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Relaciones entre las concentraciones de NO3− / Cl− y Cl−; a) Información del año 2017; b) Información del año 2019 en el agua subterránea de los municipios de Santa Cruz de Juventino Rosas y Villagrán.
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The sub-province Bajío Guanajuatense is located in Central Mexico, is one of the most important agricultural areas in Mexico, where are used large volumes of water. The current panorama of Guanajuato shows an increase of more than three times in the use of groundwater, compared to extraction 30 years ago; this water is used to maximize crop yields;...
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... 2 WT6-2019=0.2). Los resultados de la relación NO3 -/Cl -indican que hay un grado de contaminación por fuentes antropogénicas, principalmente por aplicación de fertilizantes y, posiblemente, en ciertos casos por excretas animales o aguas residuales (Fig 5a y b) como ha sido reportado en otros estudios ( Liu et al., 2006;Lang et al., 2006;Chen et al., 2009;Liu et al. 2010). La afectación podría estar ocurriendo a distintas profundidades (más visible en el año 2019), principalmente por contaminación agrícola (Fig. 5a y b). ...
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... y, posiblemente, en ciertos casos por excretas animales o aguas residuales (Fig 5a y b) como ha sido reportado en otros estudios ( Liu et al., 2006;Lang et al., 2006;Chen et al., 2009;Liu et al. 2010). La afectación podría estar ocurriendo a distintas profundidades (más visible en el año 2019), principalmente por contaminación agrícola (Fig. 5a y ...
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... los resultados de la relación NO3 -/Cl -indican que posiblemente ocurren procesos de desnitrificación en algunos pozos pertenecientes al tipo de agua WT 5 en ambos años, y un pozo del tipo de agua WT 3 de 2019 ( Fig. 5 a y b), aunque sería necesario realizar un estudio más profundo para confirmar este proceso. Por otro lado, para el tipo de agua WT 5 el contenido de cloruros es más elevado en comparación con todos los demás pozos; además, solo una muestra del tipo de agua WT 4 en el año 2017 (termal) cae en el campo como posible fuente por residuos animales ...
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... resultados de la variación en la relación molar NO3 -/Cl -vs la concentración molar de Cl -en los tipos de agua WT4 y WT6 indican una tendencia en el comportamiento que podrían estar relacionadas con fertilizantes para ambos años (Fig. 5a y b). Es evidente que la concentración de nitrato disuelto coincide con contenidos elevados de cloruros para algunas muestras, y esta tendencia es más marcada en pozos del tipo de agua WT 3, ya que se presenta un incremento muy marcado en el contenido de NO3 -/Cl -conforme incrementa el contenido de Cl - (Fig. 5b). Este proceso ya se había ...
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... con fertilizantes para ambos años (Fig. 5a y b). Es evidente que la concentración de nitrato disuelto coincide con contenidos elevados de cloruros para algunas muestras, y esta tendencia es más marcada en pozos del tipo de agua WT 3, ya que se presenta un incremento muy marcado en el contenido de NO3 -/Cl -conforme incrementa el contenido de Cl - (Fig. 5b). Este proceso ya se había observado previamente (Fig. ...
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... la zona de saturación puede transformarse cuando hay interacción con microorganismos que habitan en esta zona y que ayudan en la transformación del ion amonio (NH4 + ) en nitritos (NO2 -) y al final en nitratos (NO3 -) (reacciones 3 y 4).Durante la transformación de la materia orgánica (Norgánico) las nitrobacterias participan en la oxidación ( Fig. 5 y 6e y f), la velocidad de reacción depende de las condiciones del medio. El fin último de estos procesos es el nitrógeno soluble en agua (reacción ...
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... reacción reversible de los nitratos también produce nitritos (desnitrificación), al combinarse el nitrato con el carbono C, el cual es liberado de distintos procesos de descomposición de materia orgánica (por la acción de las bacterias), como queda evidente en algunas muestras del agua WT 5 ( Fig. 5a y b). Durante este proceso queda libre el nitrógeno N2 (Clark, 2015) y cuando se combina el N2 con el oxígeno puede volver a producir nitrito (NO2 -) y nitrato (NO3 -) (reacción 5) ( Fig. 4a y d y ...
