajo estudia y analiza, a través de diversas encuestas personalizadas, el perfil tipo que presentan los profesionales que se dedican al arte de editar libros de rol en España.

  12. Geochemical computer codes. A review

    Andersson, K.

    1987-01-01

    In this report a review of available codes is performed and some code intercomparisons are also discussed. The number of codes treating natural waters (groundwater, lake water, sea water) is large. Most geochemical computer codes treat equilibrium conditions, although some codes with kinetic capability are available. A geochemical equilibrium model consists of a computer code, solving a set of equations by some numerical method and a data base, consisting of thermodynamic data required for the calculations. There are some codes which treat coupled geochemical and transport modeling. Some of these codes solve the equilibrium and transport equations simultaneously while other solve the equations separately from each other. The coupled codes require a large computer capacity and have thus as yet limited use. Three code intercomparisons have been found in literature. It may be concluded that there are many codes available for geochemical calculations but most of them require a user that us quite familiar with the code. The user also has to know the geochemical system in order to judge the reliability of the results. A high quality data base is necessary to obtain a reliable result. The best results may be expected for the major species of natural waters. For more complicated problems, including trace elements, precipitation/dissolution, adsorption, etc., the results seem to be less reliable. (With 44 refs.) (author)

  13. Perfiles motivacionales de deportistas adolescentes españoles

    Bartolom\\u00E9 J. Almagro

    2012-01-01

    Full Text Available El objetivo del estudio fue detectar posibles perfiles motivacionales en una muestra de deportistas adolescentes. Además, el estudio analizó las diferencias en los subfactores del clima motivacional percibido y en la satisfacción de las necesidades psicológicas básicas de los diferentes perfiles encontrados. Se utilizó una muestra de 608 deportistas, con una edad media de 14.43 años. Se midió el clima motivacional percibido (PMCSQ-2, los mediadores psicológicos (BPNES y la motivación en el deporte (SMS. El análisis de cluster reveló dos perfiles: un perfil altamente motivado, con puntuaciones altas tanto en formas de motivación autodeterminada (motivación intrínseca y regulación identificada como en motivación no autodeter- minada (regulación introyectada y externa, salvando la desmotivación; y un perfil moderadamente motivado, con puntuaciones moderadas (en torno a 3 y 4 en formas de motivación autodeterminada y no autodeterminada. En el análisis multivariante de los subfactores del clima motivacional percibido y de las necesidades piscológicas básicas según el perfil, se encontraron diferencias significativas a favor del perfil altamente motivado tanto en los sub- factores del clima motivacional tarea como ego, así como en los tres mediadores psicológicos. Se discuten los resultados en función de la importancia de fomentar un clima que implique a la tarea y que trate de satisfacer las necesidades de autonomía, competencia y relación con los demás durante los entrenamientos para obtener perfiles motivacionales más autodeterminados.

  14. Application of multiple geochemical indicators, including the stable isotopes of water, to differentiate water quality evolution in a region influenced by various agricultural practices and domestic wastewater treatment and disposal

    Butler, Thomas W.

    2007-01-01

    Spatial and temporal variations in groundwater chemistry indicate that the use of low TDS lake water for irrigation, on land located just south of the City of Dixon, Solano County, California, is primarily responsible for improving groundwater quality with regards to salts. The stable isotopes of water further support this finding and suggest that TDS concentrations decrease as groundwater evolves to a more highly evaporated state. This seemingly contradictory finding was primarily attributed to infiltration of low TDS Lake Berryessa surface water, which has an isotopic signature indicative of an evaporated source and is used extensively for irrigation in the area, mixing with poorer quality locally recharged shallow groundwater. Geochemical modeling using the program PHREEQC further supports the anthropogenic aquifer freshening hypotheses through computed reductions in the saturation state of carbonate minerals in the vicinity of land irrigated by lake derived water, which is undersaturated with regards to modeled carbonates. Additionally, δ 18 O and δ 2 H were found to be useful in estimating climatic variables such as temperature and humidity, illustrating the potential for applying these models in hydrologic investigations within the area. It was however found that USDA NRCS soils data and measured water chemistry were not well correlated and thus the use of soils classifications to assess potential groundwater quality impacts was of limited utility

  15. Geochemical and mineralogical characteristics of Lithomargic clay

    Administrator

    Geochemical and mineralogical characteristics of Lithomargic clay. GEOCHEMICAL AND .... tries, as filling material in the pulp and paper, toothpaste and paint industries as well ..... tions very vital to human health and other ac- tivities of man.

  16. NOAA and MMS Marine Minerals Geochemical Database

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Minerals Geochemical Database was created by NGDC as a part of a project to construct a comprehensive computerized bibliography and geochemical database...

  17. Oak Ridge Geochemical Reconnaissance Program

    Arendt, J.W.

    1977-03-01

    The Oak Ridge reconnaissance program is responsible for the geochemical survey in a 12-state area covering Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Minnesota, Wisconsin, Michigan, Iowa, Indiana, and Illinois as part of the National Uranium Resource Evaluation Program. The program concept is outlined and the planning and organization of the program is discussed

  18. Granite-repository - geochemical environment

    1979-04-01

    Some geochemical data of importance for a radioactive waste repository in hard rock are reviewed. The ground water composition at depth is assessed. The ground water chemistry in the vicinity of uranium ores is discussed. The redox system in Swedish bedrock is described. Influences of extreme climatic changes and of repository mining and construction are also evaluated

  19. Calidad Y Perfil Del Profesor Universitario

    José Vicente Sánchez Frank

    2014-07-01

    Full Text Available La investigación se desarrolla en un enfoque mixto, combina el paradigma cuantitativo con la finalidad de conseguir patrones de regularidad, y el cualitativo en cuanto a nivel de técnica y estrategia de captura de información, con las entrevistas a profundidad, y también a nivel del análisis de datos, e interpretación de los resultados en la reducción, disposición y transformación de los mismos, a los fines de obtener de la experiencia de los cuatro grupos etarios de educadores; la investigación se realizó con 120 docentes de la Universidad Nacional Experimental del Estado Táchira. La investigación desarrolla los aspectos teóricos de los constructos perfil del docente, en el marco de constructo calidad en la docencia. Plantea como objetivo general diseñar e implementar un sistema de medición de la calidad en la docencia universitaria. Conclusión: la implementación del sistema permitió la formulación, ejecución y seguimiento de programas, orientados a la formación del personal académico para contribuir a mejorar la calidad de la docencia.

  20. Geochemical site-selection criteria for HLW repositories in Europe and North America

    Savage, David; Arthur, Randolph C.; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu

    2000-01-01

    Geochemical as well as socio-economic issues associated with the selection of potential sites to host a high-level nuclear waste repository have received considerable attention in repository programs in Europe (Belgium, Finland, France, Germany, Spain, Sweden, Switzerland and the U.K.) and North America (Canada and the United States). The objective of the present study is to summarize this international experience with particular emphasis on geochemical properties that factor into the adopted site-selection strategies. Results indicate that the geochemical properties of a site play a subordinate role, at best, to other geotechnical properties in the international site-selection approaches. In countries where geochemical properties are acknowledged in the site-selection approach, requirements are stated qualitatively and tend to focus on associated impacts on the stability of the engineered barrier system and on radionuclide transport. Site geochemical properties that are likely to control the long-term stability of geochemical conditions and radionuclide migration behavior are unspecified, however. This non-prescriptive approach may be reasonable for purposes of screening among potential sites, but a better understanding of site properties that are most important in controlling the long-term geochemical evolution of the site over a range of possible scenarios would enable the potential sites to be ranked in terms of their suitability to host a repository. (author)

  1. Perfil do idoso acusado de cometer crime

    Sérgio Vieira Brandão

    2017-06-01

    Full Text Available É verdade que o idoso, muitas vezes, é vítima de diversas formas de agressões, mas também é agente da prática de delitos. Por meio de pesquisa documental realizada em 2013 com todos os boletins de ocorrência registrados na delegacia de polícia de Imbé, Rio Grande do Sul, Brasil, realizamos análise estatística e evidenciamos o perfil do idoso acusado de cometer crime e os tipos de crimes cometidos. No período pesquisado, 3,28% do total de idosos de Imbé foi acusado de cometer algum tipo de crime. Este artigo recomenda uma ação contínua e integrada da rede de saúde e de segurança pública com as demais áreas sociais para antecipar situações de risco para idosos (e comunidade em geral, de modo a promover a cidadania, gerenciar conflitos e reduzir a violência urbana. It is genuine that the elderly frequently are victims of several kinds of hostility, but the fact remains that he or she, too, is also an agent of the committal of criminal offenses. Through documentary research realized in 2013 with the total occurrences bulletins registered in police stations in Imbé, Rio Grande do Sul, Brazil, we realize statistical analysis and show the profile of the elderly accused of committing crime and the types of crimes committed. In the period surveyed, 3.28% of the total number of elderly of Imbé was accused of committing some type of crime. Profile of the Elderly Accused of Committing Crime recommends a continuous and integrated action of the health and public safety network with the other social areas to anticipate risk situations for the elderly (and the community in general, in order to promote citizenship, manage conflicts and reduce urban violence. Keywords: violence, seniors, aging, public health, crime

  2. Perfil de salud del gamín

    Ospina, Bernarda; Soto Vélez, Cecilia; Betancur Taborda, Ceneida; Jaramillo Vélez, Diva Estela; Zuloaga Posada, Luz; Berrio Castro, Vivian Adela; Escobar, Juan Darío

    1992-01-01

    En el presente estudio se analizó el perfil de salud del gamín de medellin en 98 niños, su situación sociofamiliar, el consumo de sustancias psicoactivas, la morbilidad general y la salud mental y oral.

  3. Implications for air quality and the impact of financial and economic crisis in South Spain: Geochemical evolution of atmospheric aerosol in the ceramic region of Bailén

    Sánchez de la Campa, A. M.; de la Rosa, J. D.

    2014-12-01

    A temporal series study of atmospheric aerosol was performed over the last ten years (2003-2012) in an urban background monitoring station with ceramic industrial influence, in Bailén, SE Spain. Temporal trends of major and minor chemical components of PM10 for a long term data series were investigated, showing that PM10 concentrations have been steadily decreasing over almost a decade, with a statistical significance. Measurements indicate a reduction of elements and components related to the industrial activity of brick-ceramic production (V, Cd, Rb, La, Cr, Ni, As, Pb and SO42-). Conversely, Cu levels define an increasing trend from the beginning of the study period but with the highest step trend since 2011-2012, coinciding with the beginning of the financial and economic crisis in 2008. A similar time evolution pattern of Cu and OC, EC, and K levels may be a tracer of domestic local combustion source, and a new biomass burning source has been identified. Chemical composition of olive tree logs suggest as the combustion of wood with high concentration of Cu can imply an increase of Cu concentration in the atmospheric particles compared with other sources such as traffic.

  4. Temporal and geochemical evolution of Miocene volcanism in the Andean back-arc between 36°S and 38°S and U-series analyses of young volcanic centers in the arc and back-arc, Argentina

    Dyhr, Charlotte Thorup

    New 40Ar/39Ar, major and trace element, and Sr, Nd and Pb isotopic data for the c. 24-7 Ma volcanic rocks from the Andean back-arc (35°S – 38°S) in the Mendoza and Neuquén (Argentina) regions shed light on the Miocene evolution of the back-arc of the Southern Volcanic Zone. Incipient shallowing......-Sr-Pb isotopic compositions. The arc-like component that dominates the geochemistry of the Palaoco rocks is absent in both the Early Miocene and the Pliocene-Pleistocene in the same area. Young volcanic Provinces in the main arc, retro-arc and back-arc are further investigated by U-series analyses which confirm...... the fluid-enriched nature of arc-related rocks (U-excess are found in most rocks) and the more OIB-like nature of the Payún Matrú complex (Th-exsess is observed in all rocks). The fluid addition to the mantle source is modeled revealing timescales of 10 – 100 ka for the fluid enrichment. For the back...

  5. Esquistossomose mansônica: II - evolução dos níveis de proteínas séricas e do perfil eletroforético por técnicas de imunoeletroforese quantitativa Schistosomiasis mansoni: II - evolution of the levels of serum proteins and of their electrophoretic pattern as traced by quantitative immunoelectrophoresis

    Ajax Mercês Atta

    1981-04-01

    Full Text Available Camundongos Swiss foram infectados com 100 cercárias da linhagem mineira (BH do Schistosoma mansoni e sacrificados semanalmente no período de 8 semanas de infecção. Os níveis de proteínas séricas totais destes animais não diferiram dos apresentados pelos animais controles. Os níveis de albumina sérica determinados por "Rocket immunoelectrophoresis" acharam-se diminuídos nas 5.ª, 6.ª e 7.ª semanas de infecção. O perfil obtido por imunoeletroforese cruzada revelou alterações em componentes séricos com mobilidade nas regiões de gama, beta e em menor grau de alfa-globulinas, após a oviposição do parasito.Swiss mice were infected with 100 cercariae of the Belo Horizonte strain of Schistosoma mansoni and were sacrificed weekly during eight weeks following of infection. The levels of serum protein totals in these animals did not differ from those presented by the control animals. However, serum albumin levels that were determined by rocket immunoelectrophoresis were lower during the 5th, 6th, and 7th weeks of infection. The pattern determined by crosed immunoelectrophoresis revealed alterations in serum components with mobility in the gamma and beta regions and, to a lesser degree, alpha-globulins, after oviposition by the parasite.

  6. Resultados eleitorais, evolução das bancadas e perfil político dos prefeitos eleitos (Canoas/RS: 1947–1968 = Election results, electoral bench evolution and political profile of elected mayors (Canoas/RS: 1947-1968

    Angeli, Douglas Souza

    2014-01-01

    Full Text Available O município de Canoas, na região metropolitana de Porto Alegre, foi emancipado em 1939, obtendo nas três décadas seguintes, um expressivo aumento populacional propiciado pela migração de trabalhadores para a região metropolitana de Porto Alegre e pela industrialização. Essa fase de abertura de loteamentos, em que a cidade ampliou sua zona suburbana – formada basicamente por operários –, ocorre concomitantemente ao processo de democratização na política brasileira, com a criação de partidos nacionais, eleições diretas e aumento do número de eleitores. O presente trabalho tem como objetivo analisar os resultados das primeiras eleições municipais realizadas em Canoas/RS, entre 1947 e 1968, com foco na evolução das bancadas por partido na Câmara Municipal, e no perfil político dos cinco prefeitos eleitos nesse período. O recorte temporal tem como marcos a data da primeira eleição municipal, 1947 – quando foram eleitos os primeiros vereadores, e a última eleição para prefeito antes de Canoas/RS ser decretada Área de Segurança Nacional pelo regime civil-militar

  7. A preliminary study on the geochemical environment for deep geological disposal of high level radioactive waste in Korea

    Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Koh, Yong Kwon; Park, Byoung Yun

    2000-03-01

    Geochemical study on the groundwater from crystalline rocks (granite and gneiss) for the deep geological disposal of high-level radioactive waste was carried out in order to elucidate the hydrogeochemical and isotope characteristics and geochemical evolution of the groundwater. Study areas are Jungwon, Chojeong, Youngcheon and Yusung for granite region, Cheongyang for gneiss region, and Yeosu for volcanic region. Groundwaters of each study areas weree sampled and analysed systematically. Groundwaters can be grouped by their chemistry and host rock. Origin of the groundwater was proposed by isotope ( 18 O, 2 H, 13 C, 34 S, 87 Sr, 15 N) studies and the age of groundwater was inferred from their tritium contents. Based ont the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs

  8. A preliminary study on the geochemical environment for deep geological disposal of high level radioactive waste in Korea

    Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Koh, Yong Kwon; Park, Byoung Yun

    2000-03-01

    Geochemical study on the groundwater from crystalline rocks (granite and gneiss) for the deep geological disposal of high-level radioactive waste was carried out in order to elucidate the hydrogeochemical and isotope characteristics and geochemical evolution of the groundwater. Study areas are Jungwon, Chojeong, Youngcheon and Yusung for granite region, Cheongyang for gneiss region, and Yeosu for volcanic region. Groundwaters of each study areas weree sampled and analysed systematically. Groundwaters can be grouped by their chemistry and host rock. Origin of the groundwater was proposed by isotope ({sup 18}O, {sup 2}H, {sup 13}C, {sup 34}S, {sup 87}Sr, {sup 15}N) studies and the age of groundwater was inferred from their tritium contents. Based ont the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs.

  9. Status report on geochemical modelling

    Read, D.

    1991-12-01

    This report describes the findings of a review undertaken on behalf of the project management group of the programme 'Endlagersicherheit in der Nachbetriebsphase' based at GSF-IfT (Forschungszentrum fuer Umwelt und Gesundheit - Institut fuer Tieflagerung) to establish the current status of research into the simulation of geochemical processes relevant to radiological assessment. The review is intended to contribute to Stage 1 of a strategy formulated to enhance the use of geochemical models in Germany. Emphasis has been placed on processes deemed to be of greatest relevance to performance assessment for a HLW-repository in a salt dome principally, speciation-solubility in high salinity solutions, complexation by natural organics and generation-transport of colloids. For each of these and other topics covered, a summary is given of fundamental concepts, theoretical representations and their limitations, highlighting, where appropriate, the advantages and disadvantages of alternative approaches. The availability of data to quantify any given representation is addressed, taking into account the need for information at elevated temperatures and pressures. Mass transfer is considered in terms of aqueous, particulate and gas-mediated transport, respectively. (orig.) [de

  10. Second Symposium on Chemical Evolution and the Origin of Life

    Devincenzi, D.L.; Dufour, P.A.

    1986-05-01

    Recent findings by NASA Exobiology investigators are reported. Scientific papers are presented in the following areas: cosmic evolution of biogenic compounds, prebiotic evolution (planetary and molecular), early evolution of life (biological and geochemical), evolution of advanced life, solar system exploration, and the Search for Extraterrestrial Intelligence (SETI)

  11. TAPIR--Finnish national geochemical baseline database.

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  12. Development of thermodynamic databases and geochemical/transport models for prediction of long-term radionuclide migration (Germany)

    Kienzler, B.

    2000-01-01

    The isolation capacity of a repository system for radionuclides is described by geochemical modeling. The models for interpretation of experimental findings and for long-term extrapolation of experimental results are based on thermodynamic approaches. The geochemical models include dissolution reactions of waste forms, the evolution of the geochemical milieu, interactions of radionuclides with constituents of the groundwater (brines) and the precipitation of new solid phases. Reliable thermodynamic data, understanding of radionuclide complexation in aqueous multi-electrolyte solutions at the relevant ionic strength and knowledge on the formation of pure and mixed solids and on sorption processes are urgently needed for such model calculations. (author)

  13. Evolução geoquímica e mineralógica em perfis de alteração sobre rochas serpentinizadas no sudoeste de Minas Gerais Geochemical and mineralogical evolution in alteration profiles on serpentinized rocks in southwestern Minas Gerais, Brazil

    Pablo Vidal-Torrado

    2007-10-01

    Full Text Available Estudou-se a evolução geoquímica e mineralógica em três perfis distintos de alteração de rochas serpentinizadas que ocorrem nas imediações dos municípios de Alpinópolis e Fortaleza de Minas, no sudoeste do Estado de Minas Gerais, sob regimes de umidade e de temperatura údico e térmico, respectivamente. Nas condições atuais, o grau de evolução química e mineralógica é moderado em relação ao desenvolvido sobre outros tipos de rochas básicas e ultrabásicas da mesma área, caracterizando-se por uma importante perda de Na e Mg e, em menor proporção, de Ca e Si. O Al (localmente também o Fe é o elemento menos móvel dos sistemas. O K é escasso no material de origem e nas zonas de alteração, e ocorre enriquecimento desse elemento nos horizontes superficiais por aporte externo. Os minerais primários mais facilmente intemperizáveis, como o talco, a tremolita e a clorita trioctaédrica, são abundantes ainda na fração argila desses solos tropicais com composição mineralógica pouco comum, mas são todos termodinamicamente instáveis. Do ponto de vista geoquímico, o processo de alteração atual pode ser definido como uma bissialitização, que pode coincidir com ferruginização, com formação de minerais trioctaédricos secundários por transformação direta de estrutura e também por neoformação, todos coexistindo com os minerais primários residuais. No entanto, as fases de maior evolução, em volumes com drenagem mais eficiente, tendem à monossialitização, com formação de caulinitas de diferentes graus de cristalinidade. A assembléia mineralógica existente evidencia a metaestabilidade e o caráter incipiente do sistema pedogenético.The geochemical and mineralogical evolution was studied in three different alteration profiles of ultramafic (serpentine rocks near Alpinópolis and Fortaleza de Minas, in southwestern Minas Gerais State (Brazil. Soil moisture and temperature regimes are udic and thermic

  14. Geochemical of clay formations : study of Spanish clay REFERENCE

    Turrero, M. J.; Pena, J.

    2003-01-01

    Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

  15. Coupled geochemical and solute transport code development

    Morrey, J.R.; Hostetler, C.J.

    1985-01-01

    A number of coupled geochemical hydrologic codes have been reported in the literature. Some of these codes have directly coupled the source-sink term to the solute transport equation. The current consensus seems to be that directly coupling hydrologic transport and chemical models through a series of interdependent differential equations is not feasible for multicomponent problems with complex geochemical processes (e.g., precipitation/dissolution reactions). A two-step process appears to be the required method of coupling codes for problems where a large suite of chemical reactions must be monitored. Two-step structure requires that the source-sink term in the transport equation is supplied by a geochemical code rather than by an analytical expression. We have developed a one-dimensional two-step coupled model designed to calculate relatively complex geochemical equilibria (CTM1D). Our geochemical module implements a Newton-Raphson algorithm to solve heterogeneous geochemical equilibria, involving up to 40 chemical components and 400 aqueous species. The geochemical module was designed to be efficient and compact. A revised version of the MINTEQ Code is used as a parent geochemical code

  16. Proceedings of the workshop on geochemical modeling

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices

  17. Proceedings of the workshop on geochemical modeling

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices.

  18. Geochemical prospecting for uranium and thorium deposits

    Boyle, R.W.

    1980-01-01

    A brief review of analytical geochemical prospecting methods for uranium and thorium is given excluding radiometric techniques, except those utilized in the determination of radon. The indicator (pathfinder) elements useful in geochemical surveys are listed for each of the types of known uranium and thorium deposits; this is followed by sections on analytical geochemical surveys based on rocks (lithochemical surveys), unconsolidated materials (pedochemical surveys), natural waters and sediments (hydrochemical surveys), biological materials (biogeochemical surveys) and gases (atmochemical surveys). All of the analytical geochemical methods are applicable in prospecting for thorium and uranium, particularly where radiometric methods fail due to attenuation by overburden, water, deep leaching and so on. Efficiency in the discovery of uranium and/or thorium orebodies is promoted by an integrated methods approach employing geological pattern recognition in the localization of deposits, analytical geochemical surveys, and radiometric surveys. (author)

  19. Perfil multidimensional de personas que han realizado intento de suicidio

    Nicolás Arturo Núñez Gómez

    2008-01-01

    Full Text Available Establecer el perfil multidimensional de personas con intento de suicidio. Se estudiaron 116 personas reportadas con intento de suicidio en servicios de urgencias e instituciones educativas del departamento del Huila. Diseño descriptivo; con entrevista semi-estructurada, prueba de personalidad, inventario de depresión, evaluación de alcoholismo, evaluación de ideación e intento de suicidio. El perfil multidimensional se caracterizó: adolescentes rurales, adultos citadinos; son de consideración: ama de casa, con relación de pareja estable, y personas solas, divorciadas, desempleadas. La relación neuroticismo bajo y piscoticismo alto podría ayudar a explicar que el intento de suicidio haya sido realizado de "repente" sin existir ningún síntoma previo. La estructura y dinámica familiar disfuncional están altamente asociadas a la persona con intento de suicidio.

  20. El nuevo perfil profesional de los profesores de secundaria

    Gemma Tribó Travería

    2008-01-01

    Full Text Available El objetivo del artículo es definir el nuevo perfil profesional de los profesores de secundaria. Una de las debilidades del sistema educativo español es que ha cambiado el marco legal y no se ha aplicado un nuevo modelo de formación inicial a los docentes de secundaria. El debate sobre las competencias profesionales está en la base de la propuesta de las competencias específicas del profesor del futuro. Se insiste en la importancia de las prácticas profesionales en el proceso de adquisición y de desarrollo de las competencias profesionales. Se valora positivamente que el master de formación inicial del profesorado de secundaria tenga presente en su diseño este nuevo perfil competencial profesional.

  1. Perfil docente para alumnos/as con altas capacidades

    María Leonor Conejeros-Solar

    2013-01-01

    Full Text Available El presente artículo tiene por objeto determinar un perfil de competencias docentes construido desde la percepción de estudiantes con altas capacidades pertenecientes a un programa universitario para talentos académicos. Se utiliza una metodología cualitativa con una estrategia documental de carácter retrospectivo. Los resultados indican que los estudiantes realizan una evaluación profunda sobre la docencia, incluyendo elementos pedagógicos como flexibilidad, ritmo e integración teoría-práctica. Las percepciones de los estudiantes, poco incorporadas en discusiones relativas a la enseñanza, permiten repensar y delinear un perfil de las competencias docentes relevadas para un trabajo pedagógico efectivo con talentosos en el aula.

  2. The Earth's heterogeneous mantle a geophysical, geodynamical, and geochemical perspective

    Khan, Amir

    2015-01-01

    This book highlights and discusses recent developments that have contributed to an improved understanding of observed mantle heterogeneities and their relation to the thermo-chemical state of Earth's mantle, which ultimately holds the key to unlocking the secrets of the evolution of our planet. This series of topical reviews and original contributions address 4 themes. Theme 1 covers topics in geophysics, including global and regional seismic tomography, electrical conductivity and seismic imaging of mantle discontinuities and heterogeneities in the upper mantle, transition zone and lower mantle. Theme 2 addresses geochemical views of the mantle including lithospheric evolution from analysis of mantle xenoliths, composition of the deep Earth and the effect of water on subduction-zone processes. Theme 3 discusses geodynamical perspectives on the global thermo-chemical structure of the deep mantle. Theme 4 covers application of mineral physics data and phase equilibrium computations to infer the regional-scale ...

  3. Recolectores, verificadores y reflexivos: perfiles de la competencia informacional en estudiantes universitarios de primer semestre

    Harold Castañeda-Peña; Liliana González Niño; Gloria Marciales Vivas; Jorge Winston Barbosa Chacón; Juan Carlos Barbosa Herrera

    2010-01-01

    Artículo de investigación que explora perfiles de la competencia informacional en estudiantes universitarios de primer semestre, a partir de un concepto renovado de competencia informacional desde la perspectiva sociocultural, donde se entiende perfil como una práctica habitual que es situada y variada. Se analiza el caso de 285 estudiantes provenientes de dos universidades colombianas, por medio de un instrumento observacional (cuestionario de perfil, protocolos en voz alta y entrevistas). S...

  4. Compilation of kinetic data for geochemical calculations

    Arthur, R.C.; Savage, D.; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu

    2000-01-01

    Kinetic data, including rate constants, reaction orders and activation energies, are compiled for 34 hydrolysis reactions involving feldspars, sheet silicates, zeolites, oxides, pyroxenes and amphiboles, and for similar reactions involving calcite and pyrite. The data are compatible with a rate law consistent with surface reaction control and transition-state theory, which is incorporated in the geochemical software package EQ3/6 and GWB. Kinetic data for the reactions noted above are strictly compatible with the transition-state rate law only under far-from-equilibrium conditions. It is possible that the data are conceptually consistent with this rate law under both far-from-equilibrium and near-to-equilibrium conditions, but this should be confirmed whenever possible through analysis of original experimental results. Due to limitations in the availability of kinetic data for mine-water reactions, and in order to simplify evaluations of geochemical models of groundwater evolution, it is convenient to assume local-equilibrium in such models whenever possible. To assess whether this assumption is reasonable, a modeling approach accounting for couple fluid flow and water-rock interaction is described that can be use to estimate spatial and temporal scale of local equilibrium. The approach is demonstrated for conditions involving groundwater flow in fractures at JNC's Kamaishi in-situ tests site, and is also used to estimate the travel time necessary for oxidizing surface waters to migrate to the level of a HLW repository in crystalline rock. The question of whether local equilibrium is a reasonable assumption must be addressed using an appropriate modeling approach. To be appropriate for conditions at the Kamaishi site using the modeling approach noted above, the fracture fill must closely approximate a porous mine, groundwater flow must be purely advective and diffusion of solutes across the fracture-host rock boundary must not occur. Moreover, the mineralogical and

  5. Geochemical evolution of brines in the Salar of Uyuni, Bolivia.

    Rettig, S.L.; Jones, B.F.; Risacher, F.

    1980-01-01

    Recent analyses of brines from the Salars of Uyuni and Coipasa have been compared with published data for Lakes Titicaca and Poopo to evaluate solute compositional trends in these remnants of two large Pleistocene lakes once connected by overflow from the N to the S of the Bolivian Altiplano. From Titicaca to Poopo the water shows an increase in Cl and N somewhat greater than the total solutes. Ca and SO4 increase to a lesser extent than total dissolved solids, and carbonate species are relatively constant. Between Poopo and Coipasa proportions of Ca, SO4 and CO3 continue to decrease. At Coipasa and Uyuni, the great salars frequently evaporate to halite saturation. Halite crystallization is accompanied by an increased K, Mg and SO4 in residual brines. - from Authors

  6. Geochemical evolution of groundwater in southern Bengal Basin ...

    due to weathering of feldspathic and ferro-magnesian minerals by percolating water. The groundwater ... function of the interaction between groundwater and mineral grains of the ... groundwater quality is essential to understand the .... Lead. 0.05. 5. 0.08772. Cadmium. 0.01. 5. 0.08772. ∑wi = 57 ∑Wi = 1.000. *For each ...

  7. Collected radiochemical and geochemical procedures

    Kleinberg, J [comp.

    1990-05-01

    This revision of LA-1721, 4th Ed., Collected Radiochemical Procedures, reflects the activities of two groups in the Isotope and Nuclear Chemistry Division of the Los Alamos National Laboratory: INC-11, Nuclear and radiochemistry; and INC-7, Isotope Geochemistry. The procedures fall into five categories: I. Separation of Radionuclides from Uranium, Fission-Product Solutions, and Nuclear Debris; II. Separation of Products from Irradiated Targets; III. Preparation of Samples for Mass Spectrometric Analysis; IV. Dissolution Procedures; and V. Geochemical Procedures. With one exception, the first category of procedures is ordered by the positions of the elements in the Periodic Table, with separate parts on the Representative Elements (the A groups); the d-Transition Elements (the B groups and the Transition Triads); and the Lanthanides (Rare Earths) and Actinides (the 4f- and 5f-Transition Elements). The members of Group IIIB-- scandium, yttrium, and lanthanum--are included with the lanthanides, elements they resemble closely in chemistry and with which they occur in nature. The procedures dealing with the isolation of products from irradiated targets are arranged by target element.

  8. Proceedings of 2. Brazilian Geochemical Congress

    1989-01-01

    Some works about geochemistry are presented, including themes about geochemical exploration, lithogeochemistry and isotope geochemistry, environmental geochemistry, analytical geochemistry, geochemistry of carbonatites and rare earth elements and organic geochemistry. (C.G.C.) [pt

  9. Coupling of transport and geochemical models

    Noy, D.J.

    1986-01-01

    This report considers mass transport in the far-field of a radioactive waste repository, and detailed geochemical modelling of the ground-water in the near-field. A parallel approach to this problem of coupling transport and geochemical codes is the subject of another CEC report (ref. EUR 10226). Both studies were carried out in the framework of the CEC project MIRAGE. (Migration of radionuclides in the geosphere)

  10. Geochemical evidence for waning magmatism and polycyclic volcanism at Crater Flat, Nevada

    Perry, F.V.; Crowe, B.M.

    1992-01-01

    This paper reports that petrologic and geochemical studies of basaltic rocks in the Yucca Mountain region are currently focused on understanding the evolution of volcanism in the Crater Flat volcanic field and the mechanisms of polycyclic volcanic field and the mechanisms of polycyclic volcanism at the Lathrop Wells volcanic center, the youngest center in the Crater Flat volcanic field. Geochemical and petrologic data indicate that the magma chambers which supplied the volcanic centers at Crater Flat became situated at greater crustal depths as the field evolved. Deep magma chambers may be related to a waning magma flux that was unable to sustain upper crustal magma conduits and chambers. Geochemical data from the Lathrop Wells volcanic center indicate that eruptive units identified from field and geomorphic relationships are geochemically distinct. The geochemical variations cannot be explained by fractional crystallization of a single magma batch, indicating that several magma batches were involved in the formation of the Lathrop Wells center. Considering the low magma flux in the Yucca Mountain region in the Quaternary, the probability of several magma batches erupting essentially simultaneously at Lathrop Wells is considered remote

  11. PERFIL PARA REPRESENTAR UNA ARQUITECTURA DE COMPONENTES EN UML

    Fernando Orejas Valdés

    2006-04-01

    Full Text Available

    El lenguaje unificado de modelado (Unified Modeling Language, UML es un lenguaje de modelado estándar para problemas generales, sin embargo, es necesario extenderlo para dominios específicos como puede ser el caso de determinadas arquitecturas. Aquí se presenta una extensión mediante un perfil para una arquitectura de componentes y conectores genéricos.

  12. The geochemical atlas of Alaska, 2016

    Lee, Gregory K.; Yager, Douglas B.; Mauk, Jeffrey L.; Granitto, Matthew; Denning, Paul; Wang, Bronwen; Werdon, Melanie B.

    2016-06-21

    A rich legacy of geochemical data produced since the early 1960s covers the great expanse of Alaska; careful treatment of such data may provide significant and revealing geochemical maps that may be used for landscape geochemistry, mineral resource exploration, and geoenvironmental investigations over large areas. To maximize the spatial density and extent of data coverage for statewide mapping of element distributions, we compiled and integrated analyses of more than 175,000 sediment and soil samples from three major, separate sources: the U.S. Geological Survey, the National Uranium Resource Evaluation program, and the Alaska Division of Geological & Geophysical Surveys geochemical databases. Various types of heterogeneity and deficiencies in these data presented major challenges to our development of coherently integrated datasets for modeling and mapping of element distributions. Researchers from many different organizations and disparate scientific studies collected samples that were analyzed using highly variable methods throughout a time period of more than 50 years, during which many changes in analytical techniques were developed and applied. Despite these challenges, the U.S. Geological Survey has produced a new systematically integrated compilation of sediment and soil geochemical data with an average sample site density of approximately 1 locality per 10 square kilometers (km2) for the entire State of Alaska, although density varies considerably among different areas. From that compilation, we have modeled and mapped the distributions of 68 elements, thus creating an updated geochemical atlas for the State.

  13. Perfil unitriádico de empresas respondables (accountability

    Migdalia Caridad

    2006-01-01

    Full Text Available El artículo divulga los resultados de la investigación perfil unitriádico gerencial de empresas líderes en respondabilidad (Accountability, la cual tuvo como propósito determinar dicho perfil, considerando específicamente el rol de las empresas como organización ante sus actores internos, clientes y comunidad donde actúan. El artículo establece el valor respondabilidad (Accountability como parte de la filosofía de la empresa, facilitando su interiorización bajo un enfoque unitriádico (capital intelectual racional, emocional y operacional, que se distinga por los atributos de un liderazgo relacional, que tome en cuenta el conocimiento y talento de su gente, sistemas comunicacionales con énfasis en el diálogo empático y asertivo (estilo conversacional, apoyado en sistemas de información, medición y de auditoria, así como en la publicación sistemática de resultados y con un comportamiento centrado en sus grupos de interés internos y externos

  14. Experimental insights into geochemical changes in hydraulically fractured Marcellus Shale

    Marcon, Virginia; Joseph, Craig; Carter, Kimberly E.; Hedges, Sheila W.; Lopano, Christina L.; Guthrie, George D.; Hakala, J. Alexandra

    2017-01-01

    Hydraulic fracturing applied to organic-rich shales has significantly increased the recoverable volume of methane available for U.S. energy consumption. Fluid-shale reactions in the reservoir may affect long-term reservoir productivity and waste management needs through changes to fracture mineral composition and produced fluid chemical composition. We performed laboratory experiments with Marcellus Shale and lab-generated hydraulic fracturing fluid at elevated pressures and temperatures to evaluate mineral reactions and the release of trace elements into solution. Results from the experiment containing fracturing chemicals show evidence for clay and carbonate dissolution, secondary clay and anhydrite precipitation, and early-stage (24–48 h) fluid enrichment of certain elements followed by depletion in later stages (i.e. Al, Cd, Co, Cr, Cu, Ni, Sc, Zn). Other elements such as As, Fe, Mn, Sr, and Y increased in concentration and remained elevated throughout the duration of the experiment with fracturing fluid. Geochemical modeling of experimental fluid data indicates primary clay dissolution, and secondary formation of smectites and barite, after reaction with fracturing fluid. Changes in aqueous organic composition were observed, indicating organic additives may be chemically transformed or sequestered by the formation after hydraulic fracturing. The NaCl concentrations in our fluids are similar to measured concentrations in Marcellus Shale produced waters, showing that these experiments are representative of reservoir fluid chemistries and can provide insight on geochemical reactions that occur in the field. These results can be applied towards evaluating the evolution of hydraulically-fractured reservoirs, and towards understanding geochemical processes that control the composition of produced water from unconventional shales. - Highlights: • Metal concentrations could be at their peak in produced waters recovered 24–48 after fracturing. • Carbonate

  15. The 'glass earth' - geochemical frontiers in exploration through cover

    Carr, G.; Denton, G.; Giblin, A.; Korsch, M.; Andrew, A.; Whitford, D.

    1999-01-01

    'Glass Earth' represents a number of current and planned projects within CSIRO aimed at making 'transparent' the top 1000 m of the Earth's crust It builds upon current technologies developed within a number of CSIRO divisions as well as the Australian Mineral Exploration Technologies CRC (AMET CRC), the Australian Geodynamics CRC (AG CRC) and the CRC for Landscape Evolution and Mineral Exploration (CRC LEME). New geophysical and geochemical technologies will be developed to complement these, together with new capabilities in modelling, data integration and visualisation, including hydrogeochemistry, hydrogeology, surface geochemistry and isotope geochemistry, modelling of chemical, fluid and heat flows in rock and regolith, advanced visualisation and data fusion. This paper describes some recent work in the field of isotope geochemistry, with the principal aim of 'seeing through' cover to understand basement geology and detect hidden ore systems

  16. Application of the isotopic index in isotope geochemical investigation

    Schuetze, H.

    1982-06-01

    A method is described which allows to calculate approximately isotope exchange equilibria between different crystalline silicates. The algorithm uses a newly introduced isotopic index. It is defined using isotopic increments of the variant types of silicatic bonds. This isotopic index gives a quantitative measure of the ability to enrich 18 O or 30 Si, respectively. The dependence of isotopic fractionations on temperature can be calculated approximately by means of the isotopic index, too. On this theoretical base some problems of magmatism and two varieties of an isotope geochemical model of the evolution of the Earth's crust are treated. Finally, the possibility is demonstrated to give prognostic statements about the likelihood of ore bearing of different granites. (author)

  17. Geochemical prospecting for thorium and uranium deposits

    Boyle, R.W.

    1982-01-01

    The basic purpose of this book is to present an analysis of the various geochemical methods applicable in the search for all types of thorium and uranium deposits. The general chemistry and geochemistry of thorium and uranium are briefly described in the opening chapter, and this is followed by a chapter on the deposits of the two elements with emphasis on their indicator (pathfinder) elements and on the primary and secondary dispersion characteristics of thorium and uranium in the vicinity of their deposits. The next seven chapters form the main part of the book and describe geochemical prospecting for thorium and uranium, stressing selection of areas in which to prospect, radiometric surveys, analytical geochemical surveys based on rocks (lithochemical surveys), unconsolidated materials (pedochemical surveys), natural waters and sediments (hydrochemical surveys), biological materials (biogeochemical surveys), gases (atmochemical surveys), and miscellaneous methods. A final brief chapter reviews radiometric and analytical methods for the detection and estimation of thorium and uranium. (Auth.)

  18. Robust statistics and geochemical data analysis

    Di, Z.

    1987-01-01

    Advantages of robust procedures over ordinary least-squares procedures in geochemical data analysis is demonstrated using NURE data from the Hot Springs Quadrangle, South Dakota, USA. Robust principal components analysis with 5% multivariate trimming successfully guarded the analysis against perturbations by outliers and increased the number of interpretable factors. Regression with SINE estimates significantly increased the goodness-of-fit of the regression and improved the correspondence of delineated anomalies with known uranium prospects. Because of the ubiquitous existence of outliers in geochemical data, robust statistical procedures are suggested as routine procedures to replace ordinary least-squares procedures

  19. Coupling of transport and geochemical models

    Noy, D.J.

    1985-01-01

    This contract stipulated separate pieces of work to consider mass transport in the far-field of a repository, and more detailed geochemical modelling of the groundwater in the near-field. It was envisaged that the far-field problem would be tackled by numerical solutions to the classical advection-diffusion equation obtained by the finite element method. For the near-field problem the feasibility of coupling existing geochemical equilibrium codes to the three dimensional groundwater flow codes was to be investigated. This report is divided into two sections with one part devoted to each aspect of this contract. (author)

  20. Comments on geochemical aspects of SR 97

    Arthur, R.C.; Wei Zhou

    2000-01-01

    The Swedish Government has asked SKB to carry out a safety assessment of the KBS-3 disposal concept for spent nuclear fuel 'to demonstrate that the KBS-3 method has good prospects of being able to meet the safety and radiation protection requirements which SKI and SSI have specified in recent years.' The results of that assessment, referred to as SR 97, have recently been published. The present report summarizes the results of a review of selected geochemical aspects of SR 97. These subjects include the hydrochemical evolution of a defective canister, thermodynamic data supporting estimates of radioelement solubilities, modeling of near-field chemistry and analyses of the effects of ice melting on propagation of an oxidizing front to repository depths. The primary focus of the review is on the canister-defect scenario, and, more specifically, on supporting analyses of the hydromechanical evolution of a defective canister. The results of these analyses figure prominently in the safety assessment because they suggest that even a defective canister will, in effect, remain dry for as long as 200,000 years. This is an important constraint because it is taken in SR 97 as the period of time required for a continuous water pathway to form in the near field. The transport of most radionuclides (i.e., those that do not exist as a gas) cannot occur until this pathway is formed. It is concluded that although SKBs hydromechanical models are sound, they may suffer from an over-simplification of the chemical processes involved. Analyses using the models do not acknowledge that the chemical system within the canister is open in all respects to the chemical system in the buffer. Instead, mass transfer across the defect at the canister-buffer interface is limited to liquid H 2 O and water vapor. Consideration of mass transfer of other gases [e.g., CO 2 and H 2 S] dissolved in buffer porewaters suggests that associated reactions involving the iron insert and inner surfaces of the

  1. Geochemical prospect ion results of Treinta y Tres aerial photo

    Zeegers, H.; Bonnefoy, D.; Garau, M.; Spangenberg, J.

    1981-01-01

    This report shows the geochemical prospect ion results carried out within the framework of the multielemental geochemical strategy. The samples were studied by e spectrometry in the laboratories of Orleans.

  2. La profesión docente: escenarios, perfiles y tendencias

    Pablo PALOMERO FERNÁNDEZ

    2010-01-01

    Full Text Available En este artículo se hace una presentación del número 35, volumen 13(4 de la Revista electrónica Interuniversitaria de Formación del Profesorado: La profesión docente: escenarios, perfiles y tendencias, en el que participan autores de veintiocho instituciones pertenecientes a cinco países: España, Brasil, México, Argentina y Perú. Se trata de un volumen que consta de veintiocho artículos seguidos de un conjunto de resúmenes de tesis doctorales y recensiones bibliográficas, cuyo marco general es el escenario de la profesión docente.

