This study develops an approach based on hierarchical cluster analysis for investigating the spat... more This study develops an approach based on hierarchical cluster analysis for investigating the spatial and temporal variation of water quality governing processes. The water quality data used in this study were collected in the karst aquifer of Yucatan, Mexico, the only source of drinking water for a population of nearly two million people. Hierarchical cluster analysis was applied to the quality data of all the sampling periods lumped together. This was motivated by the observation that, if water quality does not vary significantly in time, two samples from the same sampling site will belong to the same cluster. The resulting distribution maps of clusters and box-plots of the major chemical components reveal the spatial and temporal variability of groundwater quality. Principal component analysis was used to verify the results of cluster analysis and to derive the variables that explained most of the variation of the groundwater quality data. Results of this work increase the knowledge about how precipitation and human contamination impact groundwater quality in Yucatan. Spatial variability of groundwater quality in the study area is caused by: a) seawater intrusion and groundwater rich in sulfates at the west and in the coast, b) water rock interactions and the average annual precipitation at the middle and east zones respectively, and c) human contamination present in two localized zones. Changes in the amount and distribution of precipitation cause temporal variation by diluting groundwater in the aquifer. This approach allows to analyze the variation of groundwater quality controlling processes efficiently and simultaneously.
La administracion del recurso hidraulico en Yucatan tiene como principales objetivos: a) Desarrol... more La administracion del recurso hidraulico en Yucatan tiene como principales objetivos: a) Desarrollar abastecimientos de agua subterranea para satisfacer la demanda resultante del crecimiento poblacional y del sector turismo y b) Controlar la contaminacion del agua en un sistema acuifero quimicamente sensitivo y vulnerable a las condiciones geologicas y climaticas. Para conocer los problemas del recurso hidraulico, se dividio al estado en tres areas: costera, urbana y rural. Los resultados obtenidos mostraron que los problemas de infraestructura existen en todas las areas y que los problemas de calidad del agua subterranea son causados por la inadecuada disposicion de desechos domesticos, industriales y agricolas.
Se utilizaron datos hidrogeoquímicos para describir los procesos que modifican la calidad del agu... more Se utilizaron datos hidrogeoquímicos para describir los procesos que modifican la calidad del agua subterránea en el noroeste de Yucatán. Se encontró que los procesos de disolución de rocas carbonatadas de gran pureza, la mezcla con agua salada y el intercambio iónico en calizas arcillosas están presentes en la zona en estudio. Las nuevas observaciones confirman los resultados de estudios previos sobre las medidas recomendadas para la conservación del agua subterránea en la zona. Se encontró agua salobre varios kilómetros tierra adentro, cuya presencia se debe a la intrusión de fondo de agua salada en pozos relativamente profundos o por la concentración del bombeo.
The development of vulnerability maps is considered to be the first step in promoting awareness, ... more The development of vulnerability maps is considered to be the first step in promoting awareness, development of protection strategies and sustainable use of karst aquifers. Nevertheless, high subjectivity of current methodologies for groundwater vulnerability assessment leads to contradictory results when different models are applied over the same area. This makes it difficult for water institutions and decision makers to determine a method to be used on a specific karst area. Four European methods (EPIK, PI, COP and PaPRIKa) were applied for the Yucatan karst to estimate groundwater vulnerability and determine if any of these European methods display vulnerability outcomes in correspondence with regional characteristics such as sinkhole alignments and the shallow water table. Agreement between methodologies was evaluated according to the spatial match on vulnerability rates displayed by final maps; intrinsic features influencing such match and divergent factors were highlighted. Similar vulnerabilities, with more than 52% in average of spatial agreement, were found between COP, PI and EPIK maps. A considerable average up to 33% of match in moderate vulnerability between these three methods was analysed. However, despite the methods displaying similarities regarding moderate vulnerability, these methodologies show no congruence with regional characteristics. A result of a moderate vulnerability on Yucatan coastal and central areas, where the unsaturated zone reaches just a couple of metres, is not an accurate outcome for the shallow water table. Adaptations of these methods or a new integrated methodology would be necessary to estimate groundwater vulnerability in the Yucatan karst.
Merida is the largest city in southeastern Mexico, where the urban supply is obtained mainly from... more Merida is the largest city in southeastern Mexico, where the urban supply is obtained mainly from three well®elds outside of the urban limits in a karst aquifer that is particularly vulnerable to contamination. Merida, Yucatan has a population greater than 600 000 inhabitants. The city obtains its freshwater from a thin (<50 m thick) sole-source aquifer. This aquifer also supplies water to satisfy the industrial and agricultural needs of the region. In order to help in maintaining an adequate water supply for the city, a detailed study has been conducted to determine the best area to establish a hydrogeological reserve zone (HRZ). A polygon of 900 km 2 was chosen southwest of the city. This area is upgradient from Merida, no industrial activity is present, and there are two natural boundaries that bound the proposed HRZ. These are no-¯ow boundaries that have developed as a result of the second boundary: a high permeability zone locally known as the ring of cenotes (ring of sinkholes). The major current obstacle to designate this area as a hydrogeological reserve is an industrial land®ll that is present in within the proposed area. As part of the establishment of the HRZ, the land®ll should be relocated, and a comprehensive ground water quality study should be conducted to determine the actual water quality of the aquifer.