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... 2 WT6-2019=0.2). Los resultados de la relación NO3 -/Cl -indican que hay un grado de contaminación por fuentes antropogénicas, principalmente por aplicación de fertilizantes y, posiblemente, en ciertos casos por excretas animales o aguas residuales (Fig 5a y b) como ha sido reportado en otros estudios ( Liu et al., 2006;Lang et al., 2006;Chen et al., 2009;Liu et al. 2010). La afectación podría estar ocurriendo a distintas profundidades (más visible en el año 2019), principalmente por contaminación agrícola (Fig. 5a y b). ...
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... y, posiblemente, en ciertos casos por excretas animales o aguas residuales (Fig 5a y b) como ha sido reportado en otros estudios ( Liu et al., 2006;Lang et al., 2006;Chen et al., 2009;Liu et al. 2010). La afectación podría estar ocurriendo a distintas profundidades (más visible en el año 2019), principalmente por contaminación agrícola (Fig. 5a y ...
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... los resultados de la relación NO3 -/Cl -indican que posiblemente ocurren procesos de desnitrificación en algunos pozos pertenecientes al tipo de agua WT 5 en ambos años, y un pozo del tipo de agua WT 3 de 2019 ( Fig. 5 a y b), aunque sería necesario realizar un estudio más profundo para confirmar este proceso. Por otro lado, para el tipo de agua WT 5 el contenido de cloruros es más elevado en comparación con todos los demás pozos; además, solo una muestra del tipo de agua WT 4 en el año 2017 (termal) cae en el campo como posible fuente por residuos animales ...
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... resultados de la variación en la relación molar NO3 -/Cl -vs la concentración molar de Cl -en los tipos de agua WT4 y WT6 indican una tendencia en el comportamiento que podrían estar relacionadas con fertilizantes para ambos años (Fig. 5a y b). Es evidente que la concentración de nitrato disuelto coincide con contenidos elevados de cloruros para algunas muestras, y esta tendencia es más marcada en pozos del tipo de agua WT 3, ya que se presenta un incremento muy marcado en el contenido de NO3 -/Cl -conforme incrementa el contenido de Cl - (Fig. 5b). Este proceso ya se había ...
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... con fertilizantes para ambos años (Fig. 5a y b). Es evidente que la concentración de nitrato disuelto coincide con contenidos elevados de cloruros para algunas muestras, y esta tendencia es más marcada en pozos del tipo de agua WT 3, ya que se presenta un incremento muy marcado en el contenido de NO3 -/Cl -conforme incrementa el contenido de Cl - (Fig. 5b). Este proceso ya se había observado previamente (Fig. ...
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... la zona de saturación puede transformarse cuando hay interacción con microorganismos que habitan en esta zona y que ayudan en la transformación del ion amonio (NH4 + ) en nitritos (NO2 -) y al final en nitratos (NO3 -) (reacciones 3 y 4).Durante la transformación de la materia orgánica (Norgánico) las nitrobacterias participan en la oxidación ( Fig. 5 y 6e y f), la velocidad de reacción depende de las condiciones del medio. El fin último de estos procesos es el nitrógeno soluble en agua (reacción ...
Context 14
... reacción reversible de los nitratos también produce nitritos (desnitrificación), al combinarse el nitrato con el carbono C, el cual es liberado de distintos procesos de descomposición de materia orgánica (por la acción de las bacterias), como queda evidente en algunas muestras del agua WT 5 ( Fig. 5a y b). Durante este proceso queda libre el nitrógeno N2 (Clark, 2015) y cuando se combina el N2 con el oxígeno puede volver a producir nitrito (NO2 -) y nitrato (NO3 -) (reacción 5) ( Fig. 4a y d y ...
