Las componentes ambientales en el diseño urbano: Lima - Perú

Las ciudades contemporáneas siempre tienden a relacionarse con el peatón de manera más evidente, integrando estrategias de diseño bioclimático con el fin de otorgar una urbe más sostenible y habitable. La relación entre ambiente y hábitat construido en la historia de la humanidad ha sido imprescindible, visto que los recursos naturales fueron los únicos disponibles hasta el siglo pasado. La excesiva cementificación de la ciudad ha nuevamente puesto delante de los profesionales del sector un nuevo reto: considerar las componentes ambientales en la etapa de diseño y planificación urbana. Por eso, asoleamiento, viento, humedad y vegetación, entonces no son simplemente ornamentos y decoraciones de la ciudad, sino que se convierten en factores principales de determinación de ejes viales, altura de edificios, espacios públicos y áreas verdes. El caso estudio se concentra sobre Lima, capital del Perú, que a pesar de los grandes esfuerzos efectuados durante el periodo post pandemia resulta ser una de las ciudades con mayores problemas en la consideración de diseño bioclimático como instrumento clave de su regeneración. Las características propias del lugar, como la latitud y vientos predominantes entre otros, han sido muy poco consideradas en las décadas, entregando a la población una ciudad que carece de grandes parques, que no se protege del asoleamiento sobre todo en verano y que no elimina la humedad elevada, sino que parece casi que eleva el problema a un nivel insoluble

Quantitative models of hydrothermal fluid–mineral reaction:The Ischia case

The intricate pathways of fluid–mineral reactions occurring underneath active hydrothermal systems are explored in this study by applying reaction path modelling to the Ischia case study. Ischia Island, in Southern Italy, hosts a well-developed and structurally complex hydrothermal system which, because of its heterogeneity in chemical and physical properties, is an ideal test sites for evaluating potentialities/limitations of quantitative geochemical models of hydrothermal reactions. We used the EQ3/6 software package, version 7.2b, to model reaction of infiltrating waters (mixtures of meteoric water and seawater in variable proportions) with Ischia’s reservoir rocks (the Mount Epomeo Green Tuff units; MEGT). The mineral assemblage and composition of such MEGT units were initially characterised by ad hoc designed optical microscopy and electron microprobe analysis, showing that phenocrysts (dominantly alkali–feldspars and plagioclase) are set in a pervasively altered (with abundant clay minerals and zeolites) groundmass. Reaction of infiltrating waters with MEGT minerals was simulated over a range of realistic (for Ischia) temperatures (95–260° C) and CO2 fugacities (10 ^-0.2 to 10^0.5) bar. During the model runs, a set of secondary minerals (selected based on independent information from alteration minerals’ studies) was allowed to precipitate from model solutions, when saturation was achieved. The compositional evolution of model solutions obtained in the 95–260°C runs were finally compared with compositions of Ischia’s thermal groundwaters, demonstrating an overall agreement. Our simulations, in particular, well reproduce the Mg-depleting maturation path of hydrothermal solutions, and have end-of-run model solutions whose Na–K–Mg compositions well reflect attainment of full-equilibrium conditions at run temperature. High-temperature (180–260° C) model runs are those best matching the Na–K–Mg compositions of Ischia’s most chemically mature water samples, supporting quenching of deep-reservoir conditions for these surface manifestations; whilst Fe, SiO2 and, to a lesser extent, SO4 contents of natural samples are better reproduced in low-temperature (95°C) runs, suggesting that these species reflect conditions of water–rock interaction in the shallow hydrothermal environment. The ability of model runs to reproduce the compositional features of Ischia’s thermal manifestations, demonstrated here, adds supplementary confidence on reaction path modelling as a realistic and insightful representation of mineral–fluid hydrothermal reactions. Our results, in particular, demonstrate the significant impact of host rock minerals’ assemblage in governing the paths and trends of hydrothermal fluids’ maturation

Numerical modelling of gas-water-rock interactions in volcanic-hydrothermal environment: the Ischia Island (Southern Italy) case study.