El acuifero de la Peninsula de Yucatan es un acuifero carstico caracterizado por su alta permeabi... more El acuifero de la Peninsula de Yucatan es un acuifero carstico caracterizado por su alta permeabilidad que hace del agua subterranea la principal fuente de abastecimiento y su entorno vulnerable a la contaminacion antropogenica. Dado que el agua subterranea puede ser una fuente de metales traza en el agua de abastecimiento, este trabajo tuvo como objetivo el estudio de la contaminacion por metales traza. Se realizaron los analisis de los metales traza (arsenico, bario, cadmio, cobre, cromo, hierro, manganeso, plomo y zinc) en el agua subterranea de los sistemas de abastecimiento de las cabeceras municipales en el estado de Yucatan y se compararon sus concentraciones promedio con los limites maximos permisibles de la NOM-127-SSA1-1994 con la finalidad de conocer los posibles efectos potenciales a la salud humana; asimismo, se obtuvo un modelo hidroquimico de especiacion. Las concentraciones de los metales analizados variaron de detectables a no detectables, perteneciendo al primer grupo el cadmio, el cobre, el hierro, el manganeso y el zinc, para los cuales se realizo este estudio
La ciudad de Mérida, Yucatán obtiene su agua potable principalmente de tres campos de pozos local... more La ciudad de Mérida, Yucatán obtiene su agua potable principalmente de tres campos de pozos localizados en los alrededores de la ciudad. Adicionalmente, existen pozos del sistema de agua potable dentro de la ciudad. Se ha reportado la presencia de plomo, cadmio y cromo excediendo el límite de la Norma de Agua Potable Mexicana en agua del sistema de agua potable. Los siguientes contaminantes orgánicos también han sido detectado en el agua subterránea de la porción sur de la ciudad: TCA, PCE, TCE y CTET. Mérida obtiene aproximadamente 65% de su agua potable del campo de pozos JAPAY-I, el cual extrae el agua de la sección sureste de la ciudad de Mérida. Es en esta zona donde se concentra la actividad industrial. No se cuenta con información de la calidad del agua de este campo de pozos, pero es probable que se encuentre bastante contaminada. Sugerimos que se implemente un sistema de monitoreo del agua subterránea. Una zona de reserva hidrogeológica también debería de ser establecida para permitirles a los habitantes de Mérida contar con una fuente sustentable de agua potable.
The nitrate concentration in 12 watersupply wells were monitored for the period April 1992 to Mar... more The nitrate concentration in 12 watersupply wells were monitored for the period April 1992 to March 1993. Each water-supply well was sampled once a month. The nitrate concentrations in the 12 wells ranged from 7 to 156 mg/l. Two water-supply wells (Chacsinkin and Peto) showed concentrations that reached 3.5 times the maximum permissible limit for the Drinking Water Standard (45 mg/l). A third water-supply well (Akil) exceeds the norm for 7 out of 12 months. The use of nitrogen-rich fertilizers are responsible for high nitrate concentrations in groundwater in the southern part of Yucatan, Mexico where intensive agricultural practices exist.
Groundwater vulnerability maps are important decision support tools for water resource protection... more Groundwater vulnerability maps are important decision support tools for water resource protection against pollution and helpful in minimizing environmental damage. However, these tools carry a high subjectivity along the multiple steps taken for the development of such maps. Additionally, the theoretical model on which they are based does not consider other important parameters, such as pollutant concentration or pollutant residence time in a given section of the aquifer, solely focusing on the theoretical travel time of a pollutant particle from a release point towards a target. In this work, an integrated methodology for the evaluation of potential (intrinsic) and actual vulnerability is presented. This integrated method, named Integrated Karst Aquifer Vulnerability (IKAV), was developed after the analysis of several study cases around the world and the application of multiple intrinsic groundwater vulnerability methods in a selected study area. Also, a solute transport model served as the basis to define additional parameters for vulnerability analysis for areas severely affected by anthropogenic practices. However, the focus of the transport model must not be mistaken to be hazards and risk mapping. A defined workflow and several criteria for parameters and attributes selection, rating and weighting, and vulnerability classification are presented here. The first application of the IKAV method was carried out in the Yucatán karst, demonstrating to be a reliable method for vulnerability estimation. Results demonstrated the scope of the IKAV method in highlighting important regional conditions, minimizing the subjectivity, and expanding the analysis of vulnerability. M. Moreno-Gómez et al.: First application of the Integrated Karst Aquifer Vulnerability (IKAV) method Financial support. This research has been supported by the Consejo Nacional de Ciencia y Tecnología (grant no. CVU: 466945). This open-access publication was funded by the Technische Universität Dresden (TUD). Review statement. This paper was edited by Mario Parise and reviewed by two anonymous referees.
