Publications
Low-cost electrochemical detection of arsenic in the groundwater of Guanajuato state, central Mexico using an open-source potentiostat
A low-cost, open-source potentiostat based on Arduino technology has been developed to accurately detect arsenic in groundwater at parts-per-billion levels. This method significantly outperforms traditional colorimetric test strips, reducing median error from -50% to +2.9%, precision uncertainties from ±25% to ±4.9%, and eliminating false negatives (50% with test strips vs. 0% with the potentiostat) when compared to the World Health Organization's 10 μg L-1 limit. The study, conducted in arsenic-contaminated groundwaters of Guanajuato, Mexico, used gold electrodes (screen-printed and microwire) with anodic stripping voltammetry (ASV), achieving a low detection limit of 0.7 μg L-1. This approach offers a cost-effective solution for in-house arsenic analysis by research groups and NGOs, providing superior quantitative data.
Widespread elevated concentrations of gaseous elemental mercury in Guanajuato, Mexico, centuries after historical silver refining by mercury amalgamation
Centuries after historical silver refining, gaseous elemental mercury (GEM) concentrations remain significantly elevated in Guanajuato, Mexico. Ground-level air GEM levels range from 8 to 454 ng/m³, surpassing Northern Hemispheric averages by up to two orders of magnitude, while interstitial air in reprocessed mineral wastes, sediment, and soil reaches up to 44,700 ng/m³. This persistent elevation is attributed to the disproportionation of legacy calomel (Hg₂Cl₂), a mercury compound formed during the patio process used for silver extraction. The study supports this mechanism by identifying HgI in reprocessed wastes and analyzing GEM release patterns from calomel. These findings challenge previous assumptions about historical mercury emissions, suggesting that calomel's disproportionation must be accounted for to accurately assess past atmospheric mercury contributions.
Carbon Monoxide and Particulate Matter Concentrations inside the Road Tunnels of Guanajuato City, Mexico
Road tunnels in Guanajuato, Mexico, while designed to alleviate traffic congestion and shorten pedestrian travel times, harbor significant levels of air pollution. Research reveals that although carbon monoxide (CO) concentrations remain below the World Health Organization's 30-minute exposure guideline of 50 ppm, particulate matter (PM10) levels consistently exceed the WHO's 24-hour limit of 50 µg m–3 in all three studied tunnels. The study employed advanced sensors to monitor CO, PM2.5, and PM10 concentrations, alongside vehicle counts and wind speed, while X-ray diffraction, fluorescence, and scanning electron microscopy were used to analyze the chemical composition and morphology of the particulates. Findings indicate that these particles primarily originate from eroded rhyolite rock, soil, and construction materials within the tunnels, underscoring the urgent need for ventilation systems to mitigate health risks associated with prolonged exposure.
Exploring the Links Between Biophilic and Restorative Qualities of Exterior and Interior Spaces in Leon, Guanajuato, Mexico
Research reveals that biophilic and restorative qualities of urban spaces significantly enhance mood states while reducing situational stress. The study, conducted in León, Guanajuato, Mexico, analyzed 65 public spaces using multidimensional scaling (MDS) to categorize them based on vegetation proportion, spatial extension, landmark salience, biophilic architecture, people density, street visual access, olfactory pleasantness, and noise levels. Findings indicate that environments with higher biophilic design elements—such as vegetation and natural materials—lead to decreased negative moods and perceived stress, while increasing positive emotional responses. Structural equation modeling (SEM) confirmed these relationships, underscoring the importance of integrating biophilic features in urban planning to foster restorative experiences for inhabitants.
Studying Online Travel Reviews related to tourist attractions using NLP methods: the case of Guanajuato, Mexico
A novel analysis of online travel reviews (OTRs) for Guanajuato, Mexicoreveals that cleanliness and prices are recurring negative themes, regardless of whether travelers are national or international. This study is the first to apply Natural Language Processing (NLP) techniques, specifically Mutual Information Ranking and Jaccard Coefficient, to OTRs in a Mexican context, uncovering critical insights into visitor perceptions. Surprisingly, evaluations showed little variation between domestic and foreign tourists, suggesting universal concerns that could inform tourism policy and site management.