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... This mechanism would account for the overall increase of both elements in certain wells (Fig. 4). The increase in SO 4 2− content in particular Mg-HCO 3 , Na-HCO3, and Mx-HCO 3 water types may have this origin, although the incorporation of wastewater may also occur (Kolpin et al. 1994;Morales-Arredondo et al. 2020). ...
To explain the presence and spatial distribution of NO 3 ⁻ and N–NH 3 in the Aquifer of the Metropolitan Area of Mexico City (AMAMC), a hydrogeochemical and isotopic analysis using ¹³ C DIC (as well as the stable isotopes ¹⁸ O and ² H) in groundwater was conducted. This aquifer is located in an old closed lacustrine volcano-sedimentary basin; some wells hosted in the semi-confined zone contain high N–NH 3 concentrations, while others present NO 3 ⁻ contents in the recharge zones (hosted in an oxidizing environment). In this study, a change in the isotopic signature (primarily in ¹⁸ O and ² H) was observed from the recharge zones to the basin center in some of the wells with high NO 3 ⁻ concentrations, this behavior can be attributed to evaporation during the incorporation of recently infiltrated water. In addition, the results for ¹³ C (along with ² H) in wells with the highest N–NH 3 concentrations exhibited an atypically broad range of values. Results indicated the occurrence of hydrogeochemical and/or biochemical processes in the aquifer (in an oxidizing or reducing environment), such as organic degradation, bacterial decomposition (primarily in the ancient Lake Texcoco and which acts as a natural sink for carbon, nitrogen, sulfur, and phosphorus), besides rock weathering and dissolution, which may be responsible for a very marked isotopic modification of the ¹³ C (and, to a lesser extent, ² H). Methanotrophic bacterial activity and methanogenic activity may be related to N–NH 3 removal processes by oxidation and residual water incorporation respectively, whereas the increase in the NO 3 ⁻ content in some wells is due to the recent contribution of poor-quality water due to contamination.
... Some works have characterized low-temperature thermal systems in central Mexico or water-rock interaction processes using hydrogeochemistry [15][16][17] and using a multivariate statistical analysis of geochemical data to determine the processes that control the geochemical evolution of groundwater [18,19]. On the other hand, the authors of [9] investigated the impact of geological faults on thermalism and the levels of fluoride and arsenic in the groundwater of the Laguna Seca aquifer in Guanajuato State. ...
... According to the Stiff diagrams and the geology of the study area ( According to the investigations in the surrounding areas, the groundwater with the highest temperature corresponds to bicarbonate facies (Na HCO3), indicating that it has interacted with thermal fluids and could be controlled by faults and deep regional scale water flow [37]. The water temperature in these wells ranges between 36 and 50 °C [16]. It is also assumed that high-temperature wells are located near faults and fractures and coincide with high levels of other elements, such as arsenic and fluoride, as in this study region [15][16][17]. ...
... The water temperature in these wells ranges between 36 and 50 °C [16]. It is also assumed that high-temperature wells are located near faults and fractures and coincide with high levels of other elements, such as arsenic and fluoride, as in this study region [15][16][17]. The thermal springs of the Comanjilla spa (M-22) and the well in El Salto de Abajo (M-14) have similar hydrogeochemical characteristics. ...