En el estado de Yucatan, el suministro para agua potable proviene de un acuifero no confinado, el... more En el estado de Yucatan, el suministro para agua potable proviene de un acuifero no confinado, el cual presenta alto grado de vulnerabilidad a la contaminacion debido a las caracteristicas del sustrato geologico peninsular. Entre los principales indicadores de la calidad del agua potable se encuentran los microbiologicos, que son de gran importancia por su potencial impacto en la salud humana. En este trabajo se evaluo la calidad microbiologica del agua subterranea en 106 pozos de abastecimiento del sistema de agua potable del estado, determinando la concentracion de bacterias coliformes y enterococos, y se identifica si el principal origen de la contaminacion biologica es por heces humanas o animales. En el 83.1% de los pozos muestreados, los coliformes totales o fecales excedieron los limites permisibles senalados en la NOM-127-SSA1-1994; el 84.9% de las muestras tuvieron contaminacion fecal; en el 34% de los pozos muestreados, la contaminacion fecal puede asociarse con un origen ...
Cuando se incorporan los contaminantes de una fuente al agua subterranea, la interaccion natural ... more Cuando se incorporan los contaminantes de una fuente al agua subterranea, la interaccion natural entre los procesos fisicos y quimicos que ocurren a traves del medio geologico por el cual circula, se ven alterados. El objetivo de este trabajo fue evaluar el efecto que causa la presencia del lixiviado de residuos municipales en el equilibrio de un acuifero carstico mediante la aplicacion de herramientas hidrogeoquimicas y el empleo del software PHREEQ. El sistema evaluado corresponde al acuifero de la zona del exbasurero municipal de la ciudad de Merida Yucatan, que funciono durante el periodo de 1979 a 1998. Este sistema, se encuentra emplazado sobre calizas fracturadas con un alto contenido de carstificacion, no esta impermeabilizado en su base y el nivel freatico en esta zona se encuentra a cinco metros de profundidad, aproximadamente. Se consideraron los parametros quimicos medidos en muestras de agua subterranea tomadas en 6 pozos profundos (50 metros), ubicados a 10, 25, 50, 10...
This study was conducted in order to know the status of the groundwater quality of the aquifer so... more This study was conducted in order to know the status of the groundwater quality of the aquifer south of Quintana Roo, followed by attempts to investigate the spatial and temporal distribution of physicochemical parameters to identify to identify places with the best quality for drinking consume within the study area. This goal has been achieved with the combined use of the Water Quality Index (WQI) and a geographical information system (GIS). The analyzed data correspond to the rainy seasons of 2002 and 2012. Physicochemical parameters analyzed were pH; temperature (T °); total dissolved solids (TDS); total hardness; sodium (Na +); sulfate (SO 4 2-); chlorides (Cl-), and nitrate (NO 3-). Descriptive statistics and maps of spatiotemporal distribution and ICA were used in the interpretation of the results. The results denoted conditions of spatial heterogeneity of the medium aquifer, due to processes such as mineral dissolution of carbonate rocks, dolomites and evaporates, the mixing of freshsalt water and possible anthropogenic pollution, mainly by domestic sewage and fertilizer use. The chemical constituents that exceeded the allowable limit of NOM-127-SSA1-1994 were STD (22% in 2002, and 42% in 2012); total hardness (60%); Na + (9.8%); Cl-(9.9%), and NO 3-(3%, 2012). The ICA showed that the chemical quality of groundwater for human consumption is acceptable to most of the sites studied.
