Climatological data with unreliable or missing values is an important area of research, and multiple methods are available to fill in missing data and evaluate data quality. Our study aims to compare the performance of different methods for estimating missing values that are explicitly designed for precipitation and multipurpose hydrological data. The climate variable used for the analysis was daily precipitation. We considered two different climate and orographic regions to evaluate the effects of altitude, precipitation regime and percentage of missing data on the Mean Absolute Error of imputed values and using a homogeneity evaluation of meteorological stations. We excluded from the analysis meteorological stations with more than 25% missing data. In the semi-arid region, ReddPrec (optimal for 9 stations), and GCIDW (optimal for 8) were the best performing methods for the 23 stations, with average MAE values of 1.63 mm/day and 1.46 mm/day, respectively. In the humid region, GCIDW was optimal in ~59% of stations, EM in ~24%, and ReddPrec in ~17%, with average MAE values of ~6.0 mm/day, 6.5 mm/day and ~9.8 mm/day, respectively. This research makes an important contribution to identifying the most appropriate methods to impute daily precipitation in different climatic regions of Mexico based on efficiency indicators and homogeneity evaluation.

En el presente trabajo se obtiene la curva característica del funcionamiento de una bomba como turbina para calcular la energía que se puede generar en una conducción por gravedad desde dos presas hasta una planta de tratamiento de agua potable para abastecimiento de agua, la cual es suministrada con un caudal variable en función del consumo y se encuentra ubicada en la ciudad de Guanajuato, México. La curva característica se obtiene por medio de fórmulas empíricas y curvas experimentales de bombas propuestas por diversos autores, las cuales predicen el funcionamiento de la bomba operando como turbina. Las fórmulas se utilizan para conocer el punto de funcionamiento óptimo en el que puede trabajar la máquina, mediante las variables: caudal, carga hidráulica y eficiencia. Finalmente, en el caso de estudio, la energía generada por la bomba funcionando como turbina es de 90 626.35 kWh/año.

This study presents the effect of a variable magnetic field on chromium (VI) absorption typical of a hydroponic system for Phytoabsorption using watercress (Nasturtium officinale) plants in a batch system. The experimentation was carried out applying magnetic fields of 12 and 44 mT and comparing it with the system without field; the field was generated by arrangement of coils and specific conditions for each system, for this work solutions with concentrations of 1, 10, and 20 ppm of chromium (VI) were used during a four-week process with the objective of evaluating the effect of the magnetic field in bioaccumulation in the system. The results indicate that the absorption of chromium increased per week, having that in most of the study cases (0 mT, 12 mT, 44 mT) the highest absorption was achieved in week 4, having that for all cases between week 3 and 4 the difference is minimal, likewise the results indicate that when implementing a magnetic field bioaccumulation is favored showing similar results for both magnetic fields studied in this work. The highest removal efficiency for the study cases corresponding to 1 ppm and 10 ppm was achieved when a field of 12 mT was applied, reporting values of 0.83 and 0.85 respectively, with respect to the case of 20 ppm, the highest efficiency was 0.83 applying a field of 44 mT. Statistical correlation models were found using multiple linear regression model finding significant variables (the magnetic field, concentration of chromium (VI), exposure time). With the interaction model we found significant interactions (concentration*week and field*concentration), and with the model of quadratic terms and interactions (non-significant field*week), which presented adequate adjustments description of the phenomenon, r^2=0.965 using coefficient analysis. Keywords: Chromium (VI), Removal capacity, Watercress plants, Magnetic field, Hydroponic system

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The diversity of diatoms in the hot springs of the Comanjilla geothermal zone in northern Guanajuato, Mexico was studied. Hot springs are extreme ecosystems that, despite having high temperatures, constitute an environment for many thermophilic microorganisms (bacteria, cyanobacteria, and diatoms). The thermal water studied is classified as hyperthermal water (45°C to 100°C), of deep origin, and with low mineralization, are of type sulfuric sodium chloride, since the dissolved content of hydrogen sulfide (H2S) is found in concentrations higher than 1mg/L, and its smell is similar to the one of rotten eggs, presents a pH of 7.6 to 9.1 that represents neutrophilic to alkaliphilic environments, with a variable electrical conductivity (EC) (658-698 µs / cm) and total dissolved solids (TDS) (314-24 ppm). In the same way, these hot springs present microbial mats that consist of several stratified layers of green and orange color of 100 cm2, each one, which are dominated by specific types of microorganisms such as bacteria, cyanobacteria, but mainly diatoms, the latter were studied applying the scanning electron microscope and the optical microscope. The morphological characteristics observed in the optical microscope and in the scanning electron microscopy indicate the presence of diatoms of the Bacillariophyceae class, represented by Sellaphora disjuncta (55%), Achnanthes brevipes var. intermedia (45%). This diatom present in thermophilic microbial mats in the sulphurous geothermal zone of Comanjilla represents: a) the first report of said microorganisms in the study area and Mexico; b) an ecosystem of great interest from the biotechnological and industrial point of view; c) an important taxon in terms of diversity and technology; d) an applications in biofuels, environmental monitoring, wastewater treatment, manufacture of fertilizers, production of secondary metabolites, medical compounds, energy sources and food industry and within nanotechnology. It is important to mention that the physical and chemical characteristics of thermal water such as temperature, pH, dissolved solids, electrical conductivity, hardness, alkalinity and silica concentrations, were the major environmental factors influencing the distribution of diatoms in sulphurous hot springs.