This study investigates the natural hydrogeochemical mechanisms that govern groundwater chemistry at the margins of the Silao-Romita, Valle de León, and La Muralla aquifers in Mexico's "Bajío Guanajuatense". The wells of the La Muralla aquifer have temperatures ranging from 25 to 45 • C, while in the valleys, the temperatures range from 25 to 29 • C. In the Sierra de Guanajuato recharge zone, the thermal spring registers 95 • C. High Na concentrations (125 to 178 mg/L) are measured due to thermalism. One sample includes 316 mg/L of SO 4 , which is related to a potential gypsum zone. Three hydrogeochemical facies are identified (Ca-Mg HCO 3 , Na-Ca-HCO 3 , and Na-HCO 3). The hydrogeochemical characterization and processes imply hydraulic linkage via regional thermal flows enhanced by faults and the mixing of local flow waters with intermediate flows. The isotopic results indicate that part of the groundwater volume has been exposed to local evaporation processes due to the presence of surface water bodies and irrigation returns. The highest isotopic enrichment is observed near or in the recharge regions. In contrast, the most depleted zones are in the valleys, where there is a more significant interaction with the rock and a longer residence time, implying a mixture of local water flows with deeper or intermediate flows, which, when combined with water geochemistry, indicates a connection between the aquifers studied. The Kruskal-Wallis variance tests, used to compare the differences between aquifers, show that the Valle de León aquifer has more significant differences with respect to the Silao-Romita and La Muralla aquifers. This study's findings are essential for one of central Mexico's most populous and economically active areas.
... These processes generate Na-HCO 3 type waters which are more dependent on silicate weathering, often followed by secondary precipitation reactions (Borrok et al., 2018), this water type dominates in the study area, mainly in the volcanic zones (e.g. P32, P33, P2, P16, P9, P10) ( Fig. 1)Subsequently, when groundwater is incorporated into the granular zone (P26, P8, P24, P22, P20), cationic exchange of Ca 2+ by 2Na + in Na-rich clay minerals occurs to a greater extent, generating the Na-HCO 3 composition (Knobel et al., 1998;Morales-Arredondo et al., 2020), a situation that occurs in the study area when geological characteristics change from volcanic rocks to lacustrine sediments (Fig. 1). Bowser and Jones (2002) indicate that in rocks from silicate-dominated environments, plagioclase feldspar (e.g. ...
The intensive use of the Aquifer of the Metropolitan Zone of Mexico City (AMZMC) has increased the concentrations of some trace elements due to natural or anthropogenic sources, as the release of elements from the heterogeneous mixture of the volcanic rocks and/or alluvial clay deposits, which play a very important hydrogeological role in the behavior of the aquifer. This study characterizes, examines, and compares the concentrations of Ba, B, Sr, and Rb in some wells of the AMZMC. Characterization of major elements and Ba, B, Sr concentration and their behavior in the aquifer, and some ionic ratios have been used to identify the dominant hydrogeochemical processes and the different sources of Rb, Ba, B, Sr in the water, in which mineral alteration, ion exchange, redox reactions are the dominant processes, and may intensify as the salinity, temperature and ionic strength in the medium increases. This information may be indirectly relevant as a contribution to the development of appropriate water management strategies in Mexico City. In addition to providing new data on the distribution and behavior of Rb, Ba, B, Sr in groundwater of the Mexico City Aquifer, which is used for drinking water supply.
Untreated water sources can pose health risks to people and other living beings; due to the congregation of living mass, infectious microbes, suspended solids, heavy metals, etc.; it is essential to investigate their quality ensuring their harmlessness, avoiding agents, and safeguarding the health and comfort of the community. The objective was to determine the quality of water sources for human consumption by analyzing the correlations between parameters in the community of El Frutillo, Bambamarca-Cajamarca. Seven monitoring sessions were conducted at three sites from November 2022 to May 2023; for the analysis of physical, chemical, and coliform indicators, test methods were used following the instructions of the General Directorate of Environmental Health. Comparing the maximum permissible limits of D.S. No. 031-2010-SA-DIGESA with the results, the following were achieved: temperatures between 15.4°C to 17.2°C; turbidity from 0.11 to 1.40 NTU; 163.5 to 305.0 mg/L of total dissolved solids; color < MCL; pH from 7.29 to 8.08; 0.39 to 7.73 mg/L of chlorides; 0.084 to 0.221 mg/L of fluorides; phosphates < MCL; 1.77 to 8.36 mg/L of nitrates; nitrites < MCL; 1.92 to 28.10 mg/L of sulfates; 1.8 to 920.0 MPN/100mL total coliforms and 1.8 to 11.0 MPN/100mL thermotolerant coliforms. The correlation coefficients for pH, temperature, and turbidity versus coliforms were 0.907, -0.291, and 0.975 respectively. Concluding that the physicochemical quality is good; however, the bacteriological quality is poor, not being suitable for human supply; as evidenced by the correlations, since higher contents of pH, turbidity, and temperature lead to higher concentrations of coliforms.
