Ciencias Exactas y Ciencias de la Salud

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Seawater intrusion pattern recognition supported by unsupervised learning
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-06-13) Narváez Montoya, Christian Felipe; Mahlknecht, Jürgen; emimmayorquin; Mora Polanco, Abrahan Rafael; Bertrand, Guillaume; Bonasia, Rosanna; School of Engineering and Sciences; Campus Monterrey; Torrés Martínez, Juan Antonio
Climate change and anthropogenic activities have negatively affected the world's water resources in the last 200 years. Seawater intrusion, one of the leading causes of groundwater contamination, particularly affects coastal systems. Coastal aquifers are naturally connected to seawater, with the saltwater forming a wedge beneath the freshwater due to the difference in densities. Seawater migrates further inland when the aquifer hydraulic head decreases concerning the sea level, and is driven by groundwater overexploitation or sea level rise. The resulting salty water is extracted for public water supply, irrigation, or industrial purposes. Thus, monitoring and understanding this process is essential for developing appropriate water management strategies. Environmental tracers, such as the major ions (Mg2+, Ca2+, Na+, K+, SO4 2-, HCO3-, NO3-, and Cl-), are recognized as valuable tools for identifying seawater intrusion and other salinization sources. In this context, unsupervised learning has supported the multivariate analysis to characterize the variability and range of major ions at different spatial and temporal scales. However, complex case studies with multiple processes triggering high salinity concentrations make pattern recognition of salinization sources challenging with traditional unsupervised techniques. This research identifies seawater intrusion and triggering factors for two complex case studies: the Caplina/Concordia aquifer system in the hyper-arid Atacama Desert and the Yucatan Peninsula, one of the world's largest coastal karst lowland areas. For this, novel network-based clustering was applied to major ions water quality datasets sourced from governmental institutions. The outcomes show that the Caplina/Concordia water samples associated with seawater intrusion were identified up to 5.5 km inland in zones with hydraulic heads less than 6 m.a.s.l. These findings align with a developed hydrogeological model and underscore overexploitation as a key driver for seawater intrusion. On the other hand, in the Yucatan Peninsula, water samples were indicated to be associated with seawater intrusion in zones with hydraulic heads less than 5 m.a.s.l. The natural extensive seawater wedge is the product of low hydraulic gradients, facilitating the extraction of seawater-groundwater mixture (upconing) to more than 100 km from the coast. Furthermore, gypsum dissolution and nitrate pollution are also critical concerns for water quality in the peninsula. Additionally, the thesis advocates for improved open science in water research, urging journals and researchers to make raw data publicly available.
Synthesis, characterization, and application of micro- and nanomaterials for the removal of organic contaminants from groundwater and wastewater
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-12-03) Orona Návar, Carolina; ORONA NAVAR, CAROLINA; 584962; Ornelas Soto, Nancy Edith; hermlugo, emipsanchez; Hernández Navarro, Netzahualpille; García García, Alejandra; García Morales, Raúl; Escuela de Ingeniería y Ciencias; Campus Monterrey; Jürgen, Mahlknecht
The increasing presence of chemicals and pharmaceuticals in the aquatic environment represents a latent threat both to ecosystems and to human health. Conventional treatment methods for water hardly eliminate these pollutants, which are usually dissolved in low concentrations (μgL-1 or ngL-1). Because of their physicochemical characteristics, the use of micro- and nanomaterials in advanced treatment processes represents a feasible alternative to eliminate this kind of persistent pollutants. In this study, different methods were applied to enhance the performance of micro- and nanomaterials for water treatment applications. Specifically, titanate nanotubes were synthesized, characterized, and successfully used for the adsorption of six organic pollutants of interest. First and second order kinetic models as well as, adsorption isotherms of Freundlich and Langmuir were investigated. Also, the photocatalytic activity of different bismuth-based materials was investigated. For instance, the photocatalytic efficiency of BiVO4 was enhanced through rare-earth doping (Gd3+) and a series of Bi2O3/rGO/MonO3n-1 all-solid-state ternary Z-scheme were synthesized as well. The synthesized photocatalysts were studied through photocatalytic degradation of selected contaminants and the photocatalytic experiments were carried out in different water matrices such as pure water, groundwater, or urban wastewater effluent. Also, different light sources were applied during photocatalytic processes to evaluate and compare the performance using conventional and LED light sources. To better understand the properties of the synthesized materials, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) among other techniques, were applied. All the synthesized materials, after being modified in their physical or chemical form, showed a better performance than the pristine materials during adsorption or photocatalysis treatments for the removal of persistent organic contaminants in the water.
Biocatalysts immobilization onto nanostructured supports with application in the biotransformation of emerging pollutants
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2019-05) Garcia Morales, Raul.; GARCIA MORALES, RAUL; 657020; Ornelas Soto, Nancy Edith.; Campus Monterrey; Campus Monterrey; Campus Monterrey

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