Hydrothermal systems hosted within active volcanic systems represent an excellent opportunity to investigate the interactions between aquifer rocks, infiltrating waters and deep-rising magmatic fluids, and thus allow deriving information on the activity state of dormant volcanoes. From a thermodynamic perspective, gas-water-rock interaction processes are normally far from equilibrium, but can be represented by an array of chemical reactions, in which irreversible mass transfer occurs from host rock minerals to leaching solutions, and then to secondary hydrothermal minerals. While initially developed to investigate interactions in near-surface groundwater environments, the reaction path modeling approach of Helgeson and co-workers can also be applied to quantitative investigation of reactions in high T-P environments. Ischia volcano, being the site of diffuse hydrothermal circulation, is an ideal place where to test the application of reaction-path modeling. Since its last eruption in 1302 AD, Ischia has shown a variety of hydrothermal features, including fumarolic emissions, diffuse soil degassing and hot waters discharges. These are the superficial manifestation of an intense hydrothermal circulation at depth. A recent work has shown the existence of several superposed aquifers; the shallowest (near to boiling) feeds the numerous surface thermal discharges, and is recharged by both superficial waters and deeper and hotter (150-260° C) hydrothermal reservoir fluids. Here, we use reaction path modelling (performed by using the code EQ3/6) to quantitatively constrain the compositional evolution of Ischia thermal fluids during their hydrothermal flow. Simulations suggest that compositions of Ischia groundwaters are buffered by interactions between reservoir rocks and recharge waters (meteoric fluids variably mixed - from 2 to 80% - with seawater) at shallow aquifer conditions. A CO2 rich gaseous phase is also involved in the interaction processes (fCO2 = 0.4-0.6 bar). Overall, our model calculations satisfactorily reproduce the main chemical features of Ischia groundwaters. In the model runs, attainment of partial to complete equilibrium with albite and K-feldspar fixes the Na/K ratios of the model solutions at values closely matching those of natural samples. Precipitation of secondary phases, mainly clay minerals (smectite and saponite) and zeolites (clinoptilolite), during the reaction path is able to well explain the large Mg-depletions which characterise Ischia thermal groundwaters; while pyrite and troilite are shown to control sulphur abundance in aqueous solutions. SiO2(aq) contents in model simulations fit those measured in groundwaters and are being buffered by the formation of quartz polymorphs and Si-bearing minerals. Finally, our simulations are able to reproduce redox conditions and Fe-depletion trends of natural samples. We conclude that reaction path modelling is an useful tool for quantitative exploration of chemical process within volcano-hosted hydrothermal systems

The iron roofs in Palermo’s Liberty

[SPA] La arquitectura del hierro se difunde en Europa en el siglo XIX, en coincidencia con el progreso de la siderurgia y el desarrollo de la extraordinaria estación del Art Nouveau, Movimiento que busca en la evolución del mundo moderno, del desarrollo industrial, del progreso de la tecnología, en las nuevas instancias sociales y culturales, una “forma” apropiada, satisfactoria de las nuevas instancias de representatividad. En esta atmósfera de renovación, la moderna tecnología asume un rol prioritario y el hierro se presta bien a adaptarse a las nuevas exigencias que se inspiran en la naturaleza y sus formas orgánicas. Hoy muchas manufacturas de hierro han desaparecido, han sido destruídas o demolidas, u otras se encuentran en un estado de total abandono y degradación. La presente investigación es el resultado de un estudio conducido por el Departamento de Arquitectura de la Universidad de Palermo, disertando sobre esas obras de la arquitectura de hierro realizadas en Palermo a caballo entre los dos siglos, con particular referencia a las cubiertas, que han sufrido en el curso de los años la acción del tiempo, pero sobre todo las consecuencias de la incuria de quien no reconoce estas obras testimonio histórico, artístico y cultural de la extraordinaria, aunque breve, estación del Art Nouveau en Sicilia. [ENG] The iron architecture spreads in Europe in the nineteenth century, coinciding with the advancement of the steel industry and the development of the extraordinary Art Nouveau period, a movement that analyses the evolution of the modern world, the industrial development, the advances in technology, the new social and cultural needs, to find a new suitable form to meet the new demands of representativeness. In this atmosphere of urban renewal, modern technology plays a primary role, and iron is well-suited to adapt to the new demands of taste that draw inspiration from nature and its organic forms. Many of the iron works of the period have disappeared, destroyed or demolished and others are in a total status of abandon and decay. The contribution is the result of a study carried out at the Department of Architecture of the University of Palermo, aimed to highlight those works of iron architecture made in Palermo at the turn of the century, with particular attention to the roofs which have suffered through the years the action of weather and, the consequences of neglect and superficiality regard these works and their role of historical, artistic and cultural evidence of the extraordinary Art Nouveau season in Sicily