Drinking water with a high natural concentration of fluoride (F−) has serious consequences for the health of the rural population in the state of Guanajuato, Mexico, where the water contains levels of F− that are not allowed by national and international regulations (1.5 mg/L). This health problem is very common in multiple states throughout Mexico where drinking water is generally extracted from aquifers that are hosted in fractured volcanic rocks of the Tertiary. These aquifers show similar geological characteristics: deep basins that formed as a result of felsic eruptive events and the extensional deformation of the Basin and Range and are now filled with unconsolidated sediments. In this study, we assessed the occurrence of F in volcanic rocks collected at 11 sampling sites along the Sierra de Codornices in Guanajuato (ranging between 0.01299 and 0.146 wt%, average 0.039 wt%, and SD = 0.039 wt%; n = 10), a region where both rural and urban communities consume drinking water with a high F− content (up to 7.1 (mg/L). The F content is dispersed in volcanic rocks, and the highest levels are present in felsic rocks. The statistical and hydrogeochemical results of a sampling campaign of 32 wells in the Juventino Rosas (JR) and Villagran (Vill) municipalities in 2019 suggest that F− mobilization in groundwater is the product of silicate weathering and the dissolution of volcanic glass, alkaline desorption in the surfaces of F-containing minerals, and possibly ion exchange of minerals and clays or deep fluids enriched with F−, in addition to the precipitation of carbonates that decrease the Ca2+ concentration in groundwater. All of these processes can be accelerated by groundwater geothermal characteristics within the study area. The hydrogeochemical, fluoride exposure risk, and fluoride pollution index (FPI) results, as well as the epidemiological survey, indicate that teenagers and older adults from Praderas de la Venta are at risk of exposure to F− due to the high concentrations ingested over a long period, the toxicity of the element, and its ability to accumulate in the bones. Extended exposure to elevated levels increases the risk. This work allows us to observe how the populations of JR and Vill can be exposed to high F− contents in drinking water due to the geological characteristics of the region.
Chronic exposure from drinking water with naturally high concentrations of fluoride (F⁻) has serious health consequences in several regions across the world including north-central Mexico as Guanajuato State, where the rural population is particularly dependent on untreated groundwater pumped from wells that have natural F- concentrations higher than those allowed by national and international regulations. The contaminated aquifers in the area are usually located in fractured volcanic environment that interacts with sedimentary basins and have a carbonate basement. Few studies focused on identifying the origin and hydrogeochemical processes related to fluoride release and mobilization have been developed, and even fewer that quantify the natural content of F in the geological environment. In this study, an evaluation of fluoride in volcanic rocks collected from 11 sampling sites along the Sierra de Codornices (Guanajuato State, Central Mexico) was carried out. The fluoride content is disseminated in volcanic rocks and the highest contents were obtained in felsic rocks. According to results obtained of a sampling campaign of 32 wells in 2019 their statistical and hydrogeochemical evaluation suggest that F- mobilization in groundwater from Juventino Rosas and Villagran municipalities, is a product of volcanic glass dissolution, a process involved in alkaline desorption occurring on the surfaces of F-containing minerals, and possibly on ion exchange occurring in minerals and some clays or even in deep fluids enriched in F. All these processes may be accelerated by the geothermal characteristics of the groundwater in the study area. The hydrogeochemical results and the epidemiological survey conducted indicate that children and older adults of Praderas de la Venta are at risk of exposure to F- due to the high concentrations ingested over a long period of time, to the toxicity of the element and its ability to accumulate in the bones. Prolonged exposure to high concentrations increases the risk.