  3. Estudantes de enfermagem têm perfil empreendedor?

    Paulo Fernando Roncon

    Full Text Available Estudo descritivo-exploratório que teve como objetivo conhecer o perfil dos estudantes concluintes de um curso de graduação em enfermagem quanto ao empreendedorismo. O Teste de Tendência Empreendedora Geral, contendo 54 questões, foi aplicado a 41 estudantes. Os resultados demonstraram que14% apresentam cinco tendências empreendedoras e 12% quatro tendências empreendedoras; 80% apresentam fraca ou nenhuma tendência empreendedora. A grande maioria pretende encaminhar sua a profissão em atividades assistenciais, enquanto nenhum dos estudantes pretende atuar em atividades administrativas. Conclui-se que, os estudantes possuem baixo grau de presença de características empreendedoras.

  4. Geochemical fingerprints and pebbles zircon geochronology

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 7. Geochemical fingerprints and pebbles zircon geochronology: Implications for the provenance and tectonic setting of Lower Cretaceous sediments in the Zhucheng Basin (Jiaodong peninsula, North China). Jin-Long Ni Jun-Lai Liu Xiao-Ling Tang ...

  5. Kriging - a challenge in geochemical mapping

    Štojdl, J.; Matys Grygar, Tomáš; Elznicová, J.; Popelka, J.; Váchová, T.; Hošek, Michal

    2017-01-01

    Roč. 19, APR (2017) ISSN 1607-7962. [EGU General Assembly 2017. 23.04.2017-28.04.2017, Vienna] Institutional support: RVO:61388980 Keywords : kriging * geochemical mapping Subject RIV: DD - Geochemistry http://meetingorganizer.copernicus.org/EGU2017/EGU2017-3615.pdf

  6. Appliance of geochemical engineering in radioactive waste disposal

    Li Shuang; Zhang Chengjiang; Ni Shijun; Li Kuanliang

    2008-01-01

    The basic foundation of applying geochemical engineering to control environment, common engineering models of disposal radioactive waste and the functions of the engineering barriers are introduced in this paper. The authors take the geochemical engineering barrier materiel research of a radioactive waste repository as an example to explain the appliance of geochemical engineering in the disposal of radioactive waste. And the results show that it can enhance the security of the nuclear waste repository if we use geochemical engineering barrier. (authors)

  7. Proceedings of 13. International Geochemical Exploration Symposium. 2. Brazilian Geochemical Congress

    1989-01-01

    Some works about geochemistry are presented, including themes about geochemical exploration, lithogeochemistry and isotope geochemistry, environmental geochemistry, analyical geochemistry, geochemistry of carbonatites and rare earth elements and organic geochemistry. (C.G.C.) [pt

  8. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  9. Geochemical modeling of the nuclear-waste repository system. A status report

    Deutsch, W.J.

    1980-12-01

    The primary objective of the geochemical modeling task is to develop an understanding of the waste-repository geochemical system and provide a valuable tool for estimating future states of that system. There currently exists a variety of computer codes which can be used in geochemical modeling studies. Some available codes contain the framework for simulating a natural chemical system and estimating, within limits, the response of that system to environmental changes. By data-base enhancement and code development, this modeling technique can be even more usefully applied to a nuclear-waste repository. In particular, thermodynamic data on elements not presently in the data base but identified as being of particular hazard in the waste-repository system, need to be incorporated into the code to estimate the near-field as well as the far-field reactions during a hypothetical breach. A reaction-path-simulation code, which estimates the products of specific rock/water reactions, has been tested using basalt and ground water. Results show that the mass-transfer capabilities of the code will be useful in chemical-evolution studies and scenario analyses. The purpose of this report is to explain the status of geochemical modeling as it currently applies to the chemical system of a hypothetical nuclear-waste repository in basalt and to present the plan proposed for further developmet and application

  10. Coupling between a geochemical model and a transport model of dissolved elements

    Jacquier, P.

    1988-10-01

    In order to assess the safety analysis of an underground repository, the transport of radioelements in groundwater and their interactions with the geological medium are modelled. The objective of this work is the setting up and experimental validation of the coupling of a geochemical model with a transport model of dissolved elements. A laboratory experiment was developed at the CEA center of Cadarache. Flow-through experiments were carried out on columns filled with crushed limestone, where several inflow conditions were taken into account as the temperature, the presence of a pollutant (strontium chloride) at different concentrations. The results consist of the evolution of the chemical composition of the water at the outlet of the column. The final aim of the study is to explain these results with a coupled model where geochemical and transport phenomena are modelled in a two-step procedure. This code, called STELE, was built by introducing a geochemical code, CHIMERE, into an existing transport code, METIS. At this stage, the code CHIMERE can take into account: any chemical reaction in aqueous phase (complexation, acid-base reaction, redox equilibrium), dissolution-precipitation of minerals and solid phases, dissolution-degassing of gas. The paper intends to describe the whole process leading to the coupling which can be forecasted over the next years between geochemical and transport models

  11. Geochemical mapping study of Panjang island

    Sutisna; Sumardjo

    2010-01-01

    Impact of industrial and regional development are not only related to an improvement of socio-economic, but also to an environmental conservation and sustainable. This impact could be observed on a change of geochemical mapping before and after an operational of the industry. In the relation with a regional development and resources utilization, the geochemical mapping have been done in the aim to know a resources and an elemental distribution at Panjang island. In this research, ko-Instrumental Neutron Activation Analysis (k_0-INAA) have been applied in an elemental quantification on the geochemical mapping. Pencuplikan of geochemical sample have been carried out by using a grid systematic method with a sample density of about 10 sample per square kilometre involved 85 pencuplikan point. The geochemical sample of sediment and soil have been provided as a dry weight of 100 mesh. Internal quality control have done by using a number of Standard Reference Materials obtained from US. Geological Survey. Fifteen elements of Sc, Co, In, Rb, Mo, Ba, Ce, Nd, Eu, La, Yb, Th, U, lr and Hf contained in standard materials have been evaluated. The analysis result show that a relative standard deviation less than 11 %, except for Mo (13 %) and lr (26 %). Fourteen elements of Al, Br, Ca, Co, Eu, Fe, La, U, Na, Ce, Mn, As, Sc and Th have been mapped and presented in this paper. The major elements of Ca, Al and Fe, and minor elements of Mn, U and Sc are distributed at all region. The lanthanide elements of La, Ce and Eu have vary concentration and could be found at the middle to the north of the island. (author)

  12. Geochemical baseline studies of soil in Finland

    Pihlaja, Jouni

    2017-04-01

    The soil element concentrations regionally vary a lot in Finland. Mostly this is caused by the different bedrock types, which are reflected in the soil qualities. Geological Survey of Finland (GTK) is carrying out geochemical baseline studies in Finland. In the previous phase, the research is focusing on urban areas and mine environments. The information can, for example, be used to determine the need for soil remediation, to assess environmental impacts or to measure the natural state of soil in industrial areas or mine districts. The field work is done by taking soil samples, typically at depth between 0-10 cm. Sampling sites are chosen to represent the most vulnerable areas when thinking of human impacts by possible toxic soil element contents: playgrounds, day-care centers, schools, parks and residential areas. In the mine districts the samples are taken from the areas locating outside the airborne dust effected areas. Element contents of the soil samples are then analyzed with ICP-AES and ICP-MS, Hg with CV-AAS. The results of the geochemical baseline studies are published in the Finnish national geochemical baseline database (TAPIR). The geochemical baseline map service is free for all users via internet browser. Through this map service it is possible to calculate regional soil baseline values using geochemical data stored in the map service database. Baseline data for 17 elements in total is provided in the map service and it can be viewed on the GTK's web pages (http://gtkdata.gtk.fi/Tapir/indexEN.html).

  13. Geological evolution of the center-southern portion of the Guyana shield based on the geochemical, geochronological and isotopic studies of paleoproterozoic granitoids from southeastern Roraima, Brazil; Evolucao geologica da porcao centro-sul do escudo das Guianas com base no estudo geoquimico, geocronologico e isotopico dos granitoides paleoproterozoicos do sudeste de Roraima, Brasil

    Almeida, Marcelo Esteves

    2006-07-01

    This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of Cd (1.96-1.93 Ga). Regional mapping, petrography, geochemistry and zircon geochronology carried out in the Urad have showed widespread Paleoproterozoic calc-alkaline granitic magmatism. These granitoid rocks are distributed into several magmatic associations with different Paleoproterozoic (1.97-1.89 Ga) ages, structural and geochemical affinities. Detailed mapping, petrographic and geochronological studies have distinguished two main sub domains in the UAD. In the northern UAD, the high-K calc-alkaline Martins Pereira (1.97 Ga) and Serra Dourada S-type granites (1.96 Ga) are affected by NE-SW and E-W ductile dextral shear-zones, showing coexistence of magmatic and deformational fabrics related to heterogeneous deformation. Inliers of basement (2.03 Ga) crop out northeast of this area, and are formed by meta volcano-sedimentary sequence (Cauarane Group) and TTG-like calc-alkaline association (Anaua Complex). Xenoliths of meta diorites (Anaua Complex) and para gneisses (Cauarane Group) reinforce the intrusive character of Martins Pereira

  14. Ética y perfiles administrativos de empresas diferenciadas frente al perfil deseable para el administrador de empresas de la Universidad de La Salle

    Richard Orlando Buitrago Reyes

    2005-01-01

    Full Text Available El objetivo es ilustrar cómo la investigación que se realizó, encontró componentes de éticaempresarial y perfil gerencial en cuatro empresas bogotanas de acuerdo con perfiles deseablesde desarrollo universitario. Asimismo, desde el punto de vista empresarial, corroborar sicuatro empresas bogotanas exigen a sus profesionales en Administración de Empresas perfilesde desempeño y valores de desarrollo para desenvolverse en un ambiente de negocios. Esindiscutible que los cambios tecnológicos, de sistemas económicos, sociales y políticos llevaránal profesional en Administración de Empresas a prepararse de acuerdo con las exigencias delmundo moderno y a la Universidad a adecuar todos sus sistemas para crear un perfil delestudiante y del profesional coherente con las exigencias de liderazgo y capacidad de toma dedecisiones en extrema competitividad .

  15. Perfiles clínicos y hemodinámicos en pacientes con falla cardiaca aguda

    Luis Eduardo Calderón

    2017-09-01

    Conclusiones: la falla cardíaca aguda descompensada es el perfil de presentación clínica más común en nuestra población con dos tercios del total de casos. El perfil hemodinámico más frecuente fue el “caliente y húmedo” (Stevenson B, resultados que concuerdan con lo observado en estudios locales y registros internacionales.

  16. Predictive geochemical mapping using environmental correlation

    Wilford, John; Caritat, Patrice de; Bui, Elisabeth

    2016-01-01

    The distribution of chemical elements at and near the Earth's surface, the so-called critical zone, is complex and reflects the geochemistry and mineralogy of the original substrate modified by environmental factors that include physical, chemical and biological processes over time. Geochemical data typically is illustrated in the form of plan view maps or vertical cross-sections, where the composition of regolith, soil, bedrock or any other material is represented. These are primarily point observations that frequently are interpolated to produce rasters of element distributions. Here we propose the application of environmental or covariate regression modelling to predict and better understand the controls on major and trace element geochemistry within the regolith. Available environmental covariate datasets (raster or vector) representing factors influencing regolith or soil composition are intersected with the geochemical point data in a spatial statistical correlation model to develop a system of multiple linear correlations. The spatial resolution of the environmental covariates, which typically is much finer (e.g. ∼90 m pixel) than that of geochemical surveys (e.g. 1 sample per 10-10,000 km 2 ), carries over to the predictions. Therefore the derived predictive models of element concentrations take the form of continuous geochemical landscape representations that are potentially much more informative than geostatistical interpolations. Environmental correlation is applied to the Sir Samuel 1:250,000 scale map sheet in Western Australia to produce distribution models of individual elements describing the geochemical composition of the regolith and exposed bedrock. As an example we model the distribution of two elements – chromium and sodium. We show that the environmental correlation approach generates high resolution predictive maps that are statistically more accurate and effective than ordinary kriging and inverse distance weighting interpolation

  17. Geochemical Processes During Managed Aquifer Recharge With Desalinated Seawater

    Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

    2018-02-01

    We study geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW). The DSW, post-treated at the desalination plant by calcite dissolution (remineralization) to meet the Israeli water quality standards, is recharged into the Israeli Coastal Aquifer through an infiltration pond. Water quality monitoring during two MAR events using suction cups and wells inside the pond indicates that cation exchange is the dominant subsurface reaction, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the shallow groundwater composition is similar to the recharged DSW, except for enrichment of Mg2+, Na+, Ca2+, and HCO3-. A calibrated variably-saturated reactive transport model is used to predict the geochemical evolution during 50 years of MAR for two water quality scenarios: (i) post-treated DSW (current practice) and (ii) soft DSW (lacking the remineralization post-treatment process). The latter scenario was aimed to test soil-aquifer-treatment (SAT) as an alternative post-treatment technique. Both scenarios provide an enrichment of ˜2.5 mg L-1 in Mg2+ due to cation exchange, compared to practically zero Mg2+ currently found in the Israeli DSW. Simulations of the alternative SAT scenario provide Ca2+ and HCO3- remineralization due to calcite dissolution at levels that meet the Israeli standard for DSW. The simulated calcite content reduction in the sediments below the infiltration pond after 50 years of MAR was low (<1%). Our findings suggest that remineralization using SAT for DSW is a potentially sustainable practice at MAR sites overlying calcareous sandy aquifers.

  18. Geochemical processes during managed aquifer recharge with desalinated seawater

    Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

    2017-12-01

    In this work we study the geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW) to an infiltration pond at the Menashe site, located above the Israeli coastal aquifer. The DSW is post-treated by calcite dissolution (remineralization) in order to meet the Israeli desalinated water quality criteria. Suction cups and monitoring wells inside the pond were used to monitor water quality during two MAR events on 2015 and 2016. Results show that cation exchange is dominant, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the composition of the shallow groundwater is similar to the recharged DSW, but with enrichment of Mg2+, Na+, Ca2+ and HCO3-. A calibrated variably-saturated reactive transport model was used to predict the geochemical evolution during 50 years of MAR with two water quality scenarios: post-treated DSW and soft DSW (without post-treatment). The latter scenario was aimed to test soil-aquifer-treatment as an alternative post-treatment technique. In terms of water quality, the results of the two scenarios were found within the range of the desalinated water criteria. Mg2+ enrichment was stable ( 2.5 mg L-1), higher than the zero concentration found in the Israeli DSW. Calcite content reduction was low (<1%) along the variably-saturated profile, after 50 years of MAR. This suggests that using soil-aquifer-treatment as a remineralization technique for DSW is potentially a sustainable practice, which is limited only by the current hydraulic capacity of the Menashe MAR site.

  19. Geochemical Astro- and Geochronological Constraints on the Early Jurassic

    Storm, M.; Condon, D. J.; Ruhl, M.; Jenkyns, H. C.; Hesselbo, S. P.; Al-Suwaidi, A. H.; Percival, L.

    2017-12-01

    The Early Jurassic Hettangian and Sinemurian time scales are poorly defined due to the lack of continuous geochemical records, and the temporal constrain of the Toarcian Oceanic Anoxic Event and associated global carbon cycle perturbation is afflicted by geochemical and biostratigraphical uncertainties of the existing radiometric dates from various volcanic ash bearing sections. Here we present a continuous, orbitally paced Hettangian to Pliensbachian carbon-isotope record of the Mochras drill-core (Cardigan bay Basin, UK). The record generates new insights into the evolution and driving mechanisms of the Early Jurassic carbon cycle, and is contributing to improve the Hettangian and Sinemurian time scale. Furthermore, we introduce a new high-resolution carbon-isotope chemostratigraphy, integrated with ammonite biostratigraphy and new U/Pb single zircon geochronology of the Las Overas section (Neuquén Basin, Argentina). The studied section comprises sediments from the tenuicostatum to Dumortiera Andean Ammonite zone (tenuicostatum to levesqui European standard zones). A stratigraphically expanded negative shift in d13Corg values, from -24‰ down to -32­‰, appears in the tenuicostatum and hoelderi ammonite zone, coeval to the negative excursion in European realm which is associated with the Toarcian Oceanic Anoxic Event. The negative isotope excursion appears concomitant with an increase in sedimentary mercury levels, indicating enhanced volcanic activity. TOC values and elemental data suggest a high sedimentation dilution in the tenuicostatum to pacificum zone. The new geochronological data from several volcanic ash beds throughout the section are further improving the temporal correlation between the Early Toarcian isotope event and causal mechanisms

  20. Earth's earliest biosphere: Its origin and evolution

    Schopf, J.W.

    1983-01-01

    Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

  1. Application of cluster analysis to geochemical compositional data for identifying ore-related geochemical anomalies

    Zhou, Shuguang; Zhou, Kefa; Wang, Jinlin; Yang, Genfang; Wang, Shanshan

    2017-12-01

    Cluster analysis is a well-known technique that is used to analyze various types of data. In this study, cluster analysis is applied to geochemical data that describe 1444 stream sediment samples collected in northwestern Xinjiang with a sample spacing of approximately 2 km. Three algorithms (the hierarchical, k-means, and fuzzy c-means algorithms) and six data transformation methods (the z-score standardization, ZST; the logarithmic transformation, LT; the additive log-ratio transformation, ALT; the centered log-ratio transformation, CLT; the isometric log-ratio transformation, ILT; and no transformation, NT) are compared in terms of their effects on the cluster analysis of the geochemical compositional data. The study shows that, on the one hand, the ZST does not affect the results of column- or variable-based (R-type) cluster analysis, whereas the other methods, including the LT, the ALT, and the CLT, have substantial effects on the results. On the other hand, the results of the row- or observation-based (Q-type) cluster analysis obtained from the geochemical data after applying NT and the ZST are relatively poor. However, we derive some improved results from the geochemical data after applying the CLT, the ILT, the LT, and the ALT. Moreover, the k-means and fuzzy c-means clustering algorithms are more reliable than the hierarchical algorithm when they are used to cluster the geochemical data. We apply cluster analysis to the geochemical data to explore for Au deposits within the study area, and we obtain a good correlation between the results retrieved by combining the CLT or the ILT with the k-means or fuzzy c-means algorithms and the potential zones of Au mineralization. Therefore, we suggest that the combination of the CLT or the ILT with the k-means or fuzzy c-means algorithms is an effective tool to identify potential zones of mineralization from geochemical data.

  2. Uranium geochemical exploration in northwestern Luzon

    Santos, G. Jr.; Fernandez, L.; Ogena, M.; Tauli, G.

    1980-01-01

    A reconnaissance geochemical stream water and sediment survey which was conducted in northwestern Luzon was able to detect ten (10) uranium anomalous areas. These anomalous areas are located along a north-south trending zone of Miocene marine clastics and sedimentary rocks with tuffaceous sediment intercalations. In general, northwest Luzon has low radioactivity except for two anomalous areas which have 3 to 6 times background radioactivity. Radon anomalies occur in sparsely scattered locations. The anomalous zones appear to be related to major north-south faults and secondary northeast-southwest trending structures. Geochemical correlations between uranium and other elements such as copper, lead, zinc, manganese, silver, cobalt and nickel are generally very poor. (author)

  3. Geochemical approach to evaluate deforest of mangroves

    Ishiga, Hiroaki; Diallo, Ibrahima M'bemba; Bah Mamadou Lamine Malick,; Ngulimi. Faustine Miguta,; Magai. Paschal Justin,; Shati Samwel Stanley,

    2016-01-01

    Processes of mangrove deforest related human activities were examined. To evaluate changes of soil feature, multielements geochemical compositions of mangrove muds and soils of deforest were analyzed. To describe present situation of the mangrove, Conakry in Guinea, Dar es Salaam in Tanzania, Sundarbans of Bangladesh and Nago in Okinawa of Japan were selected. Soil samples of the forests were evaluated enrichment of biologically concentrated heavy metals such as Zn, Cu and Fe, and TS (total s...

  4. Geochemical indicators of gold ore fields

    Shcherbakov, Yu.G.

    1995-01-01

    The principles of selection of indicators for genetic reconstructions and prognostic valuations of gold mineralization of diverse morphological and geochemical types have been substantiated. The neutron-activation analysis with radiochemical separation and detection limit of 1-10 -8 %, instrumental neutron-activation analysis and atomic-absorption analysis are the main methods of determination of gold low contents in the rocks, as well as diverse elements, including transition, rare earth elements and tellurium, in gold. 50 refs.; 1 fig.; 3 tabs

  5. Summary report on geochemical barrier special study

    1988-12-01

    Long-term management of uranium mill tailings must provide assurance that soluble contaminants will not migrate beyond the Point of Compliance. Conventional management alternatives provide containment through the use of physical barriers which are designed to prevent migration of water through the tailings pile. An alternative is to geochemically modify the tailings to immobilize the contaminants. This investigation examined three potential geochemical modifiers to determine their ability to immobilize inorganic groundwater contaminants found in uranium mill tailings. These modifiers were hydrated lime (Ca(OH) 2 ), limestone (CaCO 3 ), and a sphaegnum peat moss. This investigation focused on both the geochemical interactions between the tailings and the modifiers, and the effects the modifiers had on the physical strength of the tailings. The geochemical investigations began with characterization of the tailings by X-ray diffraction and scanning electron microscopy. This was followed by batch leaching experiments in which various concentrations of each modifier were added to tailings in shaker flasks and allowed to come to equilibrium. Finally, column experiments were conducted to simulate flow through a tailings pile. The results show that all of the modifiers were at least moderately effective at immobilizing most of the groundwater contaminants of concern at uranium mill tailings sites. Hydrated lime was able to achieve 90 percent concentration reduction of arsenic, cadmium, selenium, uranium, and sulfate when added at a two percent concentration. Limestone was somewhat less effective and peat removed greater than 90 percent of arsenic, lead, uranium, and sulfate at a one percent concentration. The column tests showed that kinetic and/or mass transfer limitations are important and that sufficient time must be allowed for the immobilization reactions to occur

  6. Field-based tests of geochemical modeling codes: New Zealand hydrothermal systems

    Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.

    1993-12-01

    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions

  7. Field-based tests of geochemical modeling codes usign New Zealand hydrothermal systems

    Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.

    1994-06-01

    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions

  8. Geochemical modelling of CO2-water-rock interactions for carbon storage : data requirements and outputs

    Kirste, D.

    2008-01-01

    A geochemical model was used to predict the short-term and long-term behaviour of carbon dioxide (CO 2 ), formation water, and reservoir mineralogy at a carbon sequestration site. Data requirements for the geochemical model included detailed mineral petrography; formation water chemistry; thermodynamic and kinetic data for mineral phases; and rock and reservoir physical characteristics. The model was used to determine the types of outputs expected for potential CO 2 storage sites and natural analogues. Reaction path modelling was conducted to determine the total reactivity or CO 2 storage capability of the rock by applying static equilibrium and kinetic simulations. Potential product phases were identified using the modelling technique, which also enabled the identification of the chemical evolution of the system. Results of the modelling study demonstrated that changes in porosity and permeability over time should be considered during the site selection process.

  9. Perfil del viajero internacional: el trabajo como motivo de viaje

    M.ª Belén Robles García

    Full Text Available Objetivos: describir la población a estudio y comparar el motivo de viaje laboral con el motivo turístico y con la Visita de Amigos o Familiares (VFRs para estimar si existe un perfil de riesgo diferente. Metodología: estudio de las variables edad, género, duración, motivo, destino y recomendación de quimioprofilaxis en viajeros que acuden al Centro de Atención Pre-viaje Internacional de Asturias (España entre 2008 y 2016. Un total de 9. 527 (89,83% viajeros cumplieron el criterio de inclusión (edad >18 años. Resultados: en 2013 el motivo laboral constituyó el 43,85% de todas las causas de viaje internacional. La mayoría de los trabajadores (70,89% fueron hombres (p=0,00, más jóvenes que los turistas (38 vs 40 años; p=0,00 o que los VFRs (38 vs 39 años; p=0,03. Además, los trabajadores viajaban durante más tiempo que los turistas (91 vs 23 días; p=0,00 o que los VFRs (91 vs 50 días; p=0,00. África Subsahariana fue la región más visitada por el motivo profesional (35,89%. Se recomendó quimioprofilaxis en 39,19% trabajadores vs 38,72% turistas más VFRs (p=0,68. Los desplazamientos laborales internacionales por regiones no mostraron diferencia respecto a la recomendación de quimioprofilaxis vs turistas y VFRs. Conclusiones: en la población estudiada el motivo laboral de un viaje internacional tiene un perfil del viajero específico. Se deben desarrollar iniciativas de salud pública para prevenir riesgos concretos y promover el consejo sanitario individualizado.

  10. Sharp fronts within geochemical transport problems

    Grindrod, P.

    1995-01-01

    The authors consider some reactive geochemical transport problems in groundwater systems. When incoming fluid is in disequilibrium with the mineralogy sharp transition fronts may develop. They show that this is a generic property for a class of systems where the timescales associated with reaction and diffusion phenomena are much shorter than those associated with advective transport. Such multiple timescale problems are relevant to a variety of processes in natural systems: mathematically methods of singular perturbation theory reduce the dimension of the problems to be solved locally. Furthermore, they consider how spatial heterogeneous mineralogy can impact upon the propagation of sharp geochemical fronts. The authors developed an asymptotic approach in which they solve equations for the evolving geometry of the front and indicate how the non-smooth perturbations due to natural heterogeneity of the mineralogy on underlying ground water flow field are balanced against the smoothing effect of diffusion/dispersive processes. Fronts are curvature damped, and the results here indicate the generic nature of separate front propagation within both model (idealized) and natural (heterogeneous) geochemical systems

  11. Monitoring active volcanoes: The geochemical approach

    Takeshi Ohba

    2011-06-01

    Full Text Available

    The geochemical surveillance of an active volcano aims to recognize possible signals that are related to changes in volcanic activity. Indeed, as a consequence of the magma rising inside the volcanic "plumbing system" and/or the refilling with new batches of magma, the dissolved volatiles in the magma are progressively released as a function of their relative solubilities. When approaching the surface, these fluids that are discharged during magma degassing can interact with shallow aquifers and/or can be released along the main volcano-tectonic structures. Under these conditions, the following main degassing processes represent strategic sites to be monitored.

    The main purpose of this special volume is to collect papers that cover a wide range of topics in volcanic fluid geochemistry, which include geochemical characterization and geochemical monitoring of active volcanoes using different techniques and at different sites. Moreover, part of this volume has been dedicated to the new geochemistry tools.

  12. Geochemical sensitivity analysis: Identification of important geochemical parameters for performance assessment studies

    Siegel, M.; Guzowski, R.; Rechard, R.; Erickson, K.

    1986-01-01

    The EPA Standard for geologic disposal of high level waste requires demonstration that the cumulative discharge of individual radioisotopes over a 10,000 year period at points 5 kilometers from the engineered barrier system will not exceed the limits prescribed in 40 CFR Part 191. The roles of the waste package, engineered facility, hydrogeology and geochemical processes in limiting radionuclide releases all must be considered in calculations designed to assess compliance of candidate repositories with the EPA Standard. In this talk, they will discuss the geochemical requirements of calculations used in these compliance assessments. In addition, they will describe the complementary roles of (1) simple models designed to bound the radionuclide discharge over the widest reasonable range of geochemical conditions and scenarios and (2) detailed geochemical models which can provide insights into the actual behavior of the radionuclides in the ground water. Finally, they will discuss development of sensitivity/uncertainty techniques designed to identify important site-specific geochemical parameters and processes using data from a basalt formation

  13. Determinación de perfiles para rotores de compresores de tornillo con perfil simétrico. // Profiles determination for screw compressors rotors with symmetrical profile.

    A. Rivera Torres

    2005-05-01

    Full Text Available Los compresores rotativos de tornillo, constituyeron el acontecimiento histórico más relevante del siglo XX en el campodel proceso de compresión. Dentro de los elementos fundamentales de los compresores rotativos de tornillo se encuentranlos rotores, los cuales tienen lóbulos o canales helicoidales con perfiles con formas simétricas o asimétricas.En este articulo se presenta un método para el diseño de los perfiles de rotores para compresores o bombas de tornillo, conperfil circular, a partir del empleo de una curva de cuarto orden y la condición de conjugación de los engranajes, sin incluirel empleo de cicloides en la generación de dichos perfiles, lográndose características similares a la de los perfiles SRM.Palabras claves: Rotores, rotor macho, rotor hembra._____________________________________________________________________________Abstract:Rotary screw compressors constitute the most relevant historic event of the twentieth century in the field of the process ofcompression. The most fundamental elements of rotary screw compressors are the rotors, which have helical lobes or canalsand symmetrical or asymmetrical profiles.This paper presents a method of circular profile design for screw compressors or pumps, based on fourth order curves andthe conjugation of gears, which does not include the application of cycloids in profile generation but have similarcharacteristics to SRM profiles.Key words: rotors, male rotor, female rotor.

  14. PERFIL FISIOLÓGICO DEL JUDOKA. UNA REVISIÓN

    Raquel Hernández García

    2007-01-01

    Full Text Available El judo en su aspecto competitivo requiere una elevada preparación técnica, táctica, física y psicológica, ya que cada uno de estos aspectos es imprescindible para soportar las altas cargas de entrenamiento y competición llevadas a cabo por estos deportistas. A la suma, este deporte de combate está caracterizado estructuralmente por categorías de peso, lo cual alza la importancia del control fisiológico del entrenamiento en los judokas. Por lo tanto, el presente trabajo de revisión posee como principal objeto recolectar los diferentes artículos científicos sobre el perfil fisiológico del judoka, enmarcando aspectos como parámetros antropométricos (% de grasa corporal, registro de Frecuencia Cardiaca (FC, consumo máximo de oxígeno (VO2máx, indicadores hematológicos e indicadores electrolíticos.

  15. URGÊNCIAS CLÍNICAS: PERFIL DE ATENDIMENTOS HOSPITALARES

    Mônica Franco Coelho

    2013-01-01

    Full Text Available Cambios en la morbilidad y mortalidad por enfermedades crónicas no transmisibles no traen repercusiones para asistir a los departamentos de urgencias/emergencias hospitalarios. El objetivo fue caracterizar el perfil de la atención de urgencia, según las variables demográficas, epidemiológicas y de estancia en el hospital de Enseñanza, del interior de São Paulo, 2007. Investigación documental, descriptiva, exploratoria, a partir de datos oficiales, analizados por estadística descriptiva, discutidos a través del marco teórico de reorganización de la atención de emergencia/emergencias clínicas. En el periodo, ocurrieron 5.285 tratamientos clínicos, con usuarios del sexo masculino (54,1%, con estudios primarios (73,9%, de 18 a 59 años (62,8%. Enfermedades del aparato circulatorio fueron más frecuentes y la duración de la estancia en la unidad fue de menos de seis horas (39,8%. La caracterización de la atención clínica en servicio de urgencia/emergencia proporciona subvenciones para el trabajo en la unidad de estudio y en el hospital.

  16. Some results of NURE uranium geochemical studies

    Price, V. Jr.

    1979-01-01

    Some technical developments of the National Uranium Resource Evaluation Program which are of general application in geochemical exploration are being studied. Results of stream water and suspended and bottom sediment analyses are compared for an area near Williamsport, Pennsylvania. Variations of uranium content of water samples with time in the North Carolina Piedmont are seen to correlate with rainfall. Ground water samples from coastal and piedmont areas were analyzed for helium. All media sampled provide useful information when properly analyzed and interpreted as part of a total geological analysis of an area

  17. Panay carborne radiometric and geochemical surveys

    Santos, G. Jr.

    1981-09-01

    A carborne radiometric survey and stream sediments collection were conducted in Panay and Guimaras Islands. An area in Nabas, Aklan, situated in the northwestern tip of Panay (Buruanga Peninsula) which indicated 2 to 3 times above background radioactivity was delineated. Uranium content in the stream sediment samples collected from Buruanga Peninsula was generally higher than those obtained in other parts of the island. Radioactivity measurements and uranium content in stream sediments were found to be within background levels. It is recommended that follow-up radiometric and geochemical surveys be undertaken in Buruanga Peninsula and additional stream sediments samples be collected in Panay to achieve better sampling density and coverage. (author)

  18. Landscape-geochemical factors of deposit formation

    Batulin, S.G.

    1980-01-01

    Effect of landscape-geochemical factors on hydrogenic formation of uranium ores is considered. The primary attention is paid to finding reasons for hydrogeochemical background increase in the regions of arid climate. Problems of uranium distribution in alluvial landscapes, hydrogeochemical regime of ground waters, reflecting the effect of waters of the zone of aeration are revealed. Chemical composition of porous solutions in the zone of aeration, as well as historical geochemindstry of landscape a its role from the view point of uranium solution formation in the arid zone are considered [ru

  19. DNA-based methods of geochemical prospecting

    Ashby, Matthew [Mill Valley, CA

    2011-12-06

    The present invention relates to methods for performing surveys of the genetic diversity of a population. The invention also relates to methods for performing genetic analyses of a population. The invention further relates to methods for the creation of databases comprising the survey information and the databases created by these methods. The invention also relates to methods for analyzing the information to correlate the presence of nucleic acid markers with desired parameters in a sample. These methods have application in the fields of geochemical exploration, agriculture, bioremediation, environmental analysis, clinical microbiology, forensic science and medicine.

  20. Geochemical modelling. Pt.1, Pt.2

    Skytte Jensen, B.; Jensen, H.; Pearson, F.J.

    1992-01-01

    This work is carried out under cost-sharing contract with the European Atomic Energy Community in the framework of its fourth research programme on radioactive waste management and radioactive waste storage. This final report is subdivided into two parts. In the first part, JENSEN, a computer code for the computation of chemical equilibria in aqueous systems, describes the structure, function and use of a new geochemical computer program intended for PC's. The program, which is written in Turbo Pascal, version 4, is fundamentally similar to most other geochemical programs, but combines in one program several of the merits these programs have. The intention has been to make an advanced program, which also should be user friendly and fast, and to attain this several new algorithms have been developed and implemented. The program has a built-in database mainly based on the CHEMVAL compilation containing data for 395 soluble species and 149 minerals. The program can find equilibria in the presence of all or some of these soluble species, under conditions or fixed or floating pH and / or Redox potential. The program by itself eliminates a bad guess of a candidate for precipitation. In the present version, the program can identify which minerals and how much of them there will be formed when equilibrium is established. In the second part, LITTLE JOE, an expert system to support geochemical modelling, describes the construction of a minor expert system for use in the evaluation of analytical data for the composition of ground waters from limestone formation. Although the example given is rather limited in scope, the application of the expert system for the evaluation of the analytical data clearly demonstrates the mature expert knowledge imbedded in the system which is contrasted with the uncritical acceptance of analytical or theoretical data. With the overall neglect of ion-exchange and the formation of solid solutions in geochemical calculations, geochemistry is

  1. Internauta brasileiro: perfil diferenciado, opiniões indiferenciadas

    Rogerio Schlegel

    2009-10-01

    Full Text Available O artigo pretende contribuir para melhorar a compreensão das relações entre o uso da internet, de um lado, e a participação política dos cidadãos, de outro. Sua ênfase é nos fatores que determinam o uso regular da internet e no perfil do internauta em termos de participação e valores relacionados à política. A análise dos dados do survey Latinobarómetro de 2007 aponta a idade e a escolaridade como principais determinantes do uso da internet no Brasil, sendo que a ocupação e uma proxy para renda não tiveram impacto consistente na chance de conectar-se, contrastando com os casos de Argentina e Chile. Ao mesmo tempo, o público que integra a comunidade on-line mostrou maior mobilização, em termos de participação política tradicional, e pouca diferenciação em matéria de opiniões sobre política, na comparação com os não-usuários da nova tecnologia. Essas evidências sugerem que a conexão ao mundo digital tende a dar voz a segmentos que já contam com acesso privilegiado a governantes e elaboradores de políticas, sobretudo por seu capital cultural, embora haja sinais da existência de oportunidades para outros setores sociais. Também indicam que a importância do "digital divide" no país deve ser relativizada, uma vez que os internautas não apresentam opiniões com orientação claramente destoante do restante da população.

  2. Variables que definen el perfil del inmigrante universitario

    María Gloria Pérez Serrano

    2013-05-01

    Full Text Available La diversidad cultural constituye una característica que define a la sociedad actual. Las migraciones se han convertido en los últimos años en una constante atemporal que exige la búsqueda de mecanismos adecuados para gestionar esta nueva realidad, sin producir rupturas ni enfrentamientos. Cabe afirmar que el encuentro de distintas culturas en un mismo espacio geográfico es hoy un hecho estructural. Los organismos internacionales apuestan por promover la convivencia en realidades pluriculturales y luchar para el reconocimiento de los derechos de las minorías. La Universidad, como institución de educación superior, tiene como misión formar a profesionales con un alto nivel de cualificación y ésta debe hacerse extensiva a la población foránea. El objetivo de este trabajo es definir el perfil del inmigrante universitario, a fin de identificar sus rasgos diferenciales. Se ha utilizado una metodología cuantitativa y cualitativa. Se aplicó un cuestionario de escala tipo Licker así como una entrevista semiestructurada. Se realizaron análisis de los datos utilizando distintos paquetes informáticos. Entre sus principales resultados destaca que dicha población elige la universidad para continuar su formación, mejorar su empleo y conseguir legalizar su título. Prefieren estudios de larga duración para tener más oportunidades en un mercado laboral competitivo. Sus expectativas son elevadas en orden a mejorar la calidad de vida. Concluye el trabajo aportando medidas de discriminación positiva para favorecer la inclusión social de esta población.

  3. Chilenos en Madrid: Perfiles, trayectorias y su mirada inmigrante

    Leonora Torres Matus

    2008-05-01

    Full Text Available En el presente estudio se mostrará la información recogida durante las visitas a la asociación de chilenos en España (ACHES entre los años 2005 y 2006, específicamente a 30 casos estudiados con mayor profundidad a través de un cuestionario en un primer momento, seguido con entrevistas posteriores para complementar dicha información. Los chilenos entrevistados (en su mayoría jóvenes, de sexo masculino, solteros y sin carga familiar presentan una heterogeneidad clara, tanto en su perfil socio-económico y cultural como en sus motivos para emigrar a España, que son principalmente económicos. La media de estancia en el país es de 1-2 años desde el momento de la aplicación del cuestionario. Sus mayores problemas tienen relación con la situación legal en España y también con la precariedad laboral, que han ido solventando gracias a la red social tanto de compatriotas como de otros colectivos extranjeros y de la familia en origen. Para la mayoría, es la primera vez que inician una aventura migratoria. La nostalgia, el choque cultural y la necesidad de contar con la familia son los aspectos psicológicos y sociales que más destacan a la hora de hablar de su proceso de inserción en el país.

  4. Fracture Sealing in Shales: Geological and Geochemical Factors

    Cathelineau, Michel

    2001-01-01

    The so-called self-sealing processes can be re-examined at the light of geological and geochemical consideration about the past history of the rocks. The concept of 'self sealing' needs to consider the formation and the sealing of fractures, especially three main stages: (i) the initiation of the fracture (development of micro-cracks initiated from previous heterogeneities up to fracturing), ii) the fracturing processes which occur generally at depth in presence of a fluid phase, iii) the healing or sealing of the fractures which corresponds basically to two main processes: a restoration of the initial permeability of the rock block by reducing the transmissivity of the discontinuity down to values equivalent to that of the homogeneous medium before fracturing, or the sealing of the open discontinuity by precipitation of newly formed minerals. In the latter case, the evolution of the open fracture is driven by re-arrangement of particles or precipitation of newly formed material, either by dissolution/crystallisation processes or by crystallisation from the percolating fluids (advective processes). Such processes are governed by chemical processes, especially the rate of precipitation of minerals which depends of the degree of saturation with respect to the mineral, and the kinetics of precipitation. (author)

  5. Definición cuantitativa de perfiles profesionales en ingeniería

    Marla Constanza Barrera Botero

    2015-05-01

    Full Text Available Un perfil profesional es un conjunto de conocimientos y habilidades. En el presente artículo se propone una metodología para definir perfiles profesionales basada en una evaluación cualitativa de habilidades y conocimientos asociados con un plan de estudios de ingeniería. Esta metodología puede ser usada para evaluar la flexibilidad curricular, es decir, si el plan de estudios ofrece a los estudiantes enfoques y rutas de aprendizaje que sean diversos y flexibles. Aquí se describe un modelo matemático que permite calcular el grado de satisfacción logrado por un estudiante con respecto a uno o varios perfiles. Esta propuesta ha sido aplicada en el programa de pregrado de Ingeniería Eléctrica de la Universidad Nacional de Colombia.

  6. Kinetics of Uranium(VI) Desorption from Contaminated Sediments: Effect of Geochemical Conditions and Model Evaluation

    Liu, Chongxuan; Shi, Zhenqing; Zachara, John M.

    2009-01-01

    Stirred-flow cell experiments were performed to investigate the kinetics of uranyl (U(VI)) desorption from a contaminated sediment collected from the Hanford 300 Area at the US Department of Energy (DOE) Hanford Site, Washington. Three influent solutions of variable pH, Ca and carbonate concentrations that affected U(VI) aqueous and surface speciation were used under dynamic flow conditions to evaluate the effect of geochemical conditions on the rate of U(VI) desorption. The measured rate of U(VI) desorption varied with solution chemical composition that evolved as a result of thermodynamic and kinetic interactions between the influent solutions and sediment. The solution chemical composition that led to a lower equilibrium U(VI) sorption to the solid phase yielded a faster desorption rate. The experimental results were used to evaluate a multi-rate, surface complexation model (SCM) that has been proposed to describe U(VI) desorption kinetics in the Hanford sediment that contained complex sorbed U(VI) species in mass transfer limited domains. The model was modified and supplemented by including multi-rate, ion exchange reactions to describe the geochemical interactions between the solutions and sediment. With the same set of model parameters, the modified model reasonably well described the evolution of major ions and the rates of U(VI) desorption under variable geochemical and flow conditions, implying that the multi-rate SCM is an effective way to describe U(VI) desorption kinetics in subsurface sediments

  7. Geochemical effects on the behavior of LLW radionuclides in soil/groundwater environments

    Krupka, K.M.; Sterne, R.J. [Pacific Northwest Lab., Richland, WA (United States)

    1995-12-31

    Assessing the migration potential of radionuclides leached from low-level radioactive waste (LLW) and decommissioning sites necessitates information on the effects of sorption and precipitation on the concentrations of dissolved radionuclides. Such an assessment requires that the geochemical processes of aqueous speciation, complexation, oxidation/reduction, and ion exchange be taken into account. The Pacific Northwest National Laboratory (PNNL) is providing technical support to the U.S. Nuclear Regulatory Commission (NRC) for defining the solubility and sorption behavior of radionuclides in soil/ground-water environments associated with engineered cementitious LLW disposal systems and decommissioning sites. Geochemical modeling is being used to predict solubility limits for radionuclides under geochemical conditions associated with these environments. The solubility limits are being used as maximum concentration limits in performance assessment calculations describing the release of contaminants from waste sources. Available data were compiled regarding the sorption potential of radionuclides onto {open_quotes}fresh{close_quotes} cement/concrete where the expected pH of the cement pore waters will equal to or exceed 10. Based on information gleaned from the literature, a list of preferred minimum distribution coefficients (Kd`s) was developed for these radionuclides. The K{sub d} values are specific to the chemical environments associated with the evolution of the compositions of cement/concrete pore waters.

  8. Research on geochemical exploration in geotherm development

    Hirowatari, Kazuo; Imaizumi, Yukio; Koga, Akito; Iwanaga, Tatsuto.

