María Jesús Puy-Alquiza

At present, substantial uncertainty surrounds climate change impacts on groundwater recharge, piezometric heads, and regional hydraulic gradients. This uncertainty is particularly pronounced in deep aquifers in semi-arid environments. Therefore, this study assessed the present and future impacts of climate change on the hydrodynamics of the Valle de León aquifer in central México. This assessment coupled surface-aquifer hydrological processes within a single integrated modelling framework. The methodology integrates the TETIS distributed hydrological model with MODFLOW and incorporates climate projections under different representative concentration pathway scenarios and Artificial Neural Networks within a unified modelling framework. The results indicate a mean annual groundwater drawdown ranging from 1.24 to 1.34 m. The largest drawdowns occur in the south-central part of the aquifer, modifying the regional hydraulic gradients towards the center of the cone of depression. This impact considers a simulated recharge rate corresponding to 12.8% to 13.3% of projected precipitation. The results indicate that projected recharge changes will not offset the persistent piezometric drawdown under the evaluated groundwater extraction rates.

Oily substances (oils, greases, lubricants, etc.) are among the most persistent pollutants for water. They mix with water to form emulsions that contaminate large volumes. Therefore, this project evaluated the use of porous systems (polyurethane foam) modified with polydimethylsiloxane-modified silica (SiO₂/DMS) hybrid ceramics as filtration membranes at the laboratory scale for vegetable oil. The polyurethane foam was modified using sol solutions with various SiO₂/PDMS ratios obtained via the sol–gel method. Tetraethyl-orthosilicate (TEOS) was used as the silica precursor. Three different polydimethylsiloxane chains were employed as the organic fragment: polydimethylsiloxane hydroxyl terminated (DMS-CH₃), aminopropyl-terminated polydimethylsiloxane (DMS-N), and copolymer polydiphenylsiloxane-polydimethylsiloxane hydroxyl terminated (PDS). The siloxane chain was added at a concentration of 20–40% w/w. The modification of the porous system was determined using different characterization techniques, including infrared spectroscopy, which was used to observe the main functional groups. Optical microscopy and SEM were used to identify the hybrid ceramic deposited into the pore structure of the polyurethane sponge. Contact angle measurements revealed the hydrophobic character of the modified material. The removal capacity was evaluated by using vegetable oil as a representative oily contaminant, with values ranging from 43.42 to 96.78 g of oil per gram of adsorbent. In the case of gasoline, removal capacities between 27 and 54 g were observed. This study demonstrated the influence of hydrophobicity on vegetable oil removal, confirming that higher hydrophobicity leads to greater adsorption capacity. Nevertheless, the use of a viscous contaminant introduced challenges in the extraction process from the PS/SiO₂-DMS system. Despite this limitation, the material maintained adequate removal performance for up to five reuse cycles. On the other hand, the removal capacity depends on the amount of polysiloxane chain in the ceramic, as well as the functional group, exhibiting the following behavior: DMS-N < DMS-CH₃ < PDS. This study demonstrates that hydrophobicity is a key property for enhancing the removal capacity of oily substances. Moreover, the control of intermolecular interactions further strengthens this effect, as evidenced in the PS/SiO₂–PDS system.

Thermal microbial mats are laminated organo-mineral biofilms composed of extracellular polymeric substances (EPSs) and microbially mediated silica and carbonate phases. Although extensively studied from ecological and geobiological perspectives, their potential as precursors for applied, bio-derived composite materials remains largely unexplored. In this study, geothermal microbial mats from the Comanjilla hot springs (Mexico) are investigated from a materials-oriented perspective through controlled processing, inorganic tanning, and polymeric surface conditioning. The mats were treated with potassium alum and reinforced using a polyvinyl alcohol–alginate–glycerin formulation to improve cohesion, handling behavior, and structural stability. Mineralogical, physicochemical, and microstructural analyses reveal a hierarchical laminated architecture in which EPS functions as a continuous organic matrix, while in situ silica and carbonate phases provide intrinsic mineral reinforcement. Carbonate-rich mats yield softer and more flexible composite materials, exhibiting tensile strength values of 2.17 ± 0.18 MPa and elongation at break of 15–20%, whereas silica-rich mats produce stiffer and more abrasion-resistant systems. Thermal analysis shows a main organic decomposition event near 275 °C and a stable inorganic residue of approximately 45–50 wt%, confirming the hybrid organo-mineral nature of the processed materials. Prototype-scale fabrication demonstrates structural cohesion, controlled porosity, elastic recovery, and breathability, supporting potential low-load and non-structural applications. Overall, the results identify geothermal microbial mats as a renewable and naturally pre-assembled platform for bio-derived organo-mineral composite materials and provide a foundation for future studies focused on controlled processing and structure–property optimization.

