El proceso de karstificación sobre las rocas carbonatadas y sus morfologías resultantes son aspectos que suelen abordarse desde un enfoque generalmente descriptivo. Habitualmente se parte de unos fundamentos elementales del proceso químico, para pasar directamente a la descripción del modelado del paisaje kárstico. En el presente trabajo se proponen diversas actividades cuyo objetivo conjunto es lograr una visión integral y algo más tangible del proceso de karstificación. Con un enfoque transversal con otras disciplinas, como son la química o la biología, se han planteado diferentes actividades de clase, campo y/o laboratorio, basadas en las transformaciones químicas que experimenta el agua al estar en contacto con los materiales karstificables. Las actividades se plantean para que cada docente pueda adaptarlas a su entorno más próximo, de forma que el alumnado entienda que se trata de un proceso activo y cercano. | The karstification of carbonates and the resulting geomorphological landscapes are frequently studied from a general descriptive point of view. We tend to use basic chemical concepts and then proceed right away to describing the karstic landscapes. In the present paper, we propose different activities in order to achieve a whole, real vision of the karstification process, based on the geochemical interaction between water and soluble carbonates. The proposed field, lab and class tasks present a transversal approach with other subjects such as chemistry and biology. These activities can be carried out both individually and in groups, and the teacher can adapt them to their immediate environment, so that the students understand that karstification is an active process happening in their vicinity.

The objective of this study was to evaluate the inorganic parameters in the water of the Texcoco river. Sampling took place at 10 sites along the watershed (between 2500 and 2240 m above sea level) during the four seasons of the year for three years, with repetitions. The diagnostic parameters and methods used were, for potassium, sodium, magnesium, and calcium, the internal method MI-AM-011 (atomic absorption); phosphates with MI-FQUAR-012, chlorides NMX-AA-073-1981, electrical conductivity and nitrogen of nitrates NOM-AA-93-1984 and NOM-AA-79-1986, pH NMX-AA-08-1980. The three-year average concentrations of calcium, magnesium, potassium, sodium, chlorine, nitrates, and electrical conductivity were low. However, the concentrations of sodium and electrical conductivity were close to medium quality. The concentrations of sodium during Years 2 and 3 were classified as medium. The concentration of phosphates was high. Electrical conductivity during Years 1 and 3 were classified as medium. The concentrations of sodium and electrical conductivity in Seasons 1 and 4 grade a medium quality. The concentration of phosphates during the four seasons and three years were classified as high. Variability of cations and anions at different times of the year was an almost generalized behavior and statistically significant.

En este trabajo se resumen las principales características del borde oeste de la Meseta Meridional de la Península Ibérica, desde el punto de vista hidrológico, hidrogeológico e hidroquímico. Así, se realiza una síntesis geológica y climatológica de la zona , como base al establecimiento de los recursos hidráulicos en la región. Por otra parte, se cifra la demanda de agua en la zona, tanto para abastecimiento como para agricultura, y por último, se establecen aquellos aspectos de calidad de las aguas superficiales y subterráneas más relevantes. | The main hydrological, hydrogeological and hydrochemical characteristics of the "Meseta Meridional" (Spain) are summarized in this paper. A geological and climatic synthesis is done as a basis for establishing the hydraulic resources of the region. Likewise, the water demand in the area, both for urban and industry supplies and agriculture, is estimated. Lastly the most outstanding aspects on quality of surface and underground waters are determined.

