The VISHMOD methodology with hydrochemical modeling in intermountain (karstic) aquifers: case of the Sierra Madre Oriental, Mexico

"Hydrogeochemistry can be studied qualitatively using graphics such as scatter plots and Piper, Durov, and Schoeller diagrams, among others, and quantitatively by applying mass balance mixing models. The VISHMOD methodology (Virtual Samples in Hydrochemical Modeling) combines these two forms of hydrogeochemical characterizations. It is performed by applying hydrogeochemical modeling to virtual samples. This method makes standardization and control possible in order to demonstrate the extent to which a model is able to reproduce field measurements. Therefore, hydrogeochemical models of hydrogeological systems must be calibrated. This methodology was applied to carbonate and homogeneous media in the Sierra Madre Oriental in Mexico. Using the VISHMOD methodology in this region resulted in the classification of the water type as calcium bicarbonate (Ca-HCO3), representing a ternary mixture in which 45.5% was associated with local flow, 38.5% to intermediate flow and 16.5% to water-rock interaction. The main mineral phases were saturated calcite and sub-saturated dolomite, both from limestone contained in the Tamaulipas Formation.

El sistema hidrológico Esperanza-Oriental y su impacto sobre el acuífero de Tecamachalco, Puebla, México

"El sistema hidrológico Esperanza-Oriental se alimenta principalmente de los deshielos de los volcanes Pico de Orizaba y La Malinche, que se traducen en la disponibilidad de agua subterránea para el valle de Esperanza, con su consecuente aporte al valle de Tehuacán y la formación de cuerpos de agua superficiales en el valle Del Oriental (lagos de Totolcingo y Tepeyahualco). Estos valles han reducido sus áreas de captación y disponibilidad, así como la presencia de un gran número de lagos-cráter (axalapazcos), don-de se observan los niveles estáticos del agua subterránea en la zona (algunos de ellos presentan descensos importantes); ambos sistemas alimentan al acuífero de Tecamachalco, que ha disminuido su disponibilidad de agua subterránea. Con base en un sistema de información geográfica, levantado por el Instituto Nacional de Estadística y Geografía, se identificaron las cargas hidráulicas que dan origen a los flujos subterráneos que alimentan el acuífero de Tecamachalco, así como la evolución fisicoquímica que presenta el agua subterránea, identificada mediante diagramas de Mifflin (1988), Gibbs (1970), Piper (1953), Durov (1948) y relaciones iónicas, lo que ayudó a delinear los patrones de flujos para conocer la dependencia de este acuífero con el sistema Esperanza-Oriental.""The Esperanza-Oriental hydrological system is fed mainly by the meltings that take place in Orizaba and La Malinche volcanoes, which mean availability of groundwater for Esperanza valley, with its consequent contribution to Tehuacan valley and the formation of surface water-bodies in the Del Oriental valley (Totolcingo and Tepeyahualco lakes), which have reduced their water collecting areas and availability, as well as the presence of a large number of crater-lakes (axalapazcos), since static groundwater levels are observed in the area (some of them have significant decreases). Both systems feed Tecamachalco aquifer, which has reduced its groundwater availability. Based on a Geographic Information System created by the National Institute of Statistics and Geography, the hydraulic loads that give rise to those underground streams that feed the aquifer Tecamachalco were identified as well as the physicochemical evolution present in groundwater. This was identified by Mifflin (1988), Gibbs (1970), Piper (1953), and Durov diagrams (1948), together with ionic relations, which helped to delineate those flow patterns that determine to what extent this aquifer is dependent on Esperanza-Oriental hydrological system.

Quality assessment of irrigation water related to soil salinization in Tierra Nueva, San Luis Potosí, Mexico

