Marcelino Antonio Zúñiga-Estrada

The arrangement of common filter materials can influence urban runoff treatment, but initial removal does not establish whether performance persists during repeated loading. This study evaluated a proposed stratification of soil, geotextile, coarse sand, gravel, and tezontle (volcanic scoria) through nutrient and metal breakthrough curves. Nine laboratory columns, comprising three independent replicates each of the stratified configuration, soil alone, and tezontle alone, received synthetic urban runoff during 16 eight-hour feeding cycles. Feeding occurred on weekdays, with overnight and weekend interruptions; the effluent from each feeding period and 30 min of subsequent drainage was combined for analysis. The curves represent ratios of mean effluent to mean influent concentrations for the three columns per configuration. In the stratified configuration, ammonium removal ranged from 74.53% to 91.60%, and mean nitrate removal was 68.29%. Phosphate and metal removal declined over successive cycles, and effluent lead concentrations exceeded influent concentrations during part of the experiment. Soil-only columns showed broadly similar nutrient trends, whereas tezontle provided limited, transient metal removal. These results identify pollutant-specific differences in the persistence of treatment within the proposed stratification. Their main design implication is that favorable initial removal by common materials must be considered together with subsequent breakthrough and possible release. The findings apply to the tested materials and loading sequence rather than establishing field service life.

This study evaluated recycled concrete aggregates (RCAs) as a filter medium and secondary mineral resource in bioretention cells treating synthetic urban runoff, with emphasis on pollutant retention, start-up, and stabilization dynamics. Four laboratory-scale columns containing RCAs were operated for 12 weekly cycles under unplanted and vetiver-planted configurations, with and without a 2 cm granular activated carbon layer. Ammonium, nitrate, total nitrogen, phosphate, Pb, Zn, pH, and electrical conductivity (EC) were monitored throughout the experiment. Ammonium was consistently retained, reaching removal efficiencies above 95% in all configurations by the final cycles, while Pb and Zn remained below detection in nearly all effluents. Nitrate, total nitrogen, and phosphate showed initial export and greater variability during start-up, followed by more consistent retention, particularly in the vegetated configurations. The GAC layer did not provide a consistent improvement in nutrient retention. EC generally decreased during operation, indicating progressive conditioning of the RCA media, whereas effluent pH remained persistently alkaline. Altogether, RCAs provided effective pollutant retention while exhibiting distinct conditioning and stabilization trajectories. Their use as the main mineral component of bioretention filter beds also offers a pathway for substituting virgin aggregates and valorizing construction and demolition waste, although long-term performance and life-cycle impacts require further evaluation.

This paper presents the conceptual design of blue and green infrastructure (BGI) prototype focused on the decentralized stormwater collection, treatment, and storage in urban dwellings of semi-arid areas. The proposal emerges as an adaptation strategy to address water scarcity, taking into account the poor performance of conventional supply systems in such vulnerable contexts. The BGI system integrates two complementary strategies: direct collection from rooftops and collection of surface runoff generated on impervious sidewalks, which is conducted through permeable pavement to a bioretention cell composed of vegetation and recycled construction aggregates. This configuration allows runoff water to be collected, filtered, and stored for later use. Local climate data were used to estimate surface runoff, infiltration into the system layers, and potential storage in a preliminary water balance. The design was applied to a typical home with a roof area of 39.2 m² and a daily consumption of 724.9 liters (for five inhabitants, with water-saving devices). The results indicate that, during representative rainfall events, the volume captured partially covers this allocation for at least one day, demonstrating the hydraulic viability of the system in urban environments with limited space. It should be noted that the water balance did not consider losses due to evaporation or evapotranspiration, as the objective was to make a preliminary estimate for conceptual sizing. It is concluded that the BGI prototype represents a viable and sustainable alternative for harvesting rainwater in homes with limited space and access to conventional sources, thus contributing to the circular water economy.