Este trabalho buscou avaliar a qualidade da água subterrânea de poços ponteira, que captam água do Sistema Aquífero Quaternário Costeiro (SAQC) na região de Osório (RS), através da aplicação de diferentes métodos. Para a realização do estudo foi feito um inventário e cadastramento de poços, o levantamento e interpretação de dados geológicos e hidrogeológicos, além da coleta e análise de amostras de água. Para este trabalho foram utilizados dados físico-químicos e bacteriológicos, obtidos através das análises de água (campo e laboratório), que foram coletadas em 26 poços. A avaliação dos resultados foi realizada através dos diagramas de Piper e Stiff, da comparação com os Valores Máximos Permitidos (VMP) em portarias de potabilidade e da aplicação de métodos de avaliação da qualidade da água e risco a saúde. Os resultados obtidos permitiram evidenciar que no município, a principal forma de captação da água subterrânea, ocorre por meio de poços ponteira que possuem profundidades na sua maioria, inferiores a 20 metros e que captam água de aquíferos granulares livres associados a camadas de sedimentos arenosos. Além disso, a maior parte das águas subterrâneas apresentaram valores de pH entre 5,6 e 6,5 e valores de condutividade elétrica (CE) entre 0 a 200 uS/cm. As concentrações de nitrato variaram entre 0 e 2 mg/L N-NO3, de cloretos e sódio não ultrapassam 30 mg/L, os sólidos totais dissolvidos entre 0 e 200 mg/L, indicando a ocorrência de águas doces com baixa mineralização. Os resultados das análises bacteriológicas indicaram a presença de Escherichia coli e coliformes totais. A comparação dos resultados das análises com os VMP da portaria do Ministério da Saúde Nº 2914/11 (Brasil, 2011), indicaram a ocorrência de poços que apresentam alterações nos parâmetros pH, amônia, ferro, cor, manganês, turbidez, bem como presença de Coliformes Totais e E.coli. Com o uso do Índice de Qualidade da Água Subterrânea (IQUAS), foram classificadas amostras de água como ótimas, boas e péssimas. Já o cálculo do Índice Relativo de Risco (IRR) evidenciou a ocorrência de amostras que apresentaram valores altos, a Avaliação de Risco à Saúde, indicou a ocorrência de amostras que apresentaram Risco não Carcinogênico. Por fim a partir deste estudo pode-se verificar que o uso de diferentes métodos para avaliação da qualidade da água, tem grande importância, pois torna mais consistente essa avaliação, já que cada método envolve a análise de diferentes parâmetros. | The aim objective of this work was to evaluate the groundwater quality of wells, which capture water from the Coastal Quaternary Aquifer System (SAQC) in the region of Osorio (RS), by applying different methods. In order to carry out the study, an inventory and registration of wells, the survey and interpretation of geological and hydrogeological data, as well as the collection and analysis of water samples. For this work, physicochemical and bacteriological data were obtained through water analysis (field and laboratory), which were collected in 26 wells. The evaluation of the results was carried out through the Piper and Stiff diagrams, the comparison with the Maximum Permitted Values (VMP) in potable water consumption and the application of water quality and health risk assessment methods. The results obtained showed that in the municipality, the main way of captation of groundwater occurs through pointer wells that have a depth of less than 20 meters and capture water from unconfined granular aquifers associated with layers of sandy sediments. In addition, most groundwater had pH values between 5.6 and 6.5 and values of electrical conductivity (EC) between 0 and 200 uS/cm. Nitrate concentrations ranged from 0 to 2 mg / L NNO3, with sodium chloride not exceeding 30 mg/L, total solids dissolved between 0 and 200 mg/L, indicating the occurrence of fresh water with low mineralization. The results of the bacteriological analyzes indicated the presence of Escherichia coli and total coliforms in 4 wells. The comparison of the results of the analyzes with the MPV of Ministry of Health No. 2914/11 (Brazil, 2011) indicated the occurrence of wells that present alterations in pH, ammonia, iron, color, manganese, turbidity and presence of Total Coliforms and E. coli. With the use of the Underwater Water Quality Index (IQUAS), 9 water samples were classified as optimal, 2 as good and 4 bad. The calculation of the Risk Index (IRR) evidenced the occurrence of 7 samples that presented high values, the Health Risk Assessment, indicating the occurrence of 2 samples that presented non-Carcinogenic Risk. Finally, from this study we can verify that the use of different methods to evaluate water quality, is of great importance, since it makes this evaluation more consistent, since each method involves the analysis of different parameters.