Empresarias mineras de Guanajuato, 1714-1803
A groundbreaking analysis reveals the significant yet overlooked role of women as mining entrepreneurs in 18th-century Guanajuato, Mexico. Despite their substantial contributions to the silver and gold industry—through ownership of mines, processing facilities (haciendas de beneficio), and metal recovery (rescatadoras)—women have been largely excluded from historical narratives about this period. By tracing the trajectories of two prominent female entrepreneurs, the study demonstrates their adept business acumen in managing complex transactions and maintaining strategic partnerships with male counterparts. This research challenges traditional historiography by highlighting women's economic agency during a pivotal era of colonial industrialization.
Geología y estructura de las sierras de Guanajuato y Codornices, Mesa Central, México
The Sierras de Guanajuato and Codornices, part of the UNESCO World Heritage Site 'Historic Town of Guanajuato and Adjacent Mines,' exhibit a complex tectonic history characterized by three major uplift-exhumation phases: early-middle Eocene, Oligocene, and Miocene. These phases shaped their current configuration, with the Sierra de Guanajuato rising more significantly relative to the El Bajío basin compared to the Sierra de Codornices. The study reveals that these ranges form a raised block of an Oligocene-Eocene half-graben, bounded by normal faults that migrated towards the basin over time, creating a stepped configuration along their southwestern margin. This research compiles geological data from six lithologic groups and 27 stratigraphic sections to model the Cenozoic tectonic evolution of central Mexico, providing insights into the region's dynamic geological processes.
A Comparison of Amphibian and Reptile Diversity Between Disturbed and Undisturbed Environments of Salvatierra, Guanajuato, Mexico
A study comparing amphibian and reptile diversity between disturbed (corn fields) and undisturbed (tropical deciduous forest) environments in Salvatierra, Guanajuato, Mexico, found that taxonomic distinctness was higher in undisturbed habitats, particularly in the Urireo locality. The research recorded 19 species (4 amphibians and 15 reptiles), with greater diversity observed in tropical deciduous forests than in corn fields. Seven of these species are protected under NOM-059-SEMARNAT-2010, highlighting their conservation significance. The findings suggest that long-term studies incorporating natural history traits could enhance herpetofauna conservation strategies in disturbed landscapes.
Analysis and evaluation of risks in underground mining using the decision matrix risk-assessment (DMRA) technique, in Guanajuato, Mexico
A study applying the decision matrix risk-assessment (DMRA) technique to underground mining in Guanajuato, Mexico, identified critical activities with high accident severity and probability. These included blasting, machinery use, exploitation, fortification, and amacize, which pose significant occupational risks due to suboptimal working conditions. The research classified these activities into three risk categories: those requiring immediate corrective actions, those needing control measures, and those necessitating cessation until safety improvements are made. Proposed solutions align with occupational safety regulations from the Secretaría del Trabajo y Previsión Social, aiming to mitigate accidents through documented compliance with mining activity rules.
Damage detection historical building using mapping method in music school of the University of Guanajuato, Mexico
Researchers developed a monument-mapping method to efficiently detect and quantify weathering damage on historical buildings, focusing on the Music School of the University of Guanajuato, Mexico. This approach identified five key forms of stone decay—fractures, salts, oxides, scaling, and lichen—using digital image processing. The study also characterized less-known decorative stones used in 18th- and 19th-century structures, providing mineralogical and petrophysic insights. By mapping damage size and location on green sandstone, the method offers a rapid, qualitative, and quantitative assessment tool for conservation efforts at UNESCO World Heritage Sites like Guanajuato.
Events and placemaking: the case of the Festival Internacional Cervantino in Guanajuato, Mexico
The Festival Internacional Cervantino in Guanajuato, Mexico, significantly enhances the city's cultural appeal and attracts tourists drawn to its historic and colonial heritage. While the event fosters a positive perception of urban spaces and is highly appreciated by visitors, it also reveals critical gaps in public services such as traffic management, accessibility, waste disposal, and environmental noise, which negatively impact placemaking. The study highlights that despite these challenges, the festival contributes to transient placemaking through emotional connections and integrates the figure of Cervantes into the city's intangible heritage discourse. However, current policies fail to address social sustainability issues, including the uneven distribution of economic benefits. The research applies the Event Experience Scale (EES) methodology to assess visitor perceptions and urban dynamics, offering insights that could be adapted for similar festivals in other cities.