The expansive behavior of obsidian above the glass transition temperature is strongly influenced by its initial microstructure and by the content and release of volatile species. In this work, a comprehensive study of the structural and microstructural evolution, as well as the physical properties, of a macroscopic dark obsidian variety from Cerro de las Navajas (Hidalgo, Mexico), containing dispersed crystalline domains within a glassy matrix, is presented. The expansive behavior of this material under controlled thermal treatments had not been previously addressed. A critical porosity development interval between 900 and 950 °C was identified, followed by a stability region between 950 and 1200 °C. Within this interval, minimum apparent densities of 0.32 g·cm-3 and total porosities of up to ~86.5%, predominantly closed (~99%), were achieved. The final porosity was governed by the initial porosity and the spatial distribution of the crystalline domains, which acted as heterogeneous nucleation sites for the gaseous phase without actively participating in the expansion process. Volumetric expansion was largely isotropic, with minimum densities attained even in the largest samples. These results demonstrate that, under controlled thermal treatments, this obsidian variety can develop a highly porous and low-density monolithic microstructure, with a balance between thermal insulation capability and compressive strength, highlighting its interest as a lightweight inorganic material.

Minerals have played a fundamental part in prebiotic chemistry on Earth, catalyzing the synthesis of inorganic and even organic molecules, including macromolecules such as RNA or DNA. Minerals based on silica are some of the first inorganics to be found in very ancient mineral fossils. These minerals or even volcanic glasses rich in silica, such as obsidians (a naturally volcanic glass, which is in fact an igneous rock), play an important role as supporting materials for obtaining the silico-carbonates of alkaline earth metals (usually called biomorphs). This is because, in most radiolarians, diatoms, and foraminifera, their external shells are made up of silica (SiO₂). However, it has yet to be evaluated whether the silica contained in the minerals present in the prebiotic era of the Earth interacted with the chemical elements that were also present during that era. To evaluate whether obsidian participated in the formation of the first inorganic structures of pioneering organisms, this study aimed to synthesize calcium and barium biomorphs on igneous rock and to show that dissolved organic and inorganic molecules might have interacted with the molecules of obsidian, producing a plethora of shapes that mimicked the cherts of the Precambrian.

Life is the result of a complex network of chemical reactions and molecular interactions that arose on Earth once primitive minerals were able to self-assemble in a way that allowed them to self-reproduce and evolve. However, exactly how, where and when life first appeared on our planet is still unknown. In this article, we review various theories of geochemical evidence associated with the origin of life, which provide a fundamental, although often rudimentary, view of the emergence of early life on planet Earth.

México es reconocido como el centro de origen, domesticación y diversificación del maíz (Zea mays L.). El consumo de este grano ha formado parte de la alimentación mexicana cotidiana; es esencial en la gastronomía, incluyendo, tortillas, atoles, tostadas y pan. En el presente trabajo se reporta el daño ocasionado por el tordo sargento (Agelaius phoeniceus), en una plantación de maíz nativo. Se realizaron salidas de campo para ver el daño ocasionado por esta ave durante el periodo de floración y desarrollo del elote de un material de maíz nativo proveniente de Ajacuba, Hidalgo. En esta investigación concluimos que el maíz nativo en estado lechoso es uno de sus alimentos preferidos del tordo sargento (A. phoeniceus). Los daños observados en los elotes fueron superiores al setenta por ciento, por lo que se sugiere buscar medidas de protección a este cultivo sin dañar estas especies de aves y al medioambiente. Palabras Clave: Elote, pájaro, maíz, cultivo, milpa.

El CO2 es uno de los principales gases que albergan en la atmósfera, se origina principalmente por procesos antropogénicos. En la actualidad se ha vuelto un punto de atención en la sociedad, ya que la saturación de este gas en la atmósfera ocasiona el aumento de la temperatura (calentamiento global), otra consecuencia es el aumento del nivel de mar, ambas problemáticas causan un desbalance en el desarrollo óptimo de seres vivos. Sin embargo este gas de igual forma es vital para llevar a cabo procesos naturales, como lo es el caso de la fotosíntesis donde las plantas aprovechan el CO2 de la atmosfera para convertirlo en su alimento, por lo tanto la sociedad ha buscado la manera de disminuir y a su vez aprovechar este gas mediante diferentes metodologías, una de ellas es la inyección de CO2 en invernaderos donde se desarrollan hortalizas, gracias a este método se obtienen beneficios ambientales como económicos para la sociedad.