El área de estudio comprende el sistema geotermal Domuyo (Neuquén, Argentina), el cual ha sido referido como el más importante del mundo luego de Yellowstone. El objetivo es identificar los procesos de interacción agua – roca y la hidroquímica de las aguas del valle del arroyo Manchana Covunco. La metodología consistió en la obtención de datos físicoquímicos y composicionales de aguas mediante relevamientos de campo y análisis de laboratorio. Los resultados obtenidos permitieron estimar un predominio de los procesos de interacción entre las aguas del arroyo (SO₄-Na/Ca y Ca-HCO₃) y agua termal (Na-Cl) con minerales silicáticos, carbonatos y sulfatos presentes en las litologías del área de estudio. Las aguas de los humedales (Ca-HCO₃ y Ca/Mg-HCO₃) evidencian un menor grado de interacción agua – roca, lo cual se vincularía con los tiempos de residencia por el medio que circula y por las condiciones físico-químicas. Asimismo, se determinó que los procesos hidrogeoquímicos de la interacción agua – roca, obliteran la calidad de las aguas para abastecimiento, fundamentalmente aguas abajo de las descargas termales durante el fin de la estación seca. | The study area includes the Domuyo geothermal system (Neuquén, Argentina), which has been referred to as the most important in the world after Yellowstone. This work aims to identify water – rock interaction processes in the valley of the Manchana Covunco stream, near to Cerro Domuyo. The methodology consisted mainly of water sampling and analysis to obtain physical-chemical and compositional data of waters from wetlands, thermal discharges, and the stream. The results indicates a predominance of the interaction processes between the stream water (SO₄-Na/Ca y Ca-HCO₃) and thermal water (Na-Cl) with silicate, carbonate, and sulfate minerals. These minerals are present in the lithological units of the study area. The waters from wetlands (Ca-HCO₃ y Ca/Mg-HCO₃) present a lower degree of water – rock interaction, which could be associated to the water residence times due to the medium that circulates and by their physical-chemical conditions. Besides, the hydrogeochemical processes of water-rock interaction obliterate the quality of water supply, mainly downstream of thermal discharges during the end of the dry season. | Centro de Estudios Integrales de la Dinámica Exógena

Correct understanding of groundwater/surface-water (GW–SW) interaction in karst systems is of greatest importance for managing the water resources. A typical karst region, Fangshan in northern China, was selected as a case study. Groundwater levels and hydrochemistry analyses, together with isotope data based on hydrogeological field investigations, were used to assess the GW–SW interaction. Chemistry data reveal that water type and the concentration of cations in the groundwater are consistent with those of the surface water. Stable isotope ratios of all samples are close to the local meteoric water line, and the ³H concentrations of surface water and groundwater samples are close to that of rainfall, so isotopes also confirm that karst groundwater is recharged by rainfall. Cross-correlation analysis reveals that rainfall leads to a rise in groundwater level with a lag time of 2 months and groundwater exploitation leads to a fall within 1 month. Spectral analysis also reveals that groundwater level, groundwater exploitation and rainfall have significantly similar response periods, indicating their possible inter-relationship. Furthermore, a multiple nonlinear regression model indicates that groundwater level can be negatively correlated with groundwater exploitation, and positively correlated with rainfall. The overall results revealed that groundwater level has a close correlation with groundwater exploitation and rainfall, and they are indicative of a close hydraulic connection and interaction between surface water and groundwater in this karst system.

Stable isotopes (δ¹⁸O, δD), dissolved silica (DSi) concentration and major ion composition were used to indicate groundwater/surface-water interaction between the aquifers, the rivers and a lake in the high-latitude Lake Pyhäjärvi catchment in Finland. Significant differences were recorded in water chemistry between the groundwater and surface waters, especially in the stable isotope composition and DSi concentrations, which could thus be used as tracers. The baseline data on isotopic patterns and hydrogeochemistry in the hydrological cycle were provided by a 1-year monitoring survey in this snow-type catchment area. The proportions of groundwater in the rivers, the lake inshore area and in a groundwater abstraction plant were calculated using stable isotopes and DSi. Two inflowing rivers had distinct differences in their water chemistry. DSi has potential as a tracer in the river environment, whereas stable isotopes were more applicable in the lake environment. Locally, near the shoreline, the effect of discharging groundwater on the lake-water quality could clearly be observed. Furthermore, infiltration of the lake water into the aquifer could be observed near the pumping wells onshore. This infiltration presents a potential risk for the water quality of water supply (intake) wells. Frequent sampling is needed as part of the evaluation of the level of groundwater/surface-water interaction in snow-type catchments in order to estimate the magnitude of seasonal variation. In groundwater/surface-water interaction studies, spring thaw and high-precipitation events could be problematic, in terms of both sampling and interpreting results.