    1987-01-01

    The decisive factor of geotherm development is to improve the exploration techniques. By effectively carrying out the selection of promising development spots and the decision of well drilling positions, the geotherm development exceeding existing energy sources becomes feasible. There have been many problems in conventional geotherm exploration such as the high cost and long work period, therefore, it was decided to advance the research on geochemical exploration techniques which are relatively simple and can be carried out with low cost. When the techniques of geochemistry are used, for example, in the case that there are hot springs or fumaroles, the temperature, origin, properties and so on of underground hot water reservoirs can be estimated from their chemical composition. The method of examining the mercury concentration in soil and soil air has been in practical use in the geothermal districts where the ground surface symptom lacks. This time, the method of investigation using radon, thoron and gamma ray as the exploration indices was newly studied. The index compositions for geochemical exploration, new exploration index compositions, the method of measurement, the basic investigation and on-the-spot investigation are reported. (Kako, I.)

  9. Geochemical signature of radioactive waste: oil NORM

    Costa, Gilberto T. de Paula; Costa-de-Moura, Jorge; Gomes, Carlos de Almeida; Sampaio, Emidio A. Lopes, E-mail: gilberto.costa@cnen.gov.br, E-mail: jcmoura@cnen.gov.br, E-mail: cgomes@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Div. de Controle de Rejeitos e Transporte de Materiais Radioativos

    2017-07-01

    The Brazilian Nuclear Agency (CNEN) rules all nuclear activity in Brazil as demanded by the Federal Constitution, articles 21, XXIII, and 177, V, and by the Federal Acts 4.118/62 and 10.308/2001. Therefore, the CNEN is responsible for any radioactive waste disposal in the country. Oil Naturally Occurring Radioactive Materials (Oil NORM) in this paper refers to waste coming from oil exploration. Oil NORM has called much attention during the last decades, mostly because it is not possible to determine its primary source due to the actual absence of regulatory control mechanism. There is no efficient regulatory tool which allows determining the origin of such NORM wastes even among those facilities under regulatory control. This fact may encourage non-authorized radioactive material transportation, smuggling and terrorism. The aim of this project is to provide a geochemical signature for each oil NORM waste using its naturally occurring isotopic composition to identify its origin. The here proposed method is a specific geochemical modeling of oil sludge NORM samples which are analyzed for radioisotopes normally present in oil pipes, such as {sup 228}Ac, {sup 214}Bi and {sup 214}Pb. The activity ratios are plotted in scatter diagrams. This method was successfully tested with data of different sources obtained from analysis reports from the Campos Basin/Brazil and from literature. (author)

  10. Neutron activation analysis of geochemical samples

    Rosenberg, R.; Zilliacus, R.; Kaistila, M.

    1983-06-01

    The present paper will describe the work done at the Technical Research Centre of Finland in developing methods for the large-scale activation analysis of samples for the geochemical prospecting of metals. The geochemical prospecting for uranium started in Finland in 1974 and consequently a manually operated device for the delayed neutron activation analysis of uranium was taken into use. During 1974 9000 samples were analyzed. The small capacity of the analyzer made it necessary to develop a completely automated analyzer which was taken into use in August 1975. Since then 20000-30000 samples have been analyzed annually the annual capacity being about 60000 samples when running seven hours per day. Multielemental instrumental neutron activation analysis is used for the analysis of more than 40 elements. Using instrumental epithermal neutron activation analysis 25-27 elements can be analyzed using one irradiation and 20 min measurement. During 1982 12000 samples were analyzed for mining companies and Geological Survey of Finland. The capacity is 600 samples per week. Besides these two analytical methods the analysis of lanthanoids is an important part of the work. 11 lanthanoids have been analyzed using instrumental neutron activation analysis. Radiochemical separation methods have been developed for several elements to improve the sensitivity of the analysis

  11. Geochemical signature of radioactive waste: oil NORM

    Costa, Gilberto T. de Paula; Costa-de-Moura, Jorge; Gomes, Carlos de Almeida; Sampaio, Emidio A. Lopes

    2017-01-01

    The Brazilian Nuclear Agency (CNEN) rules all nuclear activity in Brazil as demanded by the Federal Constitution, articles 21, XXIII, and 177, V, and by the Federal Acts 4.118/62 and 10.308/2001. Therefore, the CNEN is responsible for any radioactive waste disposal in the country. Oil Naturally Occurring Radioactive Materials (Oil NORM) in this paper refers to waste coming from oil exploration. Oil NORM has called much attention during the last decades, mostly because it is not possible to determine its primary source due to the actual absence of regulatory control mechanism. There is no efficient regulatory tool which allows determining the origin of such NORM wastes even among those facilities under regulatory control. This fact may encourage non-authorized radioactive material transportation, smuggling and terrorism. The aim of this project is to provide a geochemical signature for each oil NORM waste using its naturally occurring isotopic composition to identify its origin. The here proposed method is a specific geochemical modeling of oil sludge NORM samples which are analyzed for radioisotopes normally present in oil pipes, such as 228 Ac, 214 Bi and 214 Pb. The activity ratios are plotted in scatter diagrams. This method was successfully tested with data of different sources obtained from analysis reports from the Campos Basin/Brazil and from literature. (author)

  12. Investigation of a natural geochemical barrier

    1991-02-01

    Groundwater data from lysimeters and monitor wells in the vicinity of the Bowman, North Dakota, Uranium Mill Tailings Remedial Action (UMTRA) Project site indicated that there is a mechanism in the subsurface which cleans up downward-percolating fluids. It was hypothesized that clays and organic materials in the sediments sequestered hazardous constituents from infiltrating fluids. A program was designed to collect sediment cores from various locations on and around the site and to analyze the sediments to determine whether there has been a build up of hazardous constituents in any specific type of sedimentary material. Materials that concentrate the hazardous constituents would be potential candidates to be used in constructed geochemical barriers. The water quality of the groundwater contained within the sedimentary section indicates that there is a transport of contaminants down through the sediments and that these contaminants are removed from solution by the iron-bearing minerals in the organic-rich lignite beds. The data gathered during the course of this investigation indicate that the lignite ashing operations have added very little of the hazardous constituents of concern--arsenic, chromium, molybdenum, selenium, or uranium--to the sediments beneath the UMTRA Project site. At both locations, the hazardous constituents are concentrated in the upper most lignite bed. These data offer a natural analog for laboratory tests in which sphagnum peat was used to sequester hazardous constituents. Constructed geochemical barriers are a viable mechanism for the clean-up of the majority of hazardous constituents from uranium mill tailings in groundwater

  13. Geochemical controls on groundwater chemistry in shales

    Von Damm, K.L.

    1989-01-01

    The chemistry of groundwaters is one of the most important parameters in determining the mobility of species within a rock formation. A three pronged approach was used to determine the composition of, and geochemical controls, on groundwaters specifically within shale formations: (1) available data were collected from the literature, the US Geological Survey WATSTORE data base, and field sampling, (2) the geochemical modeling code EQ3/6 was used to simulate interaction of various shales and groundwaters, and (3) several types of shale were reacted with synthetic groundwaters in the laboratory. The comparison of model results to field and laboratory data provide a means of validating the models, as well as a means of deconvoluting complex field interactions. Results suggest that groundwaters in shales have a wide range in composition and are primarily of the Na-Cl-HCO 3 - type. The constancy of the Na:Cl (molar) ratio at 1:1 and the Ca:Mg ratio from 3:1 to 1:1 suggests the importance of halite and carbonates in controlling groundwater compositions. In agreement with the reaction path modeling, most of the groundwaters are neutral to slightly alkaline at low temperatures. Model and experimental results suggest that reaction (1) at elevated temperatures, or (2) in the presence of oxygen will lead to more acidic conditions. Some acetate was found to be produced in the experiments; depending on the constraints applied, large amounts of acetate were produced in the model results. 13 refs., 1 tab

  14. Perfiles motivacionales de estudiantes universitarios. Procesos de estudio y satisfacción con la vida

    Juan Antonio Moreno\\u2010Murcia

    2015-01-01

    Full Text Available El objetivo de este trabajo ha sido determinar los diferentes perfiles motivacionales en estudiantes universitarios y ver su relación con los procesos de estudio (superficial y profundo así como con la satisfacción que tiene el estudiante con su vida en general. La muestra estuvo compuesta por 431 estudiantes universitarios (202 hombres y 220 mujeres con una edad media de 22 años (DT = 2.41. Los instrumentos utilizados fueron la Escala de Motivación Académica, Cuestionario Revisado de Procesos de Estudio y la Escala de Satisfacción para la Vida. Se calcularon los estadísticos descriptivos (medias y desviaciones típicas, la consistencia interna y se realizó un análisis clúster y de varianza univariados. Los resultados muestran dos perfiles motivacionales, un perfil más autodeterminado con puntuaciones bajas en desmotivación y altas principalmente en motivación intrínseca de conocimiento, de logro y regulación identificada y un perfil menos autodeterminado con puntuaciones altas en desmotivación y moderadas en el resto de variables motivacionales. Además, los estudiantes pertenecientes al perfil más autodeterminado presentaron menor puntuación en los procesos de estudio superficial, una mayor puntuación en el proceso de estudio profundo estando más satisfechos con la vida a diferencia de los estudiantes del perfil menos autodeterminado.

  15. Recolectores, verificadores y reflexivos: perfiles de la competencia informacional en estudiantes universitarios de primer semestre

    Harold Castañeda-Peña

    2010-01-01

    Full Text Available Artículo de investigación que explora perfiles de la competencia informacional en estudiantes universitarios de primer semestre, a partir de un concepto renovado de competencia informacional desde la perspectiva sociocultural, donde se entiende perfil como una práctica habitual que es situada y variada. Se analiza el caso de 285 estudiantes provenientes de dos universidades colombianas, por medio de un instrumento observacional (cuestionario de perfil, protocolos en voz alta y entrevistas. Se encuentra que el 55% de los estudiantes de primer año de una universidad con carreras profesionales tiende a recolectar información y que el 78% de los estudiantes de primer año de una universidad con carreras tecnológicas tiende a contrastar y verificar información, en tanto que sólo entre 3% y 4% tiende a manejar la información críticamente. Se discute que, al asumir una tarea académica, estos estudiantes vinculan sus prácticas de competencia informacional a sus propias historias de vida y escolares, y que la edad y los antecedentes académicos parecen influir en tales prácticas. Los casos analizados se ubican dentro de perfiles de competencia informacional: recolectores, verificadores y reflexivos. Estos perfiles no son fijos, sino más bien fluidos, y se concretan de manera diferente según la tarea académica. Se recomienda realizar estudios de perfiles informacionales en estudiantes tanto de secundaria como universitarios, para diseñar políticas educativas sobre competencia informacional.

  16. A geochemical atlas of North Carolina, USA

    Reid, J.C.

    1993-01-01

    A geochemical atlas of North Carolina, U.S.A., was prepared using National Uranium Resource Evaluation (NURE) stream-sediment data. Before termination of the NURE program, sampling of nearly the entire state (48,666 square miles of land area) was completed and geochemical analyses were obtained. The NURE data are applicable to mineral exploration, agriculture, waste disposal siting issues, health, and environmental studies. Applications in state government include resource surveys to assist mineral exploration by identifying geochemical anomalies and areas of mineralization. Agriculture seeks to identify areas with favorable (or unfavorable) conditions for plant growth, disease, and crop productivity. Trace elements such as cobalt, copper, chromium, iron, manganese, zinc, and molybdenum must be present within narrow ranges in soils for optimum growth and productivity. Trace elements as a contributing factor to disease are of concern to health professionals. Industry can use pH and conductivity data for water samples to site facilities which require specific water quality. The North Carolina NURE database consists of stream-sediment samples, groundwater samples, and stream-water analyses. The statewide database consists of 6,744 stream-sediment sites, 5,778 groundwater sample sites, and 295 stream-water sites. Neutron activation analyses were provided for U, Br, Cl, F, Mn, Na, Al, V, Dy in groundwater and stream water, and for U, Th, Hf, Ce, Fe, Mn, Na, Sc, Ti, V, Al, Dy, Eu, La, Sm, Yb, and Lu in stream sediments. Supplemental analyses by other techniques were reported on U (extractable), Ag, As, Ba, Be, Ca, Co, Cr, Cu, K, Li, Mg, Mo, Nb, Ni, P, Pb, Se, Sn, Sr, W, Y, and Zn for 4,619 stream-sediment samples. A small subset of 334 stream samples was analyzed for gold. The goal of the atlas was to make available the statewide NURE data with minimal interpretation to enable prospective users to modify and manipulate the data for their end use. The atlas provides only

  17. Perfil formativo de los consejeros de las empresas del IBEX 35 en España

    Jurado Caraballo, María Ángeles; Rodríguez Fernández, Mercedes; Gaspar González, Ana María

    2017-01-01

    En este estudio de carácter teórico-empírico se ha relacionado la variable Perfil formativo de los Consejeros de las empresas que componen el IBEX 35 con su evolución financiera medida en base a las ventas netas. Verificadas las hipótesis, se puede decir que el perfil más adecuado para incrementar las ventas empresariales en las empresas del IBEX en 2013 lo conforma la figura de un Consejero, que presenta un nivel formativo de Doctorado, además de haber recibido una formación adecuada al carg...

  18. Perfil lipídico tecidual de ratos alimentados com diferentes fontes lipídicas

    Almeida,Martha Elisa Ferreira de; Queiroz,José Humberto de; Queiroz,Maria Eliana Lopes Ribeiro de; Costa,Neuza Maria Brunoro; Matta,Sérgio Luis Pinto

    2009-01-01

    OBJETIVO:Determinar se fontes lipídicas com diferentes razões de ácidos graxos insaturados e saturados (PUFA+MUFA)/SFA na dieta altera o perfil lipídico tecidual, a concentração de lipídios (mg/g) dos tecidos hepáticos e mesentérico e a digestibilidade lipídica. MÉTODOS: Foi realizada cromatografia gasosa para determinar o perfil de ácidos graxos nos tecidos hepático e adiposo de ratos alimentados com diferentes fontes lipídicas. O coeficiente de digestibilidade foi determinado a partir da re...

  19. Perfil cognitivo de la dependencia emocional en estudiantes universitarios en Medellín, Colombia

    Lemos Hoyos, Mariantonia; Jaller Jaramillo, Cristina; González Calle, Ana María; Díaz León, Zoraya Tatiana; De la Ossa, Daniela

    2012-01-01

    El objetivo de este estudio fue la identificación del perfil cognitivo de los estudiantes universitarios con dependencia emocional. Ésta se plantea como un patrón orientado al otro como fuente de satisfacción y seguridad personal, donde el perfil cognitivo les llevaría a interpretar los hechos de manera diferente, basándose en cubrir sus necesidades emocionales insatisfechas. Se tomó una muestra aleatoria estratificada de 569 estudiantes universitarios. Los resultados arrojaron un modelo que ...

  20. Perfiles motivacionales de usuarios de servicios deportivos públicos y privados

    Nuviala Nuviala, Alberto; Universidad Pablo de Olavide; Gómez-López, Manuel; Universidad de Murcia; Grao-Cruces, Alberto; Universidad Pablo de Olavide; Granero-Gallegos, Antonio; Universidad de Murcia; Nuviala Nuviala, Román; Universidad Pablo de Olavide

    2012-01-01

    Las altas tasas de sedentarismo y abandono deportivo y la escasez de estudios sobre motivos de práctica en el ámbito de la actividad física no competitiva han generado la necesidad de llevar a cabo investigaciones que establezcan perfiles motivacionales de usuarios de servicios deportivos. La finalidad de esta investigación fue diferenciar los perfiles motivacionales con respecto a la práctica físico-deportiva y analizar su relación con variables sociodemográficas (edad y sexo). La muestra de...

  1. Geochemical Characterization of the Upper and Middle Floridan Aquifer System, South Florida

    Mirecki, J.; Richardson, E.; Bennett, M.; Hendel, J.

    2008-05-01

    Our study focus is to characterize the water quality and geochemical environment of the Floridan Aquifer System (FAS) throughout the regional flowpath. A synoptic survey of 21 wells (n=15, upper FAS; n=6 middle FAS) was supplemented by additional samples (n=11) obtained during exploratory well development at 4 aquifer storage recovery (ASR) pilot sites. Synoptic survey samples were analyzed intensively, yielding a dataset that consists of major and trace dissolved constituents (including metals), stable isotopes (δ18O, δ13C, δD, δ34S in sulfate and sulfide), carbon species (carbonate alkalinity and organic carbon), uranium-series radionuclides, nutrients, and selected microbes and pathogens. The objectives of this study are three-fold: 1) to provide baseline water-quality and geochemical information prior to initiation of ASR activities that are part of the Comprehensive Everglades Restoration Plan; 2) to quantify the major controls on geochemical evolution along upper and middle FAS flowpaths using geochemical modeling methods; and 3) to identify areas where water- quality may limit the feasibility of ASR methods in the FAS. Preliminary interpretations water quality changes along the regional FAS flowpath can be summarized as follows. Concentrations of dissolved constituents increase from north to south along the flow path; generally, the upper FAS has lower total dissolved solids than the middle FAS at locations where well pairs were analyzed. The redox environment changes from oxic to strongly anoxic, very close to the recharge area. Redox measurements, dissolved iron, sulfide, and sulfur isotope data are consistent with sulfate-reducing conditions. Uranium-series isotope concentrations and activities generally are below regulatory criteria, with few exceptions in both the upper and middle FAS. Areas with greater radionuclide activity occur primarily at distal flowpath locations or at the coast.

  2. [Initial antiretroviral treatment in human immunodeficiency virus-infected patients in Spain: Decisions made in relation to particular immunovirological characteristics (PERFIL-es study)].

    Viciana, Pompeyo; Ocampo, Antonio; Hevia, Henar; Palazuelos, Marta; Ledesma, Francisco

    2014-02-01

    The purpose of Perfil-es study was to identify the proportion of patients starting ARV treatment based on NNRTIs or PI/r, and to identify the variables involved in the therapeutic decision-making in standard clinical practice. An observational retrospective study performed in 65 Spanish hospitals. Was a total of 1,687 starts: 53% with NNRTI-based regimen and 42% with PI/r, and of the 642 patients analyzed, 72% had a CD4 count<350 cells/μl. The initiation of ARV treatment is still late in Spain. NNRTIs are the more frequent choice, although PI/r plays an important role. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  3. Behaviour of nature and technogenic radioisotopes in buried geochemical barriers

    Kuznetsov, V.A.; Onoshko, M.P.; Generalova, V.A.

    1998-01-01

    Behaviour of potassium 40, radium 226, thorium 232, strontium 90 and cesium 137 on geochemical barriers connected with buried soils and cut-off meander sediments of the Holocene age of the Sozh river valley are examined. Some sides of the barrier geochemical structure caused by syngeneic and epigenetic processes have been taken into consideration

  4. Perfil cardiovascular em pacientes com apneia obstrutiva do sono

    Fátima Dumas Cintra

    2011-04-01

    Full Text Available FUNDAMENTO: Apneia Obstrutiva do Sono (AOS é um fator de risco para várias condições cardiovasculares incluindo aumento na mortalidade cardiovascular. Sendo assim, é essencial o conhecimento das principais repercussões cardiovasculares dos distúrbios respiratórios do sono durante uma avaliação clínica. OBJETIVO: Analisar as características cardiovasculares de pacientes com AOS. MÉTODOS: Pacientes submetidos a polissonografia basal foram consecutivamente selecionados do banco de dados do Instituto do Sono entre março de 2007 e março de 2009. Todos os pacientes foram orientados a comparecer ao ambulatório para coleta de sangue, exame físico, eletrocardiograma de 12 derivações, espirometria, teste cardiopulmonar em esteira ergométrica e ecocardiograma transtorácico. O estudo foi aprovado pelo comitê de ética e pesquisa e registrado no site http://clinicaltrials.gov/ sob o número: NCT00768625. RESULTADOS: Foram analisados 261 pacientes e 108 controles. As principais características dos pacientes com AOS foram: obesidade, hipertensão, baixos níveis plasmáticos de lipoproteínas de alta densidade (HDL e aumento no diâmetro do átrio esquerdo quando comparados com controles (3,75 ± 0,42; 3,61 ± 0,41, p = 0,001, respectivamente. Essas características associadas correspondem a um acréscimo de 16,6 vezes na probabilidade de ocorrência de AOS independentemente do relato de algum sintoma dessa desordem, como sonolência ou ronco. CONCLUSÃO: Na amostra avaliada, o perfil cardiovascular dos pacientes com AOS mais encontrado foi: obesidade, hipertensão arterial, baixos níveis plasmáticos de HDL e átrio esquerdo com diâmetro aumentado.

  5. Use of partial dissolution techniques in geochemical exploration

    Chao, T.T.

    1984-01-01

    Application of partial dissolution techniques to geochemical exploration has advanced from an early empirical approach to an approach based on sound geochemical principles. This advance assures a prominent future position for the use of these techniques in geochemical exploration for concealed mineral deposits. Partial dissolution techniques are classified as single dissolution or sequential multiple dissolution depending on the number of steps taken in the procedure, or as "nonselective" extraction and as "selective" extraction in terms of the relative specificity of the extraction. The choice of dissolution techniques for use in geochemical exploration is dictated by the geology of the area, the type and degree of weathering, and the expected chemical forms of the ore and of the pathfinding elements. Case histories have illustrated many instances where partial dissolution techniques exhibit advantages over conventional methods of chemical analysis used in geochemical exploration. ?? 1984.

  6. Methodological approaches in estimating anomalous geochemical field structure

    Gavrilov, R; Rudmin, M

    2015-01-01

    Mathematical statistic methods were applied to analyze the core samples from vertical expendable wells in Chertovo Koryto gold ore field. The following methods were used to analyse gold in samples: assay tests and atomic absorption method (AAS), while emission spectrum semiquantative method was applied to identify traces. The analysis of geochemical association distribution in one central profile demonstrated that bulk metasomatic aureoles are characteristic of concentric zonal structure. The distribution of geochemical associations is correlated to the hydrothermal stages of mineral formation identified in this deposit. It was proved that the processed geochemical data by factor and cluster analyses provided additional information on the anomalous geochemical field structure in gold- bearing black-shale strata. Such methods are effective tools in interpretating specific features of geochemical field structures in analogous potential ore-bearing areas

  7. GEOCHEMICAL CONTROLS ON NUCLEAR MAGNETIC RESONANCE MEASUREMENTS

    Knight, Rosemary

    2008-01-01

    Proton nuclear magnetic resonance (NMR) is used in the Earth Sciences as a means of obtaining information about the molecular-scale environment of fluids in porous geological materials. Laboratory experiments were conducted to advance our fundamental understanding of the link between the NMR response and the geochemical properties of geological materials. In the first part of this research project, we studied the impact of both the surface-area-to-volume ratio (S/V) of the pore space and the surface relaxivity on the NMR response of fluids in sand-clay mixtures. This study highlighted the way in which these two parameters control our ability to use NMR measurements to detect and quantify fluid saturation in multiphase saturated systems. The second part of the project was designed to explore the way in which the mineralogic form of iron, as opposed to simply the concentration of iron, affects the surface relaxation rate and, more generally, the NMR response of porous materials. We found that the magnitude of the surface relaxation rate was different for the various iron-oxide minerals because of changes in both the surface-area-to-volume ratio of the pore space, and the surface relaxivity. Of particular significance from this study was the finding of an anomalously large surface relaxivity of magnetite compared to that of the other iron minerals. Differences in the NMR response of iron minerals were seen in column experiments during the reaction of ferrihydrite-coated quartz sand with aqueous Fe(II) solutions to form goethite, lepidocrocite and magnetite; indicating the potential use of NMR as a means of monitoring geochemical reactions. The final part of the research project investigated the impact of heterogeneity, at the pore-scale, on the NMR response. This work highlighted the way in which the geochemistry, by controlling the surface relaxivity, has a significant impact on the link between NMR data and the microgeometry of the pore space.

  8. Geochemical studies on island arc volcanoes

    Notsu, Kenji

    1998-01-01

    This paper summarizes advances in three topics of geochemical studies on island arc volcanoes, which I and my colleagues have been investigating. First one is strontium isotope studies of arc volcanic rocks mainly from Japanese island arcs. We have shown that the precise spatial distribution of the 87 Sr/ 86 Sr ratio reflects natures of the subduction structure and slab-mantle interaction. Based on the 87 Sr/ 86 Sr ratio of volcanic rocks in the northern Kanto district, where two plates subduct concurrently with different directions, the existence of an aseismic portion of the Philippine Sea plate ahead of the seismic one was suggested. Second one is geochemical monitoring of active arc volcanoes. 3 He/ 4 He ratio of volcanic volatiles was shown to be a good indicator to monitor the behavior of magma: ascent and drain-back of magma result in increase and decrease in the ratio, respectively. In the case of 1986 eruptions of Izu-Oshima volcano, the ratio began to increase two months after big eruptions, reaching the maximum and decreased. Such delayed response is explained in terms of travelling time of magmatic helium from the vent area to the observation site along the underground steam flow. Third one is remote observation of volcanic gas chemistry of arc volcanoes, using an infrared absorption spectroscopy. During Unzen eruptions starting in 1990, absorption features of SO 2 and HCl of volcanic gas were detected from the observation station at 1.3 km distance. This was the first ground-based remote detection of HCl in volcanic gas. In the recent work at Aso volcano, we could identify 5 species (CO, COS, CO 2 , SO 2 and HCl) simultaneously in the volcanic plume spectra. (author)

  9. Geochemical modelling of Na-SO4 type groundwater at Palmottu using a mass balance approach

    Pitkaenen, P.

    1993-01-01

    The mass balance chemical modelling technique has been applied to the groundwaters at the Palmottu analogue study site (in southwestern Finland) for radioactive waste disposal. The geochemical modelling concentrates on the evolution of Na-SO 4 type groundwater, which is spatially connected to the uranium mineralization. The results calculated along an assumed flow path are consistent with available field data and thermodynamic constraints. The results show that essential production of sulphides is unrealistic in the prevailing conditions. The increasing concentrations of Na, SO 4 and Cl along the evolution trend seem to have the same source and they could originate mainly from the leakage of fluid inclusions. Some mixing of relict sea water is also possible

  10. Geochemical interpretation of gamma-ray spectrometry images from the Achala granite (Cordoba, Argentina)

    Lopez, Luis E.

    1998-01-01

    Data of an old spectrometry gamma-ray survey carried out in the Sierras Pampeanas Range by the National Atomic Energy Commission (Argentina) were reprocessed to obtain a corrected digital archive. The geochemical interpretation of the 250 x 250 meters spectrometric grids from the Achala batholith area was based on the behaviour of the radioelements in a peraluminous magma. Spectrometric maps of potassium, uranium, thorium and their ratios were used. In particular, the Th grid was very useful to define the primary magmatic evolution of the granitoids. K and U correlate roughly with Th distribution. The observed positive correlation between Th and U is thought to be the result of surficial leaching of U from uraninite. Finally, U/Th ratio allows to determine both, the magmatic evolution of the rocks and the mineral phase responsible for U content. (author)

  11. Geochemical differentiation processes for arc magma of the Sengan volcanic cluster, Northeastern Japan, constrained from principal component analysis

    Ueki, Kenta; Iwamori, Hikaru

    2017-10-01

    In this study, with a view of understanding the structure of high-dimensional geochemical data and discussing the chemical processes at work in the evolution of arc magmas, we employed principal component analysis (PCA) to evaluate the compositional variations of volcanic rocks from the Sengan volcanic cluster of the Northeastern Japan Arc. We analyzed the trace element compositions of various arc volcanic rocks, sampled from 17 different volcanoes in a volcanic cluster. The PCA results demonstrated that the first three principal components accounted for 86% of the geochemical variation in the magma of the Sengan region. Based on the relationships between the principal components and the major elements, the mass-balance relationships with respect to the contributions of minerals, the composition of plagioclase phenocrysts, geothermal gradient, and seismic velocity structure in the crust, the first, the second, and the third principal components appear to represent magma mixing, crystallizations of olivine/pyroxene, and crystallizations of plagioclase, respectively. These represented 59%, 20%, and 6%, respectively, of the variance in the entire compositional range, indicating that magma mixing accounted for the largest variance in the geochemical variation of the arc magma. Our result indicated that crustal processes dominate the geochemical variation of magma in the Sengan volcanic cluster.

  12. Simulation of the geochemical interactions in a natural CO2 deposit: the example of Springerville - Saint-Johns (USA). Final report

    Le Guern, C.; Gaus, I.

    2004-01-01

    The aim of the study is a better understanding of the geochemical operating of natural analogues by the simulation of scenario representative of the evolution of site since the arrival of CO 2 still today. This exercise concerns the Springerville site. Simulation tests with the PHREEQC code have been realized. This final report presents in the first part how the data are collected on a natural CO 2 , then a bibliographic synthesis on the observed impacts of the CO 2 on a deposit. The fourth part is the simulation of the geochemical interactions in the natural CO 2 deposit of Springerville. (A.L.B.)

  13. Perfil professional a les biblioteques publiques : visió dels bibliotecaris mateixos

    Delmàs Ruiz, Maria

    2015-12-01

    Full Text Available El perfil professional dels bibliotecaris ha anat evolucionant al llarg dels anys, en consonància amb els canvis que han afectat la biblioteca pública. En aquest article s'analitza com és aquest perfil actualment, des de l'òptica dels professionals mateixos. S'obté així una visió de les competències més valorades avui en dia, i es detecten els vessants del perfil que requereixen més incidència formativa. Com a resultat de l'anàlisi s'ha identificat la necessitat de perfils especialitzats, que també es podria cobrir amb la incorporació de professionals complementaris. Finalment, tot i que el perfil professional de bibliotecari s'adapta a grans trets a la nova realitat de les biblioteques públiques, també s'identifiquen les mancances percebudes pels professionals.El perfil profesional de los bibliotecarios ha ido evolucionando a lo largo de los años, en consonancia con los cambios que han afectado a la biblioteca pública. En este artículo se analiza cómo es este perfil actualmente, desde la óptica de los mismos profesionales. Se obtiene así una visión de las competencias más valoradas hoy en día, y se detectan las facetas del perfil que requieren más incidencia formativa. Como resultado del análisis se ha identificado la necesidad de perfiles especializados, que también se podría suplir con la incorporación de profesionales complementarios. Finalmente, aunque el perfil profesional de bibliotecario se adapta en gran medida a la nueva realidad de las bibliotecas públicas, también se identifican las carencias percibidas por los profesionales.The professional profile of the public librarian has evolved in response to the changes that constantly affect public libraries. In this article we analyze what the public librarian’s job involves from the point of view of the professionals themselves. This allows us to examine the competences that are most highly valued and identify those areas in which professionals require more

  14. Alligator Rivers Analogue project. Geochemical modelling of present-day groundwaters. Final Report - Volume 12

    Sverjensky, D A [The John Hopkins Univ, Dept of Earth and Planetary Sciences, Baltimore (United States)

    1993-12-31

    The main purpose of this report is to summarize geochemical modeling studies of the present-day Koongarra groundwaters. Information on the present-day geochemistry and geochemical processes at Koongarra forms a basis for a present-day analogue for nuclear waste migration. The present-day analogue is built on studies of the mineralogy and petrology of the Koongarra deposit, and chemical analyses of present-day groundwaters from the deposit. The overall approach taken in the present study has been to carry out a series of aqueous speciation and state of saturation calculations, including chemical mass transfer calculations, to address the possible control over the chemistry of the present-day for the groundwaters at Koongarra. The most important implication of the present study for the migration of radionuclides is the strong role played by the water-rock interactions, both above and below the water table, influencing the overall chemical evolution of the groundwaters. Thus, the results show that the chemical evolution of waters is strongly controlled by the initial availability of CO{sub 2} and the mineral assemblage encountered, which together determine the major element evolution of the waters by controlling the pH. The relative rates of evolution of the pH and the oxidation state of the groundwaters are also critical to the mobility of uranium. The shallow Koongarra waters are sufficiently oxidising that they can dissolve and transport uranium even under acidic conditions. Under the more reducing condition of the deep groundwaters, is the pH level that permits uranium transport as carbonate complexes. However, if the oxidation state decreases to much lower levels, it would be expected that uranium become immobile. All the speciation and state of saturation calculations carried out in the present study are available from the author, on request 22 refs., 7 tabs., 18 figs.

  15. Alligator Rivers Analogue project. Geochemical modelling of present-day groundwaters. Final Report - Volume 12

    Sverjensky, D. A. [The John Hopkins Univ, Dept of Earth and Planetary Sciences, Baltimore (United States)

    1992-12-31

    The main purpose of this report is to summarize geochemical modeling studies of the present-day Koongarra groundwaters. Information on the present-day geochemistry and geochemical processes at Koongarra forms a basis for a present-day analogue for nuclear waste migration. The present-day analogue is built on studies of the mineralogy and petrology of the Koongarra deposit, and chemical analyses of present-day groundwaters from the deposit. The overall approach taken in the present study has been to carry out a series of aqueous speciation and state of saturation calculations, including chemical mass transfer calculations, to address the possible control over the chemistry of the present-day for the groundwaters at Koongarra. The most important implication of the present study for the migration of radionuclides is the strong role played by the water-rock interactions, both above and below the water table, influencing the overall chemical evolution of the groundwaters. Thus, the results show that the chemical evolution of waters is strongly controlled by the initial availability of CO{sub 2} and the mineral assemblage encountered, which together determine the major element evolution of the waters by controlling the pH. The relative rates of evolution of the pH and the oxidation state of the groundwaters are also critical to the mobility of uranium. The shallow Koongarra waters are sufficiently oxidising that they can dissolve and transport uranium even under acidic conditions. Under the more reducing condition of the deep groundwaters, is the pH level that permits uranium transport as carbonate complexes. However, if the oxidation state decreases to much lower levels, it would be expected that uranium become immobile. All the speciation and state of saturation calculations carried out in the present study are available from the author, on request 22 refs., 7 tabs., 18 figs.

  16. Agresividad, prosocialidad y estatus social: identificando perfiles admirados entre preadolescentes chilenos

    Christian Berger

    2011-01-01

    Full Text Available Con base en la creciente evidencia de la asociación entre la agresividad y la prosocialidad con indicadores de estatus social, el presente estudio aborda la admiración entre pares adolescentes como una manera de operacionalizar el estatus y evalúa el potencial carácter funcional de estas conductas sociales. La hipótesis que guía este estudio es que en la medida en que la agresividad y la prosocialidad son características valoradas en el contexto de pares (con base en su asociación con el estatus, los adolescentes admirados, que pueden ejercer gran influencia sobre sus pares, serán aquellos que presenten este perfil. 274 estudiantes de 5º y 6º grado participaron del estudio. Los resultados muestran que la característica con mayor presencia entre los adolescentes admirados es la prosocialidad y luego la prominencia social. Sin embargo, se identifican dos perfiles de adolescentes admirados, que se distinguen principalmente por la agresividad, el perfil "fuerte" incluye además de la prosocialidad y la prominencia social altos puntajes en agresividad y popularidad, mientras que el perfil denominado "modelo" integra además de la prosocialidad y la prominencia social niveles muy bajos de agresividad y puntajes promedio en popularidad. Se identifican además diferencias de género en estos perfiles. Estos resultados son discutidos desde la perspectiva de las relaciones de pares y las posibles implicancias para el desarrollo tanto individual como grupal de los y las adolescentes.

  17. The IUGS/IAGC Task Group on Global Geochemical Baselines

    Smith, David B.; Wang, Xueqiu; Reeder, Shaun; Demetriades, Alecos

    2012-01-01

    The Task Group on Global Geochemical Baselines, operating under the auspices of both the International Union of Geological Sciences (IUGS) and the International Association of Geochemistry (IAGC), has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth’s surface or near-surface environment. The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified. In order to accomplish this long-term goal, the activities of the Task Group include: (1) developing partnerships with countries conducting broad-scale geochemical mapping studies; (2) providing consultation and training in the form of workshops and short courses; (3) organizing periodic international symposia to foster communication among the geochemical mapping community; (4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database; (5) acting as a repository for data collected by those projects meeting the criteria for standardization; (6) preparing complete metadata for the certified projects; and (7) preparing, ultimately, a global geochemical database. This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988.

  18. LOS ESTUDIOS DE MERCADO Y PERFILES DE SECTOR COMO HERRAMIENTAS ÚTILES PARA LA TOMA DE DECISIONES

    Yolanda Morejón-Bravo

    2016-01-01

    Full Text Available En primer lugar, se ofrece una breve explicación de los fundamentos teóricos de la inteligencia empresarial y sus productos, haciendo énfasis en los perfiles estratégicos, y dentro de ellos, en los perfiles de sector. También, se hace énfasis en los estudios de mercado y sus características. En segundo lugar, se presentan dos casos de estudio (un perfil de sector y un estudio de mercado, que demuestran la importancia de estos productos y servicios de inteligencia competitiva, para la toma de decisiones lo más acertada posible, en las organizaciones.

  19. Cultura moral y perfil de valores del centro educativo

    Laura RUBIO SERRANO

    2009-11-01

    Full Text Available RESUMEN: El artículo que presentamos a continuación representa una aproximación institucional a la educación moral a través del concepto de cultura moral de los centros educativos. Un concepto que introduce elementos teóricos y prácticos para profundizar en la institución escolar como uno de los principales agentes en la formación de la personalidad moral de los chicos y chicas. A nivel teórico, la aproximación permite concretar la idea de que la escuela en su totalidad educa moralmente y que los valores se aprenden por osmosis, a través de la participación en prácticas morales. A nivel práctico, establece un mecanismo para determinar el perfil de valores de un centro, los valores predominantes de su propuesta educativa y sus indicadores en la práctica diaria. En definitiva, posibles puntos de partida en procesos de evaluación interna y de mejora e innovación pedagógicas.ABSTRACT: This article presents an approach to moral education at institutional level which incorporates the concept of moral culture in schools. The concept introduces theoretical and practical elements for studying the school institution as one of the principal agents in the education of the moral personality in children. At the theoretical level, the approach stresses the idea that the school as a whole educates morally and that values are learnt by osmosis, via participation in moral practices. At the practical level, it establishes a mechanism for determining a school's values profile, the predominant values in its educational mission and indicators for these values in daily practice. The approach highlights possible starting points for processes of internal assessment and teaching innovation.SOMMIRE: Cet article représente une approche institutionnelle à l'éducation morale par le moyen du concept de culture morale des centres éducatifs. Il s'agit d'un concept introduisant des éléments théoriques et pratiques pour approfondir dans l

  20. Geochemical Study of Natural CO{sub 2} Emissions in the French Massif Central: How to Predict Origin, Processes and Evolution of CO{sub 2} Leakage; Etude geochimique des emissions naturelles de CO{sub 2} du Massif Central: origine et processus de migration du gaz

    Battani, A.; Deville, E.; Faure, J.L.; Jeandel, E.; Noirez, S.; Tocque, E.; Benoit, Y.; Schmitz, J.; Parlouar, D. [Institut francais du petrole, IFP, 92 - Rueil-Malmaison (France); Sarda, P. [Paris-11 Univ., 91 - Orsay (France); Gal, F.; Le Pierres, K.; Brach, M.; Braibant, G.; Beny, C. [Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France); Pokryszka, Z.; Charmoille, A.; Bentivegna, G. [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique ALATA, 60 - Verneuil-en-Halatte (France); Pironon, J.; De Donato, P.; Garnier, C.; Cailteau, C.; Barres, O.; Radilla, G.; Bauer, A. [Institut National Polytechnique de Lorraine (INPL), 54 - Vandoeuvre-les-Nancy (France)

    2010-07-15

    This study presents an overview of some results obtained within the French ANR (National Agency of Research) supported Geocarbone-Monitoring research program. The measurements were performed in Sainte-Marguerite, located in the French Massif Central. This site represents a natural laboratory for CO{sub 2}/fluid/rock interactions studies, as well as CO{sub 2} migration mechanisms towards the surface. The CO{sub 2} leaking character of the studied area also allows to test and validate measurements methods and verifications for the future CO{sub 2} geological storage sites. During these surveys, we analyzed soil CO{sub 2} fluxes and concentrations. We sampled and analyzed soil gases, and gas from carbo-gaseous bubbling springs. A one-month continuous monitoring was also tested, to record the concentration of CO{sub 2} both in atmosphere and in the soil at a single point. We also developed a new methodology to collect soil gas samples for noble gas abundances and isotopic analyses, as well as carbon isotopic ratios. Our geochemical results, combined with structural geology, show that the leaking CO{sub 2} has a very deep origin, partially mantle derived. The gas rises rapidly along normal and strike-slip active faults. CO{sub 2} soil concentrations (also showing a mantle derived component) and CO{sub 2} fluxes are spatially variable, and reach high values. The recorded atmospheric CO{sub 2} is not very high, despite the important CO{sub 2} degassing throughout the whole area. (authors)

  1. A geochemical and geochronological section through the Eastern Aegean

    Boehm, Katharina; Kuiper, Klaudia; Vroon, Pieter; Wijbrans, Jan

    2017-04-01

    The convergence of Africa and Eurasia and the subduction of a oceanic lithosphere of narrow basins between Gondwana terranes has controlled the geological evolution of the Eastern Mediterranean region since the Cretaceous. This resulted in back-arc extension and lithospheric thinning caused by slab roll-back together with the westward extrusion of Anatolia, in the southwards retreat and stepwise development of the subduction system and also in a low velocity seismic anomaly gap between the Cyprus and Hellenic slab and other slab segments. However, the exact timing of all these events in the Eastern Mediterranean region is still a matter of debate, and the purpose of this study is therefore to disentangle when terrains collided and slab detached in the last 30Ma. In a N-S transect magmatic rocks of the Aegean plate are studied, including volcanics from the islands Nisyros, Kos, Patmos, Chios, Lesbos and Samothraki. Major- and trace elements as well as Sr-Nd-Hf-Pb-O isotopes are used to interpret the different features of the Aegean subduction zone. With this geochemical approach the extend of upwelling hot asthenospheric material from the slab tear can be traced in the recent to Eocene volcanic rocks. The volcanic rocks give a wide scatter in classification diagrams and pose for example the question how the sodium rich volcanic products of Patmos can be explained. On the other hand Chios seems to play a key role around 15 Ma years in a phase of relatively low volcanic activity. To get a reliable timeline of the subduction in the Aegean since the Eocene we are aiming to tie our chemical and isotopic data to parallel obtained geochronological ages. New 40Ar/39Ar data will allow us to get the needed resolution for this time span and material.

  2. MINTEQ, Geochemical Equilibria in Ground Water

    Krupka, K.M.