"Soil salinization is a complex process resulting from the interaction of several factors, mainly quality of water used for irrigation, which deteriorates by aquifer overexploitation, and changes in rainfall patterns and aquifer recharge related to climate change. The purpose of this paper is to present a method to assess the variations of groundwater quality, to compare its suitability for irrigation and to decipher the possible causes of soil salinity in Tierra Nueva, San Luis Potos, Mexico. To assess salinization related to irrigation water quality, dissolved anions and cations were measured in surface and groundwater samples; the most widely used water quality indices to evaluate potential salinity risk of soils are Residual Sodium Carbonate (RSC) and Sodium Adsorption Ratio (SAR). In view of the limited number and uncertainty of using only two indices, in the present work a novel water quality assessment was applied for the first time by statistically combining eight individual quality indices: (RSC), (SAR), percentage of sodium (% Na), Kelley ratio (KR), permeability index (PI), soluble sodium percentage (SSP), magnesium adsorption ratio (MAR) and cation ratio of structural stability (CROSS). A factorial variance analysis and principal component analysis of these eight indices were performed to identify linearity and maximum variance. All irrigation water tests show dissolved ions that can easily precipitate as indicated by PI. In cropland, % Na, SSP, RSC, KR and PI had values unsuitable for irrigation, while RAS, CROSS and MAR values are within suitable levels. The main mechanism of soil salinization seems to be the cation exchange of Ca2+ to Na+ in the waters, along with the precipitation of natrite (Na2CO3) promoted by shallow groundwater and semi-desert conditions of the region. The population growth in the region has caused further demand of clean water for human consumption, affecting the water availability from the aquifer of the study zone, worsened by drought associated to climate change.""La salinización de los suelos agrícolas es un proceso complejo y el resultado de las interacciones de varios factores, principalmente la calidad del agua utilizada para riego, la cual se deteriora por factores como la sobreexplotación de los acuíferos y las modificaciones en la precipitación y la recarga debido al cambio climático. El propósito de esta investigación es presentar un método de evaluación que resalte las variaciones de la calidad del agua subterránea, para comparar su idoneidad para el riego y descifrar las posibles causas de la salinización del suelo en Tierra Nueva, San Luis Potosí, México. Para evaluar la salinización a partir de la calidad de agua de riego, se midieron los aniones y cationes disueltos en aguas superficiales y subterráneas. Los índices de calidad de agua más utilizados para evaluar el riesgo de salinización de suelos son el carbonato de sodio residual (CSR) y la relación de adsorción de sodio (RAS). Viendo el número limitado de índices y la incertidumbre que representa el uso de solo éstos dos, en el presente trabajo una nueva forma de evaluar la calidad del agua se presenta por primera vez, combinándola con un análisis estadístico de ocho índices individuales de calidad de agua: CSR, RAS, porcentaje de sodio (% de Na), la relación de Kelley (KR), el índice de permeabilidad (PI), el porcentaje de sodio soluble (PSS), relación de adsorción de magnesio (RAM) y la relación de cationes de la estabilidad estructural (CROSS). Se realizó un análisis de varianza factorial y el análisis de componentes principales de los ocho índices para identificar la linealidad y la varianza máxima. Todas las muestras de agua de riego contienen iones disueltos que pueden precipitar fácilmente como indica el PI. En las zonas de cultivo, los índices que revelaron que el agua no es adecuada para su uso en el riego fueron: % Na, PSS, CSR, KR y PI. El principal mecanismo de salinización del suelo parece ser el intercambio catiónico entre Ca2+ y Na+ en las aguas, junto con la presencia de aguas subterráneas poco profundas y condiciones semidesérticas de la región que promueven la precipitación del mineral natrita (Na2CO3). En la región, la población va en aumento, lo que ha ocasionado una mayor demanda de agua limpia para el consumo humano, repercutiendo directamente en la disponibilidad de agua del acuífero de la zona de estudio, lo cual se ha agravado por la sequía asociada al cambio climático.

Modeling of groundwater flow and water use for San Luis Potosí Valley aquifer system

"Land use changes are currently one of the indisputable factors in the alteration of processes and cycles of the aquifer system in the San Luis Potosí Valley. Due to its importance, is considered indispensable to investigate this detrimental factor of aquifers. The aim of this research is to use a numerical flow model to analyze the impact that land use changes have had on the aquifer. A finite differences numerical model was adapted to the size and hydrological properties of the aquifer system. It consisted of a regular grid with 30 columns and 34 rows with constant spacing of 1000 meters. It has two layers; the first includes the shallow aquifer and the second, the deep aquifer. The initial hydraulic head of the model corresponds to 1986 and was verified for 1995 and 2007. The model shows the development of a drawdown cone (central valley) extending toward the industrial area (southern valley). Piezometric water levels revealed a decrease of 0.6 to 1.6 meters annually during a period from 1977 to 2007. This work demonstrates that it is the consequence of land use changes and of the incessant overall decline in groundwater reserves. Based on the flow model, population growth projections and water use change, the calculated predictions indicate that by 2021, the total established volume of 136 Mm3/year for consume will be reached. The flow model of the San Luis Potosí Valley aquifer system shows a clear effect of the risks associated with aquifer mining.