Uno de los principales problemas en todo el mundo, es el abastecimiento de agua para las poblacio... more Uno de los principales problemas en todo el mundo, es el abastecimiento de agua para las poblaciones, en especial, en regiones como el estado de Yucatan en donde el agua subterranea es la principal fuente de abastecimiento y es tambien, el receptor de las aguas de desecho. El Estado, esta caracterizado por un subsuelo conformado por rocas carbonatadas, las cuales al disolverse dan origen a espesores de suelo muy reducidos y a su vez, un sistema acuifero carstico maduro considerado muy vulnerable. En este trabajo se desarrollo un modelo hidrogeoquimico del agua subterranea con base en sus caracteristicas hidrogeoquimicas espaciales y temporales y mediante la aplicacion de la modelacion inversa. Los resultados mostraron que existen diferentes tendencias espaciales y temporales en el contenido ionico del agua subterranea, que pueden asociarse a fenomenos de disolucion de las rocas subyacentes y a efectos de dilucion debido a la precipitacion pluvial o de enriquecimiento en algunos iones, como consecuencia de la contaminacion generada por las actividades humanas. Asimismo, las familias de aguas predominantes en la region fueron la calcica bicarbonatada y la mixta bicarbonatada, originada por la presencia de rocas carbonatadas en el subsuelo tales como la calcita, la aragonita y la dolomita. El modelo inverso mostro la cantidad de masa de los minerales que interactuan con el acuifero del estado de Yucatan, siendo la calcita la principal fase mineral que se encuentra en los procesos hidrogeoquimicos
Water containing nitrate levels above 45 mg/l is not recommended for human consumption and its pr... more Water containing nitrate levels above 45 mg/l is not recommended for human consumption and its prolonged intake is associated with various health conditions. In Merida city, Mexico, the only source for water supply is a karstic aquifer, but the absence of sewerage and drainage networks makes it highly vulnerable to anthropogenic contamination. In this work, the concentration and spatial distribution of nitrate in the Merida's karstic aquifer were assessed by statistical and geostatistical techniques. The sources of nitrate contamination were tracked by making statistical correlations between nitrate concentrations and key ions; the potential risk to human health was also estimated by using the Hazard Index (HI). A total of 177 groundwater samples were collected from the four water supply systems serving Merida, during 2012 and 2013. Nitrate concentrations from collected samples varied between 15.51 and 70.61 mg/l, with maximum and minimum concentrations per sampling point ranging from 47.47 to 70.61 mg/l and from 15.51 to 17.32 mg/l, respectively. Significant positive correlations (P < 0.05) between nitrates and chlorides, sulphates and potassium were found, which may indicate potential contamination from domestic wastewater and agricultural activities. The spatial distribution of nitrate concentrations in the aquifer revealed an increase in nitrates following a trajectory SoutheNorth West, towards central and northwestern zones within Merida Metropolitan Area. From the health risk analysis, it was found that infants exposed at current nitrate levels are at a higher risk (HI MAX ¼ 1.40) than adults (HR < 1.0) and therefore, there is a clear need for implementing effective strategies to protect groundwater quality and to better manage and control nitrate pollution sources.
Abstract The sewage of the City of Merida, cannot be carried to the sea economically owing to the... more Abstract The sewage of the City of Merida, cannot be carried to the sea economically owing to the low gradient of the land surface. A proposed solution to this problem is the underground injection of waste water through a deep well below an impervious layer (shale). Due to the possibility of pollution at the fresh water aquifer, it is necessary to have a monitoring system around each injection well. Natural hydrochemical variation from the aquifer at different depths were studied. Assuming the simplest monitoring system to be injection well surrounded by four observation wells tapping different depths, the results obtained from this work be used as a control reference, in order to know when a sewage leak from an injection well will be present there.
The aquatic underground mantle in the Peninsula of Yucatan (Mexico) represents the only source of... more The aquatic underground mantle in the Peninsula of Yucatan (Mexico) represents the only source of water supply for domestic consumption. Nevertheless, this mantle is extremely vulnerable to infiltration of pollutants as nitrates due to the karstic layer. Nitrates are inorganic pollutants, whose mobility and stability make them highly dangerous in aerobic systems such as underground water. This contaminant has been found at up to 223 mg/L in artesian wells, whereas the maximum limit permitted by the World Health Organization is 45 mg/L. The development of innovative biomaterials, as nitrifying and denitrifying microbiological mud encapsulated in an inert matrix using the sol-gel technique, represents a possible alternative to eliminate nitrates in situ from the underground water of Merida in the state of Yucatan, Mexico. The sol-gel method has been extensively used for the preparation of such materials permitting a higher stability and viability of useful organisms. In this work the thermal properties of nitrifying and denitrifying mud encapsulated in silica gel derived from tetraethoxysilane are presented as a function of temperature. The photopyroelectric technique was used to study how different types of mud interchanges heat with the environment. The specific surface area of the nitrified mud was determined by analyzing the pore size distribution.
The dehydration process at ambient conditions (25°C and 70% relative humidity) of titania aqueous... more The dehydration process at ambient conditions (25°C and 70% relative humidity) of titania aqueous emulsions, was monitored using the photoacoustic technique. Titania was obtained by the sol-gel method, the powders were thermally treated from ambient temperature up to 700ºC and dispersed in water to form an emulsion. The photoacoustic signal as a function of time, shows two dehydration stages which were parametrized as a sigmoidal curve. The mechanisms inducing the increase in the dehydration rate with the temperature pretreatment are discussed.