During the processes of excavation, restoration, and conservation of archaeological sites, it is common practice to perform physical and chemical characterization of the site materials. This is carried out to determine the best methods and materials for conserving and preserving the site. For this reason, techniques such as infrared spectroscopy and elemental analysis by X-ray fluorescence (XRF) are primarily used for chemical characterization, while mechanical tests such as the uniaxial compression test and hardness tests are used for physical and mechanical characterization. However, a common limitation is obtaining samples for destructive physical tests, such as compression tests, due to their invaluable cultural value. To address this problem, this work proposes the mechanical characterization of the material through nanoindentation. This technique requires a smaller sample size and can be performed in a timely manner by observing the resistance of each mineralogical phase present in the material. Thus, a preliminary predictive model of mechanical resistance is proposed based on the composition observed in the samples from the archaeological site of Cerro de los Remedios, located in the municipality of Comonfort, Guanajuato, Mexico. The samples were characterized using infrared spectroscopy, XRF, XRD, and SEM-EDS. The results indicate that the stone (caliche) is formed from 95.6–93% micrite calcite; 2.51–0.42% aluminosilicate; 3.14–1.89% high-calcium aluminosilicate; and 3.43–2.39 quartz or amorphous SiO₂. The proposed correlation models were adjusted to a linear function, a second-order polynomial, and a logarithmic function. In the M2–linear model, the non-linear effects generated by variables such as texture, porosity, phase adhesion, cement type, and cracks or discontinuities were not considered. In this model the best prediction of the experimental data was obtained within a variation of ±15%.

This study, conducted in Mexico, evaluates the agricultural potential of three compost formulations BFS1, BFS2, and BFS3 produced from mining tailings and thermophilic microbial mats and collected from geothermal environments. The physicochemical characterization included pH, electrical conductivity (EC), macronutrients (N, P, K, Ca, Mg, and S), micronutrients (Fe, Zn, B, Cu, Mn, Mo, and Ni), organic matter (OM), and the carbon-to-nitrogen (C/N) ratio. All composts exhibited neutral pH values (7.38–7.52), high OM content (38.5–48.4%), and optimal C/N ratios (10.5–13.9), indicating maturity and chemical stability. Nitrogen ranged from 19 to 21 kg·t⁻¹, while potassium and calcium were present in concentrations beneficial for crop development. However, EC values (3.43–3.66 dS/m) and boron levels (>160 ppm) were moderately high, requiring caution in saline soils or with boron-sensitive crops. A semi-quantitative Compost Quality Index (CQI) ranked BFS3 highest due to elevated OM and potassium content, followed by BFS1. BFS2, while rich in nitrogen, scored lower due to excessive boron. One-way ANOVA revealed no significant difference in nitrogen (p > 0.05), but it did reveal significant differences in potassium (p < 0.01) and boron (p < 0.001) among formulations. These results confirm the potential of mining tailings—microbial mat composts are low-cost, nutrient-rich biofertilizers. They are suitable for field crops or as components in nursery substrates, particularly when EC and boron are managed through dilution. This study promotes the circular reuse of geothermal and industrial residues and contributes to sustainable soil restoration practices in mining-affected regions through innovative composting strategies.

Incorporating waste and recycled by-products of expanded polystyrene into adobe as a construction material is seen as a promising approach for sustainable waste management, reducing environmental pollutants, and offering a viable solution for social housing. The use of recycled expanded polystyrene to strengthen adobe has gained interest in the construction and heritage sectors due to its excellent physical and mechanical properties. This article evaluates the physical and mechanical characteristics of recycled adobe stabilized with expanded polystyrene for its potential use in construction and restoration. The findings reveal that adding polystyrene at concentrations of 5% and 6% increases compressive strength by 56.53% and reduces water absorption by 23.18% compared to unstabilized recycled adobe. Scanning electron microscope images show a thin, homogeneous layer formed by the polystyrene on the recycled adobe particles, without any visible cracks, making it a strong competitor to other stabilizers such as lime, asphalt, cement, tuna gum, eggshell, rice husk, mucilage, and PET fiber. These results suggest an alternative material for the construction and restoration of heritage buildings while also addressing environmental waste and improving access to housing for marginalized populations by revitalizing adobe production as a raw material.