Índices de calidad del agua subterránea para uso agrícola en el Soconusco, Chiapas, México

"In Soconusco, Chiapas, in spite of the high availability of surface water, it is resorting to the use of groundwater. Knowledge about the quality of surface or groundwater used to irrigate crops in that region is low. This paper aims to contribute to the knowledge of the quality of groundwater for agricultural use through the characterization of the spatial variability. Assuming a random spatial distribution of 45 samples which were collected in situ were determined: acidity and alkalinity (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), cations and anions and trace elements; in addition to the agricultural index: Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Sodium Percentage (% Na), Kelly Ratio (KR), Magnesium Adsorption Ratio (MAR), Permeability Index (PI), Effective Salinity (ES), Salinity Potential (SP) and Osmotic Potential (OP). In general, SSP, % Na, KR, PI are low, there is only one anomalous point (9) with high values at W of the study area. Similarly, PS, ES, Cl, Na and SAR are low except point 16 and conversely, RSC and pH are high, except at this point located in the center of the study area. The results allow us to infer that the water in that aquifer presents no problems or sodicity toxic ions. In 27 sites sampled values above 250 µmhos/cm were found at 25°C, classified as medium to high risk of salinity, unsuitable for agricultural use. Analysis of the combined effect of the presence of sodium (SAR) and salinity (EC or TDS) shows that 27 of analyzing sites have restricted water medium at very high for use in irrigation.""En el Soconusco, Chiapas, a pesar de la alta disponibilidad de agua superficial, se recurre al uso del agua subterránea. El conocimiento de la calidad del agua superficial o subterránea utilizada para el riego de los cultivos en la región es bajo. Este trabajo contribuye al conocimiento de la calidad del agua subterránea para uso agrícola a través de la caracterización de su variabilidad espacial. Asumiendo una distribución espacial aleatoria, se colectaron 45 muestras, a las que se les determinó: acidez y alcalinidad (pH), conductividad eléctrica (CE), Sólidos Totales Disueltos (TDS), cationes y aniones y oligoelementos; además se determinaron índices agrícolas: Índice de adsorción de sodio (SAR), Carbonato de sodio residual (CSR), Porcentaje de sodio soluble (PSS), Porcentaje de sodio (% Na), Relación de Kelly (RK), Relación de Absorción de Magnesio (RAM), Índice de Permeabilidad (IP), Salinidad Efectiva (SE), Salinidad Potencial (SP) y Potencial Osmótico (OP). En general, el PSS, % Na, RK, IP son bajas, sólo hay un punto anómalo (9) con valores altos en la parte oeste del área de estudio. Del mismo modo, SP, SE, Cl, Na y el RAS son bajos, excepto en el punto 16 y en contraste, CSR y pH son altos, excepto en este punto ubicado en el centro del área de estudio. Los resultados nos permiten inferir que el agua en ese acuífero no presenta problemas de sodicidad y de tóxicos. En 27 sitios se encontraron valores superiores a 250 µm/cm a 25 ° C, clasificados como de riesgo medio a alto de salinidad, es decir inadecuados para uso agrícola. El análisis del efecto combinado de la presencia de sodio (RAS) y salinidad (CE o SDT) muestra que 27 de los sitios analizados presentan restricciones de medias a muy altas para su uso en riego.

Origen de la calidad del agua del acuífero colgado y su relación con los cambios de uso de suelo en el Valle de San Luis Potosí