This study develops an approach based on hierarchical cluster analysis for investigating the spat... more This study develops an approach based on hierarchical cluster analysis for investigating the spatial and temporal variation of water quality governing processes. The water quality data used in this study were collected in the karst aquifer of Yucatan, Mexico, the only source of drinking water for a population of nearly two million people. Hierarchical cluster analysis was applied to the quality data of all the sampling periods lumped together. This was motivated by the observation that, if water quality does not vary significantly in time, two samples from the same sampling site will belong to the same cluster. The resulting distribution maps of clusters and box-plots of the major chemical components reveal the spatial and temporal variability of groundwater quality. Principal component analysis was used to verify the results of cluster analysis and to derive the variables that explained most of the variation of the groundwater quality data. Results of this work increase the knowledge about how precipitation and human contamination impact groundwater quality in Yucatan. Spatial variability of groundwater quality in the study area is caused by: a) seawater intrusion and groundwater rich in sulfates at the west and in the coast, b) water rock interactions and the average annual precipitation at the middle and east zones respectively, and c) human contamination present in two localized zones. Changes in the amount and distribution of precipitation cause temporal variation by diluting groundwater in the aquifer. This approach allows to analyze the variation of groundwater quality controlling processes efficiently and simultaneously.
La administracion del recurso hidraulico en Yucatan tiene como principales objetivos: a) Desarrol... more La administracion del recurso hidraulico en Yucatan tiene como principales objetivos: a) Desarrollar abastecimientos de agua subterranea para satisfacer la demanda resultante del crecimiento poblacional y del sector turismo y b) Controlar la contaminacion del agua en un sistema acuifero quimicamente sensitivo y vulnerable a las condiciones geologicas y climaticas. Para conocer los problemas del recurso hidraulico, se dividio al estado en tres areas: costera, urbana y rural. Los resultados obtenidos mostraron que los problemas de infraestructura existen en todas las areas y que los problemas de calidad del agua subterranea son causados por la inadecuada disposicion de desechos domesticos, industriales y agricolas.
Se utilizaron datos hidrogeoquímicos para describir los procesos que modifican la calidad del agu... more Se utilizaron datos hidrogeoquímicos para describir los procesos que modifican la calidad del agua subterránea en el noroeste de Yucatán. Se encontró que los procesos de disolución de rocas carbonatadas de gran pureza, la mezcla con agua salada y el intercambio iónico en calizas arcillosas están presentes en la zona en estudio. Las nuevas observaciones confirman los resultados de estudios previos sobre las medidas recomendadas para la conservación del agua subterránea en la zona. Se encontró agua salobre varios kilómetros tierra adentro, cuya presencia se debe a la intrusión de fondo de agua salada en pozos relativamente profundos o por la concentración del bombeo.
The development of vulnerability maps is considered to be the first step in promoting awareness, ... more The development of vulnerability maps is considered to be the first step in promoting awareness, development of protection strategies and sustainable use of karst aquifers. Nevertheless, high subjectivity of current methodologies for groundwater vulnerability assessment leads to contradictory results when different models are applied over the same area. This makes it difficult for water institutions and decision makers to determine a method to be used on a specific karst area. Four European methods (EPIK, PI, COP and PaPRIKa) were applied for the Yucatan karst to estimate groundwater vulnerability and determine if any of these European methods display vulnerability outcomes in correspondence with regional characteristics such as sinkhole alignments and the shallow water table. Agreement between methodologies was evaluated according to the spatial match on vulnerability rates displayed by final maps; intrinsic features influencing such match and divergent factors were highlighted. Similar vulnerabilities, with more than 52% in average of spatial agreement, were found between COP, PI and EPIK maps. A considerable average up to 33% of match in moderate vulnerability between these three methods was analysed. However, despite the methods displaying similarities regarding moderate vulnerability, these methodologies show no congruence with regional characteristics. A result of a moderate vulnerability on Yucatan coastal and central areas, where the unsaturated zone reaches just a couple of metres, is not an accurate outcome for the shallow water table. Adaptations of these methods or a new integrated methodology would be necessary to estimate groundwater vulnerability in the Yucatan karst.
Merida is the largest city in southeastern Mexico, where the urban supply is obtained mainly from... more Merida is the largest city in southeastern Mexico, where the urban supply is obtained mainly from three well®elds outside of the urban limits in a karst aquifer that is particularly vulnerable to contamination. Merida, Yucatan has a population greater than 600 000 inhabitants. The city obtains its freshwater from a thin (<50 m thick) sole-source aquifer. This aquifer also supplies water to satisfy the industrial and agricultural needs of the region. In order to help in maintaining an adequate water supply for the city, a detailed study has been conducted to determine the best area to establish a hydrogeological reserve zone (HRZ). A polygon of 900 km 2 was chosen southwest of the city. This area is upgradient from Merida, no industrial activity is present, and there are two natural boundaries that bound the proposed HRZ. These are no-¯ow boundaries that have developed as a result of the second boundary: a high permeability zone locally known as the ring of cenotes (ring of sinkholes). The major current obstacle to designate this area as a hydrogeological reserve is an industrial land®ll that is present in within the proposed area. As part of the establishment of the HRZ, the land®ll should be relocated, and a comprehensive ground water quality study should be conducted to determine the actual water quality of the aquifer.
