Cotton Fiber/ZrO2, A New Material for Adsorption of Cr(VI) Ions in Water     

Alfredo Alberto Muxel  Sonia Maria Nobre Gimenez  Flaveli Aparecida de Souza Almeida  Rení Ventura da Silva Alfaya  Antonio Alberto da Silva Alfaya 《洁净——土壤、空气、水》2011,39(3):289-295

The natural cotton fiber was used to synthesize an anion exchange, containing ZrO₂ film on its surface, NCFZC (natural cotton fiber/ZrO₂ composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo‐second‐order kinetic model.  相似文献   

Local sea level change scenarios for the end of the 21st century and potential physical impacts in the lower Ria de Aveiro (Portugal)     

Carina L. Lopes  Alfredo Rocha 《Continental Shelf Research》2011,31(14):1515-1526

Sea level change is an important consequence of climate change due to its impact on society and ecosystems. Analyses of tide-gauge data have indicated that the global sea level has risen during the 20th century and several studies predict that the mean sea level will continue to rise during the 21st century, intensifying coastal hazards worldwide. In Portugal, the Ria de Aveiro is expected to be one of the regions most affected by sea level change.The main aim of this study is to evaluate the potential impacts of the mean sea level change on the hydrodynamics and morphodynamics of the Ria de Aveiro. With this purpose, local mean sea level change was projected for the period 2091-2100 relative to 1980-1999, for different Special Report on Emission Scenarios (SRES) scenarios developed by the Intergovernmental Panel on Climate Change (IPCC). These projections revealed an increase in the mean sea level between 0.28 m under scenario B1 and 0.42 m under scenario A2.The results obtained for sea level rise scenario A2 projection were used to force the morphodynamic model MORSYS2D, previously implemented for the Ria de Aveiro. The modelling results were compared with model forecasts for the present sea level. The residual sediment transport and its balance at the lagoon inlet were computed and analysed for both situations. While the residual sediment transport is generally seaward, sediments tend to deposit inside the inlet due to the weak sediment transport at its mouth. The direction of the residual flux will not change with the sea level rise, but sediment fluxes will intensify, and accretion inside the inlet will increase.The rise in mean sea level will also affect the lagoon hydrodynamics. The tidal prism at the lagoon mouth will increase by about 28% in spring tide. In the lower lagoon only a slight increase of the tidal asymmetry is predicted.  相似文献   

Geomorphological and sedimentological features in Quaternary fluvial systems affected by solution-induced subsidence (Ebro Basin, NE-Spain)     

Gerardo Benito  Francisco Gutirrez  Alfredo Prez-Gonzlez  Maria J. Machado 《Geomorphology》2000,33(3-4)

The Quaternary evolution and the morpho-sedimentary features of some of the most important rivers in Spain (Ebro and Tagus rivers among others) have been controlled by subsidence due to alluvial karstification of the evaporitic bedrock. The subsidence mechanism may range from catastrophic collapse to slow sagging of the alluvium by passive bending. In the Ebro Basin, the mechanisms and processes involved in karstic subsidence were studied through the analysis of present-day closed depressions as well as through old subsidence depressions (palaeocollapses and solution-induced basins) and associated deformations recorded in the Quaternary alluvial sediments. The Gállego–Ebro river system is presented as a case study of channel adjustments and geomorphic and sedimentary evolution of fluvial systems in dissolution-induced subsidence areas. In this fluvial system, evaporite dissolution during particular Quaternary time intervals (namely early and middle Pleistocene) have lead to the development of a solution-induced basin, approximately 30 km-long by 8 km-wide, filled by Quaternary deposits with a total thickness in excess of 190 m. The main river response to balance the subsidence in the alluvial plain was aggradation in the central reach of the subsiding area, and degradation both in the upstream reach and in the valley sides where alluvial fans and covered pediments may prograde over the fluvial sediments. The main sinking areas are recognized in the sedimentary record by anomalous thickenings in the alluvial deposits and fine-grained sediments deposited in backswamp and ponded areas.  相似文献   

Isotopes in the Hueco Bolson aquifer, Texas (USA) and Chihuahua (Mexico): local and general implications for recharge sources in alluvial basins     

Christopher J. Eastoe  Barry J. Hibbs  Alfredo Granados Olivas  James F. Hogan  John Hawley  William R. Hutchison 《Hydrogeology Journal》2008,16(4):737-747

Stable isotope data for the Hueco Bolson aquifer (Texas, USA and Chihuahua, Mexico) distinguish four water types. Two types relate to recharge from the Rio Grande: pre-dam (pre-1916) river water with oxygen-18 and deuterium (δ¹⁸O, δD, ‰) from (?11.9, ?90) to (?10.1, ?82), contrasts with present-day river water (?8.5, ?74) to (?5.3, ?56). Pre-dam water is found beneath the Rio Grande floodplain and Ciudad Juárez, and is mixed with post-dam river water beneath the floodplain. Two other types relate to recharge of local precipitation; evidence of temporal change of precipitation isotopes is present in both types. Recharge from the Franklin and Organ Mountains plots between (?10.9, ?76) and (?8.5, ?60) on the global meteoric water line (GMWL), and is found along the western side of the Hueco Bolson, north of the Rio Grande. Recharge from the Diablo Plateau plots on an evaporation trend originating on the GMWL near (?8.5, ?58). This water is found in the southeastern Hueco Bolson, north of the river; evaporation may be related to slow recharge through fine-grained sediment. Pre-dam water, recognizable by isotope composition, provides information on groundwater residence times in this and other dammed river basins.  相似文献   