"La historia de la ciudad San Luis Potosí se remonta al siglo XVI. Con el descubrimiento de yacimientos de oro y plata y la presencia de cuerpos de agua en el valle, fue fundada la ciudad San Luis Minas del Potosí, dando lugar a los dos primeros usos de suelo, urbano y minero. A partir del siglo XVII, el uso de suelo agrícola se desarrolló en huertos y fue relegado a la periferia de la zona urbana en el transcurso del tiempo. Finalmente el uso de suelo industrial surgió de manera importante en la segunda mitad del siglo XX. En la actualidad los tres usos de suelo existentes dentro del Valle de San Luis Potosí son el urbano, agrícola e industrial. A través de una campaña de muestreo hidrogeoquímico en octubre de 2008, con 44 muestras de norias y 3 de manantiales dentro del valle, se evaluaron parámetros físico-químicos, cationes, aniones y elementos traza. En los tres usos de suelo en la zona de estudio fueron detectados niveles importantes de nitratos, sulfatos, cloruros, conductividad eléctrica, coliformes totales y fecales; sin embargo, en la zona urbana existen anomalías puntuales de metales pesados principalmente de mercurio, bario, estroncio, cadmio, plomo, fósforo y plata, relacionadas a las antiguas actividades mineras y a la industria activa en la zona. Mientras que en la zona agrícola, la presencia de metales está asociada a los canales a cielo abierto que también reciben agua del Tanque Tenorio y éste a su vez de la zona industrial. En la zona industrial se detectaron grandes anomalías de tipo puntual en casi todos los metales pesados analizados; la principal fuente de estos contaminantes corresponden a un terreno industrial activo. Este trabajo está enfocado a evaluar el impacto que ha generado la actividad antropogénica sobre el acuífero colgado del Valle de San Luis Potosí desde inicios de la fundación de la ciudad hasta la actualidad, utilizando la calidad del agua como herramienta de análisis.""The history of San Luis Potosi City dates back to the sixteenth century. With the discovery of gold and silver deposits and the presence of water bodies in the valley, the city of San Luis Minas Potosí was founded, leading to the first two uses of land: urban and mining. From the seventeenth century, agricultural land developed in orchards and, over time, was relegated to the periphery of the urban area. Finally, industrial land use emerged significantly in the second half of the twentieth century. Currently the three existing land uses within the Valley of San Luis Potosi are urban, agricultural and industrial. Through a hydrogeochemical sampling campaign in October 2008 with 44 samples from wells and 3 from springs within the valley, we assessed physical and chemical parameters, cations, anions and trace elements. In the three land uses within the study area, we detected significant levels of nitrates, sulphates, chlorides, electrical conductivity, total and fecal coliforms; but in urban areas there are punctual anomalies of heavy metals, mainly mercury, barium, strontium, cadmium, lead, phosphorus and silver related to former mining and active industry in the area. However, in the agricultural zone, the presence of metals is associated with open channels, which also receive water from the Tanque Tenorio and this in turn from the industrial area. In the industrial area, puntual anomalies were detected in almost all heavy analyzed metals; the main source of these pollutants corresponds to an active industrial area. This work aims to evaluate the impact of anthropogenic activity in the perched aquifer of the Valley of San Luis Potosí since the city's foundation to the present, using water quality as an analytical tool.

Marco activo de recursos de innovación docente: Madrid

Una guía de espacios e instituciones para actividades educativas complementarias en enseñanza secundaria y Formación Profesional

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

All-cause mortality in the cohorts of the Spanish AIDS Research Network (RIS) compared with the general population: 1997Ł2010

Abstract Background: Combination antiretroviral therapy (cART) has produced significant changes in mortality of HIVinfected persons. Our objective was to estimate mortality rates, standardized mortality ratios and excess mortality rates of cohorts of the AIDS Research Network (RIS) (CoRIS-MD and CoRIS) compared to the general population. Methods: We analysed data of CoRIS-MD and CoRIS cohorts from 1997 to 2010. We calculated: (i) all-cause mortality rates, (ii) standardized mortality ratio (SMR) and (iii) excess mortality rates for both cohort for 100 personyears (py) of follow-up, comparing all-cause mortality with that of the general population of similar age and gender. Results: Between 1997 and 2010, 8,214 HIV positive subjects were included, 2,453 (29.9%) in CoRIS-MD and 5,761 (70.1%) in CoRIS and 294 deaths were registered. All-cause mortality rate was 1.02 (95% CI 0.91-1.15) per 100 py, SMR was 6.8 (95% CI 5.9-7.9) and excess mortality rate was 0.8 (95% CI 0.7-0.9) per 100 py. Mortality was higher in patients with AIDS, hepatitis C virus (HCV) co-infection, and those from CoRIS-MD cohort (1997. Conclusion: Mortality among HIV-positive persons remains higher than that of the general population of similar age and sex, with significant differences depending on the history of AIDS or HCV coinfection

More than 10,000 pre-Columbian earthworks are still hidden throughout Amazonia

Indigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected pre-Columbian earthworks beneath the forest canopy. Modeled distribution and abundance of large-scale archaeological sites across Amazonia suggest that between 10,272 and 23,648 sites remain to be discovered and that most will be found in the southwest. We also identified 53 domesticated tree species significantly associated with earthwork occurrence probability, likely suggesting past management practices. Closed-canopy forests across Amazonia are likely to contain thousands of undiscovered archaeological sites around which pre-Columbian societies actively modified forests, a discovery that opens opportunities for better understanding the magnitude of ancient human influence on Amazonia and its current state