    1990-01-01

    1 - Description of program or function: MINTEQ is a geochemical program to model aqueous solutions and the interactions of aqueous solutions with hypothesized assemblages of solid phases. It was developed for the Environmental Protection Agency to perform the calculations necessary to simulate the contact of waste solutions with heterogeneous sediments or the interaction of ground water with solidified wastes. MINTEQ can calculate ion speciation/solubility, adsorption, oxidation-reduction, gas phase equilibria, and precipitation/dissolution of solid phases. MINTEQ can accept a finite mass for any solid considered for dissolution and will dissolve the specified solid phase only until its initial mass is exhausted. This ability enables MINTEQ to model flow-through systems. In these systems the masses of solid phases that precipitate at earlier pore volumes can be dissolved at later pore volumes according to thermodynamic constraints imposed by the solution composition and solid phases present. The ability to model these systems permits evaluation of the geochemistry of dissolved traced metals, such as low-level waste in shallow land burial sites. MINTEQ was designed to solve geochemical equilibria for systems composed of one kilogram of water, various amounts of material dissolved in solution, and any solid materials that are present. Systems modeled using MINTEQ can exchange energy and material (open systems) or just energy (closed systems) with the surrounding environment. Each system is composed of a number of phases. Every phase is a region with distinct composition and physically definable boundaries. All of the material in the aqueous solution forms one phase. The gas phase is composed of any gaseous material present, and structurally distinct solid forms a separate phase. 2 - Method of solution: MINTEQ applies the fundamental principles of thermodynamics to solve geochemical equilibria from a set of mass balance equations, one for each component. Because the

  3. Geochemical surveys in the Lusi mud eruption

    Sciarra, Alessandra; Mazzini, Adriano; Etiope, Giuseppe; Inguaggiato, Salvatore; Hussein, Alwi; Hadi J., Soffian

    2016-04-01

    The Lusi mud eruption started in May 2006 following to a 6.3 M earthquake striking the Java Island. In the framework of the Lusi Lab project (ERC grant n° 308126) we carried out geochemical surveys in the Sidoarjo district (Eastern Java Island, Indonesia) to investigate the gas bearing properties of the Watukosek fault system that crosses the Lusi mud eruption area. Soil gas (222Rn, CO2, CH4) concentration and flux measurements were performed 1) along two detailed profiles (~ 1km long), trending almost W-E direction, and 2) inside the Lusi embankment (about 7 km2) built to contain the erupted mud. Higher gas concentrations and fluxes were detected at the intersection with the Watukosek fault and the antithetic fault system. These zones characterized by the association of higher soil gas values constitute preferential migration pathways for fluids towards surface. The fractures release mainly CO2 (with peaks up to 400 g/m2day) and display higher temperatures (up to 41°C). The main shear zones are populated by numerous seeps that expel mostly CH4. Flux measurements in the seeping pools reveal that φCO2 is an order of magnitude higher than that measured in the fractures, and two orders of magnitude higher for φCH4. An additional geochemical profile was completed perpendicularly to the Watukosek fault escarpement (W-E direction) at the foots of the Penanngungang volcano. Results reveal CO2 and CH4 flux values significantly lower than those measured in the embankment, however an increase of radon and flux measurements is observed approaching the foots of the escarpment. These measurements are complemented with a database of ~350 CH4 and CO2 flux measurements and some soil gas concentrations (He, H2, CO2, CH4 and C2H6) and their isotopic analyses (δ13C-CH4, δD-CH4 and δ13C-CO2). Results show that the whole area is characterized by diffused gas release through seeps, fractures, microfractures and soil degassing. The collected results shed light on the origin of the

  4. Geochemical behavior of disposed radioactive waste

    Barney, G.S.; Navratil, J.D.; Schulz, W.W.

    1984-01-01

    The papers in this book are organized to cover the chemical aspects that are important to understanding the behavior of disposed radioactive wastes. These aspects include radionuclide sorption and desorption, solubility of radionuclide compounds, chemical species of radionuclides in natural waters, hydrothermal geochemical reactions, measurements of radionuclide migration, solid state chemistry of wastes, and waste-form leaching behavior. The information in each of the papers is necessary to predict the transport of radionuclides from wastes via natural waters and thus to predict the safety of the disposed waste. Radionuclide transport in natural waters is strongly dependent on sorption, desorption, dissolution, and precipitation processes. The first two papers discuss laboratory investigations of these processes. Descriptions of sorption and desorption behavior of important radionuclides under a wide range of environmental conditions are presented in the first section. Among the sorbents studied are basalt interbed solids, granites, clays, sediments, hydrous oxides, and pure minerals. Effects of redox conditions, groundwater composition and pH on sorption reactions are described

  5. LASL approach to uranium geochemical reconnaissance

    Sharp, R.R. Jr.

    1977-01-01

    The US ERDA, as part of the NURE program, has initiated a nationwide Hydrogeochemical and Stream Sediment Reconnaissance (HSSR). The aims of the NURE program are to provide data on which to base more accurate estimates of US uranium reserves for long-range planning and to aid in meeting the nation's projected uranium demands into the next century. The HSSR objective is to complete, by 1980, a reconnaissance of the nation's surface waters, ground waters, and stream and lake sediments, to aid in assessment of uranium reserves and identification of areas of interest for exploration. Patterned after extensive uranium reconnaissance done in many other countries, the LASL project is comprised of the following five components: (1) organization and planning, which includes management, design, and execution; (2) field sampling, which includes orientation studies, generation of specifications, and contracting and inspection of field work; (3) sample receiving and analysis, which includes development of methods and hardware, quality assurance, and archival storage; (4) data handling and presentation, including verification, storage, output, and plotting; and (5) data evaluation and publication, which incorporates geochemical, geological, statistical, and empirical evaluation and report writing. The LASL approach to each component and the current status in each state are described.

  6. LASL approach to uranium geochemical reconnaissance

    Sharp, R.R. Jr.

    1977-01-01

    The US ERDA, as part of the NURE program, has initiated a nationwide Hydrogeochemical and Stream Sediment Reconnaissance (HSSR). The aims of the NURE program are to provide data on which to base more accurate estimates of US uranium reserves for long-range planning and to aid in meeting the nation's projected uranium demands into the next century. The HSSR objective is to complete, by 1980, a reconnaissance of the nation's surface waters, ground waters, and stream and lake sediments, to aid in assessment of uranium reserves and identification of areas of interest for exploration. Patterned after extensive uranium reconnaissance done in many other countries, the LASL project is comprised of the following five components: (1) organization and planning, which includes management, design, and execution; (2) field sampling, which includes orientation studies, generation of specifications, and contracting and inspection of field work; (3) sample receiving and analysis, which includes development of methods and hardware, quality assurance, and archival storage; (4) data handling and presentation, including verification, storage, output, and plotting; and (5) data evaluation and publication, which incorporates geochemical, geological, statistical, and empirical evaluation and report writing. The LASL approach to each component and the current status in each state are described

  7. Regional geochemical baselines for Portuguese shelf sediments

    Mil-Homens, M.; Stevens, R.L.; Cato, I.; Abrantes, F.

    2007-01-01

    Metal concentrations (Al, Cr, Cu, Ni, Pb and Zn) from the DGM-INETI archive data set have been examined for sediments collected during the 1970s from 267 sites on the Portuguese shelf. Due to the differences in the oceanographic and sedimentological settings between western and Algarve coasts, the archive data set is split in two segments. For both shelf segments, regional geochemical baselines (RGB) are defined using aluminium as a reference element. Seabed samples recovered in 2002 from four distinct areas of the Portuguese shelf are superimposed on these models to identify and compare possible metal enrichments relative to the natural distribution. Metal enrichments associated with anthropogenic influences are identified in three samples collected nearby the Tejo River and are characterised by the highest enrichment factors (EF; EF Pb Zn < 4). EF values close to 1 suggest a largely natural origin for metal distributions in sediments from the other areas included in the study. - Background metal concentrations and their natural variability must be established before assessing anthropogenic impacts

  8. Geochemical modeling of magmatic gas scrubbing

    B. Gambardella

    2005-06-01

    Full Text Available The EQ3/6 software package, version 7.2 was successfully used to model scrubbing of magmatic gas by pure water at 0.1 MPa, in the liquid and liquid-plus-gas regions. Some post-calculations were necessary to account for gas separation effects. In these post-calculations, redox potential was considered to be fixed by precipitation of crystalline a-sulfur, a ubiquitous and precocious process. As geochemical modeling is constrained by conservation of enthalpy upon water-gas mixing, the enthalpies of the gas species of interest were reviewed, adopting as reference state the liquid phase at the triple point. Our results confirm that significant emissions of highly acidic gas species (SO2(g, HCl(g, and HF(g are prevented by scrubbing, until dry conditions are established, at least locally. Nevertheless important outgassing of HCl(g can take place from acid, HCl-rich brines. Moreover, these findings support the rule of thumb which is generally used to distinguish SO2-, HCl-, and HF-bearing magmatic gases from SO2-, HCl-, and HF-free hydrothermal gases.

  9. Podoconiosis: non-infectious geochemical elephantiasis.

    Davey, Gail; Tekola, Fasil; Newport, Melanie J

    2007-12-01

    This article reviews peer-reviewed publications and book chapters on the history, epidemiology, genetics, ecology, pathogenesis, pathology and management of podoconiosis (endemic non-filarial elephantiasis). Podoconiosis is a non-infectious geochemical elephantiasis caused by exposure of bare feet to irritant alkalic clay soils. It is found in at least 10 countries in tropical Africa, Central America and northwest India, where such soils coexist with high altitude, high seasonal rainfall and low income. Podoconiosis develops in men and women working barefoot on irritant soils, with signs becoming apparent in most patients by the third decade of life. Colloid-sized silicate particles appear to enter through the skin, are taken up into macrophages in the lower limb lymphatics and cause endolymphangitis and obliteration of the lymphatic lumen. Genetic studies provide evidence for high heritability of susceptibility to podoconiosis. The economic burden is significant in affected areas dependent on subsistence farming. Podoconiosis is unique in being an entirely preventable non-communicable disease. Primary prevention entails promoting use of footwear in areas of irritant soil; early stages are reversible given good foot hygiene, but late stages result in considerable economic and social difficulties, and require extended periods of elevation and occasionally nodulectomy.

  10. Petroleum geochemical responses to reservoir rock properties

    Bennett, B.; Larter, S.R. [Calgary Univ., AB (Canada)

    2008-07-01

    Reservoir geochemistry is used to study petroleum basin development, petroleum mixing, and alterations. In this study, polar non-hydrocarbons were used as proxies for describing reservoir properties sensitive to fluid-rock interactions. A core flood experiment was conducted on a Carboniferous siltstone core obtained from a site in the United Kingdom. Core samples were then obtained from a typical upper shoreface in a North Sea oilfield. The samples were extracted with a dichloromethane and methanol mixture. Alkylcarbazoles and alkylfluorenones were then isolated from the samples. Compositional changes along the core were also investigated. Polar non hydrocarbons were studied using a wireline gamma ray log. The strongest deflections were observed in the basal coarsening upwards unit. The study demonstrated the correlations between molecular markers, and indicated that molecular parameters can be used to differentiate between clean sand units and adjacent coarsening upward muddy sand sequences. It was concluded that reservoir geochemical parameters can provide an independent response to properties defined by petrophysical methods. 6 refs., 2 figs.

  11. Geochemical prospect ion results of Mariscala aerial photo

    Filippini, J.

    1989-01-01

    This report shows the geochemical prospect ion results carried out within the framework of the metalical mining prospect ion in Mariscala aerial photo. Lavalleja district belong to the Mining inventory programme of Uruguay.

  12. Geochemical methodology for gold prospect ion in Uruguay

    Spangenber, J.

    1987-01-01

    This work is about the history of gold prospection in Uruguay. In this study there are considered the geochemical aspects, the gold performance, the applicability to mining prospection and the gold prospection aluvionar

  13. Drift pumice in the central Indian Ocean Basin: Geochemical evidence

    Pattan, J.N.; Mudholkar, A.V.; JaiSankar, S.; Ilangovan, D.

    Abundant white to light grey-coloured pumice without ferromanganese oxide coating occurs within the Quaternary sediments of the Central Indian Ocean Basin (CIOB). Two distinct groups of pumice are identified from their geochemical composition, which...

  14. National Geochemical Survey Locations and Results for Iowa

    Iowa State University GIS Support and Research Facility — The United States Geological Survey (USGS), in collaboration with other state and federal agencies, industry, and academia, is conducting a National Geochemical...

  15. Uruguay mining Inventory: Geochemical prospecting results of Valentines mapping

    Spangenberg, J.; Filippini, J.

    1985-01-01

    This work is about geochemical prospecting carried out into the Uruguay mining inventory framework. In this case the survey was in Valentines mapping. Florida, Durazno and Treinta y Tres provinces of Uruguay .

  16. Chlorine isotopes potential as geo-chemical tracers

    Shirodkar, P.V.; Pradhan, U.K.; Banerjee, R.

    The potential of chlorine isotopes as tracers of geo-chemical processes of earth and the oceans is highlighted based on systematic studies carried out in understanding the chlorine isotope fractionation mechanism, its constancy in seawater and its...

  17. The geochemical chararateristics of the marble deposits east of ...

    ), marbles were investigated with the view to establishing marble occurrences and their geochemical characteristics. Crystalline rocks of the Nigerian Basement Complex (migmatite – gneiss complex) underlie the area. Ten marble bodies were ...

  18. Evaluation and prediction of oil biodegradation: a novel approach integrating geochemical and basin modeling techniques in offshore Brazil

    Baudino, Roger [YPF S.A. (Argentina); Santos, Glauce Figueiredo dos; Losilla, Carlos; Cabrera, Ricardo; Loncarich, Ariel; Gavarrino, Alejandro [RepsolYPF do Brasil, Sao Paulo, SP (Brazil)

    2008-07-01

    Oil fields accounting for a large portion of the world reserves are severely affected by biological degradation. In Brazil, giant fields of the Campos Basin are producing biodegraded oils with widely variable fluid characteristics (10 to 40 deg API) and no apparent logical distribution nor predictability. Modern geochemical techniques allow defining the level of biodegradation. When original (non-degraded) oil samples and other with varying degradation level are available it might be possible to define a distribution trend and to relate it to present day geological factors such as temperature and reservoir geometry. However, other critical factors must be taken into account. But most of all, it is fundamental to have a vision in time of their evolution. This can only be achieved through 3D Basin Models coupled with modern visualization tools. The multi-disciplinary work-flow described here integrates three-dimensional numerical simulations with modern geochemical analyses. (author)

  19. Geochemical, hydrological, and biological cycling of energy residual. Research plan

    Wobber, F.J.

    1983-03-01

    Proposed research goals and specific research areas designed to provide a base of fundamental scientific information so that the geochemical, hydrological, and biophysical mechanisms that contribute to the transport and long term fate of energy residuals in natural systems can be understood are described. Energy development and production have resulted in a need for advanced scientific information on the geochemical transformations, transport rates, and potential for bioaccumulation of contaminants in subsurface environments

  20. Integrated geophysical-geochemical methods for archaeological prospecting

    Persson, Kjell

    2005-01-01

    A great number of field measurements with different methods and instruments were conducted in attempts to develop a method for an optimal combination of various geochemical and geophysical methods in archaeological prospecting. The research presented in this thesis focuses on a study of how different anthropogenic changes in the ground can be detected by geochemical and geophysical mapping and how the results can be presented. A six-year pilot project, Svealand in Vendel and Viking periods (S...

  1. The ceramic artifacts in archaeological black earth (terra preta from Lower Amazon Region, Brazil: chemistry and geochemical evolution Artefatos cerâmicos em sítios arqueológicos com terra preta na região do baixo Amazonas, Brasil: composição química e evolução geoquímica

    Marcondes Lima da Costa

    2004-09-01

    de P2O5 são relativamente elevados (2,37 % em média sob a forma de (Al,Fe-fosfatos, incomuns em cerâmicas vermelhas primitivas, mas encontrados em algumas cerâmicas arqueológicas egípcias e romanas. As concentrações dos elementos traços são comparáveis ou mesmo inferiores ao nível crustal, embora a composição total seja próxima a mesma. A composição química (exceto P2O5 em conjunto com os dados mineralógicos e texturais indicam material saprolítico derivado de rochas ígneas félsicas ou rochas sedimentares como matéria-prima das cerâmicas. Os teores de K, Ca e Na mostram que os feldspatos e fragmentos de rochas foram adicionados ao material argiloso, como sugerido pela mineralogia. Os altos teores de sílica respondem pela presença de cauixi, cariapé e/ou areias quartzosas. Fósforo deve ter sido incorporadoà matriz argilosa da cerâmica, quando do cozimento de alimentos nos vasos cerâmicos, e ainda, em parte, durante a formação do perfil de solo tipo ABE sobre Latossolos Amarelos. A matéria prima e os temperos (cauixi, cariapé, rochas trituradas e fragmentos de vasos cerâmicos descartados encontram-se disponíveis próximos aos sítios até a atualidade, e portanto foram a área fonte dos mesmos para a confecção dos artefatos cerâmicos..

  2. Simulación del perfil tensión-corriente para paneles solares mediante convertidor CC-CC reductor

    Muñoz Palaguachi, Henry Patricio; Patiño Guiracocha, Claudio Vinicio

    2017-01-01

    El desarrollo de este proyecto tiene como objetivo la reconstrucción del perfil tensión-corriente para paneles solares ante diferentes condiciones de funcionamiento al variar la temperatura e irradiancia. Este perfil se logra con el control de un convertidor reductor de tipo conmutado mediante controladores de corriente y tensión. In this work the emulation of voltage-current profiles for photovoltaic panels is developed for different operating conditions, specifically for variations in ir...

  3. Rock–water interactions and pollution processes in the volcanic aquifer system of Guadalajara, Mexico, using inverse geochemical modeling

    Morán-Ramírez, J.; Ledesma-Ruiz, R.; Mahlknecht, J.; Ramos-Leal, J.A.

    2016-01-01

    In order to understand and mitigate the deterioration of water quality in the aquifer system underlying Guadalajara metropolitan area, an investigation was performed developing geochemical evolution models for assessment of groundwater chemical processes. The models helped not only to conceptualize the groundwater geochemistry, but also to evaluate the relative influence of anthropogenic inputs and natural sources of salinity to the groundwater. Mixing processes, ion exchange, water–rock–water interactions and nitrate pollution and denitrification were identified and confirmed using mass-balance models constraint by information on hydrogeology, groundwater chemistry, lithology and stability of geochemical phases. The water–rock interactions in the volcanic setting produced a dominant Na−HCO_3 water type, followed by Na−Mg−Ca−HCO_3 and Na−Ca−HCO_3. For geochemical evolution modeling, flow sections were selected representing recharge and non-recharge processes and a variety of mixing conditions. Recharge processes are dominated by dissolution of soil CO_2 gas, calcite, gypsum, albite and biotite, and Ca/Na exchange. Non-recharge processes show that the production of carbonic acid and Ca/Na exchange are decreasing, while other minerals such as halite and amorphous SiO_2 are precipitated. The origin of nitrate pollution in groundwater are fertilizers in rural plots and wastewater and waste disposal in the urban area. This investigation may help water authorities to adequately address and manage groundwater contamination. - Highlights: • The Inverse geochemical modeling was used to study to processes occurring in a volcanic aquifer. • Three flow sections were selected to apply inverse hydrogeochemical modeling. • Three main groundwater flows were identified: a local, intermediate and regional flow. • The models show that in the study area that groundwater is mixed with local recharge. • In the south, the aquifer has thermal influence.

  4. Concerning evaluation of eco-geochemical background in remediation strategy

    Korobova, Elena; Romanov, Sergey

    2015-04-01

    The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

  5. Development of thermodynamic databases for geochemical calculations

    Arthur, R.C.; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu; Neyama, Atsushi

    1999-09-01

    Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000degC. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25degC) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25degC and l bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100degC at 1 bar. All equilibrium constants, reaction enthalpies, and log K(T) coefficients in PHREEQE.JNC are calculated using SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT model, and because primary

  6. Development of thermodynamic databases for geochemical calculations

    Arthur, R.C. [Monitor Scientific, L.L.C., Denver, Colorado (United States); Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Neyama, Atsushi [Computer Software Development Corp., Tokyo (Japan)

    1999-09-01

    Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000degC. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25degC) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25degC and l bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100degC at 1 bar. All equilibrium constants, reaction enthalpies, and log K(T) coefficients in PHREEQE.JNC are calculated using SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT model, and because primary

  7. Geochemical investigation of iron transport into bentonite as steel corrodes

    Hunter, Fiona; Bate, Fiona; Heath, Tim; Hoch, Andrew

    2007-09-01

    some experiments. Using the experimental data as a guide, a modelling investigation has been carried out. The objectives of the modelling investigation were: To develop a geochemical model of the transport of iron into bentonite based on the clear experimental evidence of the penetration of iron into bentonite. To improve our understanding of the desaturation of the bentonite as water is consumed during the corrosion process and the resultant gas(es) escapes. The production of iron from the corroding source was modelled using a rate of gas evolution that had been fitted. It was shown that ion exchange and surface complexation processes do not provide sufficient sorption to predict the high amount of iron observed in the solid phase. Therefore alternative processes, such as iron-containing mineral formation or mineral transformations, were also suggested to account for the amount of iron observed within the bentonite phase. Magnetite was identified as the most thermodynamically stable solubility limiting phase under the experimental conditions. A one-dimensional transport model was constructed to include all relevant processes. The simulations considered the diffusive transport of Fe 2+ ions away from a corroding source, using the rate of gas evolution resulting from the corrosion process. Ion exchange and surface complexation processes were allowed within the bentonite which would provide sorption of iron onto and within the bentonite solid. The pH was buffered by allowing protonation and deprotonation of the surface sites of the bentonite solid. In addition, saturation of iron-containing minerals was permitted. The base case model suggests that about 4.4 wt % of iron could form in the bentonite if the formation of magnetite was allowed. However, the maximum theoretical amount of iron available from the source term is limited to 4.5 wt % of iron by the cumulative gas evolution rate, which is lower than the observed amount of iron in the bulk bentonite (6.6 wt %). A

  8. Geochemical investigation of iron transport into bentonite as steel corrodes

    Hunter, Fiona; Bate, Fiona; Heath, Tim; Hoch, Andrew [Serco Assurance, Harwe ll (United Kingdom)

    2007-09-15

    some experiments. Using the experimental data as a guide, a modelling investigation has been carried out. The objectives of the modelling investigation were: To develop a geochemical model of the transport of iron into bentonite based on the clear experimental evidence of the penetration of iron into bentonite. To improve our understanding of the desaturation of the bentonite as water is consumed during the corrosion process and the resultant gas(es) escapes. The production of iron from the corroding source was modelled using a rate of gas evolution that had been fitted. It was shown that ion exchange and surface complexation processes do not provide sufficient sorption to predict the high amount of iron observed in the solid phase. Therefore alternative processes, such as iron-containing mineral formation or mineral transformations, were also suggested to account for the amount of iron observed within the bentonite phase. Magnetite was identified as the most thermodynamically stable solubility limiting phase under the experimental conditions. A one-dimensional transport model was constructed to include all relevant processes. The simulations considered the diffusive transport of Fe{sup 2+} ions away from a corroding source, using the rate of gas evolution resulting from the corrosion process. Ion exchange and surface complexation processes were allowed within the bentonite which would provide sorption of iron onto and within the bentonite solid. The pH was buffered by allowing protonation and deprotonation of the surface sites of the bentonite solid. In addition, saturation of iron-containing minerals was permitted. The base case model suggests that about 4.4 wt % of iron could form in the bentonite if the formation of magnetite was allowed. However, the maximum theoretical amount of iron available from the source term is limited to 4.5 wt % of iron by the cumulative gas evolution rate, which is lower than the observed amount of iron in the bulk bentonite (6.6 wt

  9. Perfil de los usuarios activos y finales de clubes deportivos de Bogotá D. C.

    Billy Crissien

    2010-08-01

    hacia los clubes en las diferentes disciplinas deportivas y analizar el caso particular de los hinchas de equipos profesionales. Para esto, se desarrolló una investigación descriptiva con encuestas a 336 usuarios activos y finales de clubes deportivos en la ciudad de Bogotá. Los resultados muestran un perfil diferencial para jugadores y espectadores a nivel de estilo de vida, hábitos saludables y patrón de interacción con los eventos deportivos. Los hinchas de los equipos profesionales de fútbol poseen un perfil similar al de los usuarios finales de los clubes de otras disciplinas, pero evidencian un nivel de involucramiento mucho más alto.

  10. Los perfiles cognitivos psicopatológicos en la formulación cognitiva de caso

    Ronald Toro

    2010-01-01

    Full Text Available Se resaltó la relevancia de incluir los perfiles cognitivos desarrollados de acuerdo con las categorías diagnósticas del DSM-IV TR para los trastornos de la personalidad en la formulación cognitiva de caso. Los contenidos informacionales deben dar cuenta del perfil cognitivo específico del paciente, con el fin de facilitar la planeación y el curso del tratamiento ajustado a sus necesidades, aunque no presente diagnóstico en el eje II. También se analizaron las implicaciones del uso inadecuado de las categorías diagnósticas en los trastornos de la personalidad; la necesidad de generar investigación en torno al soporte empírico y psicométrico derivado de la presente propuesta, y el entrenamiento de terapeutas cognitivos en formulación cognitiva de caso.

  11. LOS PERFILES COGNITIVOS PSICOPATOLÓGICOS EN LA FORMULACIÓN COGNITIVA DE CASO

    Ronald Toro

    2010-01-01

    Full Text Available Se resaltó la relevancia de incluir los perfiles cognitivos desarrolladosde acuerdo con las categorías diagnósticas delDSM-IV TR para los trastornos de la personalidad en la formulacióncognitiva de caso. Los contenidos informacionalesdeben dar cuenta del perfil cognitivo específico del paciente,con el fin de facilitar la planeación y el curso del tratamientoajustado a sus necesidades, aunque no presente diagnósticoen el eje II. También se analizaron las implicaciones del usoinadecuado de las categorías diagnósticas en los trastornos dela personalidad; la necesidad de generar investigación en tornoal soporte empírico y psicométrico derivado de la presentepropuesta, y el entrenamiento de terapeutas cognitivos en formulacióncognitiva de caso.

  12. ELEMENTOS PARA LA CONSTRUCION DE UN PERFIL PARA EL GERENTE SOCIAL EN UN ENTORNO GLOBALIZADO

    Antonio Bastidas Unigarro

    2009-07-01

    Full Text Available El perfil del gerente social adecuado para enfrentar los retos del mundo globalizado se ha estructurado a partir de cuatro requerimientos fundamentales: los conocimientos, la experiencia, las habilidades y las actitudes, los cuales se analizan como competencias indispensables para administrar la problemática compleja, llena de incertidumbres y desafíos del nuevo milenio. La propuesta para la construcción de un perfil de este gerente parte de considerar tres tipos de competencias: las funcionales, las comportamentales y los requisitos de estudio y experiencia. Su construcción parte del análisis de la Gerencia Social en el estado neoliberal, escenario, que reclama la formación de gerentes sociales comprometidos en la construcción de una sociedad mas justa, incluyente, participativa, democrática y solidaria.

  13. DIÁLOGO DE LAS PERSPECTIVAS DE PERFIL CONCEPTUAL Y CONGLOMERADOS DE RELEVANCIA

    Rosa I. Pedreros-M.

    2013-12-01

    Full Text Available El presente artículo forma parte del desarrollo de la investigación doctoral titulada “Perfil conceptual del calor en comunidades culturalmente diferenciadas” y tiene como intención socializar las perspectivas de perfil conceptual y conglomerados de relevancia como referentes teóricos y metodológicos que permitan proponer nuevas opciones para pensar la enseñanza-aprendizaje de las ciencias o la educación en ciencias, que observen los modos de pensar y hablar de los estudiantes y las relaciones entre la cultura local y el conocimiento escolar. Se exponen el origen, los referentes, las consideraciones sobre la enseñanza-aprendizaje de las ciencias y las razones para investigar desde estas perspectivas.

  14. Comportamiento termodinámico de rotores para compresores de tornillo con nuevo perfil.

    A. Rivera Torres

    2007-01-01

    Full Text Available En el presente artículo se evalúa el comportamiento termodinámico de rotores para compresores de tornillo con nuevos perfiles, realizado con ayuda del software Scorpath 2000. Ello permite predecir con precisión el desempeño completo del compresor y su evaluación termodinámica, así como realizar comparaciones, en igualdad de condiciones, con el trabajo de otros compresores dotados de perfiles de otros tipos.The article displays an evaluation of the thermodynamic behaviour of screw compressor rotors with new profiles, obtained with the help of the Scorpath 2000 software. This allows predicting precisely the operation of the compressor, as well as its thermodynamic evaluation, under equal conditions, with the work of other compressors fitted with rotor profiles of other kinds.

  15. Aspectos del control de flujo con un flap Gurney rotante sobre un perfil NACA 4412

    García Sainz, Mariano O.; Muñoz, Federico; Colman Lerner, Jorge León; Marañón Di Leo, Julio; Delnero, Juan Sebastián; Camocardi, Mauricio E.

    2011-01-01

    En el Laboratorio de Capa Límite y Fluidodinámica Ambiental, Dto. de Aeronáutica, Facultad de Ingeniería (UNLP), se realizaron ensayos con un modelo de ala con perfil NACA 4412, provisto de un miniflap Gurney móvil en el intradós, ubicado al 8%c desde el borde de fuga (c: cuerda del perfil). El modelo de ala, sin torsión, tiene 50cm de cuerda y 80cm de envergadura. El miniflap, de longitud 79.5cm y altura 2%c, posee movimiento de rotación alrededor de su eje, a través de un sistema electromec...

  16. Perfiles de personas con diferencia mental basados en las funciones motrices gruesas

    Isabel Ma. Ferrándiz Vindel

    2002-01-01

    Full Text Available El propósito de este estudio ha sido identificar posibles subtipos de alumnos con Deficiencia Mental basados en funciones motrices gruesas. Se seleccionó un grupo de alumnos de un centro específico de Deficiencia Mental, que no presentaron deficiencias motóricas asociadas, y se les administraron los subtests de motricidad gruesa del «Test Bruininks-Ozeretsky para medir la eficacia motriz»- Los cuatro subtipos resultantes mostraron diferentes perfiles de desarrollo motor A partir de estos resultados, se recomienda diseñar programas específicos que intenten paliar los trastornos motrices gruesos, analizados para cada uno de los subtipos hallados, y realizar adaptaciones curriculares pertinentes, teniendo en cuenta los perfiles motrices estudiados

  17. Uncertainty in reactive transport geochemical modelling

    Oedegaard-Jensen, A.; Ekberg, C.

    2005-01-01

    Full text of publication follows: Geochemical modelling is one way of predicting the transport of i.e. radionuclides in a rock formation. In a rock formation there will be fractures in which water and dissolved species can be transported. The composition of the water and the rock can either increase or decrease the mobility of the transported entities. When doing simulations on the mobility or transport of different species one has to know the exact water composition, the exact flow rates in the fracture and in the surrounding rock, the porosity and which minerals the rock is composed of. The problem with simulations on rocks is that the rock itself it not uniform i.e. larger fractures in some areas and smaller in other areas which can give different water flows. The rock composition can be different in different areas. In additions to this variance in the rock there are also problems with measuring the physical parameters used in a simulation. All measurements will perturb the rock and this perturbation will results in more or less correct values of the interesting parameters. The analytical methods used are also encumbered with uncertainties which in this case are added to the uncertainty from the perturbation of the analysed parameters. When doing simulation the effect of the uncertainties must be taken into account. As the computers are getting faster and faster the complexity of simulated systems are increased which also increase the uncertainty in the results from the simulations. In this paper we will show how the uncertainty in the different parameters will effect the solubility and mobility of different species. Small uncertainties in the input parameters can result in large uncertainties in the end. (authors)

  18. Geochemical factors influencing vault design and layout

    Gascoyne, M.; Stroes-Gascoyne, S.; Sargent, F.P.

    1995-01-01

    The design and construction of a vault for used nuclear fuel in crystalline rock may be influenced by a number of geochemical factors. During the siting stage, information is needed regarding the rock type, heterogeneities in its composition and the mineralogy of permeable zones because these will cause variations in thermal conductivity, strength and radionuclide sorptive properties of the rock. These factors may affect decisions regarding depth of vault construction, tunnel dimensions and spacing of panels and waste containers. The decision on whether groundwaters are allowed to flow freely into a planned excavation may depend on measurements of their chemical compositions, microbiological contents and presence of hazardous or corrosive constituents. During site characterization, borehole drilling from the surface and subsequent hydraulic testing will introduce both chemical and microbiological contaminants that may further influence this decision. During vault construction, the geochemistry of the rock may cause changes to the characterization, design and construction of the vault. For example, high salinity fluids in micropores in the rock could prevent the use of radar surveys to detect fractures in the surrounding rock. High rock salinity may also cause unacceptably high total dissolved solids loadings in water discharged from the facility. Again, the presence of toxic, corrosive or radioactive constituents in inflowing groundwater may require grouting or, if inflow is needed for service operations, development of treatment facilities both above and below ground. In addition, the use of explosives will cause high organic and nitrate loadings in service water as well as the possible impregnation of these chemicals in the damaged wall-rock surrounding an excavation. These chemicals may remain despite cleaning efforts and act as nutrients to promote microbial activity in the post-closure phase. In the operational phase, further design and construction, changes

  19. Predictive geophysics: geochemical simulations to geophysical targets

    Chopping, R. G.; Cleverley, J.

    2017-12-01

    With an increasing focus on deep exploration for covered targets, new methods are required to target mineral systems under cover. Geophysical responses are driven by physical property contrasts; for example, density contrasts provide a gravity signal, acoustic impedance contrasts provide a seismic reflection signal. In turn, the physical properties for basement, crystalline rocks which host the vast majority of mineral systems are determined almost wholly by the mineralogy of the rocks in question. Mineral systems, through the transport of heat and reactive fluids, will serve to modify the physical properties of country rock as they chemically alter the hosting strata. To understand these changes, we have performed 2D reactive transport modelling that simulates the formation of Archean gold deposits of the Yilgarn Craton, Western Australia. From this, we derive a model of mineralogy that we can use to predict the density, magnetic susceptibility and seismic reflection changes associated with ore formation. It is then possible to predict the gravity, magnetic and seismic reflection responses associated with these deposits. Scenario mapping, such as testing the ability to resolve buried ore bodies or the geophysical survey spacing required to resolve the mineral system, can be performed to produce geophysical targets from these geochemical simulations. We find that there is a gravity response of around 9% of the unaltered response for deposits even buried by 1km of cover, and there is a magnetic spike associated with proximal alteration of the ore system. Finally, seismic reflection response is mostly characterised by additional reflections along faults that plumb the alteration system.

  20. Geochemical Study of Natural CO2 Emissions in the French Massif Central: How to Predict Origin, Processes and Evolution of CO2 Leakage Étude géochimique des émissions naturelles de CO2 du Massif Central : origine et processus de migration du gaz

    Battani A.

    2010-05-01

    Full Text Available This study presents an overview of some results obtained within the French ANR (National Agency of Research supported Géocarbone-Monitoring research program. The measurements were performed in Sainte-Marguerite, located in the French Massif Central. This site represents a natural laboratory for CO2/fluid/rock interactions studies, as well as CO2 migration mechanisms towards the surface. The CO2 leaking character of the studied area also allows to test and validate measurements methods and verifications for the future CO2 geological storage sites. During these surveys, we analyzed soil CO2 fluxes and concentrations. We sampled and analyzed soil gases, and gas from carbo-gaseous bubbling springs. A one-month continuous monitoring was also tested, to record the concentration of CO2 both in atmosphere and in the soil at a single point. We also developed a new methodology to collect soil gas samples for noble gas abundances and isotopic analyses, as well as carbon isotopic ratios. Our geochemical results, combined with structural geology, show that the leaking CO2 has a very deep origin, partially mantle derived. The gas rises rapidly along normal and strike-slip active faults. CO2 soil concentrations (also showing a mantle derived component and CO2 fluxes are spatially variable, and reach high values. The recorded atmospheric CO2 is not very high, despite the important CO2 degassing throughout the whole area. Cette étude présente les principaux résultats de campagnes de monitoring géochimique menées en 2006 et 2007 dans le cadre du projet Géocarbone-Monitoring, sur le site de Sainte-Marguerite, situé dans le Massif Central. Ce site constitue un « laboratoire naturel » pour l’étude des interactions CO2/fluides/roches et des mécanismes de migration du CO2 vers la surface, à l’échelle des temps géologiques. Le caractère particulièrement émissif de cet « analogue » permet également de tester et valider des méthodes de mesure et

  1. Modeling background radiation using geochemical data: A case study in and around Cameron, Arizona.

    Marsac, Kara E; Burnley, Pamela C; Adcock, Christopher T; Haber, Daniel A; Malchow, Russell L; Hausrath, Elisabeth M

    2016-12-01

    This study compares high resolution forward models of natural gamma-ray background with that measured by high resolution aerial gamma-ray surveys. The ability to predict variations in natural background radiation levels should prove useful for those engaged in measuring anthropogenic contributions to background radiation for the purpose of emergency response and homeland security operations. The forward models are based on geologic maps and remote sensing multi-spectral imagery combined with two different sources of data: 1) bedrock geochemical data (uranium, potassium and thorium concentrations) collected from national databases, the scientific literature and private companies, and 2) the low spatial resolution NURE (National Uranium Resource Evaluation) aerial gamma-ray survey. The study area near Cameron, Arizona, is located in an arid region with minimal vegetation and, due to the presence of abandoned uranium mines, was the subject of a previous high resolution gamma-ray survey. We found that, in general, geologic map units form a good basis for predicting the geographic distribution of the gamma-ray background. Predictions of background gamma-radiation levels based on bedrock geochemical analyses were not as successful as those based on the NURE aerial survey data sorted by geologic unit. The less successful result of the bedrock geochemical model is most likely due to a number of factors including the need to take into account the evolution of soil geochemistry during chemical weathering and the influence of aeolian addition. Refinements to the forward models were made using ASTER visualizations to create subunits of similar exposure rate within the Chinle Formation, which contains multiple lithologies and by grouping alluvial units by drainage basin rather than age. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Preliminary Geochemical and Rock Magnetic Study of a Stalagmite From Quintana Roo, Northeastern Yucatan Peninsula

    Urrutia-Fucugauchi, J.; Perez-Cruz, L.; Zhao, X.; Rebolledo-Vieyra, M.; Rodriguez, A.

    2012-04-01

    We present the preliminary results of geochemical, stable isotopes and rock magnetic studies of a stalagmite from a cave in eastern Quintana Roo, northern Yucatan peninsula. In the past years, there has been increased interest in understanding the paleoclimatic and paleoenvironmental evolution of the Yucatan peninsula and northern Central America, investigating the relationships between climate variations and the development of the Maya civilization. In particular, the variations in regional precipitation and occurrence of several drought periods, which might have been related to the collapse of the Classic Maya period. Stable isotope data on speleothems from different sites in Yucatan and Central America have provided evidence on changes in precipitation, which have affected the Maya region. The stalagmite is ~47 cm long and about 4-5 cm wide at its base. It was collected from the Hilariós Well cave in Tulum, Quintana Roo. Magnetic susceptibility and geochemical analyses have been completed as part of the initial characterization of the stalagmite, with measurements taken every centimeter. Geochemical analyses have been carried out for x-ray fluorescence, with a Niton XRF analyzer. Magnetic susceptibility was determined with a Bartington MS2 instrument using the high resolution surface probe. Additional rock magnetic analyses include magnetic hysteresis loops and isothermal remanent magnetization (IRM) acquisition, and saturation IRM demagnetization, which have been measured with a MicroMag instrument. Hysteresis loops are diamagnetic, with small varying low-coercivity ferromagnetic components. The elemental compositions of major oxides and trace elements vary with depth. Calcium is the major element and displays a pattern of small amplitude fluctuations with a trend to lower values at the bottom, which are also shown in other elements such as barium. Silica and elements such as titanium and strontium are positively correlated and show an apparent cyclic pattern

  3. Role of soil geochemical and microbiological components on selenium behaviour in oxic and anoxic conditions

    Darcheville, O.

    2008-09-01

    Selenium (Se) is naturally present in the environment. Se is essential for living organisms at trace concentrations, but it becomes rapidly toxic with their increases. The 79 Se radioactive isotopes of Se, is found in nuclear wastes that may be buried in deep geological formations. In soil, Se exists in many forms and its mobility is affected by the redox potential and microbial activity. Very few studies have focused on Se behaviour at trace concentration. We have tried to distinguish the major abiotic geochemical and microbiological processes involved in the fate of trace selenite (Se(IV)) in a soil. The study was based on batch incubation in oxic or anoxic conditions of slurry suspension artificially contaminated with Se (IV) to 0.4 mg Se.kg -1 dry soil. The incubation involved sterilized and non-sterile soil samples with or without organic amendment to stimulate microbial activities. For each incubation, we followed the distribution of Se between solid, liquid and gaseous phases as well as the geochemical evolution of the solution, the composition of the atmosphere gas bottles and the soil microflora. The results showed that Se was relatively few mobile in the soil studied. Geochemical processes played a major role in controlling the Se mobility. Over time, some abiotic transformations in the solid phase contributed to increase the Se immobilisation. The microbiological processes contributed to this increase in the solid phase. Moreover, in oxic as in anoxic conditions, some microbial processes were responsible, to a lesser extent, for a dispersion of Se in the atmosphere by the production of volatile compounds. (author)

  4. Propuesta de perfiles varios y competencias laborales asociadas al profesional de la información

    Ramón Antonio Piña Rodríguez

    2006-01-01

    Se formula, desde el enfoque de la Gestión por competencias, el paradigma de las competencias cognitivas laborales y perfiles de algunos cargos definidos a desempeñar en las organizaciones por el profesional de la información. Es demostrada la versatilidad del desempeño de éste y las oportunidades que le ofrece a los empresarios que apuestan por la empresa del siglo XXI, inmersa en la era del conocimiento.

  5. Las necesidades formativas del profesorado en TIC: perfiles formativos y elementos de complejidad

    Almerich, Gonzalo

    2011-09-01

    Full Text Available Las necesidades formativas del profesorado en las Tecnologías de la Información y de la Comunicación (TIC se constituyen como uno de los aspectos claves para la integración de las TIC en la práctica educativa diaria, junto con las competencias en TIC y el uso de estos recursos tecnológicos por parte del profesorado. El objetivo de este artículo es establecer perfiles formativos del profesorado y relacionarlos con sus competencias en TIC y el uso de las mismas, junto con factores personales y contextuales. Para ello, se ha utilizado un diseño de encuesta, con una muestra de 868 profesores y profesoras de Educación Primaria y Secundaria de la Comunidad Valenciana, siendo el instrumento de recogida de la información un cuestionario. Los resultados indican que el profesorado demanda formación de mayor nivel en el plano personal-profesional, necesitándose más formación en los planos con el alumnado en el aula y la integración de estos recursos en el aula. Además, estas necesidades se pueden estructurar en cuatro perfiles: inicial, inicial-medio, medio y avanzado. Asimismo, se ha hallado una relación clara entre estos perfiles de necesidades formativas con las competencias en TIC, esencialmente las tecnológicas; el uso de las TIC, principalmente el plano personal-profesional. También se encuentra una influencia en estos perfiles de la edad del profesorado y la frecuencia de uso del ordenador. Esto implica que las administraciones educativas han de considerar estos resultados en el desarrollo de los planes de formación del profesorado para producir programas de mayor calidad, tal y como se demanda desde diversos ámbitos.

  6. EL PERFIL COMPETITIVO LOCAL COMO FACTOR DETERMINANTE PARA EL DESARROLLO DE LA FLORICULTURA EN MADRID (CUNDINAMARCA

    DANIEL HERNÁN SANTIAGO ROMERO

    2011-01-01

    Full Text Available Este artículo describe los atributos del perfil competitivo del municipio de Madrid y establece las relaciones que, con dicho perfil, ha tenido el desarrollo de cultivos de flores. Se parte de la descripción de la situación actual de la industria de la floricultura en el país. Después, tras establecer los determinantes que desde la teoría se han propuesto para medir la competitividad de un territorio, se analiza el caso particular del municipio de Madrid y define los atributos competitivos que lo caracterizan. Se presentan las relaciones entre el perfil competitivo del municipio y la floricultura, mostrando cómo aquél, se convirtió en un factor determinante para dicha actividad económica. Finalmente se presentan las conclusiones del artículo, las cuales son antecedidas por la presentación de los elementos que representan la mayor fortaleza para el desarrollo económico del municipio en el futuro.

  7. Perfil dos trabalhadores de enfermagem no Programa de Saúde da Família

    Rafaela Azenha Teixeira

    2000-09-01

    Full Text Available O estudo objetiva caracterizar a configuração demográfica dos trabalhadores ligados à enfermagem de equipes do PSF de 3 municípios de São Paulo e analisar a percepção destes quanto ao perfil profissional necessário à atuação junto ao PSF. Utilizou-se como instrumento para coleta de dados a entrevista semi-estruturada. Para a sistematização inicial dos dados utilizou-se do software ETHNOGRAPH, e, posteriormente realizou-se análise temática. Os temas identificados na fala dos trabalhadores, apontam para um "perfil necessário" à atuação no PSF: há uma percepção de que os trabalhadores devem ser comunicativos, dedicados, envolvidos, solidários, carinhosos, ter bom relacionamento, disponibilidade e ajudar a população. O conjunto dos dados, embora aponte em alguns momentos para um perfil profissional que contemple uma prática de caráter assistencialista, ao mesmo tempo encaminha para uma reflexão acerca de uma nova configuração da prática assistencial alicerçada na humanização e integralidade da assistência, assim como na construção da cidadania.

