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Microcystis aeruginosa is one of the main harmful bloom-forming cyanobacteria species worldwide. Plant extracts are considered an appropriate practice to obtain effective, economical and sustainable algaecides. For the first time, the effects of Argemone mexicana, Bougainvillea spectabilis, Larrea tridentata and Tradescantia zebrina on the growth of M. aeruginosa in solid and liquid media were investigated by measuring cell density, Chl-a concentration, malondialdehyde (MDA), proteins and nucleotides. Total polyphenol content was quantified to reveal the nature of inhibition. The results in solid medium showed that the methanolic extract of L. tridentata had the greatest effect, showing an inhibition zone of 28.67±0.58 mm. In liquid medium, the methanolic extract of L. tridentata again showed the greatest effects on the cell density of M. aeruginosa (93.80%, pB. spectabilis (87.66%, pA. mexicana with (87.11%, p50 = 13.63, 20.27 and 24.47 mg/L, respectively. L. tridentata also showed a decrease of Chl-a of 91.51% (PL. tridentata showed the highest total polyphenol content, 363.51 mgGAEq/gDE. These results indicate that the decrease in photosynthetic capacity and lipid peroxidation are the most probable mechanisms of action of this species against M. aeruginosa.

Iron and manganese have been studied as a proposal for new materials that could be used for the adsorption of arsenic (V) (As (V)), in order to remove this contaminant. The objective of this work was to study the effect of the molar ratio of three Mn/Fe + Mn composites (X = 0.17, 0.32, 0.47) on the properties of adsorbent media, and to determine their influence on arsenic removal by comparing them with two metallic oxyhydroxides, that are commonly used as adsorbents of As(V) in aqueous solution (goethite and birnessite). These media were synthesized by chemical precipitation while controlling particle size. They were characterized using X-ray diffraction (XDR), scanning electron microscopy with X-ray dispersive energy spectrometry (SEM-EDS), surface area analysis by the BET method, Fourier transform infrared spectroscopy (FTIR), and isoelectric point analysis (IEP). The surface area (286 m2/g) of the composite with a molar ratio of X = 0.17 was larger than that of the other media. The adsorption kinetics and isotherms were fitted to the mathematical models, specifically, the pseudo-second order and Langmuir, respectively. The X = 017 composite had an adsorption capacity of 3.28 mg/g and removed 99% of As(V) with an initial concentration of 0.5 and 97% with an initial concentration of 10 mg/L, at 180 min, 25 °C, and pH 7. The five adsorbent media were tested with well water with an initial As(V) concentration of 0.075 mg/L, and the best behavior was exhibited with a molar ratio of X = 0.17 at 90 min, resulting in 100% removal of As(V). The results suggest that this material is an effective and viable alternative to remove this contaminant from water.

The urban area of Puebla Valley aquifer is seated in Puebla City and neighbor municipalities. Puebla is the fourth largest city in Mexico, where there are significant industrial zones and a large population. Water needs are almost exclusively met by groundwater, which has brought intense exploitation of groundwater resources and water quality degradation. The present study investigates the hydrogeochemical changes in groundwater, particularly focuses on the chemical changes produced by upwelling mineralized water. These concentrations may represent potential risks to the health of the population. The groundwater presented five types of families Ca-HCO3, Mg-HCO3, Mix-HCO3, HCO3-Ca-SO4 and Ca-SO4. The high concentrations of sulphates, calcium and magnesium are reflected in high TDS and Total Hardness. The samples collected showed detectable concentrations of F−, Fe, Mn, Ba, Sr, Cu, Zn, B and Li. The limitations for its use as drinking water are given by the high values of TDS, sulphates, total hardness and Mn. Geochemical modeling using Geochemist's Workbench (GWB) and PHREEQC software enabled the computation of the saturation index of mineral phases with ions in solution and speciation ions. Groundwater was initially in equilibrium with calcite; however, due to the changes in hydrogeological conditions, gypsum and dolomite are being dissolved until new equilibrium conditions are met. The additional calcium and carbonate in the water causes calcite to become oversaturated and to precipitate. Evidence of dedolomitization reactions and common ion effect is illustrated by concurrent increases in calcium and magnesium concentrations in the groundwater.

The Valley of Puebla aquifer (VPA), at the central region of Mexico, is subject to intensive exploitation to satisfy the urban and industrial demand in the region. As a result of this increased exploitation, a number of state and federal agencies in charge of water management are concerned about the problems associated with the aquifer (decline of groundwater table, deterioration in water quality, poor well productivity and increased pumping and water treatment costs). This study presents a groundwater management model that combines “MODFLOW” simulation with optimization tools “MODRSP”. This simulation–optimization model for groundwater evaluates a complex range of management options to identify the strategies that best fit the objectives for allocating resources in the VPA. Four hypothetical scenarios were defined to analyze the response of the hydrogeological system for future pumping schemes. Based on the simulation of flow with the MODFLOW program, promising results for the implementation of the optimization of water quantity were found in scenarios 3 and 4. However, upon comparison and analysis of the feasibility of recovery of the piezometric level (considering the policy of gradual reductions of pumping), scenario 4 was selected for optimization purposes. The response functions of scenario 4 were then obtained and optimized, establishing an extraction rate of 204.92 millions of m3/year (Mm3/year). The reduction in groundwater extraction will be possible by substituting the volume removed by 35 wells (that should be discontinued) by the same volume of water from another source.

The spatial and temporal variation of water quality in the urban area of the Puebla Valley aquifer was evaluated using historical and present data obtained during this investigation. The current study assessed water quality based on the Water Quality Index developed by the Canadian Council of Ministers of the Environment (CCME-WQI), which provides a mathematical framework to evaluate the quality of water in combination with a set of conditions representing quality criteria, or limits. This index is flexible regarding the type and number of variables used by the evaluation given that the variables of interest are selected according to the characteristics and objectives of development, conservation and compliance with regulations. The CCME-WQI was calculated using several variables that assess the main use of the wells in the urban area that is public supply, according to criteria for human use and consumption established by Mexican law and international standards proposed by the World Health Organization. The assessment of the index shows a gradual deterioration in the quality of the aquifer over time, as the amount of wells with excellent quality have decreased and those with lower index values (poor quality) have increased throughout the urban area of the Puebla Valley aquifer. The parameters affecting groundwater quality are: total dissolved solids, sulfate, calcium, magnesium and total hardness.

Tesis (Maestro en Programa de Gestión Integrada de los Recursos Hídricos) -- Instituto Mexicano de Tecnología del Agua. Coordinación de Desarrollo Profesional e Institucional. Subcoordinación de Posgrado. Tabla de contenido: 1. El ombudsman en México -- 2. Justificación constitucional de la Prodagua -- 3. Justificación económica de la Prodagua (referencia general) -- 4. La institucionalidad de la Procuraduría para la defensa de los usuarios de agua -- 5. Conclusiones.