Groundwater in the Yinchuan Plain (China) is a critical domestic resource that is also used for agricultural irrigation and to maintain ecological environments, among other purposes. Recent research has shown that ineffective planning of water resources, along with large-scale groundwater pumping (mining) has led to ecological problems. To further analyze the characteristics of the regional groundwater flow patterns, and guide the development and utilization of water resources, potentiometric, hydrochemical, and isotopic data were collected along a 60-km transect that crosses the middle Yinchuan Plain. The data were used to develop a two-dimensional conceptual model of the sources, flow patterns, and geochemical evolution of groundwater from the Helan Mountains in the west across the Yellow River in the east. An important component of the model is that in the process of groundwater flow from west to east, the flow direction changes due to the influence of a thick fine-grained sandy-clay unit and long-term groundwater pumping. Local lakes and the shallow groundwater system are recharged by water from the Yellow River. Geochemically, water within the proluvial deposits exhibits relatively low concentrations of total dissolved solids. Further east, the water gradually becomes brackish. The geochemical composition of the shallow groundwater beneath the fluviolacustrine plain west of the Yellow River is also controlled by evaporation, precipitation and cation exchange processes. In other areas, groundwater chemistry is mainly controlled by water–rock interactions and cation exchange. This study enhances understanding of groundwater flow in the region, and provides information critical to water resources development and management.

Baseline monitoring of groundwater quality aims to characterize the ambient condition of the resource and identify spatial or temporal trends. Sites comprising any baseline monitoring network must be selected to provide a representative perspective of groundwater quality across the aquifer(s) of interest. Hierarchical cluster analysis (HCA) has been used as a means of assessing the representativeness of a groundwater quality monitoring network, using example datasets from New Zealand. HCA allows New Zealand’s national and regional monitoring networks to be compared in terms of the number of water-quality categories identified in each network, the hydrochemistry at the centroids of these water-quality categories, the proportions of monitoring sites assigned to each water-quality category, and the range of concentrations for each analyte within each water-quality category. Through the HCA approach, the National Groundwater Monitoring Programme (117 sites) is shown to provide a highly representative perspective of groundwater quality across New Zealand, relative to the amalgamated regional monitoring networks operated by 15 different regional authorities (680 sites have sufficient data for inclusion in HCA). This methodology can be applied to evaluate the representativeness of any subset of monitoring sites taken from a larger network.

The largest undeveloped uranium deposit in the United States, at Coles Hill, is located in the Piedmont region of Pittsylvania County, south-central Virginia, and is hosted in crystalline rocks that are adjacent to and immediately west of Chatham Fault, which separates these crystalline rocks from the metasedimentary rocks of the Danville Triassic Basin (in the east). Groundwater at the site flows through a complex network of interconnected fractures controlled by the geology and structural setting. The role of Chatham Fault in near-surface (<≈200 m) groundwater flow is examined using electrical resistivity profiling, borehole logging, a pumping test, groundwater age dating and water chemistry to determine if the fault represents a permeability barrier or conduit for groundwater flow. The volumetric flow per unit width flowing eastward across the fault is estimated at 0.069–0.17 m2/day. Geochemical data indicate that groundwater in the granitic crystalline rocks represents a mixture of modern and old water, while the Triassic basin contains a possible deeper and older source of water. In regions with shallow water tables, mine dewatering during operation presents significant mining costs. The study’s results yield important information concerning the effect that Chatham Fault would have on groundwater flow during Coles Hill mining operations.