  8. Comportamento do Consumidor Educacional: seu Perfil e o Processo de Decisão de Compra

    Alessandra Daiana Schinaider

    2016-08-01

    Full Text Available O estudo do comportamento do consumidor é importante para elaboração das estratégias de marketing da empresa visando atender seu público-alvo, garantindo a satisfação dos seus clientes. Este artigo tem como objetivo analisar o comportamento do consumidor do Centro Universitário Internacional – UNINTER identificando seu perfil e como acontece seu processo de decisão de compra. Foi realizado um estudo de caso com uma pesquisa qualitativa-quantitativa e descritiva utilizando a técnica de amostragem não-probabilística por conveniência. Verificou-se que o perfil feminino jovem que possui uma vida financeira independente é o principal público-alvo desse centro universitário. Além disso, o comportamento do consumidor educacional enquadra-se em um perfil econômico e de estudante não-tradicional tendo seu processo decisório de compra influenciado por diversos fatores culturais, pessoais, sociais e psicológicos. Os resultados permitem entender o comportamento do consumidor educacional do centro universitário auxiliando os profissionais de marketing na elaboração de melhores estratégias para atingir esse público.

  9. Perfiles de aprendizaje y trabajo colaborativo en entornos de simulación en 3D

    Byron Ernesto Vaca-Barahona

    2016-06-01

    Full Text Available Los entornos de simulación 3D con mediación pedagógica favorecen la comunicación e interacción de los estudiantes inmersos en la actividad formativa en el contexto de la secuencia pedagógica planteada, promoviendo así de manera natural el aprendizaje de los estudiantes, generándose dos tipos de comunicación: interacción entre participante y objeto 3D, e interacción del tipo participante con otro participante que en la experiencia es la que se desarrolla más espontáneamente y en mayor cantidad. Se evidencia que el comportamiento y la actuación de los perfiles Strong-Willed y Bridge son distintos. El perfil Strong-Willed se caracteriza por organizar, asumir y distribuir responsabilidades, tomar decisiones, colaborar, liderar el trabajo del grupo, ser persistente y constante. Sin embargo, el perfil Bridge se caracteriza por ser comunicativo, expresivo y motivador del grupo; se apoya en el conocimiento de los miembros del grupo para aprender y desarrollar sus actividades y carece de continuidad durante el desarrollo del trabajo grupal.

  10. PERFIL DE LIDERANÇA E TOMADA DE DECISÃO

    Eduardo Botti Abbade

    2009-04-01

    Full Text Available O objetivo geral deste estudo foi o de identificar o estilo de liderança, perfil comportamental e decisório dos dirigentes das empresas do Distrito Industrial de Santa Maria / RS. Este estudo se configura como sendo uma pesquisa de levantamento (survey descritiva onde foram selecionadas 14 empresas, das 20 existentes, localizadas no Distrito Industrial do município de Santa Maria-RS. Com o objetivo de definir o perfil gerencial dos pesquisados, esta investigação utilizou-se de perspectivas psicológicas, de observação, de decisão e de aprendizagem. Os entrevistados correspondem a indivíduos que possuem um perfil com tendências a enfatizar detalhes e fatos, possuem foco no curto prazo e são muito realistas. Costumam elaborar regras e regulamentos para o julgamento do desempenho. Sugeremse para estudos futuros que seja realizado estudos onde se proponha um cruzamento entre os perfis observados com demais aspectos organizacionais como clima, cultura e comunicação organizacional. Propõe-se também que seja realizada a pesquisa com uma amostra mais abrangente. Aconselha-se que seja realizada a entrevista com gestores ou responsáveis de todas as áreas das empresas pesquisadas, para que se possam analisar perfis de gestores com diferentes competências e atribuições na mesma organização.

  11. Perfil de clientes colostomizados inscritos em programa de atenção aos estomizados

    Mara Rúbia Violin

    2008-12-01

    Full Text Available A experiência de ter uma colostomia conduz as pessoas a viverem situações diferenciadas. O objetivo deste estudo descritivo, exploratório, de natureza quantitativa, foi o de identificar o perfil do paciente colostomizado, inscrito no Programa de Atenção ao Estomizado – PAE, da 15ª Regional de Saúde do Paraná. A coleta foi realizada no mês de maio de 2007 e foi considerado o intervalo de tempo das fichas inscritas no PAE de janeiro de 2003 a maio de 2007. O perfil foi caracterizado segundo dados demográficos, doença base que levou a confecção do estoma, tipo de dispositivo, tratamento e tempo de uso do dispositivo coletor. Os resultados do estudo permitiram a obtenção de dados de importância epidemiológica para futuras intervenções como campanhas de prevenção, diagnóstico e tratamento precoce, assim como, o conhecimento da estrutura do atendimento profissional existente e as necessidades de informação das famílias dos pacientes. A definição do perfil dos pacientes além de contribuir para a melhoria do atendimento prestado permite o estabelecimento de novas proposições para a melhoria da qualidade de vida dos pacientes e da família.

  12. Significance of geochemical characterization to performance at Yucca Mountain, Nevada

    Simmons, A.M.

    1993-01-01

    The U.S. concept for permanent disposal of high-level radioactive waste resembles those of other countries in that it relies upon burial in a deep geologic medium. This concept relies upon multiple barriers to retard transport of radionuclides to the accessible environment; those barriers consist of the waste form, waste container, engineered barrier system (including possible backfill) and retardant properties of the host rock. Because mobilization of radionuclides is fundamentally a geochemical problem, an understanding of past, present, and future geochemical processes is a requisite part of site characterization studies conducted by the U.S. Department of Energy at Yucca Mountain, Nevada. Geochemical information is needed for evaluating three favorable conditions (the rates of geochemical processes, conditions that promote precipitation or sorption of radionuclides or prohibit formation of colloids, and stable mineral assemblages) and four potentially adverse conditions of the site (groundwater conditions that could increase the chemical reactivity of the engineered barried system or reduce sorption, potential for gaseous radionuclide movement, and oxidizing groundwaters) for key issues of radionuclide release, groundwater quality, and stability of the geochemical environment. Preliminary results of long-term heating experiments indicate that although zeolites can be modified by long-term, low temperature reactions, their beneficial sorptive properties will not be adversely affected. Mineral reactions will be controlled by the aqueous activity of silica in groundwater with which the minerals are in contact. Geochemical barriers alone may satisfy release requirements to the accessible environment for many radionuclides; however, additional site specific geochemical and mineralogical data are needed to test existing and future radionuclide transport models

  13. Geochemical and geochronological constrains on the Chiang Khong volcanic rocks (northwestern Thailand) and its tectonic implications

    Qian, Xin; Feng, Qinglai; Chonglakmani, Chongpan; Monjai, Denchok

    2013-12-01

    Volcanic rocks in northwestern Thailand exposed dominantly in the Chiang Khong area, are commonly considered to be genetically linked to the tectonic evolution of the Paleo-Tethyan Ocean. The volcanic rocks consist mainly of andesitic to rhyolitic rocks and are traditionally mapped as Permian-Triassic sequences. Our zircon U-Pb geochronological results show that two andesitic samples (TL-1-B and TL-31-B), are representative of the Doi Yao volcanic zone, and give a mean weighted age of 241.2±4.6 Ma and 241.7±2.9 Ma, respectively. The rhyolitic sample (TL-32-B1) from the Doi Khun Ta Khuan volcanic zone erupted at 238.3±3.8 Ma. Such ages indicate that Chiang Khong volcanic rocks erputed during the early Middle Triassic period. Seven samples from the Doi Yao and Doi Khun Ta Khuan zones exhibit an affinity to arc volcanics. Three rhyolitic samples from the Chiang Khong area have a geochemical affinity to both arc and syn-collisional volcanic rocks. The Chiang Khong arc volcanic rocks can be geochemically compared with those in the Lampang area in northern Thailand, also consistent with those in Jinghong area of southwestern Yunnan. This indicates that the Chiang Rai arc-volcanic zone might northwardly link to the Lancangjiang volcanic zone in southwestern China.

  14. Perfiles de personalidad relacionados con la vulnerabilidad del deportista a lesionarse

    Joel Manuel Prieto Andreu

    2014-01-01

    Full Text Available En el ámbito deportivo competitivo se hace necesaria una aproximación al perfil de vulnerabilidad psicológico a la lesión del deportista. La muestra total del estudio fue de 285 hombres (23 no lesionados y 168 mujeres (24 no lesionadas, los hombres tenían una media de edad de 21.77 años y las mujeres de 20.55 años. La muestra estuvo compuesta por jugadores de deportes individuales (tenis, atletismo y natación y por jugadores de deportes colectivos (fútbol, baloncesto y balonmano pertenecientes a distintos Clubes Deportivos de la Comunidad Valenciana. Para la evaluación de la ansiedad competitiva, se utilizó el Sport Competitive Anxiety Test (SCAT; para evaluar la personalidad resistente, se utilizó la escala EPR; para evaluar la competitividad, se utilizó la escala de Competitividad-10; y, para la evaluación de las lesiones, se utilizó una hoja de registro específica. El diseño del estudio fue descriptivo, observacional y correlacional. El estudio partió de la siguiente hipótesis: el número de lesiones aumentará cuando menor sea la personalidad resistente y la motivación orientada al éxito, y cuando mayor sea la ansiedad competitiva y la motivación orientada a evitar el fracaso. Se planteó como objetivo analizar las diferencias en el número de lesiones entre los deportistas que presentaban un perfil de vulnerabilidad a la lesión frente a los que no presentaban dicho perfil. Según la fundamentación teórica, situarse en dicho perfil implicaría lesionarse más, sin embargo, los resultados del estudio indican que los hombres con perfil de vulnerabilidad a la lesión (los que se lesionarían más tuvieron menor número de lesiones moderadas, totales e índice de lesión. Se discuten los resultados y se señalan algunas conclusiones del estudio.

  15. Geochemical Exploration Techniques Applicable in the Search for Copper Deposits

    Chaffee, Maurice A.

    1975-01-01

    Geochemical exploration is an important part of copper-resource evaluation. A large number of geochemical exploration techniques, both proved and untried, are available to the geochemist to use in the search for new copper deposits. Analyses of whole-rock samples have been used in both regional and local geochemical exploration surveys in the search for copper. Analyses of mineral separates, such as biotite, magnetite, and sulfides, have also been used. Analyses of soil samples are widely used in geochemical exploration, especially for localized surveys. It is important to distinguish between residual and transported soil types. Orientation studies should always be conducted prior to a geochemical investigation in a given area in order to determine the best soil horizon and the best size of soil material for sampling in that area. Silty frost boils, caliche, and desert varnish are specialized types of soil samples that might be useful sampling media. Soil gas is a new and potentially valuable geochemical sampling medium, especially in exploring for buried mineral deposits in arid regions. Gaseous products in samples of soil may be related to base-metal deposits and include mercury vapor, sulfur dioxide, hydrogen sulfide, carbon oxysulfide, carbon dioxide, hydrogen, oxygen, nitrogen, the noble gases, the halogens, and many hydrocarbon compounds. Transported materials that have been used in geochemical sampling programs include glacial float boulders, glacial till, esker gravels, stream sediments, stream-sediment concentrates, and lake sediments. Stream-sediment sampling is probably the most widely used and most successful geochemical exploration technique. Hydrogeochemical exploration programs have utilized hot- and cold-spring waters and their precipitates as well as waters from lakes, streams, and wells. Organic gel found in lakes and at stream mouths is an unproved sampling medium. Suspended material and dissolved gases in any type of water may also be useful

  16. Adjustment of geochemical background by robust multivariate statistics

    Zhou, D.

    1985-01-01

    Conventional analyses of exploration geochemical data assume that the background is a constant or slowly changing value, equivalent to a plane or a smoothly curved surface. However, it is better to regard the geochemical background as a rugged surface, varying with changes in geology and environment. This rugged surface can be estimated from observed geological, geochemical and environmental properties by using multivariate statistics. A method of background adjustment was developed and applied to groundwater and stream sediment reconnaissance data collected from the Hot Springs Quadrangle, South Dakota, as part of the National Uranium Resource Evaluation (NURE) program. Source-rock lithology appears to be a dominant factor controlling the chemical composition of groundwater or stream sediments. The most efficacious adjustment procedure is to regress uranium concentration on selected geochemical and environmental variables for each lithologic unit, and then to delineate anomalies by a common threshold set as a multiple of the standard deviation of the combined residuals. Robust versions of regression and RQ-mode principal components analysis techniques were used rather than ordinary techniques to guard against distortion caused by outliers Anomalies delineated by this background adjustment procedure correspond with uranium prospects much better than do anomalies delineated by conventional procedures. The procedure should be applicable to geochemical exploration at different scales for other metals. ?? 1985.

  17. Inverse modeling of geochemical and mechanical compaction in sedimentary basins

    Colombo, Ivo; Porta, Giovanni Michele; Guadagnini, Alberto

    2015-04-01

    We study key phenomena driving the feedback between sediment compaction processes and fluid flow in stratified sedimentary basins formed through lithification of sand and clay sediments after deposition. Processes we consider are mechanic compaction of the host rock and the geochemical compaction due to quartz cementation in sandstones. Key objectives of our study include (i) the quantification of the influence of the uncertainty of the model input parameters on the model output and (ii) the application of an inverse modeling technique to field scale data. Proper accounting of the feedback between sediment compaction processes and fluid flow in the subsurface is key to quantify a wide set of environmentally and industrially relevant phenomena. These include, e.g., compaction-driven brine and/or saltwater flow at deep locations and its influence on (a) tracer concentrations observed in shallow sediments, (b) build up of fluid overpressure, (c) hydrocarbon generation and migration, (d) subsidence due to groundwater and/or hydrocarbons withdrawal, and (e) formation of ore deposits. Main processes driving the diagenesis of sediments after deposition are mechanical compaction due to overburden and precipitation/dissolution associated with reactive transport. The natural evolution of sedimentary basins is characterized by geological time scales, thus preventing direct and exhaustive measurement of the system dynamical changes. The outputs of compaction models are plagued by uncertainty because of the incomplete knowledge of the models and parameters governing diagenesis. Development of robust methodologies for inverse modeling and parameter estimation under uncertainty is therefore crucial to the quantification of natural compaction phenomena. We employ a numerical methodology based on three building blocks: (i) space-time discretization of the compaction process; (ii) representation of target output variables through a Polynomial Chaos Expansion (PCE); and (iii) model

  18. Geochemical nature of sub-ridge mantle and opening dynamics of the South China Sea

    Zhang, Guo-Liang; Luo, Qing; Zhao, Jian; Jackson, Matthew G.; Guo, Li-Shuang; Zhong, Li-Feng

    2018-05-01

    The Indian-type mantle (i.e., above the north hemisphere reference line on the plot of 208Pb/204Pb vs. 206Pb/204Pb) has been considered as a "Southern Hemisphere" geochemical signature, whose origin remains enigmatic. The South China Sea is an extensional basin formed after rifting of the Euro-Asia continent in the Northern Hemisphere, however, the geochemical nature of the igneous crust remains unexplored. For the first time, IODP Expedition 349 has recovered seafloor basalts covered by the thick sediments in the Southwest sub-basin (Sites U1433 and U1434) and the East sub-basin (Site U1431). The Southwest sub-basin consists of enriched (E)-MORB type basalts, and the East sub-basin consists of both normal (N)-MORB-type and E-MORB-type basalts based on trace element compositions. The basalts of the two sub-basins are Indian-type MORBs based on Sr-Nd-Pb-Hf isotope compositions, and the Southwest sub-basin basalts show isotopic compositions (i.e., 206Pb/204Pb of 17.59-17.89) distinctly different from the East sub-basin (i.e., 206Pb/204Pb of 18.38-18.57), suggesting a sub-basin scale mantle compositional heterogeneity and different histories of mantle compositional evolution. Two different enriched mantle end-members (EM1 and EM2) are responsible for the genesis of the Indian-type mantle in the South China Sea. We have modeled the influences of Hainan mantle plume and lower continental crust based on Sr-Nd-Pb-Hf isotope compositions. The results indicate that the influence of Hainan plume can explain the elevated 206Pb/204Pb of the East sub-basin basalts, and the recycling of lower continental crust can explain the low 206Pb/204Pb of the Southwest sub-basin basalts. Based on the strong geochemical imprints of Hainan plume in the ridge magmatism, we propose that the Hainan plume might have promoted the opening of the South China Sea, during which the Hainan plume contributed enriched component to the sub-ridge mantle and caused thermal erosion and return of lower

  19. Geochemical evaluation of the near-field for future HLW repository at Olkiluoto

    Idiart, A.; Maia, F.; Arcos, D.

    2013-10-01

    The concept for the final disposal of spent nuclear fuel in Finland considers an engineered and natural (crystalline rock) multi-barrier system surrounding the spent fuel. This work aims at predicting and making a quantitative assessment of the geochemical evolution of the near-field (canister, buffer, backfill and adjacent fractured bedrock) during the unsaturated thermal period and in the long-term, after saturation has been completed. The groundwater/bentonite buffer interaction during the unsaturated thermal period is tackled through a two-dimensional (2D) axisymmetric scheme using the thermo-hydro-geochemical code TOUGHREACT. In turn, the long-term interaction of the fully water-saturated buffer and backfill with groundwater is assessed through 3D numerical models using the reactive transport code PHAST under isothermal conditions. A set of base cases have been set up based on the most plausible set of input data. In addition, a limited number of sensitivity cases have been conducted to analyse the influence of key parameters controlling the system and reduce uncertainty. Predicted mineralogical changes of accessory minerals in the bentonite for the thermal period are controlled by the dependence of mineral solubilities on temperature and on the solute transport by advection during the saturation process, and diffusion during the whole period. The results of the thermal period indicate that a small amount of the primary amorphous silica is redistributed in the buffer: dissolution close to the canister and precipitation close to the buffer - rock interface. Primary calcite dissolution/precipitation is minimal, remaining stable throughout the simulation time in all cases. Anhydrite precipitates near the canister due to the elevated temperature, while it dissolves from the outside of the buffer. The results indicate that there is no significant evaporation of water near the copper canister and thus no chloride salt reaches saturation. The geochemical changes of

  20. Geochemical studies of granitic rocks of Kallur area, Manvi Taluk, Raichur district, Karnataka (India).

    Raghavendra, N R; Reddy, R Purushottam; Nijagunappa, R

    2011-01-01

    The geochemical data is much widely used in establishing the overall chemical relation existing between the different rock types with their parentage. A major impetus for this shift comes not only from the need to understand and quantify better the spatial and temporal evolution, with emphasis on the younger greenstone belts (Kallur copper formations), but also from the recognition that such knowledge could form the basis for the sustainable development of our natural resources. In addition, the recurrence of natural hazards has reinforced the need to learn more about the mechanics and to develop predictive modeling with advanced technical tools. This paper is emphasizing on Granodiorites of Kallur area of Manvi Taluk, Raichur District to substantiate the classical approaches of exploration and data gathering through quantitative methods of data processing and interpretation. The trilinear diagram indicates that the granites are rich in Potash and Soda. This clearly indicates that Granites are fairly rich in K2O than Na2O.

  1. The New Mars Synthesis: A New Concept Of Mars Geo-Chemical History

    Brandenburg, J. E.

    2005-02-01

    A new concept of Mars climatic and geo-chemical evolution is proposed, called the NMS (New Mars Synthesis) drawing on the full spectrum of available Mars data. The proposed synthesis is that Mars and Earth, having begun with similar surface conditions, did not strongly diverge from their similar paths 4.0 Billion years ago, in the Early Noachian, instead, under the NMS, they diverged much more recently in geologic time, in the Early Amazonian. Under the NMS, biology strongly affected the geo-chemical evolution of Mars, and allowed a stable and persistent greenhouse by producing a large oxygen component in the atmosphere. The NMS assumes Mars held biology form early on, has been geologically active throughout its history, that it had a northern paleo-ocean, that it has high, approximately, 4xLunar, cratering rates and that its climate changed recently in geologic time from being basically terrestrial to its present conditions. The proposed mechanism for the stability of the Mars greenhouse was a large oxygen component in the atmosphere that created acidic and highly oxidized conditions that prevented formation of Carbonates, and the thermal and gas buffering of the paleo-ocean. The greenhouse was thus biologically and hydrologically stabilized. The greenhouse was terminated by a large atmospheric cooling event in the Early Amazonian that killed the biosphere and froze the ocean stabilizing the greenhouse. This cooling event was probably caused by the formation of the Lyot impact basin. Given the long duration of this terrestrial biosphere in this NMS, the possible appearance of fossils in some rover images is not to be unexpected and the colonization of Mars by humanity may be aided extensive fossil biomass to use as raw material.

  2. Kinetic and thermodynamic modelling of geochemical effects of a nuclear waste storage in granitic environment

    Made, B.; Fritz, B.

    1993-01-01

    In the world, various experimental sites are selected to study the behavior of different types of source rocks under nuclear waste storage influence. The surrounding rock tested to receive the waste storage must be a stable geological formation. In France, four geological formations are preselected for the feasibility study of repository for spent nuclear fuel at long term: shale, salt, clay and granite. At present time, numerous studies are carried out in Europe (Germany, Belgium, Sweden, Switzerland, United-Kingdom...), in North America (U.S.A. and Canada) and in Japan. Water-rock interactions control the most of rock transformations near the surface of the earth. The rock forming minerals react with the aqueous solutions, the primary minerals dissolution releases ionic species in solution and secondary minerals precipitate if equilibrium or oversaturation is reached. The weathering processes (hydrothermal or not) are always very complicated thus, geochemical codes has been developed to simulate the water-rock interactions. The first generation of codes is based on purely thermodynamic laws without reference to the time dependence of chemical reactions and then the dissolution path calculation refer to the irreversible dissolution of reactants and reversible precipitation of products ([1] to [4]). The system evolution is followed according to the reaction progress ξ which has been introduced in chemical system by Gibbs. Since few years, the experimental studies on the kinetics of minerals dissolution have allowed to take into account of dissolution rates data for the major minerals (silicates, carbonates...). More recently, a new geochemical codes generation appears based on thermodynamic potential and kinetic laws ([5] to [8]). The system evolution is followed according to the reaction time. (authors). 8 figs., 4 tabs., 24 refs

  3. Cyanobacterial evolution during the Precambrian

    Schirrmeister, Bettina E.; Sanchez-Baracaldo, Patricia; Wacey, David

    2016-07-01

    Life on Earth has existed for at least 3.5 billion years. Yet, relatively little is known of its evolution during the first two billion years, due to the scarceness and generally poor preservation of fossilized biological material. Cyanobacteria, formerly known as blue green algae were among the first crown Eubacteria to evolve and for more than 2.5 billion years they have strongly influenced Earth's biosphere. Being the only organism where oxygenic photosynthesis has originated, they have oxygenated Earth's atmosphere and hydrosphere, triggered the evolution of plants -being ancestral to chloroplasts- and enabled the evolution of complex life based on aerobic respiration. Having such a strong impact on early life, one might expect that the evolutionary success of this group may also have triggered further biosphere changes during early Earth history. However, very little is known about the early evolution of this phylum and ongoing debates about cyanobacterial fossils, biomarkers and molecular clock analyses highlight the difficulties in this field of research. Although phylogenomic analyses have provided promising glimpses into the early evolution of cyanobacteria, estimated divergence ages are often very uncertain, because of vague and insufficient tree-calibrations. Results of molecular clock analyses are intrinsically tied to these prior calibration points, hence improving calibrations will enable more precise divergence time estimations. Here we provide a review of previously described Precambrian microfossils, biomarkers and geochemical markers that inform upon the early evolution of cyanobacteria. Future research in micropalaeontology will require novel analyses and imaging techniques to improve taxonomic affiliation of many Precambrian microfossils. Consequently, a better understanding of early cyanobacterial evolution will not only allow for a more specific calibration of cyanobacterial and eubacterial phylogenies, but also provide new dates for the tree

  4. Geophysical and geochemical techniques for exploration of hydrocarbons and minerals

    Sittig, M.

    1980-01-01

    The detailed descriptive information in this book is based on 389 US patents that deal with geophysical and geochemical techniques useful for the exploration of hydrocarbons and minerals. Where it was necessary to round out the complete technological picture, a few paragraphs from cited government reports have been included. These techniques are used in prospecting for oil, coal, oil shale, tar sand and minerals. The patents are grouped under the following chapters: geochemical prospecting; geobiological prospecting; geophysical exploration; magnetic geophysical prospecting; gravitational geophysical prospecting; electrical geophysical prospecting; nuclear geophysical prospecting; seismic geophysical prospecting; and exploratory well drilling. This book serves a double purpose in that it supplies detailed technical information and can be used as a guide to the US patent literature in this field. By indicating all the information that is significant, and eliminating legal jargon and juristic phraseology, this book presents an advanced, industrially oriented review of modern methods of geophysical and geochemical exploration techniques

  5. Geochemical methods for identification of formations being prospective for uranium

    Zhukova, A.M.; Komarova, N.I.; Spiridonov, A.A.; Shor, G.M.

    1985-01-01

    Geochemical methods of uranium content evaluation in metamorphic, ultrametamorphic and sedimentary formations are considered. At that, the following four factors are of the highest importance: 1) average uranium content-geochemical background; 2) character of uranium distribution; 3) forms of uranium presence; 4) the value of thorium-uranium ratio. A complex of radiogeochemical criteria, favourable for uranium presence is formulated: high average background content of total and '' mobile''uranium and high value of variation coefficient (80-100% and above); low (approximately one or lower) thorium-uranium ratio; sharp increase in uranium concentration in accessory minerals. Radiogeochemical peculiarities of metamorphic and ultrametamorphic formations prospective for uranium are enumerated. The peculiarities condition specificity of geochemical prospecting methods. Prospecting methods first of all must be directed at the evaluation of radioelement distribution parameters and specification of the forms of their presence

  6. Initial geochemical characteristics of fluid fine tailings in an oil sands end pit lake

    Dompierre, Kathryn A. [Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A9 (Canada); Lindsay, Matthew B.J., E-mail: matt.lindsay@usask.ca [Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Cruz-Hernández, Pablo [Department of Geology, University of Huelva, Campus ‘El Carmen’, E-21071 Huelva (Spain); Halferdahl, Geoffrey M. [Environmental Research and Development, Syncrude Canada Limited, Edmonton, Alberta T6N 1H4 (Canada)

    2016-06-15

    Geochemical characteristics of fluid fine tailings (FFT) were examined in Base Mine Lake (BML), which is the first full-scale demonstration oil sands end pit lake (EPL) in northern Alberta, Canada. Approximately 186 Mm{sup 3} of FFT was deposited between 1994 and 2012, before BML was established on December 31, 2012. Bulk FFT samples (n = 588) were collected in July and August 2013 at various depths at 15 sampling sites. Temperature, solid content, electrical conductivity (EC), pH, Eh and alkalinity were measured for all samples. Detailed geochemical analyses were performed on a subset of samples (n = 284). Pore-water pH decreased with depth by approximately 0.5 within the upper 10 m of the FFT. Major pore-water constituents included Na (880 ± 96 mg L{sup −1}) and Cl (560 ± 95 mg L{sup −1}); Ca (19 ± 4.1 mg L{sup −1}), Mg (11 ± 2.0 mg L{sup −1}), K (16 ± 2.3 mg L{sup −1}) and NH{sub 3} (9.9 ± 4.7 mg L{sup −1}) were consistently observed. Iron and Mn concentrations were low within FFT pore water, whereas SO{sub 4} concentrations decreased sharply across the FFT–water interface. Geochemical modeling indicated that FeS{sub (s)} precipitation was favoured under SO{sub 4}-reducing conditions. Pore water was also under-saturated with respect to gypsum [CaSO{sub 4}·2H{sub 2}O], and near saturation with respect to calcite [CaCO{sub 3}], dolomite [CaMg(CO{sub 3}){sub 2}] and siderite [FeCO{sub 3}]. X-ray diffraction (XRD) suggested that carbonate-mineral dissolution largely depleted calcite and dolomite. X-ray absorption near edge structure (XANES) spectroscopy revealed the presence of FeS{sub (s)}, pyrite [FeS{sub 2}], and siderite. Carbonate-mineral dissolution and secondary mineral precipitation have likely contributed to FFT dewatering and settlement. However, the long-term importance of these processes within EPLs remains unknown. These results provide a reference for assessing the long-term geochemical evolution of oil sands EPLs, and offer

  7. Geochemical Modeling of ILAW Lysimeter Water Extracts

    Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-22

    Geochemical modeling results of water extracts from simulated immobilized low-activity waste (ILAW) glasses, placed in lysimeters for eight years suggest that the secondary phase reaction network developed using product consistency test (PCT) results at 90°C may need to be modified for field conditions. For sediment samples that had been collected from near the glass samples, the impact of glass corrosion could be readily observed based upon the pH of their water extracts. For unimpacted sediments the pH ranged from 7.88 to 8.11 with an average of 8.04. Sediments that had observable impacts from glass corrosion exhibited elevated pH values (as high as 9.97). For lysimeter sediment samples that appear to have been impacted by glass corrosion to the greatest extent, saturation indices determined for analcime, calcite, and chalcedony in the 1:1 water extracts were near equilibrium and were consistent with the secondary phase reaction network developed using PCT results at 90°C. Fe(OH)3(s) also appears to be essentially at equilibrium in extracts impacted by glass corrosion, but with a solubility product (log Ksp) that is approximately 2.13 units lower than that used in the secondary phase reaction network developed using PCT results at 90°C. The solubilities of TiO2(am) and ZrO2(am) also appear to be much lower than that assumed in the secondary phase reaction network developed using PCT results at 90°C. The extent that the solubility of TiO2(am) and ZrO2(am) were reduced relative to that assumed in the secondary phase reaction network developed using PCT results at 90°C could not be quantified because the concentrations of Ti and Zr in the extracts were below the estimated quantification limit. Gibbsite was consistently highly oversaturated in the extract while dawsonite was at or near equilibrium. This suggests that dawsonite might be a more suitable phase for the secondary phase reaction network

  8. Effect of source integration on the geochemical fluxes from springs

    Frisbee, Marty D.; Phillips, Fred M.; White, Art F.; Campbell, Andrew R.; Liu, Fengjing

    2013-01-01

    Geochemical fluxes from watersheds are typically defined using mass-balance methods that essentially lump all weathering processes operative in a watershed into a single flux of solute mass measured in streamflow at the watershed outlet. However, it is important that we understand how weathering processes in different hydrological zones of a watershed (i.e., surface, unsaturated, and saturated zones) contribute to the total geochemical flux from the watershed. This capability will improve understanding of how geochemical fluxes from these different zones may change in response to climate change. Here, the geochemical flux from weathering processes occurring solely in the saturated zone is investigated. This task, however, remains exceedingly difficult due to the sparsity of subsurface sampling points, especially in large, remote, and/or undeveloped watersheds. In such cases, springflow is often assumed to be a proxy for groundwater (defined as water residing in fully saturated geologic formations). However, springflow generation may integrate different sources of water including, but not limited to, groundwater. The authors’ hypothesis is that long-term estimates of geochemical fluxes from groundwater using springflow proxies will be too large due to the integrative nature of springflow generation. Two conceptual models of springflow generation are tested using endmember mixing analyses (EMMA) on observations of spring chemistries and stable isotopic compositions in a large alpine watershed in the San Juan Mountains of southwestern Colorado. In the “total springflow” conceptual model, springflow is assumed to be 100% groundwater. In the “fractional springflow” conceptual model, springflow is assumed to be an integration of different sources of water (e.g., groundwater, unsaturated flow, preferential flow in the soil, etc.) and groundwater is only a fractional component. The results indicate that groundwater contributions in springflow range from 2% to 100

  9. Geochemical characteristics of peat from two raised bogs of Germany

    Mezhibor, A. M.

    2016-11-01

    Peat has a wide range of applications in different spheres of human activity, and this is a reason for a comprehensive study. This research represents the results of an ICP-MS study of moss and peat samples from two raised bogs of Germany. Because of the wide use of sphagnum moss and peat, determining their geochemical characteristics is an important issue. According to the results obtained, we can resume that the moss samples from Germany are rich in Cu, As, Y, Zr, Nb, and REE. The geochemical composition of the bogs reflects the regional environmental features and anthropogenic influence.

  10. Propuesta de un perfil profesional para el diseño del doctorado curricular colaborativo en estomatología

    Dadonim Vila Morales

    2013-03-01

    Full Text Available El perfil profesional constituye un modelo, una idealización de las características, conocimientos, habilidades que debe poseer el egresado de cualquier nivel de estudios tanto terciario como del cuarto nivel. La Facultad de Estomatología de la Universidad de Ciencias Médicas de La Habana ha estado trabajando en pro de desarrollar un doctorado curricular en ciencias estomatológicas. Esta investigación pedagógica tuvo como propósito analizar teóricamente la importancia del perfil profesional y proponer un diseño de perfil profesional para un doctorado curricular colaborativo en ciencias estomatológicas. Se realizó una revisión bibliográfica de los fundamentos teóricos-metodológicos del perfil profesional, se analizó su implementación en el diseño curricular. Se señaló la importancia de un perfil de egresado correctamente instrumentado como sustento teórico-pedagógico, socio-crítico.

  11. Estudantes de enfermagem têm perfil empreendedor? ¿Estudiantes de enfermería tienen perfil emprendedor? Do nursing students have entrepreuner profile?

    Paulo Fernando Roncon

    2009-10-01

    Full Text Available Estudo descritivo-exploratório que teve como objetivo conhecer o perfil dos estudantes concluintes de um curso de graduação em enfermagem quanto ao empreendedorismo. O Teste de Tendência Empreendedora Geral, contendo 54 questões, foi aplicado a 41 estudantes. Os resultados demonstraram que14% apresentam cinco tendências empreendedoras e 12% quatro tendências empreendedoras; 80% apresentam fraca ou nenhuma tendência empreendedora. A grande maioria pretende encaminhar sua a profissão em atividades assistenciais, enquanto nenhum dos estudantes pretende atuar em atividades administrativas. Conclui-se que, os estudantes possuem baixo grau de presença de características empreendedoras.Estudio descriptivo-exploratorio que tvo como objetivo conocer el perfil de los estudiantes concluintes de un curso de grado de enfermería cuanto al espíritu emprendedor. El Test General de Tendencia Emprendedora contiendo 54 cuestiones fue aplicado a 41 estudiantes. Resultados demostraran que 14% tienen cinco tendencias de emprendedor, 12% tienen cuatro tendencias de emprendedor, 80% no tienen tendencias de emprendedor. La mayoría desea trabajar con actividades asistenciales, mientras ninguno de ellos desean trabajar con actividades administrativas. Se concluye que los estudiantes tienen bajo grado de presencia de características emprendedoras.Descriptive-exploratory study that aimed at knowing the profile of nursing students regarding entrepreneurship. The General Entrepreneurship Trend Test with 54 questions was applied to 41 students. Results demonstrated that 14% present five entrepreneur tendencies, 12% present four entrepreneur tendencies, and 80% do not present entrepreneur tendencies. The majority of student intent to work as clinical nurses, while none of them intent to work in management activities. It was concluded that students have low grade of the entrepreneurship characteristics.

  12. COMPARACIÓN DEL PERFIL LIPÍDICO POR SEXO Y EDAD EN OVINOS

    J. H. Osorio

    2015-01-01

    Full Text Available Se comparó el perfil lipídico y la correlación entre los componentes lipídicos del suero en cuatro grupos de ovinos. A tal fin, se tomaron muestras de sangre de 98 ovinos en ayuno, diferenciados por género y edad (23 machos y 25 hembras mayores de un año de edad; 22 machos y 28 hembras menores a un año. Se determinaron las concentraciones séricas de: triglicéridos, colesterol total (CT y colesterol de lipoproteínas de alta densidad (C-HDL mediante el método enzimático colorimétrico. El colesterol de lipoproteína de muy baja densidad (C-VLDL y de baja densidad (C-LDL se determinó usando la fórmula de Friedewald. Las medias para CT, triglicéridos, C-HDL, C-VLDL y C-LDL (mg/dL fueron de 86.19, 21.57, 39.32, 4.31 y 42.55, respectivamente. En el grupo de adultos existe diferencia significativa (P ≤0.05 en los niveles de: CT (P 0.90 para ambos, machos (P >0.405 para ambos, jóvenes (P >0.487 para ambos y adultos (P >0.179 para ambos no mostraron diferencias significativas (P -valor ≥0.05 con un nivel de confianza del 95.0%. En conclusión, debido a las diferencias estadísticamente significativas en las comparaciones del perfil lipídico entre grupos de ovinos, pueden ser considerados cuatro perfiles lipídicos: machos adultos, hembras adultas, machos jóvenes y hembras jóvenes.

  13. Perfil dos Psicólogos Inscritos na Subsede Leste do CRP-04

    Keicy Rocha Santos

    Full Text Available O objetivo deste estudo foi fazer um levantamento do perfil profissional dos psicólogos inscritos na Subsede Leste do Conselho Regional de Psicologia nº 04 (CRP-04, atuantes no município de Governador Valadares até 2010. Trata-se de um estudo quantitativo e comparativo entre os dados da presente pesquisa e aqueles que compõem o banco nacional, que se encontra na obra O trabalho do Psicólogo no Brasil, organizado por Bastos, Gondim e colaboradores (2010. Utilizou-se um questionário via e-mail marketing, respondido por 85 participantes que abarcaram as categorias do perfil profissional. Os dados levantados foram tabulados no programa Microsoft Excel e analisados no programa Sphinx Survey Edição Léxica. Verificou-se que a maioria dos participantes é branca, casada, do gênero feminino, com idade entre 26 e 30 anos e graduada em instituição privada, tendo especialização, principalmente em clínica organizacional e atuação na clínica. Ganha entre 3 e 4 salários mínimos como psicólogo, na condição de assalariado. Geralmente, a maioria não possui outra atividade profissional e a renda familiar é de, aproximadamente, 10 salários mínimos. Os dados corroboram com a média nacional do perfil profissional dessa classe de trabalhadores, trazendo algumas peculiaridades do município de Governador Valadares.

  14. PERFIL DE LIDERANÃA E TOMADA DE DECISÃO

    Eduardo Botti Abbade

    2009-04-01

    Full Text Available O objetivo geral deste estudo foi o de identificar o estilo de liderança, perfil comportamental e decisório dos dirigentes das empresas do Distrito Industrial de Santa Maria / RS. Este estudo se configura como sendo uma pesquisa de levantamento (survey descritiva onde foram selecionadas 14 empresas, das 20 existentes, localizadas no Distrito Industrial do município de Santa Maria-RS. Com o objetivo de definir o perfil gerencial dos pesquisados, esta investigação utilizou-se de perspectivas psicológicas, de observação, de decisão e de aprendizagem. Os entrevistados correspondem a indivíduos que possuem um perfil com tendências a enfatizar detalhes e fatos, possuem foco no curto prazo e são muito realistas. Costumam elaborar regras e regulamentos para o julgamento do desempenho. Sugeremse para estudos futuros que seja realizado estudos onde se proponha um cruzamento entre os perfis observados com demais aspectos organizacionais como clima, cultura e comunicação organizacional. Propõe-se também que seja realizada a pesquisa com uma amostra mais abrangente. Aconselha-se que seja realizada a entrevista com gestores ou responsáveis de todas as áreas das empresas pesquisadas, para que se possam analisar perfis de gestores com diferentes competências e atribuições na mesma organização.

  15. PERFIL ALIMENTAR E ESTADO NUTRICIONAL DE CRIANÇAS NO PRIMEIRO ANO DE VIDA

    Marisa da Silva Corrêa

    2016-11-01

    Full Text Available Resumo – O leite materno é a base alimentar do lactente, devendo ser oferecido de maneira exclusiva nos primeiros seis meses de vida e mantido até os dois anos de idade ou mais. O presente estudo teve como finalidade avaliar o perfil alimentar e estado nutricional de crianças no primeiro ano de vida. Para tal fim, foram captadas crianças de 0 a 12 meses atendidas na Clínica Escola de Nutrição da UFES/Alegre-ES. O perfil alimentar foi avaliado qualitativamente e o estado nutricional através das medidas de peso e comprimento, convertidos nos índices peso/idade, comprimento/idade e Índice de Massa Corporal/Idade. O estudo contemplou 34 lactentes com idade entre 10 dias e 1 ano, sendo 56% do sexo feminino. Verificou-se que 14,7% apresentavam risco de sobrepeso ou sobrepeso, 82,35% dos lactentes consumia leite materno exclusivamente ou com fórmula infantil, 66,6% das mães introduziram alimentos com 6 meses e 10% das crianças já havia consumido refrigerante, biscoito recheado e bolos artificiais no primeiro ano de vida. Faz-se necessária conscientização das mães quanto à introdução alimentar infantil. Palavras-chave: lactente, perfil alimentar, estado nutricional, aleitamento materno, introdução alimentar. Área do Conhecimento: Ciências da Saúde

  16. PERFIL SENSORIAL DE CULTIVARES DE FEIJÃO SOB DIFERENTES TEMPOS DE COZIMENTO

    Viviani Ruffo de OLIVEIRA

    2013-04-01

    Full Text Available O objetivo deste trabalho foi determinar o tempo necessário de cozimento de cultivares de feijão de grãos preto e carioca, em panela de pressão doméstica, para a identificação de cultivares de melhor perfil sensorial para o consumo. Para tanto, utilizaram-se grãos de quatro cultivares de feijão: BRS Expedito, BRS Campeiro, Pérola e Carioca e o cozimento foi realizado em panela de pressão doméstica por 15, 20, 25 e 30 minutos. A avaliação do perfil sensorial foi efetuada em três etapas: seleção, treinamento para a Análise Descritiva Quantitativa (ADQ e ADQ propriamente dita, com sete avaliadores treinados. Os avaliadores reconheceram diferenças para as cultivares de feijão quanto à uniformidade da cor do grão, cor do caldo, à viscosidade, à dureza e a granulosidade. A ruptura no tegumento dos grãos foi maior à medida que se aumentou o tempo de cozimento. A dureza e a granulosidade apresentaram maiores intensidades conforme aumentou o tempo de cozimento dos grãos de feijão. A utilização de 20 a 25 minutos de cozimento em panela de pressão doméstica possibilita a identificação de cultivares de feijão de grãos preto e carioca com melhor perfil sensorial para o consumo, mantendo a integridade dos grãos cozidos.

  17. Diálogo de las perspectivas de perfil conceptual y conglomerados de relevancia

    Rosa I. Pedreros-M

    2013-01-01

    Full Text Available El presente artículo forma parte del desarrollo de la investiga - ción doctoral titulada “Perfil conceptual del calor en comu - nidades culturalmente diferenciadas” y tiene como intención socializar las perspectivas de perfil conceptual y conglomera - dos de relevancia como referentes teóricos y metodológicos que permitan proponer nuevas opciones para pensar la ense - ñanza-aprendizaje de las ciencias o la educación en ciencias, que observen los modos de pensar y hablar de los estudiantes y las relaciones entre la cultura local y el conocimiento escolar. Se exponen el origen, los referentes, las consideraciones so - bre la enseñanza-aprendizaje de las ciencias y las razones para investigar desde estas perspectivas.Nuestro país está conformado por comunidades culturalmen - te diferenciadas, lo cual constituye un reto y desafío para la comunidad académica. Exige, entre otras cosas, propiciar una enseñanza-aprendizaje de las ciencias que tenga en cuenta la diversidad de sistemas de conocimiento, las visiones de mun - do y los modos de pensar y hablar de las comunidades con las que se realiza la acción pedagógica. En este sentido, los perfiles conceptuales y los conglomerados de relevancia se constituyen en referentes teóricos y metodológicos que per - miten reconocer el contexto cultural, las creencias, los valores y las significaciones del entorno físico y natural que tienen los estudiantes.