Modern tectonic stress field in the Mediterranean region: evidence for variation in stress directions at different scales   总被引：4，自引：0，他引：4  

Samira Rebaï  Hervé Philip  Alfredo Taboada 《Geophysical Journal International》1992,110(1):106-140

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Terremoti dell'Appennino Vogherese-Tortonese e la geologia della regione     

Prof. Dott. Alfredo Boni 《Pure and Applied Geophysics》1947,10(1-2):114-143

Riassunto L'A. studia macro- e microsismicamente i terremoti del 14 giugno, 29 giugno e 15 dicembre 1945, determinandone la posizione delf'epicentio, che pei i primi due viene a cadere nell'Appennino Vogherese fra la Val Staffora e la Val di Nizza, per il terzo invece a N della congiungente Tortona-Alessandria. La profondita ipocentrale del terremoto del 29 giugno 1945 oscilla fra un valore minimo di 9 Km ottenuto macrosismicamente ed un valore massimo, ricavato per via microsismica, di 25 km; quello del 15 dicembre 1945 ha una profondità, microsismicamente calcolata sui 25 km; per quello del 14 giugno 1945 i risultati sono molto incerti. La scossa all'epicentro ha sempre nei tre sismi il carattere di sprofondamento.Posta a confronto colla struttura geologica della regione tale attività sismica non sembra derivare da un determinato elemento strutturale rilevabile; essa è probabilmente dovuta a sprofondamenti avvenuti a media profondità e presenta un'intensificazione in corrispondenza a direttrici tettoniche trasversali al locale andamento del corrugamento. I danni maggiori poi si possono mettere in stretto rapporto colla presenza di esigue formazioni alluvionali sciolte su roccia in posto.

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Summary The author studies macro-microseismically the earthquakes which we have ascertained on the 14^th of June, the 29^th of June and the 15^th of December in the year 1945, giving us the position of the epicentrum, which in the first two falls in Vogherese Appennino between Staffora and Nizza valleys, for the third instead north of Tortona-Alessandria connecting. The ipocentrum depth of the earthquake on the 29^th of June goes from a lowest value of 9 km had macro-seismically to a maximum value had micro-seismically of about 25 km. The 15^th of December one has a depth microseismically computed about 25 km, for the other on the 14^th of June the outcomes are very dubious.The skate at the ipocentrum has in all these three seisms the sinking type.Having made a comparison with the geological structure of the country such a seismical activity does not seem to come from a determinate structural relieving element; it is of course owed sinkings that we had in a middle depth and has an intensity which are in conformity with transversal tectonical directresses. The biggest damages can be put in strait relation with the presence of very little alluvial formations.

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Distacco e scivolamento di masse a Cissone frazione di Serravalle delle Langhe     

Prof Dott. Alfredo Boni 《Pure and Applied Geophysics》1941,3(1):142-160

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Reply     

Javier Aparicio  Moisés Berezowsky 《水文科学杂志》2013,58(4):416-418

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Detection of Miocene saucer‐shaped sills (offshore Senegal) via integrated interpretation of seismic,magnetic and gravity data     

Sergio Rocchi  Alfredo Mazzotti  Michele Marroni  Luca Pandolfi  Paolo Costantini  Bertozzi Giuseppe  Davide di Biase  Francesco Federici  Papa Goumbo L 《地学学报》2007,19(4):232-239

The Atlantic margin offshore Senegal has been explored by seismic reflection and GRAV‐MAG surveys. High‐amplitude, laterally transgressive seismic reflectors are found to coincide with gravimetric and magnetic highs. Once seismic data are integrated with potential fields modelling, these reflectors can be safely interpreted as saucer‐shaped igneous sills, up to some hundreds of metres thick, some km wide. The occurrence of hydrothermal vent complexes and forced folds in the stratigraphic sequence above the sills constrain the intrusion age to the Miocene. Field observations and in‐situ magnetic susceptibility measurements of Oligocene–Miocene and Quaternary igneous rocks emplaced in coastal Senegal support this interpretation.  相似文献   

Comparing mixing-length models of the diabatic wind profile over homogeneous terrain   总被引：1，自引：0，他引：1  

Alfredo Peña  Sven-Erik Gryning  Charlotte Bay Hasager 《Theoretical and Applied Climatology》2010,100(3-4):325-335

Models of the diabatic wind profile over homogeneous terrain for the entire atmospheric boundary layer are developed using mixing-length theory and are compared to wind speed observations up to 300 m at the National Test Station for Wind Turbines at Høvsøre, Denmark. The measurements are performed within a wide range of atmospheric stability conditions, which allows a comparison of the models with the average wind profile computed in seven stability classes, showing a better agreement than compared to the traditional surface-layer wind profile. The wind profile is measured by combining cup anemometer and lidar observations, showing good agreement at the overlapping heights. The height of the boundary layer, a parameter required for the wind profile models, is estimated under neutral and stable conditions using surface-layer turbulence measurements, and under unstable conditions based on the aerosol backscatter profile from ceilometer observations.  相似文献