Facies analysis, stratigraphic architecture and depositional environments of the Guanajuato conglomerate in the Sierra de Guanajuato, Mexico
The Guanajuato conglomerate, spanning over 2000 meters in thickness and extending more than 100 kilometers, reveals the sedimentary history of post-Laramide extensional basins in Mexico's Central Plateau. This study identifies two distinct members within the conglomerate: a lower member characterized by fluvial braided systems, featuring coarse-grained deposits, lava flows, and debris flows; and an upper member dominated by alluvial fan environments with clast-supported conglomerates and fine-grained sediments. Facies analysis across nine localities uncovered 14 facies types, including traction-dominated conglomerates, hyperconcentrated flow deposits, and desiccation cracks, providing insights into the depositional dynamics of Cenozoic sedimentary systems. The research combines stratigraphic architecture with sedimentological observations to reconstruct paleoenvironments, offering a detailed model for understanding the evolution of extensional basins in this UNESCO World Heritage Site.
Regulating groundwater use: The challenges of policy implementation in Guanajuato, Central Mexico
Despite efforts by both national and state governments to regulate groundwater use through multiple mechanisms—including direct state control, groundwater markets, energy pricing, and user self-regulation—the effectiveness of these policies has been undermined in Guanajuato, Mexico. The study reveals that the close interdependencies among regulatory instruments have hindered their ability to reduce groundwater consumption, preventing progress toward sustainable exploitation levels. Researchers analyzed policy outcomes in the field, demonstrating how complex governance structures can inadvertently weaken environmental sustainability efforts.
Semiarid ethnoagroforestry management: Tajos in the Sierra Gorda, Guanajuato, Mexico
Tajos, traditional biocultural systems in Mexico's Sierra Gorda, demonstrate exceptional agrobiodiversity and subsistence value. These stone-walled terraces, adapted to semiarid conditions, support high levels of native and introduced plant species, including maize and beans, while providing nearly 70% of household subsistence needs. The study, conducted through qualitative interviews and vegetation sampling in three communities, highlights tajos as a heritage of traditional ecological knowledge (TEK) that integrates pre-Columbian and Mediterranean agricultural techniques with modern practices. Their ability to create fertile soils in arid valleys underscores their potential as sustainable models for similar regions worldwide.
Turismo gentrificador en ciudades patrimoniales. Exclusión y transformaciones urbano-arquitectónicas del patrimonio en Guanajuato, México
El turismo de élite actúa como un factor transformador en ciudades patrimoniales, alterando las tipologías tradicionales y generando una arquitectura fachadista que acentúa la exclusión social y fragmentación urbana. En Guanajuato, México, este proceso revela contradicciones donde el prestigio del destino depende de recursos culturales y patrimoniales, pero estos pueden verse amenazados por la explotación turística. El estudio analiza cómo el Estado, el mercado y una ciudadanía débil influyen en estas transformaciones, destacando los impactos negativos en el patrimonio urbano.
Marginación visual y espacial de las mujeres indígenas en la ciudad histórica de Guanajuato
Systematic exclusion of indigenous women traders from Guanajuato's historic center, designated as UNESCO World Heritage Site, undermines both economic benefits and cultural heritage preservation. Since 2012, authorities under the Institutional Revolutionary Party have marginalized these women through visual and spatial policies, displacing them from commercial spaces despite their role in sustaining local handicraft traditions. The study reveals a tension between heritage tourism's economic gains and social equity, highlighting how political interests drive exclusionary urban policies that disproportionately affect indigenous women.
Mineral deposits of the Guanajuato Mining District, Guanajuato
A comprehensive synthesis of the economic geology of Mexico's Guanajuato Mining District, published in 1988 and translated into English in the early 2000s, reveals critical insights into its geothermal, coal, and metal-mining sectors. The study, led by Ing. G.P. Salas with contributions from Ing. Hugo Cortez Guzmán and Dr. Cecily Petzall, compiles data on mineral deposits available up to the mid-1980s. It highlights the district's rich diversity of non-metallic and metallic resources, including gold, silver, lead, zinc, and coal, while also addressing its geothermal potential. The research approach involved extensive fieldwork, historical documentation, and geological analysis, providing a foundational reference for understanding the region's mineral wealth. This work remains a valuable contribution to the Geology of North America series.
New stratigraphic, geochronological, and structural data from the southern Guanajuato Mining District, México: implications for the caldera hypothesis
A new geological map and geochronological data reveal that the volcanic activity in the southern Guanajuato Mining District (GMD) occurred between approximately 33.5 and 31.3 million years ago, coinciding with NW–SE normal faulting. This activity is linked to the formation of the Bufa, Calderones, and Cedro formations, which are part of a volcanic center that also contributed to the world-class silver ore deposits in the region. The study suggests that the Chichíndaro Rhyolite, though sparsely present in the area, is more extensive outside it and postdates major faulting. Structural analysis indicates an extensional phase that continued throughout the Oligocene, with the hydrothermal event beginning shortly after the emplacement of the Cedro Formation and lasting for at least two million years due to the subsequent rhyolitic volcanism.