  18. Suscetibilidade a desinfetantes e perfil de resistência a antimicrobianos em isolados de Escherichia coli

    Carina C. Krewer

    2012-11-01

    Full Text Available A colibacilose, causada por Escherichia coli, é a enfermidade entérica de maior impacto na produção de suínos, podendo levar à morte do animal. Esta bactéria possui grande capacidade de desenvolver resistência a múltiplos antimicrobianos e a desinfetantes. Desta forma, estudos que abordem mecanismos de resistência e perfil de amostras de campo tornam-se necessários. E. coli é amplamente utilizada como modelo de estudos que exploram a resistência intrínseca e extrínseca a multidrogas. Neste trabalho, buscou-se verificar o perfil de sensibilidade de 62 isolados de E. coli de suínos frente a três desinfetantes e a 13 antimicrobianos. Ainda, em 31 destes isolados foi pesquisada a presença de mecanismo de efluxo. Dos três desinfetantes avaliados, o cloreto de alquil dimetil benzil amônio+poliexietilenonilfenileter foi o que se mostrou mais eficaz (100%, seguido do glutaraldeído+cloreto de alquil dimetil benzil amônio (95,2% e do cloreto de alquil dimetil benzil amônio (88,8%. Dentre os antimicrobianos testados, observou-se maior resistência para a tetraciclina (62,2% e maior sensibilidade para o florfenicol (88,6%. A alta sensibilidade dos isolados frente aos desinfetantes pode estar relacionada à ausência de mecanismo de efluxo. O índice de resistência múltipla médio aos antimicrobianos foi de 0,52, o que demonstra um perfil multirresistente dos isolados, conduzindo para a necessidade do uso racional destas drogas em suinocultura.

  19. Perfiles de regulación emocional y estrés académico en estudiantes de fisioterapia

    Ramón González Cabanach

    2017-12-01

    Se obtuvieron diferencias estadísticamente significativas entre los diferentes perfiles tanto para la percepción de estresores como para las respuestas psicofisiológicas de estrés. Los estudiantes con un perfil de alta regulación emocional percibieron en menor medida el entorno académico como amenazante y experimentaron con menor frecuencia manifestaciones psicofisiológicas de estrés. Los estudiantes con perfiles de baja regulación y baja regulación con alta atención emocional mostraron resultados similares, a excepción de las alteraciones del sueño. En conclusión, los estudiantes de fisioterapia con elevadas puntuaciones en control y aceptación de sus estados emocionales perciben las circunstancias académicas de forma más adaptativa y experimentan menores respuestas de estrés.

  20. Perfil Logístico de Colombia – Sector textil y confecciones

    Gomez Diaz, Stephania; Porras Rodriguez, Julian Felipe

    2014-01-01

    El sector textil en los últimos 10 años se ha caracterizado por pertenecer a uno de los rubros superiores frente a la economía nacional por lo cual actualmente se está enfrentando a economías emergentes como la china y a mercados como el americano con costos muchos más competentes. Este proyecto, describirá de manera específica el perfil logístico del sector textil en Colombia, el cual debido al auge que ha tenido en los últimos años es importante destacar la relevancia de la logística pa...

  1. Perfil del incendiario forestal español: aplicación del perfilamiento criminal inductivo

    Sotoca, Andrés; González, José Luis; Fernández, Santiago; Kessel, Dominique; Montesinos, Olga; Ruíz, Miguel Ángel

    2013-01-01

    La técnica del perfil criminológico, entendida como el proceso de inferir características identificativas de un delincuente analizando las evidencias obtenidas en la escena del delito que ha cometido, ha recibido críticas por su dudoso carácter científico y su falta de apoyo teórico y empírico. No obstante, en la actualidad ha surgido un modelo que trabaja en la profesionalización del análisis del comportamiento delictivo en los cuerpos policiales mediante la aplicación de los conocimient...

  2. Perfil clínico del adulto mayor atendido ambulatoriamente en un hospital general.

    Casas, Paola; Varela, Luis; Tello, Tania; Ortiz, Pedro; Chávez, Helver

    2012-01-01

    Objetivo: Describir el perfil clínico del adulto mayor atendido ambulatoriamente en un hospital general. Material y métodos: Estudio descriptivo, transversal, realizado a través de encuestas aplicadas a pacientes en la consulta ambulatoria de geriatría del Hospital Nacional Cayetano Heredia (HNCH), entre agosto de 2011 y enero 2012. Resultados: Se evaluaron 290 pacientes, el 69,3% fueron mujeres; el 65,5% tenía entre 60 y 79 años. La hipertensión arterial fue el diagnóstico más frecuente (55,...

  3. Perfil de la mujer en la alta dirección en Colombia

    Morales Castro, Clara Viviana

    2011-01-01

    El objetivo del presente estudio descriptivo fenomenológico es identificar los perfiles sociodemográficos que predominan en un grupo de mujeres directivas en Colombia, y observar las características de su liderazgo; para tal propósito se realizó un estudio cualitativo y un análisis de los determinantes de la participación laboral de las mujeres en Colombia. Se tomó como base de información encuestas realizadas a un grupo de mujeres de la alta dirección en Colombia, implementando un análi...

  4. Un estudio exploratorio del perfil de las mujeres empresarias en el Perú

    Avolio Alecchi, Beatrice

    2008-01-01

    La investigación identifica el perfil de las mujeres empresarias en el Perú mediante la exploración cualitativa de sus características demográficas; sus antecedentes educativos, laborales y familiares; sus habilidades administrativas; la naturaleza de sus empresas; los factores que las han estimulado a convertirse en empresarias; y los obstáculos para el desarrollo de sus empresas. El estudio utiliza el paradigma cualitativo basado en estudios de caso de veinticuatro mujeres empresarias en el...

  5. Perfil de la Arquitectura de la Gestion del Conocimiento en Empresas Manufactureras.

    Gómez Hernández, Marian; Rodríguez Monroy, Carlos; Guaita, Wilfredo

    2009-01-01

    La investigación tuvo como propósito determinar el perfil de la arquitectura de la GC en empresas manufactureras, tomando como referencia las variables asociadas al conocimiento organizacional en las etapas: creación; identificación y adquisición; clasificación, almacenamiento y protección; aplicación y actualización; transferencia y medición. Soportado por cuatro pilares correspondiente a la plataforma interna: cultura y liderazgo, memorias corporativas, TIC, comunidades colaborativas ...

  6. O perfil dos cuidadores de pacientes pediátricos com fibrose cística

    Alves, Stella Pegoraro; Bueno, Denise

    2018-01-01

    Resumo O objetivo desse estudo foi identificar o perfil do cuidador principal de pacientes pediátricos com Fibrose Cística (FC). Estudo transversal, descritivo e prospectivo, no qual foi realizado, durante consulta farmacêutica, entrevista com cuidadores de pacientes fibrocísticos acompanhados em um centro de referência de um Hospital Universitário do Sul do Brasil. Foram obtidas informações gerais sobre os cuidadores, sobre o entendimento da doença, os medicamentos em uso do paciente e a din...

  7. PERFIL DA DISFAGIA APÓS UM ACIDENTE VASCULAR CEREBRAL: UMA REVISÃO INTEGRATIVA

    CARINA TEIXEIRA PAIXÃO; LOLITA DOPICO DA SILVA; FLAVIA GIRON CAMERINI

    2010-01-01

    Este artículo trata de disfagia decurrente de una enfermedad vascular cerebral (EVC). El objetivo fue determinar el perfil de las publicaciones acerca de la disfagia en pacientes víctimas de EVC. Investigación de revisión integradora que usó los mismos descriptores en las bases Medline, Scielo e Lilacs, seleccionando 17 artículos entre 1998 a 2008. Los datos fueron analizados a partir de las categorías correspondientes a los enfoques de las publicaciones encontradas. Los resultados muestran d...

  8. Perfil biopsicossocial de portadores de anoftalmia no sul de Minas Gerais - Brasil

    Cabral,Luiz Gustavo Megda; Martelli Júnior,Hercílio; Leite,Denise Moura; Sabatini Júnior,David; Freitas,Amanda Beatriz Dahdah Aniceto de; Miranda,Roseli Teixeira; Swerts,Mário Sérgio Oliveira; Barros,Letízia Monteiro de

    2008-01-01

    OBJETIVO: Avaliar o perfil biopsicossocial de portadores de anoftalmia, com ênfase no impacto psicológico e funcional da perda ocular e na reintegração social dessa população. MÉTODOS: Realizou-se estudo transversal com 84 pacientes (50 do gênero masculino e 34 do feminino), reabilitados ou em processo de reabilitação com próteses oculares, avaliados por meio de questionário que contemplava dimensões como: etiologia da perda ocular, grau de adaptação à prótese e impacto nas atividades profiss...

  9. “El perfil sociocultural de los graduados universitarios: el caso de la UNGS”

    Fernández, Marcos Silvestre

    2015-01-01

    La presente ponencia se enmarca en un proyecto de beca de investigación otorgada por Consejo Interuniversitario Nacional (CIN) en Octubre del 2014, en la carrera de grado Lic. En Educación de La Universidad Nacional de General Sarmiento (UNGS). El trabajo tiene como objetivo presentar el análisis, las metodologías empleadas y las primeras conclusiones sobre el estudio "El perfil Sociocultural de los graduados universitario: el caso de la UNGS". El proyecto se propuso elaborar un es...

  10. Investigación perfil en competencias y habilidades del empresario bogotano: trabajo de campo

    Granada Forero, José Andrés; Lara Salinas, Karen Eliana

    2013-01-01

    Este documento corresponde al trabajo de campo para la investigación doctoral de Luis Alberto Estrada titulado “Perfil en competencias del empresario bogotano”. El objetivo que el equipo de investigación definió fue concretar las habilidades y competencias que acompañan a los emprendedores y fundadores de empresa en la primera década del siglo XXI. Para ello, se tomó una base de datos de la Cámara de Comercio de Bogotá, la cual contiene la información comercial de las empresas de la ciudad...

  11. Perfil do estoque domiciliar de medicamentos em residências com crianças

    Gabriela Colonetti Beckhauser; Cleidson Valgas; Dayani Galato

    2012-01-01

    Com o objetivo de identificar o perfil do estoque domiciliar de medicamentos em residências com crianças, foi realizado um estudo baseado na técnica de entrevista aplicado aos responsáveis pelos medicamentos. Para caracterização dos estoques, os medicamentos foram classificados de acordo com o primeiro nível da Anatomical Therapeutic Chemical e adotaram-se indicadores de armazenamento. Foram aplicados 83 questionários em domicílios contendo de uma a três crianças (6...

  12. Perfiles motivacionales de estudiantes universitarios. Procesos de estudio y satisfacción con la vida

    Juan Antonio Moreno\\u2010Murcia; Yolanda Silveira Torregrosa

    2015-01-01

    El objetivo de este trabajo ha sido determinar los diferentes perfiles motivacionales en estudiantes universitarios y ver su relación con los procesos de estudio (superficial y profundo) así como con la satisfacción que tiene el estudiante con su vida en general. La muestra estuvo compuesta por 431 estudiantes universitarios (202 hombres y 220 mujeres) con una edad media de 22 años (DT = 2.41). Los instrumentos utilizados fueron la Escala de Motivación Académica, Cuestionario Revisado de Proc...

  13. Un acercamiento a la comprensión del perfil de la Inteligencia Emocional

    Gloria María Isaza-Zapata; Juan Santiago Calle-Piedrahíta

    2016-01-01

    Este artículo es resultado de un estudio de inteligencia emocional. En la investigación nos propusimos como objetivo general, analizar el perfil de inteligencia emocional y social de una muestra de 110 docentes de educación básica primaria, vinculados a diez instituciones educativas de la ciudad de Medellín, Colombia. El alcance es descriptivo, no experimental, y correlacional; y está apoyado con método probabilístico, simple al azar y estratificado. Los resultados obtenidos desde el perf...

  14. Perfil de los adultos mayores usuarios de atención primaria

    Fabianne de Jesus Dias de Sousa

    2017-05-01

    Full Text Available Introducción: Las proyecciones indican que Brasil será el sexto país del mundo con el mayor número de adultos mayores. El objetivo de este estudio fue caracterizar las condiciones de perfil y de vida socio-demográficos y de salud de los usuarios adultos mayores de la atención primaria de un municipio en la región amazónica del Brasil. Es oportuno porque el envejecimiento de la población está creciendo rápidamente, especialmente en países en desarrollo como el Brasil. Materiales y Métodos: Estudio transversal con una muestra de 441 individuos con edad inferior a 60 años de la población de usuarios de la atención básica en el municipio de Benevides, en la Amazonia brasileña. Os datos fueron obtenidos a través del Elder notebook, un protocolo clínico del Ministerio de la Salud. La prueba del chi-cuadrado con un nivel de significancia de 5% para explorar fue utilizada las asociaciones entre las variables de las condiciones de salud y de vida, y las variables socio-demográficas. Resultados: Se presentaron un perfil predominantemente joven adultos mayores (46.0%, que no practican actividad física (p<0.02, con condiciones crónicas y uso de drogas para inducir el sueño (p<0.05. Discusión y Conclusiones: El perfil de vida desfavorable y de salud encontrados en adultos mayores exige la adopción de medidas reforzadas, sobre la salud y los presupuestos de atención integral como un desafío para efectuar la colocación de sus necesidades, principalmente por la enfermería, en la Atención Básica de Salud en áreas más necesitadas de la región amazónica. Cómo citar este artículo: Sousa FJD, Andrade FS. Perfil de los adultos mayores usuarios de atención primaria. Rev Cuid. 2017; 8(2: 1573-81. http://dx.doi.org/10.15649/cuidarte.v8i2.376

  15. EL PERFIL DEL CONTADOR PÚBLICO Y DE LOS ESTUDIOS DE POSTGRADO

    Polar Falcón, Ernesto Augusto

    2014-01-01

    La Facultad de Ciencias Contables de la UNMSM, desde su fundación hasta la fecha, siempre ha tenido muy claro el perfil del Contador Público que forma profesional mente. Su filosofía educativa está cimentada en cumplir con dos objetivos: el primero, mantener el alto nivel de formación del Contador Público que se ofrece año tras año a la sociedad peruana; y el segundo, destacar su liderazgo de educación universitaria en el consenso de dirección y ejemplo a nivel de las Facultades de la Univers...

  16. Perfil lipídico em pacientes adultos com artrite idiopática juvenil

    Thelma Larocca Skare

    2013-08-01

    Full Text Available O processo inflamatório articular de uma criança com artrite idiopática juvenil (AIJ pode persistir na vida adulta. A inflamação tem sido ligada a distorções do perfil lipídico e à aterogênese acelerada. Neste trabalho, estudou-se o perfil lipídico de indivíduos adultos com AIJ, comparando-o ao de pessoas saudáveis. Foram recrutados 54 adultos com AIJ (57,3% poliarticular, 37% oligoarticular, 1,9% do subtipo entesítica e 3,7% do subtipo sistêmica e 54 indivíduos saudáveis para comparação de perfil lipídico. Nos adultos AIJ, coletaram-se dados sobre sexo, idade e idade de início da doença, presença de fator reumatoide (FR e fator antinuclear (FAN, HAQ (Health Assessment Questionnaire e tempo de doença. Observou-se que hipercolesterolemia, aumento de LDL e diminuição de HDL foram mais comuns em pacientes com AIJ do que nos controles (com P = 0,016; P < 0,0001 e P = 0,0008, respectivamente. Alterações no colesterol total (CT e no LDL foram mais comuns em indivíduos com início de doença mais tardio (P = 0,0017 para CT e P = 0,023 para LDL. Em todo o grupo de pacientes com AIJ nenhuma outra variável pode ser ligada à dislipidemia tal como presença de FR, FAN, duração de doença e HAQ (P = ns. Concluiu-se que pacientes adultos com AIJ apresentam um perfil lipídico com aumento de CT e de LDL, e diminuição de HDL em relação aos controles. Nenhuma característica clínica pode ser ligada a essa alteração, exceto idade de início da doença.

  17. Perfil dos Servidores da UFES com Empréstimo Consignado

    RIBEIRO, A. B.

    2014-01-01

    O crédito consignado é uma modalidade de empréstimo cujo valor da parcela incide sobre o salário do devedor. Com alto índice de adesão nos últimos anos,é o meio de acesso ao crédito mais comum entre os servidores públicos, pelas baixas taxas de juros, entre outros atrativos, o que contribui para expor a risco seus vencimentos com dívidas. Buscando atender ao objetivo principal de identificar se características do perfil demográfico dos servidores ativos da Universidade Federal do Espírito San...

  18. Perfil cognitivo y psicopatológico asociados a la conducta antisocial

    John Jairo Cifuentes González; Nora Helena Londoño Arredondo

    2011-01-01

    El objetivo del presente estudio fue establecer los componentes del perfil cognitivo y psicopatológico que caracterizan a los individuos judicialmente condenados, discriminando además el diagnóstico de trastorno de la personalidad antisocial (TPA). Participaron 607 personas que se dividieron en dos grupos: 398 casos (con TPA) y 209 controles (sin TPA). Instrumentos: YSQ-L (Young y Brown, 1999) validado por Castrillón et al. (2005), EEC-M (Londoño et al., 2006), el MCMI-II (Millon, 1999) y la ...

  19. Determinantes del perfil de ahorro en Colombia : una estimación para hogares e individuos

    Daza Báez, Nancy Aireth

    2011-01-01

    En este documento se presenta un análisis de los determinantes del perfil de ahorro para hogares e individuos con el objetivo de contrastar la Hipótesis de Ciclo de Vida, utilizando la metodología expuesta en Deaton y Paxson (2000a y 2000b) con datos de la Encuesta Nacional de Ingresos y Gastos (ENIG) para los periodos 1984-1985, 1994-1995 y 2006-2007. Se encontró que para el análisis por hogar no hay evidencia que determine el cumplimiento de la Hipótesis del Ciclo de Vida, mientras que para...

  20. Influencia del perfil docente en el proceso de enseñanza aprendizaje de la UFG

    Cóbar Menjívar, Margarita Esperanza

    2011-01-01

    Todas las sociedades, en las diversas épocas se han elaborado imágenes y valores sobre la persona del maestro y su labor pedagógica. Estas representaciones expresan la finalidad social asociada a la educación y son legitimadas a través de las doctrinas pedagógicas hegemónicas en cada momento histórico En la sociedad actual en El Salvador, específicamente en el sector educativo, se maneja el concepto de perfil docente como el de una persona que facilita el aprendizaje siendo un ente o agent...

  1. Perfil cromatográfico dos componentes polifenólicos de Maytenus ilicifolia mart. (Celastraceae

    Haroudo Satiro Xavier

    Full Text Available Buscando-se fornecer subsídios farmacognósticos para uma melhor caracterização da "espinheira santa" (Mavtenus ilicifolia, elaborou-se urn perfil cromatográfico a partir de folhas do vegetal disponíveis no comércio local. Heterosídeos flavonólicos a proantocianidinas foram constatados, podendo perfeitamente estas moléculas, servirem como marcadores para afeição da originalidade da droga ou de sua qualidade coma insumo farmacêutico.

  2. Perfil do geoturista do Parque Estadual da Serra do Rola-Moça (MG)

    Fonseca Filho, Ricardo Eustáquio; Universidade Federal de Ouro Preto, Ouro Preto, MG; Ribeiro, Gabriela Sousa; Circuito Turístico Montanhas e Fé, MG

    2016-01-01

    O Parque Estadual da Serra do Rola-Moça (PESRM) é uma unidade de conservação de Proteção Integral em Minas Gerais, com características geológicas e geomorfológicas que o caracterizam como um geossítio do Geoparque do Quadrilátero Ferrífero, com alto potencial para o geoturismo. A pesquisa teve por objetivo conhecer o perfil do visitante do PESRM, na tentativa de identificar se há entre os visitantes potenciais geoturistas. A metodologia incluiu revisão bibliográfica e digital, e trabalho de c...

  3. Transtorno afetivo bipolar: perfil farmacoterapêutico e adesão ao medicamento

    Miasso,Adriana Inocenti; Carmo,Bruna Paiva do; Tirapelli,Carlos Renato

    2012-01-01

    Este estudo teve como objetivos verificar a adesão de portadores de transtorno afetivo bipolar (TAB) à terapêutica medicamentosa e identificar possíveis causas de adesão e não adesão ao medicamento de acordo com o perfil farmacoterapêutico. Trata-se de estudo transversal, descritivo, realizado em Núcleo de Saúde Mental de um município do interior paulista. Participaram do estudo 101 pacientes com TAB. Para coleta dos dados, utilizou-se a entrevista estruturada e o teste de Morisky-Green e, pa...

  4. Perfil de adolescentes gestantes de um município do interior do Paraná

    Beatriz Rosana Gonçalves de Oliveira; Claudia Silveira Viera; Juliene Flávia Noris Almeida Fonseca

    2011-01-01

    Este estudio planteó como objetivo identificar el perfil de adolescentes embarazadas, en un municipio de Paraná, teniendo en cuenta la influencia de factores biológicos, psicológicos y sociales, para apoyar las acciones preventivas del embarazo precoz. Investigación cuantitativa con datos obtenidos mediante entrevista. y análisis estadístico descriptivo. Se analizaron: edad de la menarqula, ginecológica y al quedar embarazada, uso de anticonceptivos antes del embarazo, relación familiar, acep...

  5. El perfil del consumidor de hostel en Brasil y sus motivaciones

    Mané, Alexandra; Ferreira, Lissa

    2017-01-01

    El creciente número de hostels en Brasil ha atraído cada vez más brasileños que buscan este tipo de establecimiento para hospedarse. No obstante, vale destacar que deben realizarse más estudios que aborden la importancia de los hostels y sus consumidores en el mercado de turismo. Podrán contribuir al conocimiento teórico y práctico posibilitando un mejor entendimiento sobre este segmento. El objetivo de este artículo es identificar y describir el perfil del consumidor de hostel, sus motivacio...

  6. Perfil dos Supervisores de Psicologia em Serviços-Escola Brasileiros

    Fabiana Vieira Gauy

    Full Text Available Perfil dos supervisores de psicologia em Serviços-Escola Brasileiros (treino/atendimento Este trabalho teve como objetivo descrever o perfil demográfico dos supervisores dos cursos de graduação em Psicologia, obtidos pelo projeto de pesquisa intitulado "Serviços-Escola de Psicologia no Brasil", que tinha entre seus objetivos a caracterização dos serviços-escola de psicologia brasileiros. A pesquisa foi disponibilizada on-line em umsite da internet específico para a pesquisa, divulgado através de vários meios de comunicação, no qual, o participante em potencial da pesquisa (supervisor, estagiário ou gestor de uma das clinica escolas de Psicologia do Brasil, depois de acessar a pagina e o seu campo específico, informava dados pessoais (sexo e idade, dados institucionais (vínculo de trabalho, tipo de instituição e localização e dados profissionais (abordagem teórica e tempo de experiência/área. Do total de 846 participantes potenciais apenas 147 eram supervisores de cursos de Psicologia que haviam completado totalmente o questionário e foram, por isso, considerados para presente análise. Os dados coletados, no período de 2008 a 2010, apontaram que a maioria dos respondentes era do sexo feminino (77,6%, tinha idade entre 38 a 45 anos (45,5%, possuía vínculo formal de trabalho (90% com instituições de ensino privado (56%, localizadas nas Regiões Sul e Sudeste (78%. A Psicanálise figurou como abordagem mais referida (24% e aqueles que referiam ter mais de 10 anos de experiência em Psicodiagnóstico/Psicoterapia (64,4%. Apesar do tamanho da amostra não ser representativa do perfil dos supervisores brasileiros, os dados obtidos forneceram informações importantes sobre o perfil dos supervisores, peça chave na formação do aluno de graduação.

  7. Geochemical and hydrodynamic phosphorus retention mechanisms in lowland catchments

    van der Grift, B.

    2017-01-01

    The release of phosphorus (P) to surface water from heavily fertilised agricultural fields is of major importance for surface water quality. The research reported in this thesis examined the role of geochemical and hydrodynamic processes controlling P speciation and transport in lowland catchments

  8. Geothermal investigations with isotope and geochemical techniques in Latin America

    1992-03-01

    The IAEA Co-ordinated Research Programme (CRP) for Latin America on the Use of Isotope and Geochemical Techniques in Geothermal Exploration started in 1984. The first activity carried out was a Seminar on isotope and geochemical techniques in geothermal exploration, which took place in June 1984 in Morelia, Mexico. During the seminar, which was attended by representatives of the institutions which later took part in the programme, the objectives, main research lines, and geothermal fields to be studied during the CRP were discussed. The first research contracts were awarded towards the end of 1984. The field work started in 1985 and continued through 1990. During the implementation of the CRP a considerable number of geothermal fields were studied in the nine participating countries. The investigations carried out were geochemically quite comprehensive in most cases, but in some others they were still in a reconnaissance stage when the CRP ended: the latter studies are not reported in these proceedings, but the data obtained are in principle available from the relevant national institutions. While investigations with conventional geochemical techniques had already started in several fields before 1985, isotope methods were applied for the first time in all cases during this CRP. Due to the remoteness and high elevation of many of the fields studied and the adverse meteorological conditions during long periods of the year, the investigations could not proceed rapidly: this is the main reason for the unusually long duration of the CRP, which could be concluded only after more than five years after its inception

  9. Comparison of thermodynamic databases used in geochemical modelling

    Chandratillake, M.R.; Newton, G.W.A.; Robinson, V.J.

    1988-05-01

    Four thermodynamic databases used by European groups for geochemical modelling have been compared. Thermodynamic data for both aqueous species and solid species have been listed. When the values are directly comparable any differences between them have been highlighted at two levels of significance. (author)

  10. Overview of geochemical modeling needs for nuclear waste management

    Isherwood, D.J.; Wolery, T.J.

    1985-01-01

    Geochemical modeling needs for nuclear waste management are discussed with an emphasis on data base development and computer code. Other areas for future research include: precipitation kinetics, fixed fugacity, sorption, glasslt. slashwater interactions, redox disequilibrium and kinetics, radiolysis, solid solutions, and isotopic fractionation. 15 references

  11. Geochemical reactivity of rocks of the Czech Republic

    Chuman, T.; Gürtlerová, P.; Hruška, Jakub; Adamová, M.

    2014-01-01

    Roč. 10, č. 2 (2014), s. 341-349 ISSN 1744-5647 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : geochemical reactivity * Czech Republic * susceptibility to weathering Subject RIV: EH - Ecology, Behaviour Impact factor: 1.193, year: 2014

  12. Geochemical trends in the weathered profiles above granite gneiss ...

    Geochemical trends in the weathered profiles above granite gneiss and schist of Abeokuta area, southwestern Nigeria. Anthony T Bolarinwa, Anthony A Elueze. Abstract. No Abstract. Journal of Mining and Geology 2005, Vol. 41(1): 19-31. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...

  13. Mineralogical and geochemical studies of phosphorite nodules in ...

    Mineralogical and geochemical studies of phosphorite nodules in the Dange Formation Sokoto Basin, Northwestern Niveria. OA Adekeye, SO Akande. Abstract. No Abstract Available Journal of Mining and Geology Vol.40(2) 2004: 101-106. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...

  14. Geochemical characterization of the siliciclastic rocks of Chitravati ...

    V Somasekhar

    2018-05-23

    May 23, 2018 ... Chitravati Group of Cuddapah Supergroup to decipher the provenance and depositional environment. Both the units ... Based on major element geochemical classification diagram, Pulivendla Quartzite .... The youngest age limit of the Nallamalai ...... eastern Oregon and western Idaho, USA: Implications for.

  15. Uruguay Mining inventory. Florida fotoplano geochemical prospecting results

    Zeegers, H.; Artignan, D.; Vairon, P.

    1982-01-01

    This work is about the geochemical prospecting carried out in Florida fotoplano within the framework of Uruguay Mining inventory. In this work were covered 660 km2 obtaining 752 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories

  16. Geochemical assessment of light gaseous hydrocarbons in near ...

    Light hydrocarbons in soil have been used as direct indicators in geochemical hydrocarbon exploration, which remains an unconventional path in the petroleum industry. The occurrence of adsorbed soil ... Kalpana1 D J Patil1 A M Dayal1. National Geophysical Research Institute, Uppal Road, Hyderabad 500606, India.

  17. Uruguay Mining inventory. Las Animas fotoplano geochemical prospecting results

    Zeegers, H.; Spangenberg, J.

    1981-01-01

    This work is about the geochemical prospecting carried out in Las Animas fotoplano within the framework of Uruguay Mining inventory. In this work were covered 660 km2 obtaining 738 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories.

  18. Uruguay Mining inventory. Minas fotoplano geochemical prospecting results

    Zeegers, H.; Artignan, D.; Vairon, P.

    1982-01-01

    This work is about the geochemical prospecting carried out in Minas fotoplano within the framework of Uruguay Mining inventory. In this work were covered 380 km2 obtaining with 433 samples for study which were analized by Plasma Emission Spectrometry in Orleans BRGM laboratories

  19. Mining inventory of Uruguay. Polanco fotoplano geochemical prospecting results

    Zeegers, H; Artignan, D; Vairon, P

    1982-01-01

    This work is about the geochemical prospecting carried out in Polanco fotoplano within the framework of Uruguay Mining inventory . In this work were covered 660 km2 obtaining 685 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories

  20. The geochemical behavior of protactinium 231 and its chosen geochemical analogue thorium in the biosphere

    Gillberg-Wickman, M.

    1983-03-01

    To be able to judge whether protactinium 231 might represent a major contribution to the human radiation risk from high level radioactive waste a literature study of the geochemical behavior of protactinium has been made. The interest in protactinium determinations has, as far, been in the field of marine geochemistry and geochronology. These investigations show that thorium may be used as a chemical analogue. The content of protactinium 231 is determined by the 235 U content and consequently the occurrence of protactinium in nature is directly associated to the geochemistry of uranium. The pronounced hydrolytic tendency of protactinium and its great sorption and coprecipitation capacity ought to prevent or at least appreciably delay its transport from a back-filled nuclear waste vault to the uppermost surface of the earth. It also has a tendency to form colloids or particulates which may be strongly fixed on a rock surface. In adsorption and desorption processes kinetics must play an important role. Our knowledge in this field is quite limited. Under the physico-chemical conditions in the sea, protactinium is rapidly scavenged from the water column by particulates. It accumulates in the sediments. (author)

  1. Schumpeter's Evolution

    Andersen, Esben Sloth

    reworking of his basic theory of economic evolution in Development from 1934, and this reworking was continued in Cycles from 1939. Here Schumpeter also tried to handle the statistical and historical evidence on the waveform evolution of the capitalist economy. Capitalism from 1942 modified the model...

  2. Galactic evolution

    Pagel, B.

    1979-01-01

    Ideas are considered concerning the evolution of galaxies which are closely related to those of stellar evolution and the origin of elements. Using information obtained from stellar spectra, astronomers are now able to consider an underlying process to explain the distribution of various elements in the stars, gas and dust clouds of the galaxies. (U.K.)

  3. Darwinian evolution

    Jagers op Akkerhuis, Gerard A.J.M.; Spijkerboer, Hendrik Pieter; Koelewijn, Hans Peter

    2016-01-01

    Darwinian evolution is a central tenet in biology. Conventionally, the defi nition of Darwinian evolution is linked to a population-based process that can be measured by focusing on changes in DNA/allele frequencies. However, in some publications it has been suggested that selection represents a

  4. Regional geochemical maps of uranium in Northern Scotland. Environmental and economic considerations

    Plant, J.

    1978-01-01

    The Institute of Geological Studies geochemical mapping programme is outlined. The natural levels of uranium in rocks, soils and waters are discussed. Some practical details of geochemical mapping are given. Applications of geochemical maps of uranium in Scotland are considered: economic applications and medical geography and agriculture. A list of 38 references is appended. (U.K.)

  5. Well sediments: a medium for geochemical prospecting, an example from the Nisa region, Portugal

    Vriend, S.P.; Dekkers, M.J.; Janssen, M.A.; Commandeur, J.

    1991-01-01

    Vriend, S.P., Dekkers, M.J.. Janssen, M.A. and Commandeur, J., 1991. Well sediments: a medium for geochemical prospecting, an example from the Nisa region. Portugal. In: A.W. Rose and P.M. Taufen I Editors). Geochemical Exploration ! 989. J. Geochem. Expior., 4 ! : ! 5 I- 167. Tile potential of

  6. GEOBASI: The geochemical Database of Tuscany Region (Italy

    Brunella Raco

    2015-03-01

    Full Text Available In this study the new Regional Geochemical Database (RGDB, called GEOBASI, is presented and illustrated in the framework of a joint collaboration among the three Tuscan universities (Florence, Pisa and Siena, CNR-IGG (Institute of Geosciences and Earth Resources of Pisa, ARPAT (Regional Agency for the Environmental Protection, LAMMA (Environmental Modelling and Monitoring Laboratory for Sustainable Development Consortium and S.I.R.A. (Territorial and Environmental Informative System of Tuscany. The database has permitted the construction of a repository where the geochemical information (compositional and isotopic has been stored in a structured way so that it can be available for different groups of users (e.g. institutional, public and private companies. The information contained in the database can in fact be downloaded freely and queried to correlate geochemistry to other non compositional variables. The first phase of the project was aimed at promoting the use of the geochemical data already available from previous investigations through a powerful Web-GIS interface to implement the exploratory statistics graphical-numerical tools used to: 1 analyse the spatial variability of the investigated context, 2 highlight the geographic location of data pertaining to classes of values or single cases, 3 compare the results of different analytical methodologies applied to the determination of the same element and/or chemical species, 4 extract the geochemical data related to specific monitoring plans and/or geographical areas, and finally 5 recover information about data below the detection limit to understand their impact on the behaviour of the investigated variable. Developments of this project will be focused on the definition of rules and standardized methods in a way that external users could also interactively pursue the RGDB. Furthermore, a detailed investigation of the Scarlino-Follonica plain will permit the improvement and test of

  7. Geochemical Anomalies in the Sediments of Lake Druksiai

    Kleinas, A.

    1999-01-01

    In order to evaluate the impact of Ignalina Nuclear Power Plant (NPP) on natural processes in Lake Druksiai and accumulation of pollutants, in 19931997, carrying on the state scientific program, the Marine Geochemistry Division of the Institute of Geography performed lithological geochemical mapping of lake bottom sediments on a scale of 1 .50 000. The results obtained enabled to distinguish zones of higher anthropogenous geochemical load, where geochemical anomalies of pollutants, including oil hydrocarbons and heavy metals, had been taken into account. Applying concentration coefficients for oil hydrocarbons and heavy metals (Cr, Cu, Ni, Pb, and Zn) and their natural background, the attempt was made to differentiate natural and technogenous components in the geochemical anomalies As expected, the finer sediments -aleurite-pelite mud - showed amounts of oil hydrocarbons and heavy metals being 12.1 times higher than in fine sand - the most coarse of the sediments studied Sediments with organic mater exceeding 20% contained 11.7 times more pollutants than those with organic matter below 1 .5%. Calculations of concentration coefficients (CC) showed no elements in no stations exceeded 10 - the sediments did not reach the category of high pollution However, in many sites, the coefficients exceeded values of 1-2, thus, showing sediments attributable to the categories of weakly polluted or just polluted. Mapping model done by GIS methods (by superimposing schemes of pollutant CCs distribution in the lake and summing them) for geochemical anomalies two derivative map-schemes were obtained for oil hydrocarbons and heavy metals. They showed that clean sediments cover just 24.75% (according to the pollutant background for soil types) and 12.35% (according to the organic matter background for its amount intervals) lake bottom area. Zones slightly polluted by an element at least cover 69.7 and 80.29% of lake area, correspondingly; whereas zones slightly polluted by all

  8. Validation of the WATEQ4 geochemical model for uranium

    Krupka, K.M.; Jenne, E.A.; Deutsch, W.J.

    1983-09-01

    As part of the Geochemical Modeling and Nuclide/Rock/Groundwater Interactions Studies Program, a study was conducted to partially validate the WATEQ4 aqueous speciation-solubility geochemical model for uranium. The solubility controls determined with the WATEQ4 geochemical model were in excellent agreement with those laboratory studies in which the solids schoepite [UO 2 (OH) 2 . H 2 O], UO 2 (OH) 2 , and rutherfordine ((UO 2 CO 3 ) were identified as actual solubility controls for uranium. The results of modeling solution analyses from laboratory studies of uranyl phosphate solids, however, identified possible errors in the characterization of solids in the original solubility experiments. As part of this study, significant deficiencies in the WATEQ4 thermodynamic data base for uranium solutes and solids were corrected. Revisions included recalculation of selected uranium reactions. Additionally, thermodynamic data for the hydroxyl complexes of U(VI), including anionic (VI) species, were evaluated (to the extent permitted by the available data). Vanadium reactions were also added to the thermodynamic data base because uranium-vanadium solids can exist in natural ground-water systems. This study is only a partial validation of the WATEQ4 geochemical model because the available laboratory solubility studies do not cover the range of solid phases, alkaline pH values, and concentrations of inorganic complexing ligands needed to evaluate the potential solubility of uranium in ground waters associated with various proposed nuclear waste repositories. Further validation of this or other geochemical models for uranium will require careful determinations of uraninite solubility over the pH range of 7 to 10 under highly reducing conditions and of uranyl hydroxide and phosphate solubilities over the pH range of 7 to 10 under oxygenated conditions

  9. CONSUMO ALIMENTAR, PERFIL ANTROPOMÉTRICO E CONHECIMENTOS EM NUTRIÇÃO DE CORREDORES DE RUA

    Ferreira, Vanessa Roriz; Bento, Ana Paula Nunes; Silva, Mara Reis

    2015-01-01

    Introdução A nutrição esportiva e a composição corporal são fatores importantes para o desempenho de atividades esportivas. A corrida de rua se popularizou no mundo, especialmente na última década. Os corredores de rua devem consumir uma dieta nutricionalmente adequada e ter conhecimento sobre nutrição para manter um perfil nutricional adequado. Objetivo Avaliar a adequação dietética, o perfil antropométrico e os conhecimentos em nutrição de corredores de rua. Métodos Os corredores adultos ...

  10. Perfiles y estilos gerenciales, de la administracion de una empresa social del estado en el departamento de Cundinamarca

    Serrano Trujillo, Adriana Carolina; Cortés Arboleda, Andrea

    2015-01-01

    El estudio “Identificar el perfil y el estilo del gerente, para administrar una Empresa Social del Estado en el Departamento de Cundinamarca” tiene como propósito conocer el perfil como conocimientos, habilidades o aptitudes, experticia y actitudes o comportamientos, lo mismo que el estilo gerencial en las organizaciones de hoy, como puede hacerla rentable y enfrentar los retos de un mundo globalizado, en una administración compleja, con incertidumbres y desafíos propios del Siglo XXI. Es...

  11. Análisis de Perfil de Textura en Plátanos Pelipita, Hartón y Topocho

    Granados, Clemente; Acevedo, Diofanor; Cabeza, Adis; Lozano, Adriana

    2014-01-01

    El objetivo de este trabajo fue evaluar la textura del plátano Pelipita (Musa ABB) crudo y cocido en comparación con plátanos crudos y cocidos Hartón verde (Musa AAB) y Topocho (Musa ABB del subgrupo Silver Bluggoe) mediante un análisis de perfil de textura. El estudio de la textura como propiedad física del alimento es de suma importancia para determinar la aceptabilidad del mismo. A muestras de plátanos Pelipita de la variedad Musa ABB se les aplicó un análisis del perfil de textura a tiemp...

  12. El perfil de la víctima y el agresor en casos de violencia de género

    Coll Mora, Miriam

    2016-01-01

    El present treball aprofundeix en l’estudi del perfil de la víctima i l’agressor en casos de violència de gènere, analitzant la manera en que ambdues persones es relacionen i interactuen immersos dins la relació de violència. Es pretén constatar la inexistència d’un perfil universal definit de víctima o agressor i descriure les característiques essencials de la personalitat que ambdós comparteixen i la expressió de la qual els diferencia. Com a objectiu secundari, es persegueix descriure l...

  13. El perfil motivacional para la práctica del deporte escolar de la ciudad de Tubarao (Santa Catarina, Brasil)

    Ferreira Sene, Richard

    2012-01-01

    Este trabajo tiene como objetivo delinear un perfil de motivación para los deportes de los escolares entre 10 y 18 años en la ciudad de Tubarão Santa Catarina en Brasil. Además, relacionar la experiencia deportiva de los padres con la motivación de los niños. Se ha utilizado una investigación descriptiva y de campo con la participación voluntaria de 418 escolares de la red municipal El instrumento utilizado para trazar este perfil fue el inventario de motivación para práctica d...

  14. Geochemical and petrological considerations about the basalts of upper aluminium in the Fildes Peninsula. (Rei George), Antartica

    Machado, A.; Fernandes de Lima, E.; Chemale, F.

    1998-01-01

    Petrographic, geochemical and petrological studies of lower Tertiary basaltic rocks from Fildes Peninsula in Antarctica were made to characterize their source and magmatic evolution. These basaltic rocks have porphyritic, glomeroporphyritic, intergranular and intersertal textures. The phenocrysts are of plagioclase (An), augite, pigeonite and Ti-magnetite. These basaltic rocks have AL O from 16 to 22%, Ni from 6 to 88 ppm, Co from 24 to 33 ppm and Cr from 54 to 123 ppm. Enrichment of Rb. Ba, Sr and LREE with respect to HREE is observed as relative depleted in HFSE is detected. The mass balance realized to understand the evolution of liquid that gave source the different basaltic rocks. Showed that the extracted mineral fractions were 76% of plagioclase, 2% of clinopiroxene and 21% of olivine. The intermediate volcanic rocks of Fildes Peninsula can be explained by cristalization fractionation of a basic liquid. The isotopic dates showed initial rations of Sr/Sr <0,704 and positive values of Nd epsilon. These results are strong support a mantelic source for basaltic rocks of Fildes Peninsula. On basis of geochemical, petrological and isotopic characteristics is possible concluded that these rocks were formed in an island are environment with parcial melting of mantle wedge. (author)

  15. Concerning initial and secondary character of radionuclide distribution in elementary landscape geochemical systems

    Korobova, Elena; Romanov, Sergey

    2017-04-01

    study confirms that Cs-137 as a label helps to trace processes and patterns of chemical elements' migration on the level of ELGS that are numerously reproduced elsewhere in natural systems. The study is aimed at and believed to provide solution for a number of important problems related to generation and evolution of soil structure, spatial redistribution of fertilizers and pesticides, other important processes of matter redistribution on the level of local LGS. References Korobova E.M., Korovaykov P.A., 1990. Landscape and geochemical approach to drawing up a soil distribution profile for Chernobyl radionuclides in distant areas //Seminar "Comparative assessment of the environmental impact of radionuclides released during three major nuclear accidents: Kyshtum, Windscale, Chernobyl". V. 1. Luxembourg, 309-327. Linnik V.G., 2008. Landscape differentiation of technogenic radionuclides: geoinformation systems and models. Thesis. Moscow: Moscow State University, 42 p. Romanov S.L., 1989. Principles of formation of radionuclide dispersion and concentration fields // Abstracts of the All-Union Conference "Principles and methods of landscape geochemical studies of radionuclide migration". Moscow: Vernadsky Institute, p. 46. Shcheglov A.I., Tsvetnova O.B., KlyashtorinA.L., 2001. Biogeochemical migration of technogenic radionuclides in forest ecosystems. Moscow: Nauka, 235 p.