El acuifero de la Peninsula de Yucatan es un acuifero carstico caracterizado por su alta permeabi... more El acuifero de la Peninsula de Yucatan es un acuifero carstico caracterizado por su alta permeabilidad que hace del agua subterranea la principal fuente de abastecimiento y su entorno vulnerable a la contaminacion antropogenica. Dado que el agua subterranea puede ser una fuente de metales traza en el agua de abastecimiento, este trabajo tuvo como objetivo el estudio de la contaminacion por metales traza. Se realizaron los analisis de los metales traza (arsenico, bario, cadmio, cobre, cromo, hierro, manganeso, plomo y zinc) en el agua subterranea de los sistemas de abastecimiento de las cabeceras municipales en el estado de Yucatan y se compararon sus concentraciones promedio con los limites maximos permisibles de la NOM-127-SSA1-1994 con la finalidad de conocer los posibles efectos potenciales a la salud humana; asimismo, se obtuvo un modelo hidroquimico de especiacion. Las concentraciones de los metales analizados variaron de detectables a no detectables, perteneciendo al primer grupo el cadmio, el cobre, el hierro, el manganeso y el zinc, para los cuales se realizo este estudio
La ciudad de Mérida, Yucatán obtiene su agua potable principalmente de tres campos de pozos local... more La ciudad de Mérida, Yucatán obtiene su agua potable principalmente de tres campos de pozos localizados en los alrededores de la ciudad. Adicionalmente, existen pozos del sistema de agua potable dentro de la ciudad. Se ha reportado la presencia de plomo, cadmio y cromo excediendo el límite de la Norma de Agua Potable Mexicana en agua del sistema de agua potable. Los siguientes contaminantes orgánicos también han sido detectado en el agua subterránea de la porción sur de la ciudad: TCA, PCE, TCE y CTET. Mérida obtiene aproximadamente 65% de su agua potable del campo de pozos JAPAY-I, el cual extrae el agua de la sección sureste de la ciudad de Mérida. Es en esta zona donde se concentra la actividad industrial. No se cuenta con información de la calidad del agua de este campo de pozos, pero es probable que se encuentre bastante contaminada. Sugerimos que se implemente un sistema de monitoreo del agua subterránea. Una zona de reserva hidrogeológica también debería de ser establecida para permitirles a los habitantes de Mérida contar con una fuente sustentable de agua potable.
The nitrate concentration in 12 watersupply wells were monitored for the period April 1992 to Mar... more The nitrate concentration in 12 watersupply wells were monitored for the period April 1992 to March 1993. Each water-supply well was sampled once a month. The nitrate concentrations in the 12 wells ranged from 7 to 156 mg/l. Two water-supply wells (Chacsinkin and Peto) showed concentrations that reached 3.5 times the maximum permissible limit for the Drinking Water Standard (45 mg/l). A third water-supply well (Akil) exceeds the norm for 7 out of 12 months. The use of nitrogen-rich fertilizers are responsible for high nitrate concentrations in groundwater in the southern part of Yucatan, Mexico where intensive agricultural practices exist.
Groundwater vulnerability maps are important decision support tools for water resource protection... more Groundwater vulnerability maps are important decision support tools for water resource protection against pollution and helpful in minimizing environmental damage. However, these tools carry a high subjectivity along the multiple steps taken for the development of such maps. Additionally, the theoretical model on which they are based does not consider other important parameters, such as pollutant concentration or pollutant residence time in a given section of the aquifer, solely focusing on the theoretical travel time of a pollutant particle from a release point towards a target. In this work, an integrated methodology for the evaluation of potential (intrinsic) and actual vulnerability is presented. This integrated method, named Integrated Karst Aquifer Vulnerability (IKAV), was developed after the analysis of several study cases around the world and the application of multiple intrinsic groundwater vulnerability methods in a selected study area. Also, a solute transport model served as the basis to define additional parameters for vulnerability analysis for areas severely affected by anthropogenic practices. However, the focus of the transport model must not be mistaken to be hazards and risk mapping. A defined workflow and several criteria for parameters and attributes selection, rating and weighting, and vulnerability classification are presented here. The first application of the IKAV method was carried out in the Yucatán karst, demonstrating to be a reliable method for vulnerability estimation. Results demonstrated the scope of the IKAV method in highlighting important regional conditions, minimizing the subjectivity, and expanding the analysis of vulnerability. M. Moreno-Gómez et al.: First application of the Integrated Karst Aquifer Vulnerability (IKAV) method Financial support. This research has been supported by the Consejo Nacional de Ciencia y Tecnología (grant no. CVU: 466945). This open-access publication was funded by the Technische Universität Dresden (TUD). Review statement. This paper was edited by Mario Parise and reviewed by two anonymous referees.