Arsenic Removal by Nanoscale Magnetite in Guanajuato, Mexico
A pilot-scale demonstration using nanoscale magnetite successfully removed arsenic from groundwater in Guanajuato, Mexico, proving its potential for real-world water treatment applications. Researchers packed 20 nm magnetite particles into sand columns and tested their efficiency under field conditions, finding that magnetite-to-sand ratio and residence time were critical factors affecting arsenic removal. While batch tests showed improved adsorption at lower pH levels, pilot-scale results did not reflect this trend, suggesting complex interference effects in continuous systems. This study highlights the challenges of scaling up nanotechnology-based solutions for full-scale water treatment while offering a promising low-cost method (ca. $2.50 USD) to address arsenic contamination in drinking water, a pressing issue in Latin America.
Active sinking at the bottom of the Rincón de Parangueo Maar (Guanajuato, México) and its probable relation with subsidence faults at Salamanca and Celaya
Research at the Rincón de Parangueo Maar, a Quaternary maar in Guanajuato, Mexico, reveals active sinking at its lakebed with a fault displacement rate of approximately 50 cm/year—significantly higher than regional subsidence faults. The study identifies an annular normal fault system and evidence of rotational slides, planar slides, and rollover anticlines, suggesting dynamic sediment mass movement toward the crater's depocenter. Abundant evaporites in the playa-lake sediments imply salt dissolution and brine infiltration may contribute to this process, potentially linked to aquifer subsidence or diatreme activity. The findings contrast with other dried crater-lakes in the region, highlighting unique deformation mechanisms at Rincón de Parangueo.
El trabajo en las minas de Guanajuato durante la segunda mitad del siglo xviii
During the second half of the 18th century, labor practices in Guanajuato's mines were shaped by state-led mining modernization, which imposed forced labor and stringent regulations. This study reveals that despite the diversity of trades among workers, their development was constrained by a complex system of labor control involving both state intervention and corporate influence. The findings highlight how these measures limited workforce growth in one of the era's most advanced industrial sectors.
Variability of precipitation and temperature in Guanajuato, Mexico
A significant increase in the frequency of extreme heat days—more than doubling—has been observed in Guanajuato, Mexico, between 1979 and 2011, while the number of days with heavy rainfall exceeding the 90th percentile has remained stable. This shift toward hotter conditions, coupled with a near-halving of days with temperatures below the 10th percentile, suggests a growing water scarcity threat to agriculture, a key economic activity in the region. The study also reveals that precipitation patterns are strongly influenced by the Madden-Julian Oscillation (MJO), with phases 1-3 correlating with above-normal rainfall and phases 4-7 with below-normal rainfall. These findings were derived from surface station data across Guanajuato and North American Regional Reanalysis (NARR) data, analyzing atmospheric anomalies linked to wet and dry conditions.
Anthropogenic Metal Content and Natural Background of Overbank Sediments from the Mining District of Guanajuato, Mexico
Research reveals that overbank sediments in the Guanajuato River, Mexico, exhibit significant metal contamination, with moderate to strong levels of Cu, Zn, Sb, and Pb linked to historical mine tailings discharges. The study established geochemical background values using direct and indirect methods, showing natural anomalies for elements like Cu, Cs, and Pb that exceed crustal levels due to mineral deposits in the region. Ni and Cr were attributed to ultramafic rocks, while contamination was confirmed by the geoaccumulation index (Igeo). These findings highlight the potential threat of anthropogenic metals stored in the fluvial plain as a pollutant source for downstream waters in the Lerma-Santiago basin.
Gangue mineral textures and fluid inclusion characteristics of the Santa Margarita Vein in the Guanajuato Mining District, Mexico
A newly discovered gold-silver vein, the Santa Margarita, parallel to the Veta Madre in Guanajuato's historic mining district, contains exceptionally high grades of up to 249 g/t Au and 2,280 g/t Ag. This study identifies distinct gangue mineral textures and fluid inclusion characteristics that correlate with high mineralization potential. Fluid inclusions in rich samples exhibit temperatures between 184–300°C and salinities up to 5 wt.% NaCl, while barren samples show lower salinity (≤3 wt.%). Evidence of boiling, particularly vapor-rich inclusions linked to intense 'flashing,' strongly correlates with high gold grades, offering a robust exploration tool for identifying economically viable targets in epithermal deposits.