  16. PERFIL DE ENGAJAMENTO PARA O AUTOCUIDADO EM PORTADORES DE HIPERTENSÃO ARTERIAL

    GISELLE ANDRADE DOS SANTOS SILVA

    2008-01-01

    Full Text Available Estudio descriptivo con el objetivo de identificar el perfil de compromiso con el auto cuidado en personas hipertensas acompañadas clínicamente en la Unidad Básica de Salud de la Familia. Utilizamos los instrumentos para establecer el perfil de compromiso en el autocuidado teniendo como conjetura la teoría del autocuidado de Orem. Pesquisadas 31 personas, registradas en (HIPER/DÍA el año 2004. Identificados los requisitos de autocuidado con calificación positiva en relación a las eliminaciones, a la adaptación a los cambios del ciclo vital; ajuste social; al conocimiento de la enfermedad y del tratamiento; aceptación del diagnóstico; adaptación al problema con la salud y a las conductas orientadas. Y calificación no satisfactoria a la ingestión de alimentos y líquidos; desequilibrio entre soledad e interacción social; a la prevención de riesgo de vida y al bienestar; a la promoción de la salud. Constatamos que una fracción de portadores de hipertensión acompañados clínicamente por el PSF se compromete con el auto-cuidado frente a las acciones llevadas a cabo.

  17. PERFIL LÍPIDICO DOS PACIENTES HIV POSITIVOS EM USO DA TERAPIA ANTIRRETROVIRAL

    Maria Roseane dos Santos

    2017-07-01

    Full Text Available Corresponde a estudo descritivo de corte transversal, buscou-se evidenciar o impacto da TARV sobre o perfil lipídico. Realizada com 37 pacientes atendidos no ambulatório de Doenças Infecciosas e Parasitárias do centro de referência para HIV do Hospital Universitário Oswaldo Cruz em Recife-PE/Brasil. Através da realização de entrevistas, coleta de informações sobre terapia antirretroviral, curva de CD4 e carga viral obtidas nos prontuários. Tendo como aprovação no comitê de ética e pesquisa CAAE de nº 11365112.8.0000.5192. Revela o impacto no perfil lipídico associado ao uso contínuo da TARV, demostrando aumento do TG 54%, CT 49%, VLDL (41%, LDL-c 19% e diminuição do HDL-c 24%.   As associações de esquemas de ITRN e IRNN apresentaram o maior número de alterações. As drogas da TARV induzem distúrbios metabólicos graves e associados com outros fatores encontrados como HAS 19%, tabagismo 35% e sedentarismo 81% constituem uma forte predisposição de aterosclerose e consequentemente riscos cardiovasculares.

  18. Los perfiles de exigencias en la ocupación del profesional de recursos humanos

    Santiago Pereda Marín

    2003-01-01

    Full Text Available En este trabajo se presentan los resultados de un estudio exploratorio que se llevó a cabo en la Universidad Complutense de Madrid para definir el perfil de exigencias ocupacionales del profesional de recursos humanos. En este estudio se considera como profesional de recursos humanos al licenciado, ingeniero o doctor que desarrolla su actividad en el área de recursos humanos sin ocupar puestos directivos dentro de la estructura de la organización. Los resultados de este estudio, que se obtuvieron a partir de una muestra de 37 profesionales de recursos humanos en activo, señalan seis competencias como claves para el desempeño de la ocupación; éstas son, por orden de importancia: trabajo en equipo, orientación al cliente, planificación/organización, comunicación, flexibilidad y colaboración. Asimismo, se comprobó que la metodología empleada es útil, aunque se considera que es preciso introducirle pequeños cambios para optimizar el trabajo en la definición de los perfiles de exigencias ocupacionales.

  19. Un acercamiento a la comprensión del perfil de la Inteligencia Emocional

    Gloria María Isaza-Zapata*

    2016-02-01

    Full Text Available Este artículo es resultado de un estudio de inteligencia emocional. En la investigación nos propusimos como objetivo general, analizar el perfil de inteligencia emocional y social de una muestra de 110 docentes de educación básica primaria, vinculados a diez instituciones educativas de la ciudad de Medellín, Colombia. El alcance es descriptivo, no experimental, y correlacional; y está apoyado con método probabilístico, simple al azar y estratificado. Los resultados obtenidos desde el perfil destacan la relación con: autorregulación, automotivación, empatía, tiempo de métodos asertivos, eficaz el método y juzgarse a sí mismo; detectando una correlación con tendencia a cero entre las variables. En conclusión, la inteligencia emocional y social del maestro o maestra de básica primaria tiende a establecer un reconocimiento de sus habilidades, sus limitaciones, su sensibilidad hacia el aprendizaje personal y su influencia en el sujeto estudiante.

  20. Un acercamiento a la comprensión del perfil de la Inteligencia Emocional

    Gloria María Isaza-Zapata

    2016-01-01

    Full Text Available Este artículo es resultado de un estudio de inteligencia emocional. En la investigación nos propusimos como objetivo general, analizar el perfil de inteligencia emocional y social de una muestra de 110 docentes de educación básica primaria, vinculados a diez instituciones educativas de la ciudad de Medellín, Colombia. El alcance es descriptivo, no experimental, y correlacional; y está apoyado con método probabilístico, simple al azar y estratificado. Los resultados obtenidos desde el perfil destacan la relación con: autorregulación, automotivación, empatía, tiempo de métodos asertivos, eficaz el método y juzgarse a sí mismo; detectando una correlación con tendencia a cero entre las variables. En conclusión, la inteligencia emocional y social del maestro o maestra de básica primaria tiende a establecer un reconocimiento de sus habilidades, sus limitaciones, su sensibilidad hacia el aprendizaje personal y su influencia en el sujeto estudiante.

  1. Personalidad y demencia: aproximación al perfil diferencial del cuidador

    Elena de Andrés-Jiménez

    2011-12-01

    Full Text Available El objetivo de este estudio es determinar la existencia de un perfil de personalidad característico de los cuidadores y cuidadoras familiares de personas con demencia. El adecuado conocimiento y manejo de las variables psicológicas que afectan de alguna manera al cuidador, ayuda a promover las acciones oportunas destinadas a atenuar el impacto del cuidado y mejorar la calidad de vida del cuidador y la persona cuidada. La población objeto de estudio está formada por 69 cuidadores familiares de personas con demencia, miembros de distintas asociaciones y centros de día. Los resultados obtenidos permiten identificar un perfil de personalidad característico para estos cuidadores, revelador de un funcionamiento psicológico específico en esta muestra, que si bien no podemos relacionar directamente con las tareas propias del cuidado de una persona con esta enfermedad, si nos proporciona información muy relevante para atender de forma más precisa a las necesidades de este colectivo. Asimismo, el análisis de los estilos de personalidad en función del sexo muestra una vez más que la mujer se encuentra en este ámbito en una situación de mayor vulnerabilidad.

  2. Perfil de adolescentes gestantes de um município do interior do Paraná

    Beatriz Rosana Gonçalves de Oliveira

    2011-01-01

    Full Text Available Este estudio planteó como objetivo identificar el perfil de adolescentes embarazadas, en un municipio de Paraná, teniendo en cuenta la influencia de factores biológicos, psicológicos y sociales, para apoyar las acciones preventivas del embarazo precoz. Investigación cuantitativa con datos obtenidos mediante entrevista. y análisis estadístico descriptivo. Se analizaron: edad de la menarqula, ginecológica y al quedar embarazada, uso de anticonceptivos antes del embarazo, relación familiar, aceptación y planificación del embarazo, nivel educativo, repetición y abandono escolar, renta. familiar, estado civil, número de compañeros hasta el embarazo y medios de acceso a educación sexual. El perfil obtenido mostró menarquia precoz, sólo una pareja sexual, poco uso de anticonceptivos, reacción familiar positiva en relación al embarazo actual, repetición y abandono escolar, falta de empleo remunerado, baja renta familiar. Los datos aportan informaciones al equipo de salud del municipio en cuestión para que desarrolle acciones específicas que prevengan el embarazo en la adolescencia.

  3. Perfil cognitivo de niños con rendimientos bajos en comprensión lectora

    Lorena Canet-Juric

    2013-10-01

    Full Text Available La mayoría de los niños con dificultades en la comprensión lectora poseen rendimientos inferiores en un conjunto de procesos cognitivos. El objetivo del presente estudio es establecer un perfil cognitivo asociado al bajo rendimiento en comprensión lectora en relación a la habilidad de monitoreo, a la producción de inferencias, al vocabulario, a la amplitud de memoria de trabajo y a la capacidad inhibitoria, en niños hispanoparlantes. Para ello se administraron tareas correspondientes a dichos procesos en niños con altos y bajos rendimientos en comprensión lectora. Los resultados mostraron que si bien los niños con mala comprensión presentan bajos rendimientos en estas habilidades, no puede establecerse un perfil consistente ya que hay niños con problemas en comprensión que presentan normal o superior rendimiento en algunas de estas habilidades cognitivas.

  4. Perfil, competencias e fluencia digital dos enfermeiros do Programa de Aprimoramento Profissional

    Lyvia Pini Tanabe

    2013-08-01

    Full Text Available Estudo descritivo, exploratório, realizado na cidade de São Paulo, que objetivou identificar o perfil, as competências e a fluência digital do enfermeiro aprimorando para uso da tecnologia no trabalho. A população composta por 60 aprimorandos do Programa de Aprimoramento Profissional respondeu um questionário com dados sobre o perfil, a fluência digital e as competências profissionais. Verificou-se que 95,0% dos participantes eram do sexo feminino, 61,7% na faixa etária entre 23 a 25 anos, 75,0% graduados em escolas públicas, 58,3% cursando enfermagem cardiovascular, 98,3% teve contato com recursos computacionais na graduação; 100,0% possuía computador em casa; 86,7% acessava a internet diariamente; 96,7% utilizava o Messenger e 58,3% apresentava grau intermediário de conhecimento e habilidade em informática. As competências profissionais requeridas frente à tecnologia referiram-se ao saber ser inovador, criativo, atualizado para conhecer e gerenciar programas e saber utilizar os recursos tecnológicos.

  5. ACERCAMIENTO AL PERFIL DE USO DE TIC POR DOCENTES EN EL SECTOR RURAL COLOMBIANO

    Dolly Vargas García

    2015-12-01

    Full Text Available El artículo pretende hacer un acercamiento al perfil, en cuanto al uso de las TIC, por parte de docentes de instituciones educativas ubicadas en el sector rural de cuatro departamentos colombianos (Caldas, Caucas, Huila y Nariño. Se inicia con un recorrido por la influencia de las TIC en el ámbito educativo, especialmente en cuanto al rol del docente en ese nuevo ambiente escolar. Luego se presenta la metodología utilizada en el estudio, para a continuación mostrar algunos resultados que concuerdan con trabajos anteriores en otros sitios y niveles académicos, sobre los aspectos indispensables para conformar el perfil del docente de la era informáticaApproach of ICT use profile by Colombian rural sector teachersABSTRACTThe article attempts approaching profile, in the use of ICT by teachers of educational institutions located in rural areas of four Colombian departments (Caldas, Cauca, Huila and Nariño. It begins with a tour of the influence of ICT in education, especially regarding the role of the teacher in the new school environment. Then it comes to the methodology used in the study, to then show some results are consistent with previous work on other sites and academic levels on the essential aspects to form the profile of teachers in the information age.Keywords: Use profile, ICT and education, Professor, Rural Area.

  6. Stellar evolution

    Meadows, A J

    2013-01-01

    Stellar Evolution, Second Edition covers the significant advances in the understanding of birth, life, and death of stars.This book is divided into nine chapters and begins with a description of the characteristics of stars according to their brightness, distance, size, mass, age, and chemical composition. The next chapters deal with the families, structure, and birth of stars. These topics are followed by discussions of the chemical composition and the evolution of main-sequence stars. A chapter focuses on the unique features of the sun as a star, including its evolution, magnetic fields, act

  7. Merging metagenomics and geochemistry reveals environmental controls on biological diversity and evolution.

    Alsop, Eric B; Boyd, Eric S; Raymond, Jason

    2014-05-28

    The metabolic strategies employed by microbes inhabiting natural systems are, in large part, dictated by the physical and geochemical properties of the environment. This study sheds light onto the complex relationship between biology and environmental geochemistry using forty-three metagenomes collected from geochemically diverse and globally distributed natural systems. It is widely hypothesized that many uncommonly measured geochemical parameters affect community dynamics and this study leverages the development and application of multidimensional biogeochemical metrics to study correlations between geochemistry and microbial ecology. Analysis techniques such as a Markov cluster-based measure of the evolutionary distance between whole communities and a principal component analysis (PCA) of the geochemical gradients between environments allows for the determination of correlations between microbial community dynamics and environmental geochemistry and provides insight into which geochemical parameters most strongly influence microbial biodiversity. By progressively building from samples taken along well defined geochemical gradients to samples widely dispersed in geochemical space this study reveals strong links between the extent of taxonomic and functional diversification of resident communities and environmental geochemistry and reveals temperature and pH as the primary factors that have shaped the evolution of these communities. Moreover, the inclusion of extensive geochemical data into analyses reveals new links between geochemical parameters (e.g. oxygen and trace element availability) and the distribution and taxonomic diversification of communities at the functional level. Further, an overall geochemical gradient (from multivariate analyses) between natural systems provides one of the most complete predictions of microbial taxonomic and functional composition. Clustering based on the frequency in which orthologous proteins occur among metagenomes

  8. Geochemical Parameters Required from the SKB Site Characterisation Programme

    Bath, Adrian

    2002-01-01

    SKB has described its approach to site characterisation in a number of Technical Reports. One of the scientific topics in which specific information requirements and priorities are set out is geochemistry. This report for SKI examines critically whether the geochemical parameters identified in the SKB programme documents will be adequate for safety and regulatory requirements. It also examines some of the details of parameter requirements and interpretation tools that will be necessary to convert site investigation data into knowledge about chemical conditions and groundwater movements. The SKB strategy for geochemical data focuses on a small number of 'suitability indicators', primarily dissolved oxygen, pH and salinity. Their parameter requirements aim to assess those primary characteristics, as well as to acquire a wider range of data that will support those assessments and provide a broader understanding of candidate areas. An initial observation in this review that, though it is a primary suitability indicator, dissolved oxygen apparently will not be measured and instead will be inferred from other redox indicators. This raises a number of issues about sampling and monitoring measures, analytical data reliability and sensitivity, and the degree of confidence in geochemical understanding. A geochemical programme involves reconnaissance by desk study and acquisition of new data at levels of details that are appropriate to the stage of site investigations. As early as possible, a conceptual model of a candidate area should help to define the objectives of geochemical measurements on both rock and groundwater samples. It is recommended that parameters requirements should be defined and considered not only in terms of isolated measurements but more in terms of addressing broader objectives that relate to safety and also to geoscientific understanding. The safety priorities remain (e.g. dissolved oxygen) but will then be supported by an understanding of processes

  9. Geochemical Parameters Required from the SKB Site Characterisation Programme

    Bath, Adrian [Intellisci Ltd., Loughborough (United Kingdom)

    2002-01-01

    SKB has described its approach to site characterisation in a number of Technical Reports. One of the scientific topics in which specific information requirements and priorities are set out is geochemistry. This report for SKI examines critically whether the geochemical parameters identified in the SKB programme documents will be adequate for safety and regulatory requirements. It also examines some of the details of parameter requirements and interpretation tools that will be necessary to convert site investigation data into knowledge about chemical conditions and groundwater movements. The SKB strategy for geochemical data focuses on a small number of 'suitability indicators', primarily dissolved oxygen, pH and salinity. Their parameter requirements aim to assess those primary characteristics, as well as to acquire a wider range of data that will support those assessments and provide a broader understanding of candidate areas. An initial observation in this review that, though it is a primary suitability indicator, dissolved oxygen apparently will not be measured and instead will be inferred from other redox indicators. This raises a number of issues about sampling and monitoring measures, analytical data reliability and sensitivity, and the degree of confidence in geochemical understanding. A geochemical programme involves reconnaissance by desk study and acquisition of new data at levels of details that are appropriate to the stage of site investigations. As early as possible, a conceptual model of a candidate area should help to define the objectives of geochemical measurements on both rock and groundwater samples. It is recommended that parameters requirements should be defined and considered not only in terms of isolated measurements but more in terms of addressing broader objectives that relate to safety and also to geoscientific understanding. The safety priorities remain (e.g. dissolved oxygen) but will then be supported by an understanding of

  10. Estudo de metodologias para o dimensionamento de vigas mistas de aço e concreto com perfil celular

    A. BADKE-NETO

    Full Text Available Resumo Atualmente, com o avanço da tecnologia de corte e solda, perfis de aço com aberturas sequenciais na forma circular, denominados perfis celulares, vêm sendo bastante utilizadas como vigas de edificações. A ABNT NBR 8800:2008 e as normas estrangeiras não abordam vigas de aço e vigas mistas de aço e concreto com perfil celular, o que contribui para que o seu uso seja limitado. Foi desenvolvido e aferido um programa computacional para o dimensionamento de vigas mistas de aço e concreto com perfil celular biapoiadas de acordo com duas metodologias distintas da literatura. Um estudo paramétrico abordando vigas mistas com perfis celulares obtidos de dois perfis I de aço laminados comerciais foi realizado. Nesse estudo, a influência dos parâmetros geométricos do perfil celular e do comprimento do vão da viga na resistência e na forma de colapso foi analisada. Foi possível concluir que em muitas situações o uso de vigas mistas com perfil celular é vantajoso em relação às vigas mistas de alma cheia.

  11. Efectos terapéuticos del ejercicio con sobrecarga en el perfil lipídico de adultos sedentarios

    Felipe Caamaño Navarrete

    2015-10-01

    Conclusiones. Si bien se observa una tendencia a la baja en el perfil lipídico, una mayor duración y/o frecuencia de intervención podría ser necesaria para modificar significativamente las variables plasmáticas.

  12. Version 4. 00 of the MINTEQ geochemical code

    Eary, L.E.; Jenne, E.A.

    1992-09-01

    The MINTEQ code is a thermodynamic model that can be used to calculate solution equilibria for geochemical applications. Included in the MINTEQ code are formulations for ionic speciation, ion exchange, adsorption, solubility, redox, gas-phase equilibria, and the dissolution of finite amounts of specified solids. Since the initial development of the MINTEQ geochemical code, a number of undocumented versions of the source code and data files have come into use at the Pacific Northwest Laboratory (PNL). This report documents these changes, describes source code modifications made for the Aquifer Thermal Energy Storage (ATES) program, and provides comprehensive listings of the data files. A version number of 4.00 has been assigned to the MINTEQ source code and the individual data files described in this report.

  13. Version 4.00 of the MINTEQ geochemical code

    Eary, L.E.; Jenne, E.A.

    1992-09-01

    The MINTEQ code is a thermodynamic model that can be used to calculate solution equilibria for geochemical applications. Included in the MINTEQ code are formulations for ionic speciation, ion exchange, adsorption, solubility, redox, gas-phase equilibria, and the dissolution of finite amounts of specified solids. Since the initial development of the MINTEQ geochemical code, a number of undocumented versions of the source code and data files have come into use at the Pacific Northwest Laboratory (PNL). This report documents these changes, describes source code modifications made for the Aquifer Thermal Energy Storage (ATES) program, and provides comprehensive listings of the data files. A version number of 4.00 has been assigned to the MINTEQ source code and the individual data files described in this report.

  14. A preliminary report of geochemical investigations in the Blackbird District

    Canney, F.C.; Hawkes, H.E.; Richmond, G.M.; Vhay, J. S.

    1953-01-01

    This paper reviews an experimental geochemical prospecting survey in the Blackbird cobalt-copper mining district. The district is in east-central Idaho, about 20 miles west-southwest of Salmon. The area is one of deeply weathered nearly flat-topped upland surfaces cut by steep-walled valleys which are tributary to the canyon of Panther Creek. Most of the area has a relatively heavy vegetative cover, and outcrops are scarce except on the sides of the steeper valleys* Because of the importance of the surficial deposits and soils and the physiographic history of the region on the interpretation of the geochemical data, a separate chapter on this subject by Gerald H. Richmond follows the following brief description of the geology of the district.

  15. Status report on geochemical field results from Atlantic study sites

    Wilson, T.R.S.; Thomson, J.; Hydes, D.J.; Colley, S.

    1983-01-01

    This report summarises the results of preliminary geochemical investigations at three North Atlantic study areas. The two eastern sites, on the Cape Verde abyssal plain (CV2) and east of Great Meteor Seamount (GME) were visited during 1982. The results presented are preliminary. Studies in the western Atlantic, close to the Nares Abyssal Plain study site are more detailed and are presented in a separate paper. The report shows for the first time the relative redox status of the three sites. The differences are unexpectedly large, the most reduced cores being recovered at GME and the most oxidised at CV2. The sporadic nature of Recent sediment accumulation at these sites is also emphasised. In order to place these preliminary results in context their relevance to the production of mathematical system models is discussed in a closing section. The necessity for such models to rest on sound foundations of geochemical understanding is noted. Suggestions on future research priorities are offered for discussion. (author)

  16. Determinación del comportamiento bajo cargas concentradas de perfiles de lámina delgada ( MM

    Maritzabel Molina Herrera

    2006-09-01

    Full Text Available En el campo de la lámina delgada continuamente aparecen nuevos tipos de perfiles que son desarrollados con el objeto de mejorar los ya existentes. Un ejemplo de esto es la aparición del perfil M, elaborado para melorar la eficiencia a corte del perfil C y su resistencia al arrugamiento del alma por efecto de cargas concentradas. Teóricamente, se logra el objetivo de mejorar la resistencia a corte del perfil C y de algún modo su resistencia al arrugamiento del alma, pero debido a los dobleces generados en el alma (rigidizadores intermedios para acortar la longitud de pandeo, se producen comportamientos que desde el punto de vista de esfuerzos por flexión y deflexiones no pueden ser analizados con los fundamentos teóricos de la mecánica tradicional. Este comporta- miento se ve acentuado con la presencia de cargas concentradas. Por la razón expuesta anteriormente, a parte de la determinación de la resistencia teórica del perfil M (basada en el AISI 1996, se desarrollan pruebas sobre cuatro modelos de los que se obtienen tópicos como: carga máxima resistida, identificación visual del posible tipo de falla, deflexiones (centro de la luz y deformaciones unitarias (x, y, xy, y adicionalmente se elaboran modelos matemáticos simplificados y por elementos finitos (en el programa COSMOS/M, con el fin de hacer una revisión detallada del comportamiento de los esfuerzos y deformaciones en el perfil. La calibración de estos modelos se lleva a cabo con base en los resultados obtenidos de los ensayos. De otra parte, se hacen pruebas cíclicas balo cargas pseudoestáticas, con el objeto de estudiar el comportamiento histerético del perfil MM, con y sin rigidizadores.

  17. New evidence of effusive and explosive volcanism in the Lower Carboniferous formations of the Moroccan Central Hercynian Massif: Geochemical data and geodynamic significance

    Ntarmouchant, A.; Smaili, H.; Bento dos Santos, T.; Dahire, M.; Sabri, K.; Ribeiro, M. L.; Driouch, Y.; Santos, R.; Calvo, R.

    2016-03-01

    The Azrou-Khénifra basin, located in the SE sector of the Moroccan Central Hercynian Massif of the Western Meseta of Morocco comprises volcanic and volcanoclastic rocks where two magmatic sequences can be distinguished: i) the Dhar Lahmar Sequence, composed of Upper Visean basaltic lava flows and pyroclastic deposits; and ii) the Kef Al Asri Sequence, composed of Visean - Serpukhovian intermediate to acid rocks. A continuous spatial and temporal evolution between the two volcano-sedimentary sequences was observed during the detailed geological work performed in the studied area. Petrography and geochemical studies additionally suggest a continuous compositional evolution from the more basic magmatic rocks to the intermediate/acid rocks, which implies a cogenetic magmatic differentiation controlled by crystal fractionation (with minor crustal assimilation) of a calc-alkaline trend magmatic suite. The inferred magmatic evolution is consistent with a geodynamic environment of an orogenic zone within an active continental margin setting. This partly explosive Visean - Serpukhovian volcanism, identified for the first time in the Western Meseta of Morocco, displays very similar petrographic and geochemical characteristics to its Eastern Meseta analogues, which implies that the emplacement of these magmatic rocks must have occurred in similar collisional geodynamic settings for both major geological domains, further constraining the evolution of this major crustal segment within the Carboniferous events that shaped the Hercynian Orogeny.

  18. Introduction to geochemistry and its applications. Tome 2. Transfer of elements. Geochemical evolution of exogenous domains

    Hagemann, R.; Treuil, M.

    1998-01-01

    This second tome of the introduction to geochemistry and its applications is divided into 9 chapters dealing with: the chloro-fluoro-methanes as tracers of the oceanic circulation; the study of radioactive disequilibria and their applications; the submarine hydrothermal activity; geochemistry and diagenesis, example of the Trias and Lias of Ardeche (France); the chemistry of deep waters in granitic environment, application to the underground storage of radioactive wastes; the impact of volcanism on atmosphere chemistry; the role of methane and light hydrocarbons in the atmosphere; the challenges of carbon; and the polar caps as recorders of atmosphere geochemistry and climates. (J.S.)

  19. Modern and ancient geochemical constraints on Proterozoic atmosphere-ocean redox evolution

    Hardisty, D. S.; Horner, T. J.; Wankel, S. D.; Lu, Z.; Lyons, T.; Nielsen, S.

    2017-12-01

    A detailed understanding of the spatiotemporal oxygenation of Earth's atmosphere-ocean system through the Precambrian has important implications for the environments capable of sustaining early eukaryotic life and the evolving oxidant budget of subducted sediments. Proxy records suggest an anoxic Fe-rich deep ocean through much of the Precambrian and atmospheric and surface-ocean oxygenation that started in earnest at the Paleoproterozoic Great Oxidation Event (GOE). The marine photic zone represented the initial site of oxygen production and accumulation via cyanobacteria, yet our understanding of surface-ocean oxygen contents and the extent and timing of oxygen propagation and exchange between the atmosphere and deeper ocean are limited. Here, we present an updated perspective of the constraints on atmospheric, surface-ocean, and deep-ocean oxygen contents starting at the GOE. Our research uses the iodine content of Proterozoic carbonates as a tracer of dissolved iodate in the shallow ocean, a redox-sensitive species quantitatively reduced in modern oxygen minimum zones. We supplement our understanding of the ancient record with novel experiments examining the rates of iodate production from oxygenated marine environments based on seawater incubations. Combining new data from iodine with published shallow marine (Ce anomaly, N isotopes) and atmospheric redox proxies, we provide an integrated view of the vertical redox structure of the atmosphere and ocean across the Proterozoic.

  20. Geochemical constraints on the evolution of mafic and felsic rocks in ...

    basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption ..... Canary Hill of Hazaribagh town which is believed to retain record of the ... beam current of 10 nA at the Electron Microprobe. Analyzer Laboratory ...

  1. Effects of Subsurface Microbial Ecology on Geochemical Evolution of a Crude-Oil Contaminated Aquifer

    Bekins, B. A.; Cozzarelli, I. M.; Godsy, E. M.; Warren, E.; Hostettler, F. D.

    2001-12-01

    We have identified several subsurface habitats for microorganisms in a crude oil contaminated located near Bemidji, Minnesota. These aquifer habitats include: 1) the unsaturated zone contaminated by hydrocarbon vapors, 2) the zones containing separate-phase crude oil, and 3) the aqueous-phase contaminant plume. The surficial glacial outwash aquifer was contaminated when a crude oil pipeline burst in 1979. We analyzed sediment samples from the contaminated aquifer for the most probable numbers of aerobes, iron reducers, fermenters, and three types of methanogens. The microbial data were then related to gas, water, and oil chemistry, sediment extractable iron, and permeability. The microbial populations in the various contaminated subsurface habitats each have special characteristics and these affect the aquifer and contaminant chemistry. In the eight-meter-thick, vapor-contaminated vadose zone, a substantial aerobic population has developed that is supported by hydrocarbon vapors and methane. Microbial numbers peak in locations where access to both hydrocarbons and nutrients infiltrating from the surface is maximized. The activity of this population prevents hydrocarbon vapors from reaching the land surface. In the zone where separate-phase crude oil is present, a consortium of methanogens and fermenters dominates the populations both above and below the water table. Moreover, gas concentration data indicate that methane production has been active in the oily zone since at least 1986. Analyses of the extracted separate-phase oil show that substantial degradation of C15 -C35 n-alkanes has occurred since 1983, raising the possibility that significant degradation of C15 and higher n-alkanes has occurred under methanogenic conditions. However, lab and field data suggest that toxic inhibition by crude oil results in fewer acetate-utilizing methanogens within and adjacent to the separate-phase oil. Data from this and other sites indicate that toxic inhibition of acetoclastic methanogenesis in the proximity of separate phase contaminant sources may result in build-up of acetate in contaminant plumes. Within the aqueous-phase contaminant plume steep vertical hydrocarbon concentration gradients are associated with sharp transitions in the dominant microbial population. In the 20 years since the aquifer became contaminated, sediment iron oxides have been depleted and the dominant physiologic type has changed in areas of high contaminant flux from iron reducing to methanogenic. Thus, methanogens are found in high permeability horizons down gradient from the oil while iron reducers persist in low permeability zones. Expansion of the methanogenic zone over time has resulted in a concomitant increase in the aquifer volume contaminated with the highest concentrations of benzene and ethylbenzene.

  2. Petro-geochemical constraints on the source and evolution of magmas at El Misti volcano (Peru)

    Rivera, M.; Martin, H.; Le Pennec, Jean-Luc; Thouret, J. C.; Gourgaud, A.; Gerbe, M. C.

    2017-01-01

    El Misti volcano, a large and hazardous edifice of the Andean Central Volcanic Zone (CVZ) of southern Peru, consists of four main growth stages. Misti 1 (>112 ka) is an old stratovolcano partly concealed by two younger stratocones (Misti 2, 112-40 ka; Misti 3, 38-11 ka), capped in turn by a recent summit cone (Misti 4,

  3. Emplacement and geochemical evolution of eocene plutonic rocks in the Colville batholith

    Holder, R.W.

    1986-01-01

    Eocene plutonic rocks in the Colville batholith are divided on the basis of field evidence and chemical composition into, in order of decreasing age, (1) several calc-alkalic biotite-hornblende monzodiorite to granodiorite intrusions referred to as the Devils Elbow suite, and (2) compositionally variable calc-alkalic to alkali-calcic intrusions referred to as the Herron Creek suite. These Eocene suites are distinct from older, more voluminous, leucocratic granite and granodiorite intrusions, designated the Keller Butte suite, which are calcic and characteristically lack hornblende. Results of qualitative and computer modeling of major element variation and quantitative models of trace element variation in the chemically coherent Bridge Creek intrusions, a member of the Herron Creek suite, are compatible with fractionation of plagioclase feldspar + hornblende + biotite + magnetite + apatite from a parent magma of andesitic composition to account for the observed variation. Strongly curved variation trends preclude mixing as the primary mechanism for the observed variation. It is suggested that parallel variation trends in the other Eocene intrusions are also the result of crystal fractionation. Lateral chemical variations including a decrease in silica saturation suggest the chemical characteristics of these rocks reflect those of parental magmas derived from the mantle, with an unknown amount of crustal contribution. Rotated and angular xenoliths, discordant contacts, and temporal and spatial proximity to graben structures indicate that the Eocene plutons were passively implaced into the upper crust along graben-bounding faults during graben formation, the earlier stages of which appear to have been contemporaneous with regional mylonitic deformation

  4. Geochemical signatures of tephras from Quaternary Antarctic Peninsula volcanoes

    Kraus,Stefan; Kurbatov,Andrei; Yates,Martin

    2013-01-01

    In the northern Antarctic Peninsula area, at least 12 Late Plelstocene-Holocene volcanic centers could be potential sources of tephra layers in the region. We present unique geochemical fingerprints for ten of these volcanoes using major, trace, rare earth element, and isotope data from 95 samples of tephra and other eruption products. The volcanoes have predominantly basaltic and basaltic andesitic compositions. The Nb/Y ratio proves useful to distinguish between volcanic centers located on ...

  5. Geochemical prospecting for rare earth elements using termite mound materials

    Horiuchi, Yu; Ohno, Tetsuji; Hoshino, Mihoko; Shin, Ki-Cheol; Murakami, Hiroyasu; Tsunematsu, Maiko; Watanabe, Yasushi

    2014-12-01

    The Blockspruit fluorite prospect, located in North West State of the Republic of South Africa, occurs within an actinolite rock zone that was emplaced into the Kenkelbos-type granite of Proterozoic age. There are a large number of termite mounds in the prospect. For geochemical prospecting for rare earth elements (REEs), in total, 200 samples of termite mound material were collected from actinolite rock and granite zones in the prospect. Geochemical analyses of these termite mound materials were conducted by two methods: portable X-ray fluorescence (XRF) spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS). Comparison of the two methods broadly indicates positive correlations of REEs (La, Ce, Pr, Nd, and Y), in particular Y and La having a strong correlation. As the result of modal abundance analyses, the actinolite rock at surface mainly consists of ferro-actinolite (89.89 wt%) and includes xenotime (0.26 wt%) and monazite (0.21 wt%) grains as REE minerals. Termite mound materials from actinolite rock also contain xenotime (0.27 wt%) and monazite (0.41 wt%) grains. In addition, termite mound materials from the actinolite rock zone have high hematite and Fe silicate contents compared to those from granite zone. These relationships suggest that REE minerals in termite mound materials originate form actinolite rock. Geochemical anomaly maps of Y, La, and Fe concentrations drawn based on the result of the portable XRF analyses show that high concentrations of these elements trend from SW to NE which broadly correspond to occurrences of actinolite body. These results indicate that termite mounds are an effective tool for REE geochemical prospection in the study area for both light REEs and Y, but a more detailed survey is required to establish the distribution of the actinolite rock body.

  6. Geochemical normalization of magnetic susceptibility for investigation of floodplain sediments

    Faměra, Martin; Matys Grygar, Tomáš; Elznicová, J.; Grison, Hana

    2018-01-01

    Roč. 77, č. 5 (2018), č. článku 189. ISSN 1866-6280 R&D Projects: GA ČR(CZ) GA15-00340S Institutional support: RVO:61388980 ; RVO:67985530 Keywords : Background functions * Geochemical normalization * Mass-specific magnetic susceptibility * Post-depositional processes * Provenance Subject RIV: DD - Geochemistry OBOR OECD: Environmental sciences (social aspects to be 5.7); Geology (GFU-E) Impact factor: 1.569, year: 2016

  7. Regional geochemical prospecting of uranium in the Amazon region

    Zenker, A.O.; Hohn, H.

    1982-01-01

    A regional geochemical prospecting program for uranium in the Serra dos Carajas area, south of Para, was performed by NUCLEBRAS using stream sediment samples obtained from other companies acting in this area. The results of the survey are presented compared to regional geology and an aerial total count map. The different data showed a good correlation, particularly in areas mapped regionally as granitic rocks. (Author) [pt

  8. Use of natural geochemical tracers to improve reservoir simulation models

    Huseby, O.; Chatzichristos, C.; Sagen, J.; Muller, J.; Kleven, R.; Bennett, B.; Larter, S.; Stubos, A.K.; Adler, P.M.

    2005-01-01

    This article introduces a methodology for integrating geochemical data in reservoir simulations to improve hydrocarbon reservoir models. The method exploits routine measurements of naturally existing inorganic ion concentration in hydrocarbon reservoir production wells, and uses the ions as non-partitioning water tracers. The methodology is demonstrated on a North Sea field case, using the field's reservoir model, together with geochemical information (SO{sub 4}{sup 2}, Mg{sup 2+} K{sup +}, Ba{sup 2+}, Sr{sup 2+}, Ca{sup 2+}, Cl{sup -} concentrations) from the field's producers. From the data-set we show that some of the ions behave almost as ideal sea-water tracers, i.e. without sorption to the matrix, ion-exchange with the matrix or scale-formation with other ions in the formation water. Moreover, the dataset shows that ion concentrations in pure formation-water vary according to formation. This information can be used to allocate produced water to specific water-producing zones in commingled production. Based on an evaluation of the applicability of the available data, one inorganic component, SO{sub 4}{sup 2}, is used as a natural seawater tracer. Introducing SO{sub 4}{sup 2} as a natural tracer in a tracer simulation has revealed a potential for improvements of the reservoir model. By tracking the injected seawater it was possible to identify underestimated fault lengths in the reservoir model. The demonstration confirms that geochemical data are valuable additional information for reservoir characterization, and shows that integration of geochemical data into reservoir simulation procedures can improve reservoir simulation models. (author)

  9. Geochemical characterization of Parana Basin volcanic rocks: petrogenetic implications

    Marques, L.S.

    1988-01-01

    A detailed study of the geochemical characteristics of Parana Basin volcanic rocks is presented. The results are based on the analyses of major and trace elements of 158 samples. Ninety three of these volcanic samples belong to 8 flow sequences from Rio Grande do Sul and Santa Catarina States. The remaining sixty five samples are distributed over the entire basin. In order to study the influence of crustal contamination processes in changing chemical characteristics of the volcanic rocks, 47 samples representative of the crystalline basement of the southern and southeastern Parana Basin were also analysed. Several petrogenetic models were tested to explain the compocional variability of the volcanic rocks, in particular those of southern region. The results obtained sugest an assimilation-fractional crystallization process as viable to explain the differences of both the chemical characteristics and Sr isotope initial ratios observed in basic and intermediate rocks. A model involving melting processes of basic material, trapped at the base of the crust, with composition similar to low and high TiO 2 basalts appears to be a possibility to originate the Palmas and Chapeco acid melts, respectively. The study of ''uncontaminated'' or poorly contaminated low TiO 2 basic rocks from the southern, central and northern regions shows the existence of significant differences in the geochemical charactetistics according to their geographical occurrence. A similar geochemical diversity is also observed in high TiO 2 basalts and Chapeco volcanics. Differences in incompatible element ratios between low and high TiO 2 ''uncontaminated'' or poorly contaminated basalts suggest that they could have been produced by different degrees of melting in a garnet peridotite source. Geochemical and isotopic (Sr and Nd) data also support the view that basalts from northern and southern regions of Parana Basin originated from mantle source with different composition. (author) [pt

  10. New results for Palaeozoic volcanic phases in the Prague Basin – magnetic and geochemical studies of Lištice, Czech Republic

    Tiiu Elbra

    2015-02-01

    Full Text Available Palaeo-, rock magnetic and geochemical studies were conducted on volcanic samples from the Lištice area to improve the knowledge of Palaeozoic volcanic evolution in the Prague Basin. The magnetic data display no significant differences between two studied localities, indicating one magnetizing event for both localities. Geochemical data suggest that Lištice basalt could have originated from deep melting of the garnet peridotite mantle source during the attenuation and rifting of the continental lithosphere connected with asthenospheric mantle upwelling. The dataset furthermore supports the evidence of syn- or post-intrusive fluid interactions and low-temperature stages of alteration. The Ti-magnetite within amygdales of the samples was found to be carrying the characteristic remanent magnetization and reflects probably the Permo-Carboniferous remagnetization of volcanic phases.

  11. The geochemical environment of nuclear fuel waste disposal

    Gascoyne, M.

    1995-01-01

    The concept for disposal of Canada's nuclear fuel waste in a geologic environment on the Canadian Shield has recently been presented by Atomic Energy of Canada Limited (AECL) to governments, scientists, and the public, for review. An important part of this concept concerns the geochemical environment of a disposal vault and includes consideration of rock and groundwater compositions, geochemical interactions between rocks, groundwaters, and emplaced vault materials, and the influences and significance of anthropogenic and microbiological effects following closure of the vault. This paper summarizes the disposal concept and examines aspects of the geochemical environment. The presence of saline groundwaters and reducing conditions at proposed vault depths (500-1000 m) in the Canadian Shield has an important bearing on the stability of the used nuclear fuel, its container, and buffer and backfill materials. The potential for introduction of anthropogenic contaminants and microbes during site investigations and vault excavation, operation, and sealing is described with examples from AECL's research areas on the Shield and in their underground research laboratory in southeastern Manitoba. (author)

  12. Evaluation of disposal site geochemical performance using a containment factor

    Lerman, A.; Domenico, P.A.; Bartlett, J.W.

    1988-01-01

    The containment factor is a measure of retention by geologic setting of wastes released from a repository. The factor is alternatively defined either in terms of several measurable hydrological and geochemical parameters, or in terms of amounts of waste components that may be released to the geologic setting and, subsequently, to the environment. Containment factors for individual waste components in a given geologic setting are functions of groundwater to rock volume ratios, sorption or exchange characteristics of the rocks, and containment time to groundwater travel time ratios. For high-level radioactive wastes, containment factors based on the NRC and EPA limit values for cumulative releases from waste and to the environment provide a measure of the geochemical performance of the geologic setting in tuff, basalt, and salt. The containment factor values for individual nuclides from high-level wastes indicate that for some of the nuclides containment may be achieved by groundwater travel time along. For other nuclides, additional performance functions need to be allocated to geochemical retention by such processes as sorption, ion-exchange or precipitation

  13. In situ geochemical properties of clays subject to thermal loading

    Chapman, N.A.

    1980-01-01

    Compositional variation and geochemical environment in an argillaceous unit are a function of age, depth of burial and mode of origin. This paper considers the variation limits likely to be encountered in potential repository host rocks and examines the significance of factors such as porosity, pore-fluid pressure, total fluid content, and major and accessory mineral component behaviors in controlling the geochemical environment in the neighbourhood of a thermally active waste canister. Particular attention is paid to the use of Eh-pH diagrams in assessing corrosion environments and nuclide speciation. The paper outlines the variables which must be considered when endeavouring to interpret such plots (e.g. temperature, concentration, concurrent reactions and probabilities) and uses the behavior of various iron minerals found in clay deposits under specific conditions to illustrate the complexities. The overall thermal stability of various clay and accessory minerals is discussed and extended to attempt to predict behavior under deep repository conditions, using available data on the diagenetic characteristics of clay-rich sediments. The physical behavior of fluids in plastic clays is considered and methods evaluated for deriving induced geochemical conditions in a thermally active repository. The latter section is particularly related to canister corrosion studies, in situ experiments, and waste dissolution parameters

  14. The role of atomic absorption spectrometry in geochemical exploration

    Viets, J.G.; O'Leary, R. M.

    1992-01-01

    In this paper we briefly describe the principles of atomic absorption spectrometry (AAS) and the basic hardware components necessary to make measurements of analyte concentrations. Then we discuss a variety of methods that have been developed for the introduction of analyte atoms into the light path of the spectrophotometer. This section deals with sample digestion, elimination of interferences, and optimum production of ground-state atoms, all critical considerations when choosing an AAS method. Other critical considerations are cost, speed, simplicity, precision, and applicability of the method to the wide range of materials sampled in geochemical exploration. We cannot attempt to review all of the AAS methods developed for geological materials but instead will restrict our discussion to some of those appropriate for geochemical exploration. Our background and familiarity are reflected in the methods we discuss, and we have no doubt overlooked many good methods. Our discussion should therefore be considered a starting point in finding the right method for the problem, rather than the end of the search. Finally, we discuss the future of AAS relative to other instrumental techniques and the promising new directions for AAS in geochemical exploration. ?? 1992.

  15. Proyecto Docente e Investigador. Catedrático de Universidad. Perfil Docente: Ingeniería del Software y Gobierno de Tecnologías de la Información. Perfil Investigador: Tecnologías del Aprendizaje. Área de Ciencia de la Computación e Inteligencia Artificial

    García-Peñalvo, F. J.

    2018-01-01

    Proyecto Docente e Investigador. Catedrático de Universidad. Perfil Docente: Ingeniería del Software y Gobierno de Tecnologías de la Información. Perfil Investigador: Tecnologías del Aprendizaje. Área de Ciencia de la Computación e Inteligencia Artificial. Universidad de Salamanca 15 de mayo de 2018

  16. Treinamento desportivo: perfil acadêmico dos líderes de grupos de estudo brasileiros

    Hudson Fabricius Peres Nunes

    Full Text Available Resumo Este estudo objetivou caracterizar o perfil acadêmico dos professores líderes de grupos de estudo brasileiros que desenvolvem pesquisas na subárea de treinamento desportivo. A metodologia usada foi a pesquisa descritiva dos currículos acadêmicos encontrados no banco de dados da Plataforma Lattes, tendo em vista que os dados quantitativos foram interpretados a partir da análise qualitativa das informações. Os resultados revelam que os grupos estão vinculados principalmente a universidades da Região Sudeste, a maioria dos líderes é doutor e a prevalência da produção científica está relacionada à preparação orgânica, pedagógica, psicológica e desportiva dos atletas.