En el estado de Yucatan, el suministro para agua potable proviene de un acuifero no confinado, el... more En el estado de Yucatan, el suministro para agua potable proviene de un acuifero no confinado, el cual presenta alto grado de vulnerabilidad a la contaminacion debido a las caracteristicas del sustrato geologico peninsular. Entre los principales indicadores de la calidad del agua potable se encuentran los microbiologicos, que son de gran importancia por su potencial impacto en la salud humana. En este trabajo se evaluo la calidad microbiologica del agua subterranea en 106 pozos de abastecimiento del sistema de agua potable del estado, determinando la concentracion de bacterias coliformes y enterococos, y se identifica si el principal origen de la contaminacion biologica es por heces humanas o animales. En el 83.1% de los pozos muestreados, los coliformes totales o fecales excedieron los limites permisibles senalados en la NOM-127-SSA1-1994; el 84.9% de las muestras tuvieron contaminacion fecal; en el 34% de los pozos muestreados, la contaminacion fecal puede asociarse con un origen ...
Cuando se incorporan los contaminantes de una fuente al agua subterranea, la interaccion natural ... more Cuando se incorporan los contaminantes de una fuente al agua subterranea, la interaccion natural entre los procesos fisicos y quimicos que ocurren a traves del medio geologico por el cual circula, se ven alterados. El objetivo de este trabajo fue evaluar el efecto que causa la presencia del lixiviado de residuos municipales en el equilibrio de un acuifero carstico mediante la aplicacion de herramientas hidrogeoquimicas y el empleo del software PHREEQ. El sistema evaluado corresponde al acuifero de la zona del exbasurero municipal de la ciudad de Merida Yucatan, que funciono durante el periodo de 1979 a 1998. Este sistema, se encuentra emplazado sobre calizas fracturadas con un alto contenido de carstificacion, no esta impermeabilizado en su base y el nivel freatico en esta zona se encuentra a cinco metros de profundidad, aproximadamente. Se consideraron los parametros quimicos medidos en muestras de agua subterranea tomadas en 6 pozos profundos (50 metros), ubicados a 10, 25, 50, 10...
This study was conducted in order to know the status of the groundwater quality of the aquifer so... more This study was conducted in order to know the status of the groundwater quality of the aquifer south of Quintana Roo, followed by attempts to investigate the spatial and temporal distribution of physicochemical parameters to identify to identify places with the best quality for drinking consume within the study area. This goal has been achieved with the combined use of the Water Quality Index (WQI) and a geographical information system (GIS). The analyzed data correspond to the rainy seasons of 2002 and 2012. Physicochemical parameters analyzed were pH; temperature (T °); total dissolved solids (TDS); total hardness; sodium (Na +); sulfate (SO 4 2-); chlorides (Cl-), and nitrate (NO 3-). Descriptive statistics and maps of spatiotemporal distribution and ICA were used in the interpretation of the results. The results denoted conditions of spatial heterogeneity of the medium aquifer, due to processes such as mineral dissolution of carbonate rocks, dolomites and evaporates, the mixing of freshsalt water and possible anthropogenic pollution, mainly by domestic sewage and fertilizer use. The chemical constituents that exceeded the allowable limit of NOM-127-SSA1-1994 were STD (22% in 2002, and 42% in 2012); total hardness (60%); Na + (9.8%); Cl-(9.9%), and NO 3-(3%, 2012). The ICA showed that the chemical quality of groundwater for human consumption is acceptable to most of the sites studied.