Geología de la región de Salamanca, Guanajuato, México
A detailed geological mapping of the Salamanca-Aldama region, Guanajuato, Mexico, reveals the complex stratigraphy and tectonic history of the area. The study identified sixteen mappable units, with the oldest exposed unit being a polymictic conglomerate correlated to the Rojo de Guanajuato Formation. Overlying this are andesites and rhyolitic domes and lavas, part of the Oligocene volcanism in the Mesa Central region, though topaz-bearing rocks were not found within the studied area. Three ignimbrite units from the late Oligocene to early Miocene, with intercalated andesites, were also mapped, covering much of the region. The study further identified two andesite-basalt units, one associated with the La Ordeña caldera and another forming widespread lava plateaus. Monogenetic volcanic apparatuses and lava flows were linked to the Trans-Mexican Volcanic Belt (FVTM). Tectonic structures include older NW-SE faults in the northeast that affect Oligocene rhyolitic rocks, NE-ENE trending faults cutting through ignimbrites, and the significant El Bajío fault, which has a NW-SE strike, ~500 m displacement, and formed the El Bajío tectonic depression—a key boundary between the FVTM and Mesa Central. Additional N-S normal faults in the south affect Pliocene-Quaternary rocks of the FVTM.
Kinematics of the Guerrero terrane accretion in the Sierra de Guanajuato, central Mexico: new insights for the structural evolution of arc–continent collisional zones
Research reveals that the accretion of the Guerrero terrane to the North American craton during the late Early Cretaceous led to significant structural evolution, including the closure of the Arperos oceanic basin and the formation of a 100 km-wide fold–thrust belt. The Sierra de Guanajuato, an exposure of this suture belt, exhibits a complex tectonic pile formed through three major shortening phases (D1SG, D2SG, D3SG). D1SG and D2SG involved NE–SW shortening, while D3SG showed NW–SE contraction with SE-vergent ductile thrusts. These findings suggest that the top-to-the-SE emplacement of the El Paxtle arc assemblage may be due to tectonic escape caused by continuous NE impingement of the Guerrero terrane during its collisional addition to the Mexican mainland.
Moisture expansion associated to secondary porosity: an example of the Loseros Tuff of Guanajuato, Mexico
Research on the Loseros Tuff, a volcanic rock used extensively in Guanajuato's UNESCO-listed colonial buildings, reveals that moisture expansion—driven by secondary porosity and high clay mineral content—is a key factor in its deterioration. The study found that once liquid water penetrates the rock, it triggers matrix dissolution, creating additional pores that amplify expansion. This process is influenced by pore radius distribution, which affects water transport and porosity effectiveness. To uncover these mechanisms, scientists analyzed the tuff's petrographic, mineralogical, geochemical, and petrophysical properties, providing critical insights into its weathering behavior and potential conservation strategies for historic structures.
Waste and Potency: Making Men with Minerals in Guanajuato and Tucson
Minerals once considered waste or byproducts from mining operations in Guanajuato, Mexico, have been transformed into highly valued commodities, fetching thousands of dollars at mineral shows and collector hubs like Tucson, Arizona. This study reveals how these minerals transition from being discarded materials to sought-after scientific specimens and aesthetic collectibles, challenging traditional perceptions of their economic and cultural significance. The research employs a comparative approach, examining the social and economic dynamics in Guanajuato's mines and Tucson's collecting communities. By analyzing the movement and valuation of these minerals, the study highlights their dual role as both industrial byproducts and prized commodities, offering insights into the intersection of mining practices, market forces, and cultural appreciation.
Nuevos registros y extensiones de distribución de mamíferos para Guanajuato, México
A new study expands the known mammal biodiversity of Guanajuato, Mexico, by documenting 11 previously unrecorded species and extending the distribution ranges of 14 others. The research, conducted between 2003 and 2006 in the Sierra Gorda Biosphere Reserve, identified 25 mammal species—including three endemic Mexican rodents (Peromyscus difficilis, P. levipes, and P. melanophrys) and the first record of the vampire bat (Desmodus rotundus) for the state. The findings, based on 364 specimens from five families, update the region's mammal inventory to 98 species. Notably, Leptonycteris yerbabuenae was flagged as a protected species. This work strengthens baseline data for conservation efforts in one of Mexico's UNESCO-listed sites.
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