  17. Determinantes y perfiles de la participacion laboral en Colombia en el periodo 2002-2013

    Nestor Ivan Gonzalez-Quintero

    2015-06-01

    Full Text Available Para establecer los determinantes de la participación laboral en Colombia, sobre una muestra de individuos con representatividad nacional, así como el aporte de cada uno de estos determinantes a la dinámica de la tasa de participación en el periodo 2002-2013, se estiman modelos tipo probit y se establecen perfiles de participación, a partir de las probabilidades estimadas, condicionadas para cuatro grupos de mujeres y hombres en diferentes rangos de edad. Se concluye que alcanzar niveles de educación superior, contar con un ingreso por pensión y la presencia de menores en el hogar son factores importantes para explicar tal dinámica.

  18. Implantación y perfil de los sindicatos en Euskadi

    ANDONI KAIERO URÍA

    1991-01-01

    Full Text Available El trabajo utiliza los resultados de las elecciones sindicales de 1980, 1982 y 1986 para describir el aspecto sindical de Euskal Herria. Análisis de la distribución de los votos a los sindicatos (elecciones de 1982 en los colegios electorales y en las empresas del territorio y de los sectores es utilizado para llegar a una primera aproximación de las características de los sindicatos. El perfil de los sindicatos mayoritarios se completa con los resultados de una encuesta, llevada a cabo en 1982, que ha permitido conocer la afiliación sindical y algunos datos personales y de opinión de los afiliados y votantes a los sindicatos.

  19. Perfil dos professores de ensino medio profissionalizante de enfermagem na região de Piracicaba

    Greicelene Aparecida Hespanhol Bassinello

    2002-01-01

    Resumo: O objetivo de conhecer as escolas e traçar o perfil dos professores de nível médio profissionalizante de enfermagem na região de Piracicaba e discuti-lo à luz da sociologia das profissões, justifica-se por questionamentos da prática profissional como enfermeiro-docente, sobretudo em relação à prática pedagógica. Para tanto resgatou-se a história do ensino de enfermagem no Brasil, com ênfase no ensino médio profissionalizante e no cenário de formação de docente de nível médio. A caract...

  20. PERFIL DEL TURISTA DE FESTIVALES: EL CASO DEL FESTIVAL INTERNACIONAL DE LAS CULTURAS PIRINEOS SUR

    María José Barlés Arizón

    2012-01-01

    Full Text Available El Festival Internacional de las Culturas Pirineos Sur es un festival consolidado y de éxito. Pese a ello, su organizador, la Diputación Provincial de Huesca, necesitaba conocer con detalle el perfil del público asistente, el grado de fidelidad que genera y hasta qué punto supone un recurso turístico para la zona. Para cumplir dichos objetivos se llevó a cabo una encuesta in situ a 664 personas. Los resultados ponen de manifiesto que la edad influye tanto en las actividades a las que se asiste como en el alojamiento elegido y el gasto. El grado de fidelidad es elevado. El Festival es claramente un recurso turístico de gran importancia para el Valle de Tena, lugar de celebración del evento.

  1. Perfil lipídico de ovos desidratados com ênfase no seu teor de gorduras trans

    Guassi,Silce Adeline Danelon; Salgado,Jocelem Mastrodi; Lanna,Dante Pazzanese Duarte

    2008-01-01

    O presente trabalho objetivou a determinação do perfil lipídico de ovos integrais desidratados, bem como de gemas desidratadas, a fim de enfatizar seu conteúdo de ácidos graxos de configuração trans. A fração lipídica das amostras foi extraída com hexano/isopropanol e, a seguir, metilada. Os ácidos graxos foram identificados via cromatografia gasosa. Constatou-se que a natureza lipídica dos ovos tem caráter predominantemente insaturado: 63,65% dos lipídios totais nos ovos integrais e 62,63% n...

  2. Hacia una caracterización del lugar y el perfil del elector colombiano

    Víctor Arteaga Villa

    2011-01-01

    Full Text Available El artículo presenta una aproximación a la caracterización del lugar que se le ha dado y del perfil con que se ha configurado el elector colombiano. A partir de la metodología del estado de arte, analiza la literatura más relevante que se ha producido en torno a la relación elecciones-partidos políticos-elector y señala las categorías de énfasis que se han privilegiado. Además, a partir del establecimiento de las razones de la decisión y de la orientación del voto, enlista algunos de los factores que, desde motivaciones muy particulares -cívicas (deber ser del ciudadano, cínicas (ser de la contraprestación-, inducen al elector a su participación.

  3. Convergencia Europea y profesorado. Hacia un nuevo perfil para el aprendizaje flexible

    Mª OLGA ESCANDELL BERMÚDEZ

    2005-01-01

    práctica, de la profesión docente, de la cultura del profesorado universitario, de sus competencias y su saber hacer. Su actuación profesional ha de ajustarse a unas exigencias de calidad que demandan un fuerte compromiso personal y laboral que pasa, sin duda, por aceptar que el EEES supondrá un cambio sustancial del proceso de enseñanza-aprendizaje convencional y electrónico (e-learning; en los perfiles profesionales que tendrán que adaptarse a las demandas crecientes de una sociedad de la información y del conocimiento y, también, en la forma de concebir la formación a lo largo de la vida (long life learning.

  4. A Spatially Constrained Multi-autoencoder Approach for Multivariate Geochemical Anomaly Recognition

    Lirong, C.; Qingfeng, G.; Renguang, Z.; Yihui, X.

    2017-12-01

    Separating and recognizing geochemical anomalies from the geochemical background is one of the key tasks in geochemical exploration. Many methods have been developed, such as calculating the mean ±2 standard deviation, and fractal/multifractal models. In recent years, deep autoencoder, a deep learning approach, have been used for multivariate geochemical anomaly recognition. While being able to deal with the non-normal distributions of geochemical concentrations and the non-linear relationships among them, this self-supervised learning method does not take into account the spatial heterogeneity of geochemical background and the uncertainty induced by the randomly initialized weights of neurons, leading to ineffective recognition of weak anomalies. In this paper, we introduce a spatially constrained multi-autoencoder (SCMA) approach for multivariate geochemical anomaly recognition, which includes two steps: spatial partitioning and anomaly score computation. The first step divides the study area into multiple sub-regions to segregate the geochemical background, by grouping the geochemical samples through K-means clustering, spatial filtering, and spatial constraining rules. In the second step, for each sub-region, a group of autoencoder neural networks are constructed with an identical structure but different initial weights on neurons. Each autoencoder is trained using the geochemical samples within the corresponding sub-region to learn the sub-regional geochemical background. The best autoencoder of a group is chosen as the final model for the corresponding sub-region. The anomaly score at each location can then be calculated as the euclidean distance between the observed concentrations and reconstructed concentrations of geochemical elements.The experiments using the geochemical data and Fe deposits in the southwestern Fujian province of China showed that our SCMA approach greatly improved the recognition of weak anomalies, achieving the AUC of 0.89, compared

  5. Animal evolution

    Nielsen, Claus

    This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes it possi......This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes...

  6. Experiencias y consideraciones en la conformación de perfiles de competencias

    Jorge Haddad Barthelemy

    2007-06-01

    Full Text Available La investigación se desarrolló en el Banco Popular de Ahorro, en Santiago de Cuba, donde durante tres años se trabajó en la conformación de diversos Perfiles de Competencias Directivos y un Perfil Único o Genérico, adaptable a cualquier directivo de esta institución y otras organizaciones. Se obtuvieron y confirmaron diversas concepciones de competencias como las simples, compuestas, básicas, secundarias, genéricas y especificas, importantes y claves, y diversas experiencias como la importancia de establecer sus dimensiones, las contradicciones y similitudes entre competencias y valores, su posibilidad de enfocarse hacia diversas tareas organizacionales, como el mejoramiento del medio ambiente, la calidad del trabajo de mandos superiores, intermedios, técnicos y obreros, con el objetivo de perfeccionar la gestión del desempeño de los trabajadores y la organización.---This study was carried out in the Banco Popular de Ahorro, in Santiago de Cuba. During three years, different Profiles of Directive Competitions were made as well as a Unique or Generic Profile, adaptable to any executive of this or other organizations. Different conceptions of competitions were obtained and confirmed, such as simple, compound, basic, secondary, generic and specific competitions. Various experiences were confirmed, such as the importance of establishing their dimensions, contradictions and similarities between competitions and values, their possibility to focus on different organizational tasks, such as the improvement of the environment, the quality in the performance of top and intermediate management, technicians and workers, with the objective of improving the performance of the employees and the organization.

  7. O Secretário Executivo com Perfil de Relações Públicas

    Jéssica Aparecida Artico

    2013-06-01

    Full Text Available As diversas evoluções teórica e prática do perfil do Secretário Executivo (SE tornam-no staff, pois atua de maneira multifuncional, como assessor e/ou gestor, na alta administração. Além disso, o profissional exerce papel de “cartão de visita” da empresa onde trabalha, visto que é a ponte de comunicação interna (entre os níveis operacional-tático-estratégico e externa (empresa-mercado: fornecedores, clientes, parceiros – sociedade em geral, ademais de assessorar em negociações e em gestão/organização de eventos empresariais. Por isso, possui o papel de manter a identidade (o que a empresa realmente é e estabelecer, adequadamente, a imagem (como a empresa deve ser vista perante a sociedade da organização, considerando sua missão, visão, metas, nicho de atuação e demais quesitos relacionados. Nesse sentido, observa-se a necessidade de o SE obter conhecimentos relacionados à atuação do profissional de Relações Públicas (RP, para exercer seu papel com eficiência e eficácia. Assim, este estudo objetiva analisar o SE com perfil de RP e como essa área complementa a outra.DOI:10.7769/gesec.v4i1.90

  8. Perfiles de adolescentes on line y su comportamiento en el medio interactivo

    Belinda de Frutos Torres

    2014-01-01

    Full Text Available Normal 0 21 false false false ES X-NONE X-NONE  Internet se ha convertido en el medio de referencia entre los jóvenes y su uso está muy extendido se pueden identificar perfiles de usuarios respecto a la actitud hacia el medio interactivo y su estilo de navegación. El objetivo del estudio se centra en identificar dicho perfiles y poner a prueba su relación con su comportamiento en Internet. El estudio utiliza una metodología correlacional, con una muestra de conveniencia formada por 320 jóvenes entre 14 y 19 años procedentes de varios centros de educación secundaria. Los resultados muestran que se pueden identificar varios patrones de los adolescentes en el consumo de medios interactivos en función de su estilo de navegación y actitud hacia el medio. El estilo de navegación exploratorio está asociado a participar en actividades comerciales de la red y a dedicar más tiempo al medio interactivo particularmente durante la semana. Así mismo, los jóvenes que se enfrentan al medio con una actitud más confiada y ven el medio como un vehículo de socialización y éxito social también dedican más tiempo al medio interactivo y participan en mayor medida de las propuestas publicitarias que se ofrecen en Internet.  

  9. Perfil dos discentes ingressos do Centro de Ciências da Saúde UFPE

    Ludmila Galindo França Gurgel

    Full Text Available A busca pelo conhecimento das características e da opinião dos estudantes do nível superior fornece importantes subsídios para o planejamento e reorganização do desenvolvimento acadêmico. Com o objetivo de traçar o perfil do aluno do Centro de Ciências da Saúde da Universidade Federal de Pernambuco (UFPE, foram distribuídos formulários aos acadêmicos do 2º período, contendo perguntas referentes aos seus aspectos socioeconômicos e pessoais. O perfil dos estudantes (n = 210 caracterizou-se por um predomínio feminino, com idades entre 19 e 21 anos, provenientes de escolas privadas e classes sociais economicamente mais favorecidas, que receberam grande influência do núcleo familiar na escolha da profissão. A maioria dos estudantes não estava matriculada nos cursos de primeira opção, porém possuía alta expectativa com relação ao curso, considerando-o correspondente às suas expectativas. Após formados pretendem realizar algum curso de pós-graduação e trabalhar no serviço público. No entanto, persiste um problema relativo à escolha da profissão, regulada pela condição socioeconômica e influência familiar.

  10. Perfil lipídico e uso de anti-TNF-α

    Antonio Carlos Ferraz Filho

    2013-10-01

    Full Text Available O uso do anti-TNF alfa tem sido associado a várias alterações no perfil lipídico, embora o estudo dessas alterações tenha gerado resultados que ainda são conflitantes. O conhecimento desse fato é de grande importância quando se observa a associação entre doenças reumáticas e aterogenêse acelerada. Esta pesquisa foi feita com o intuito de verificar alterações no perfil lipídico de usuários de anti-TNF-α na população do sul do Brasil e sua associação com tempo de uso, indicações, gênero do paciente e tipo de anti-TNF. Para tanto, analisaram-se os perfis de colesterol total (TC, HDL colesterol (HDLc, LDL colesterol (LDLc, índice aterogênico (IAT e triglicerídeos (TGs de 58 pacientes (42 com artrite reumatoide e 16 com espondiloartrites antes e depois do uso desse medicamento por um tempo mediano de 16,0 meses. Não se observaram alterações nos níveis de CT, HDLc, LDLc e IAT (P = NS. Todavia, houve um aumento significativo nos níveis de TGs (P = 0,03. A diferença mediana dos valores de TGs entre primeira e segunda medidas foi de 16 mg/dL, e esse aumento não estava associado ao gênero do paciente, tempo de uso, indicação de uso ou tipo de anti-TNF-α (P = NS. Concluiu-se que o uso de anti TNF-α está associado com aumento nos valores de TGs.

  11. Perfil lipídico sérico de ratos tratados com surfactante

    Karina Ferreira de Castro

    2012-06-01

    Full Text Available A aterosclerose é uma doença multifatorial, lenta e progressiva e a hiperlipidemia um dos fatores potenciais no desenvolvimento de doenças cardíacas ateroscleróticas. As vantagens da indução das dislipidemias experimentais são a produção de lesões ateromatosas em curto espaço de tempo; adequado controle dietético e fatores ambientais; a possibilidade de estudos sobre a reversibilidade de lesões ateroscleróticas e ensaios pré-clínicos de substâncias hipolipidêmicas. Este estudo visou avaliar o perfil lipídico sérico de ratos tratados com surfactante. Foram utilizados 28 ratos Wistar, machos, albinos, adultos e hígidos. Estes foram distribuídos em quatro grupos experimentais formados por sete animais cada, a saber: Grupo I – (controle; Grupo II – tratado com tyloxapol, na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante duas semanas; Grupo III – tratado com tyloxapol na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante três semanas; Grupo IV – tratado com tyloxapol na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante quatro semanas. Na avaliação do perfil lipídico, os valores de triacilgliceróis e HDL demonstraram que o grupo III diferiu significativamente do grupo I e os valores de colesterol total e LDL indicaram que o grupo I diferiu significativamente dos grupos II, III e IV. Conclui-se que o surfactante tyloxapol foi efetivo na indução da hiperlipidemia.

  12. Comunicar la ciencia: El perfil del periodista científico en España

    2018-04-01

    Full Text Available El periodista científico es uno de los principales responsables en la cadena de transmisión e interpretación hacia la sociedad de toda noticia, novedad o avance de carácter científico. A su vez, una información científica rigurosa, comprensible y de calidad es, además, un indicador del desarrollo social. La demanda de este tipo de información crece cada día en nuestras sociedades, tanto por parte de los gobiernos como de los ciudadanos. Por este motivo, y con el objetivo de esclarecer cuál es el perfil de los periodistas científicos que deben lidiar con tal responsabilidad, cómo se han formado y cómo ellos mismos creen que deberían haber sido formados, en esta investigación analizamos los perfiles académicos (tanto el real como el ideal de estos profesionales en España. Utilizando una metodología etnográfica, basada en entrevistas, cuestionarios y focus group con periodistas científicos que trabajan en los principales medios españoles, analizamos su trayectoria académica y sus consideraciones y propuestas al respecto. Los resultados muestran un escenario complejo y heterogéneo, pero también revelan que la mayoría de los periodistas científicos no solo no goza de una titulación universitaria en el ámbito científico, sino que tampoco la considera necesaria. Los periodistas científicos son críticos con el sistema educativo y consideran que la mejor forma de aprender es trabajar en los medios, más que estudiar.

  13. Perfil dos acidentes de trabalho em refinaria de petróleo

    Carlos Augusto Vaz de Souza

    2002-10-01

    Full Text Available OBJETIVO: O trabalho em refinarias de petróleo envolve o risco de acidentes triviais e ampliados. Os dados nacionais apontam para a relevância dos acidentes nesse setor. Assim, realizou-se pesquisa com o objetivo de identificar o perfil e avaliar a adequação dos instrumentos de registro dos acidentes de trabalho em refinaria. MÉTODOS: Foram padronizadas e analisadas informações referentes aos acidentes de trabalho nas atividades de produção e manutenção registradas em uma refinaria de petróleo do Estado do Rio de Janeiro, no ano de 1997. A população estudada constituiu-se de 153 pessoas, sendo 83 trabalhadores próprios lesionados e 69 trabalhadores terceirizados lesionados. As variáveis analisadas foram: tipo de acidente, modo de operação e função do trabalhador lesionado. RESULTADOS: Em relação aos trabalhadores próprios, houve predominância dos chamados acidentes triviais (54,2% e quanto ao modo de operação, houve concentração dos acidentes nas atividades em operação normal (62,9%. Quanto aos trabalhadores terceirizados, os acidentes triviais (75,5% tiveram predominância mais acentuada; e quanto ao modo de operação, houve um domínio quase total dos acidentes na atividade de manutenção (96,8%. CONCLUSÕES: Os resultados mostraram um perfil de acidentes que afeta principalmente os níveis hierárquicos mais baixos, concentrando-se de modo geral nas atividades de manutenção, além da necessidade de modificações no sistema de registro e investigação de acidentes por parte da empresa.

  14. Perfiles docentes y excelencia: un estudio en la Universidad Técnica Particular de Loja, Ecuador

    Ruth Marlene Aguilar Feijoo

    2015-03-01

    Full Text Available El docente universitario constituye un pilar fundamental en la mejora de la calidad de la educación superior, la formación de las nuevas generaciones y la innovación educativa. Su rol no es único y experimenta modificaciones a medida que cambia el enfoque o perspectiva desde el cual se concibe y gestiona el proceso de aprendizaje. Por lo tanto, requiere de un perfil competencial que le permita asumir con éxito los retos que el nuevo paradigma educativo y la sociedad de la información reclaman. La finalidad principal del presente trabajo de investigación es identificar las competencias que poseen en la actualidad los profesores bimodales de la Universidad Técnica Particular de Loja (Ecuador, a fin de promover el desarrollo de aquellas que no han alcanzado un nivel adecuado. Asumimos la premisa de que estos profesionales deben actuar en un entorno cada vez más complejo, plural, con un acelerado desarrollo tecnológico y demandas formativas diversificadas. Con este propósito se diseñó un cuestionario de autoevaluación que incluye 20 competencias (114 indicadores, con una escala de 5 niveles de dominio. Este cuestionario se aplicó a 403 profesores universitarios bimodales de esta Universidad. A partir de los resultados empíricos obtenidos se establecieron tres perfiles competenciales (alto, medio y bajo e identificaron las competencias específicas y transversales en las que los profesores bimodales tienen un mayor y menor dominio para, desde este conocimiento, determinar sus necesidades formativas.

  15. O perfil urbano e o comportamento socioecononômico do DF

    Rômulo José da Costa Ribeiro

    2007-12-01

    especialmente índices simples e compostos de exclusão/inclusão social baseados na distribuição de renda, nível de escolaridade, condições ambientais e níveis de equidade. Associam-se a esses índices a análise do perfil urbano (Bertaud, 2004, que mostra a distribuição de terras por habitante e a densidade populacional, a partir do CBD, por quilômetro. Pode-se verificar, também, a relação entre exclusão-inclusão social à medida que se distancia do CBD. Para o cruzamentos dos diversos dados foram utilizadas ferramentas de geoprocessamento tais como análise por overlay, álgebra de mapas, análises zonais. Os resultados obtidos mostram que quanto mais distante do CBD piores são as condições de vida da população. Os mesmos permitiram mensurar o grau de exclusão em função da distância ao CBD e em relação ao perfil urbano. A aplicação da modelagem estruturada nos elementos anteriormente descritos permitirá o desenvolvimento de um modelo analítico que visa fornecer uma nova visão para o planejamento urbano das áreas mais críticas socio-economicamente, o que poderá vir a permitir a elaboração de propostas que visem à minimização das tensões urbanas, dando condições de vida mais dignas e socialmente mais inclusivas às populações que ali habitam.

  16. Thermo-hydro-geochemical modelling of the bentonite buffer. LOT A2 experiment

    Sena, Clara; Salas, Joaquin; Arcos, David (Amphos 21 Consulting S.L., Barcelona (Spain))

    2010-12-15

    /condensation process /Karnland et al. 2009/. Once bentonite is water saturated, the transport of solutes is driven by diffusion. Although Donnan equilibrium /Birgersson and Karnland 2009/ and anion exclusion /Muurinen et al. 2004/ are able to influence the mobility of chloride in the bentonite buffer, under the high temperature LOT A2 test conditions, measured data seem to indicate a relatively low influence of these processes on the transport of chloride. For this reason, the transport of chloride has been modelled taking into account advective, dispersive and diffusive fluxes that are believed to have occurred in the LOT A2 test. Numerical results were conducted at fixed thermal gradients for both heated and non-heated bentonite based on the temperatures recorded during the experiment for both heated and non-heated bentonite. The computed evolution of the bentonite saturation indicates that, within approximately one year, the bentonite blocks located at the depth of the heater are completely water saturated which agrees with measured data. The simulated transport of chloride is also in good agreement with data measured at the end of the LOT A2 test for the two cases considered, reflecting the reliability of the conceptual model defined for the LOT A2 test. Based on the geochemical data obtained at end of the LOT A2 test, and on previous modelling exercises /Arcos et al. 2006/, the main geochemical processes that are believed to have developed during the LOT A2 test are: (i) precipitation/dissolution of carbonate, sulphate and silica minerals and, (ii) cation exchange in the montmorillonite interlayer. Numerical results predict the dissolution - precipitation of anhydrite, calcite and silica in the heated bentonite in agreement with data measured at the end of the LOT A2 test

  17. Thermo-hydro-geochemical modelling of the bentonite buffer. LOT A2 experiment

    Sena, Clara; Salas, Joaquin; Arcos, David

    2010-12-01

    /condensation process /Karnland et al. 2009/. Once bentonite is water saturated, the transport of solutes is driven by diffusion. Although Donnan equilibrium /Birgersson and Karnland 2009/ and anion exclusion /Muurinen et al. 2004/ are able to influence the mobility of chloride in the bentonite buffer, under the high temperature LOT A2 test conditions, measured data seem to indicate a relatively low influence of these processes on the transport of chloride. For this reason, the transport of chloride has been modelled taking into account advective, dispersive and diffusive fluxes that are believed to have occurred in the LOT A2 test. Numerical results were conducted at fixed thermal gradients for both heated and non-heated bentonite based on the temperatures recorded during the experiment for both heated and non-heated bentonite. The computed evolution of the bentonite saturation indicates that, within approximately one year, the bentonite blocks located at the depth of the heater are completely water saturated which agrees with measured data. The simulated transport of chloride is also in good agreement with data measured at the end of the LOT A2 test for the two cases considered, reflecting the reliability of the conceptual model defined for the LOT A2 test. Based on the geochemical data obtained at end of the LOT A2 test, and on previous modelling exercises /Arcos et al. 2006/, the main geochemical processes that are believed to have developed during the LOT A2 test are: (i) precipitation/dissolution of carbonate, sulphate and silica minerals and, (ii) cation exchange in the montmorillonite interlayer. Numerical results predict the dissolution - precipitation of anhydrite, calcite and silica in the heated bentonite in agreement with data measured at the end of the LOT A2 test

  18. Representing Evolution

    Hedin, Gry

    2012-01-01

    . This article discusses Willumsen's etching in the context of evolutionary theory, arguing that Willumsen is a rare example of an artist who not only let the theory of evolution fuel his artistic imagination, but also concerned himself with a core issue of the theory, namely to what extent it could be applied...

  19. Security Evolution.

    De Patta, Joe

    2003-01-01

    Examines how to evaluate school security, begin making schools safe, secure schools without turning them into fortresses, and secure schools easily and affordably; the evolution of security systems into information technology systems; using schools' high-speed network lines; how one specific security system was developed; pros and cons of the…

  20. Cepheid evolution

    Becker, S.A.

    1984-05-01

    A review of the phases of stellar evolution relevant to Cepheid variables of both Types I and II is presented. Type I Cepheids arise as a result of normal post-main sequence evolutionary behavior of many stars in the intermediate to massive range of stellar masses. In contrast, Type II Cepheids generally originate from low-mass stars of low metalicity which are undergoing post core helium-burning evolution. Despite great progress in the past two decades, uncertainties still remain in such areas as how to best model convective overshoot, semiconvection, stellar atmospheres, rotation, and binary evolution as well as uncertainties in important physical parameters such as the nuclear reaction rates, opacity, and mass loss rates. The potential effect of these uncertainties on stellar evolution models is discussed. Finally, comparisons between theoretical predictions and observations of Cepheid variables are presented for a number of cases. The results of these comparisons show both areas of agreement and disagreement with the latter result providing incentive for further research

  1. Venom Evolution

    IAS Admin

    Therefore, the platypus sequence was studied to quantify the role of gene duplication in the evolution of venom. ... Platypus venom is present only in males and is used for asserting dominance over com- petitors during the ... Certain toxin gene families are known to re- peatedly evolve through gene duplications. The rapidly ...

  2. Perfil clínico y parasitológico de la malaria por Plasmodium falciparum y Plasmodium vivax no complicada en Córdoba, Colombia.

    Angélica Knudson Ospina

    2015-10-01

    Conclusión. Se identificaron algunas diferencias clínicas entre los enfermos con Plasmodium vivax y los enfermos con Plasmodium falciparum, y las variables estudiadas se agruparon en cuatro perfiles que permiten una variedad de interpretaciones.

  3. Geochemical study of water-rock interaction processes on geothermal systems of alkaline water in granitic massif

    Buil gutierrez, B.; Garcia Sanz, S.; Lago San Jose, M.; Arranz Yague, E.; Auque Sanz, L.

    2002-01-01

    The study of geothermal systems developed within granitic massifs (with alkaline waters and reducing ORP values) is a topic of increasing scientific interest. These systems are a perfect natural laboratory for studying the water-rock interaction processes as they are defined by three main features: 1) long residence time of water within the system, 2) temperature in the reservoir high enough to favour reaction kinetics and finally, 3) the comparison of the chemistry of the incoming and outgoing waters of the system allows for the evaluation of the processes that have modified the water chemistry and its signature, The four geothermal systems considered in this paper are developed within granitic massifs of the Spanish Central Pyrenes; these systems were studied from a geochemical point of view, defining the major, trace and REE chemistry of both waters and host rocks and then characterizing the composition and geochemical evolution of the different waters. Bicarbonate-chloride-sodic and bicarbonate-sodic compositions are the most representative of the water chemistry in the deep geothermal system, as they are not affected by secondary processes (mixing, conductive cooling, etc). (Author)

  4. Semi-detailed uranium geochemical survey in Northwestern Samar (27 March 1979 - 4 July 1979)

    Santos, G. Jr.; Ogena, M.; Tauli, G.

    1980-04-01

    A uranium geochemical survey was conducted to delineate in detail the uranium prospective area(s) in northwestern Samar. A total of 805 stream sediments and 1.115 water samples were obtained from the target areas from uranium analysis. Geochemical anomalies were indicated in San Isidro and Mauo. Geochemical correlations between uranium and trace elements (Pb, Ag, Ni, Cu, Co, Zn and Mn) were generally poor. (ELC)

  5. Geochemical investigation of UMTRAP designated site at Durango, Colorado

    Markos, G.; Bush, K.J.

    1983-09-01

    This report is the result of a geochemical investigation of the former uranium mill and tailings site at Durango, Colorado. This is one in a series of site specific geochemical investigations performed on the inactive uranium mill tailings included in the UMTRA Project. The objectives of the investigation are to characterize the geochemistry, to determine the contaminant distribution resulting from the former milling activities and tailings, and to infer chemical pathways and transport mechanisms from the contaminant distribution. The results will be used to model contaminant migration and to develop criteria for long-term containment media such as a cover system which is impermeable to contaminant migration. This report assumes a familiarity with the hydrologic conditions of the site and the geochemical concepts underlying the investigation. The results reported are based on a one-time sampling of waters and solid material from the background, the area adjacent to the site, and the site. The solid samples are water extracted remove easily soluble salts and acids extracted to remove cabonates and hydroxides. The water extracts and solid samples were analyzed for the major and trace elements. A limited number of samples were analyzed for radiological components. The report includes the methods of sampling, sample processing, analysis, and data interpretation. Three major conclusions are: (1) carbonate salts and low TDS characterize the tailings; (2) the adjacent area and raffinate ponds contain contaminants deposited by a single event of fluid permeation of the soils; and (3) the Animas River adjacent to the site has elevated gross alpha activity attributed to 226 Ra in the sediments derived from the tailings or milling activities

  6. Geochemical investigations at Maxey Flats radioactive waste disposal site

    Dayal, R.; Pietrzak, R.F.; Clinton, J.

    1984-09-01

    As part of the NRC efforts to develop a data base on source term characteristics for low level wastes, Brookhaven National Laboratory (BNL) has produced and analyzed a large amount of data on trench leachate chemistry at existing shallow land burial sites. In this report, we present the results of our investigations at the Maxey Flats, Kentucky disposal site. In particular, data on trench leachate chemistry are reviewed and discussed in terms of mechanisms and processes controlling the composition of trench solutes. Particular emphasis is placed on identifying both intra- and extra-trench factors and processes contributing to source term characteristics, modifications, and uncertainties. BNL research on the Maxey Flats disposal site has provided important information not only on the source term characteristics and the factors contributing to uncertainties in the source term but also some generic insights into such geochemical processes and controls as the mechanics of leachate formation, microbial degradation and development of anoxia, organic complexation and radionuclide mobility, redox inversion and modification of the source term, solubility constraints on solute chemistry, mineral authigenesis, corrosion products and radionuclide scavenging, and the role of organic complexants in geochemical partitioning of radionuclides. A knowledge of such processes and controls affecting the geochemical cycling of radionuclides as well as an understanding of the important factors that contribute to variability and uncertainties in the source term is essential for evaluating the performance of waste package and the site, making valid predictions of release for dose calculations, and for planning site performance monitoring as well as remedial actions. 43 references, 47 figures, 30 tables

  7. Geochemical modeling of uranium mill tailings: a case study

    Peterson, S.R.; Felmy, A.R.; Serne, R.J.; Gee, G.W.

    1983-08-01

    Liner failure was not found to be a problem when various acidic tailings solutions leached through liner materials for periods up to 3 y. On the contrary, materials that contained over 30% clay showed a decrease in permeability with time in the laboratory columns. The decreases in permeability noted above are attributed to pore plugging resulting from the precipitation of minerals and solids. This precipitation takes place due to the increase in pH of the tailings solution brought about by the buffering capacity of the soil. Geochemical modeling predicts, and x-ray characterization confirms, that precipitation of solids from solution is occurring in the acidic tailings solution/liner interactions studied. X-ray diffraction identified gypsum and alunite group minerals, such as jarosite, as having precipitated after acidic tailings solutions reacted with clay liners. The geochemical modeling and experimental work described above were used to construct an equilibrium conceptual model consisting of minerals and solid phases. This model was developed to represent a soil column. A computer program was used as a tool to solve the system of mathematical equations imposed by the conceptual chemical model. The combined conceptual model and computer program were used to predict aqueous phase compositions of effluent solutions from permeability cells packed with geologic materials and percolated with uranium mill tailings solutions. An initial conclusion drawn from these studies is that the laboratory experiments and geochemical modeling predictions were capable of simulating field observations. The same mineralogical changes and contaminant reductions observed in the laboratory studies were found at a drained evaporation pond (Lucky Mc in Wyoming) with a 10-year history of acid attack. 24 references, 5 figures 5 tables

  8. Reconnaisance geochemical survey of heavy minerals in Northern Luzon, Philippines

    Santos, G. Jr.; Seguis, J.E.; Fernandez, L.G.

    1983-07-01

    A reconnaissance sampling was undertaken in northern Luzon to study the distribution of uranium as well as copper, lead, zinc, manganese, silver, cobalt and nickel in heavy minerals. The average background and threshold values of the elements were determined. Uranium content in the heavy mineral was low, in the order of 0.5-0.6 ppm U. Three uranium anomaly zones were delineated in Malanas Rever-Licuan area, Abra, Itogon, Benguet and Bambang, Nueva Viscaya, all within the Central Cordillera. The anomalous zones appeared to be related to copper-gold mineral areas. Geochemical correlations between uranium and the other elements were generally poor. (author)

  9. Neutron activation analysis in reconnaissance geochemical survey of Northwestern Mindoro

    Santos, G. Jr.; Fernandez, L.G.

    1987-01-01

    Instrumental neutron activation analysis (NAA) technique was used to analyze stream sediments collected in Northwestern Mindoro. The concentration levels of 18 elements were determined. It was noted that NAA is suitable for the determination of rare earth, gold, arsenic and cobalt among others because of favorable high neutron cross sections. Samples collected in regional reconnaissance geochemical surveys could be analyzed usng NAA technique to complement other non-nuclear techniques, such as atomic absorption and X-ray fluorescence analysis. (Author). 11 figs.; 2 tabs.; 12 refs

  10. A Low-Li Geochemical Province in the NE Atlantic

    Bailey, J. C.; Gwozdz, R.

    1978-01-01

    Lithium was analysed in 392 basalts and related igneous rocks from the North Atlantic Tertiary-Recent province using activation analysis and Čerenkov counting. Monotonous Li values of 5.5±2 ppm in NE Atlantic basalts define a low-Li geochemical province which has persisted for 60 million years...... basalt series. No whole-rock coherence is observed between Li and Mg, K, Rb or Ca. Mantle phlogopite is considered to play an insignificant rôle in controlling the Li levels of NE Atlantic basalts....

  11. Geochemical association of plutonium in marine sediments from Palomares (Spain)

    Anton, M.P.; Gasco, C.; Sanchez-Cabeza, J.A.; Pujol, L.

    1994-01-01

    The geochemical association of plutonium in sediments from the marine ecosystem of Palomares has been studied. A sequential leaching technique using selective extractants has been employed to determine the percentages of Pu in the following forms: (a) readily available, (b) exchangeable and adsorbed to specific sites, (c) associated with organic matter, (d) sesquioxides, (e) residual. Plutonium was found to be associated mainly with phases (c), (d) and (e), and therefore, appears to be relatively immobile and not readily available to bottom feeding biota. The effect of different source terms on Pu distribution is also discussed. (orig.)

  12. Geochemical Interactions and Viral-Prokaryote Relationships in Freshwater Environments

    Kyle, J. E.; Ferris, G.

    2009-05-01

    Viral and prokaryotic abundances were surveyed throughout southern Ontario aquatic habitats to determine relationships with geochemical parameters in the natural environment. Surface water samples were collected from acid mine drainage in summer of 2007 and 2008 and from circum-neutral pH environments in October to November 2008. Site determination was based on collecting samples from various aquatic habitats (acid mine drainage, lakes, rivers, tributaries, wetlands) with differing bedrock geology (limestone and shale dominated vs granitic Canadian Shield) to obtain a range of geochemical conditions. At each site, measurements of temperature, pH, and Eh were conducted. Samples collected for microbial counts and electron imaging were preserved to a final concentration of 2.5 % (v/v) glutaraldehyde. Additional sample were filtered into 60 mL nalgene bottles and amber EPA certified 40 mL glass vials to determine chemical constituents and dissolved organic carbon (DOC), respectively. Water was also collected to determine additional physiochemical parameters (dissolved total iron, ferric iron, nitrate, sulfate, phosphate, alkalinity, and turbidity). All samples were stored at 4 °C until analysis. Viral and prokaryotic abundance was determined by staining samples with SYBR Green I and examining with a epifluorescence microscope under blue excitation. Multiple regression analysis using stepwise backwards regression and general linear models revealed that viral abundance was the most influential predictor of prokaryotic abundance. Additional predictors include pH, sulfate, phosphate, and magnesium. The strength of the model was very strong with 90 % of the variability explained (R2 = 0.90, p < 0.007). This is the first report, to our knowledge, of viruses exhibiting such strong controls over prokaryotic abundance in the natural environment. All relationships are positively correlated with the exception of Mg, which is negatively correlated. Iron was also noted as a

  13. The Narssaq-project - a geochemical, ecological environmental research project

    Soerensen, H.; Rose-Hansen, J.

    1978-01-01

    Two types of mineral occurrences near the town of Narssaq in South Greenland are recorded to be worth mining in the near future: the uranium occurrences at Kvanefjeld in the northern part of the Ilimaussaq intrusion and the zirconium occurrences in the southern part on the south coast of the Kangerdluarssuk fjord. Consideration of the environment plays a large part in discussions regarding the exploitation of these minerals. A report is given of the geochemical, ecological environmental investigations carried out at Narssaq since 1974. (BP)

  14. Overview of geochemical modeling needs for nuclear waste management

    Isherwood, D.; Wolery, T.

    1984-01-01

    Research needs include, but are not limited to: measurement of basic thermodynamic data at elevated temperatures for species identified by modelers as potentially important; evaluation of substances which control or limit precipitation and/or nucleation kinetics; sorption studies specifically designed to provide data needed for modeling. This includes the rate of sorption, desorption, and the characterization of the solid and aqueous phases; site-mixing models and thermodynamic data for secondary minerals that form solid solutions; the development of standard techniques for measuring rate laws for precipitation and dissolution kinetics; and measurement of rate laws describing redox kinetics, dissolution, and precipitation involving aqueous species and solid phases of interest to geochemical modelers

  15. Review of geochemical measurement techniques for a nuclear waste repository in bedded salt

    Knauss, K.G.; Steinborn, T.L.

    1980-01-01

    A broad, general review is presented of geochemical measurement techniques that can provide data necessary for site selection and repository effectiveness assessment for a radioactive waste repository in bedded salt. The available measurement techniques are organized according to the parameter measured. The list of geochemical parameters include all those measurable geochemical properties of a sample whole values determine the geochemical characteristics or behavior of the system. For each technique, remarks are made pertaining to the operating principles of the measurement instrument and the purpose for which the technique is used. Attention is drawn to areas where further research and development are needed

  16. Análisis multivariante del perfil psicológico de los deportistas universitarios. Aplicación del CPRD en México

    Adriana Isabel Andrade Sánchez

    2015-12-01

    Full Text Available El presente trabajo tiene como objetivo conocer el perfil psicológico de los deportistas universitarios colimenses y analizar si existen diferencias significativas entre practicantes de modalidades individuales y colectivas. Así mismo, se pretende encontrar los perfiles de riesgo para los deportistas. Se trata de un estudio transversal, basado en una muestra no probabilística de 122 alumnos de la Licenciatura en Educación Física y Deporte de la Universidad de Colima, en México. Utilizando como instrumento de medida el cuestionario “Características Psicológicas Relacionadas con el Rendimiento Deportivo” (CPRD, en la versión adaptada para deportistas mexicanos. El cuestionario mide control de estrés, motivación, cohesión de equipo, influencia de la evaluación del rendimiento y habilidad mental. Entre los principales hallazgos, se encontraron siete perfiles de riesgo, ordenados según un gradiente de necesidad de intervención por medio de la definición de puntos de corte, para todas y cada una de las subescalas. Se encontró que, casi un 40 % de los deportistas se encuentran en algún perfil de riesgo, de los cuales 6,6 % se encontraban en el perfil menor, y un 4,1 % en el perfil de riesgo máximo.

  17. Geochemical tracing and hydrogeochemical modelling of water-rock interactions during salinization of alluvial groundwater (Upper Rhine Valley, France)

    Lucas, Y., E-mail: yann.lucas@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Schmitt, A.D., E-mail: anne-desiree.schmitt@univ-fcomte.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)] [Universite de Franche-Comte et CNRS-UMR 6249, Chrono-Environnement, 16, Route de Gray, 25030 Besancon Cedex (France); Chabaux, F., E-mail: francois.chabaux@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Clement, A.; Fritz, B. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Elsass, Ph. [BRGM, GEODERIS, 1, rue Claude Chappe, 57070 Metz (France); Durand, S. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)

    2010-11-15

    Research highlights: {yields} Major and trace elements along with strontium and uranium isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect a conservative mixing. {yields} A coupled hydrogeochemical model demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process. {yields} The model requires only a small amount of montmorillonite. {yields} It is necessary to consider the pollution history to explain the important chloride, sodium and calcium concentration modifications. {yields} The model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer. - Abstract: In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves

  18. 2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal

    2005-01-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

  19. Assessment of microbiological development in nuclear waste geological disposal: a geochemical modeling approach

    Esnault, Loic [ECOGEOSAFE, Technopole de l' Environnement Arbois-Mediterranee, 13545 Aix en Provence (France); Libert, Marie; Bildstein, Olivier [CEA, DEN, DTN/SMTM/LMTE - 13108 Saint Paul lez Durance (France)

    2013-07-01

    Deep geological environments are very often poor or devoid of biodegradable organic molecules, but hydrogen could be an efficient energetic source to replace organic matter and promote redox processes such as reduction of O{sub 2}, NO{sub 3}{sup -}, Fe{sup 3+}, SO{sub 4}{sup 2-} and CO{sub 2}. Moreover, the accessibility and availability of H{sub 2} and nutrients depend on gas/liquid permeability and their migration in the clay-stone porosity through the excavation damaged zone (EDZ). This study evaluates the spatial and temporal evolution of the geochemical conditions with regard to microbial development. The corrosion process in the argillite is investigated using numerical modeling over a period of 100,000 years. The development of bacterial biomass is estimated using potential redox reactions catalyzed by microorganisms and available nutrients. The simulations show that after the thermal peak (ca. 100-1000 years), physico-chemical conditions are favourable to support bacterial life. Relevant amounts of H{sub 2} and nutrients are released and migrate over the first 2 m of the argillite. Most of the biological redox process are localised close to the container where a high amount of magnetite is produced, providing Fe(III) (electron acceptor) that favours the development of iron-reducing bacteria (IRB). (authors)

  20. Coupled processes of fluid flow, solute transport, and geochemical reactions in reactive barriers

    Kim, Jeongkon; Schwartz, Franklin W.; Xu, Tianfu; Choi, Heechul, and Kim, In S.

    2004-01-02

    A complex pattern of coupling between fluid flow and mass transport develops when heterogeneous reactions occur. For instance, dissolution and precipitation reactions can change a porous medium's physical properties, such as pore geometry and thus permeability. These changes influence fluid flow, which in turn impacts the composition of dissolved constituents and the solid phases, and the rate and direction of advective transport. Two-dimensional modeling studies using TOUGHREACT were conducted to investigate the coupling between flow and transport developed as a consequence of differences in density, dissolution precipitation, and medium heterogeneity. The model includes equilibrium reactions for aqueous species, kinetic reactions between the solid phases and aqueous constituents, and full coupling of porosity and permeability changes resulting from precipitation and dissolution reactions in porous media. In addition, a new permeability relationship is implemented in TOUGHREACT to examine the effects of geochemical reactions and density difference on plume migration in porous media. Generally, the evolutions in the concentrations of the aqueous phase are intimately related to the reaction-front dynamics. Plugging of the medium contributed to significant transients in patterns of flow and mass transport.