Uno de los principales problemas en todo el mundo, es el abastecimiento de agua para las poblacio... more Uno de los principales problemas en todo el mundo, es el abastecimiento de agua para las poblaciones, en especial, en regiones como el estado de Yucatan en donde el agua subterranea es la principal fuente de abastecimiento y es tambien, el receptor de las aguas de desecho. El Estado, esta caracterizado por un subsuelo conformado por rocas carbonatadas, las cuales al disolverse dan origen a espesores de suelo muy reducidos y a su vez, un sistema acuifero carstico maduro considerado muy vulnerable. En este trabajo se desarrollo un modelo hidrogeoquimico del agua subterranea con base en sus caracteristicas hidrogeoquimicas espaciales y temporales y mediante la aplicacion de la modelacion inversa. Los resultados mostraron que existen diferentes tendencias espaciales y temporales en el contenido ionico del agua subterranea, que pueden asociarse a fenomenos de disolucion de las rocas subyacentes y a efectos de dilucion debido a la precipitacion pluvial o de enriquecimiento en algunos iones, como consecuencia de la contaminacion generada por las actividades humanas. Asimismo, las familias de aguas predominantes en la region fueron la calcica bicarbonatada y la mixta bicarbonatada, originada por la presencia de rocas carbonatadas en el subsuelo tales como la calcita, la aragonita y la dolomita. El modelo inverso mostro la cantidad de masa de los minerales que interactuan con el acuifero del estado de Yucatan, siendo la calcita la principal fase mineral que se encuentra en los procesos hidrogeoquimicos
Water containing nitrate levels above 45 mg/l is not recommended for human consumption and its pr... more Water containing nitrate levels above 45 mg/l is not recommended for human consumption and its prolonged intake is associated with various health conditions. In Merida city, Mexico, the only source for water supply is a karstic aquifer, but the absence of sewerage and drainage networks makes it highly vulnerable to anthropogenic contamination. In this work, the concentration and spatial distribution of nitrate in the Merida's karstic aquifer were assessed by statistical and geostatistical techniques. The sources of nitrate contamination were tracked by making statistical correlations between nitrate concentrations and key ions; the potential risk to human health was also estimated by using the Hazard Index (HI). A total of 177 groundwater samples were collected from the four water supply systems serving Merida, during 2012 and 2013. Nitrate concentrations from collected samples varied between 15.51 and 70.61 mg/l, with maximum and minimum concentrations per sampling point ranging from 47.47 to 70.61 mg/l and from 15.51 to 17.32 mg/l, respectively. Significant positive correlations (P < 0.05) between nitrates and chlorides, sulphates and potassium were found, which may indicate potential contamination from domestic wastewater and agricultural activities. The spatial distribution of nitrate concentrations in the aquifer revealed an increase in nitrates following a trajectory SoutheNorth West, towards central and northwestern zones within Merida Metropolitan Area. From the health risk analysis, it was found that infants exposed at current nitrate levels are at a higher risk (HI MAX ¼ 1.40) than adults (HR < 1.0) and therefore, there is a clear need for implementing effective strategies to protect groundwater quality and to better manage and control nitrate pollution sources.
Abstract The sewage of the City of Merida, cannot be carried to the sea economically owing to the... more Abstract The sewage of the City of Merida, cannot be carried to the sea economically owing to the low gradient of the land surface. A proposed solution to this problem is the underground injection of waste water through a deep well below an impervious layer (shale). Due to the possibility of pollution at the fresh water aquifer, it is necessary to have a monitoring system around each injection well. Natural hydrochemical variation from the aquifer at different depths were studied. Assuming the simplest monitoring system to be injection well surrounded by four observation wells tapping different depths, the results obtained from this work be used as a control reference, in order to know when a sewage leak from an injection well will be present there.
The aquatic underground mantle in the Peninsula of Yucatan (Mexico) represents the only source of... more The aquatic underground mantle in the Peninsula of Yucatan (Mexico) represents the only source of water supply for domestic consumption. Nevertheless, this mantle is extremely vulnerable to infiltration of pollutants as nitrates due to the karstic layer. Nitrates are inorganic pollutants, whose mobility and stability make them highly dangerous in aerobic systems such as underground water. This contaminant has been found at up to 223 mg/L in artesian wells, whereas the maximum limit permitted by the World Health Organization is 45 mg/L. The development of innovative biomaterials, as nitrifying and denitrifying microbiological mud encapsulated in an inert matrix using the sol-gel technique, represents a possible alternative to eliminate nitrates in situ from the underground water of Merida in the state of Yucatan, Mexico. The sol-gel method has been extensively used for the preparation of such materials permitting a higher stability and viability of useful organisms. In this work the thermal properties of nitrifying and denitrifying mud encapsulated in silica gel derived from tetraethoxysilane are presented as a function of temperature. The photopyroelectric technique was used to study how different types of mud interchanges heat with the environment. The specific surface area of the nitrified mud was determined by analyzing the pore size distribution.
The dehydration process at ambient conditions (25°C and 70% relative humidity) of titania aqueous... more The dehydration process at ambient conditions (25°C and 70% relative humidity) of titania aqueous emulsions, was monitored using the photoacoustic technique. Titania was obtained by the sol-gel method, the powders were thermally treated from ambient temperature up to 700ºC and dispersed in water to form an emulsion. The photoacoustic signal as a function of time, shows two dehydration stages which were parametrized as a sigmoidal curve. The mechanisms inducing the increase in the dehydration rate with the temperature pretreatment are discussed.
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