Bartolomé Andreo

Sedimentary patterns in perched spring travertines near Granada (Spain) as indicators of the paleohydrological and paleoclimatological evolution of a karst massif

Perched spring travertines of the Granada basin (South Spain) constitute a perched system with four well-defined steps, which are formed by several facies associations deposited in different sub-environments (travertine pools, dams and cascades). These perched travertines are considered as a freshwater reef system with a facies zonation and stratigraphic architecture closely resembling that of marine reef terraces and prograding carbonate platforms. The travertine deposits have been dated by 230 Th/ 234 U and 14 C methods. As in other Mediterranean areas, the travertine deposition occurred episodically during warm and wet interglacial periods coinciding with isotopic stages 9, 7 and 5, and with the transition between isotopic stages 2/1. During these periods, underground dissolution, large outflow in the springs and subsequent calcium carbonate precipitation occurred. In the same way that evolution of reef systems indicates sea level changes, the geomorphology, age and architecture of perched spring travertine systems may be used to interpret former climatically controlled changes in outflow, in base level marked by the altitude of springs and in the chemistry of spring waters. Thus, aggradation or climbing progradation may indicate an increase of outflow at the spring, progradation with toplap is due to a stable base level and, conversely, dowlapping progradation may signify that the base level was gradually dropping. Therefore, the travertines can be considered semiquantitative indicators of the paleohydrological evolution of karstic massifs and used as an important terrestrial proxy climate record. D 2003 Elsevier Science B.V. All rights reserved.

Advances in Research in Karst Media

The right to water use does not imply total sovereignty by some to the detriment of others over one of the most basic natural resources necessary to sustain life. Both developed and developing countries must find a workable balance for managing water resources. Water use decisions like those affecting Figeh Spring, Damascus, Syria, and Kharga Oases, Egypt, are controlled both by natural parameters, as well as human factors such as land use and population growth. Sustainable Water Development (SWD) is an internationally accepted program for balancing water use issues and goals among competing consumers.

The aquifer pollution vulnerability concept: aid or impediment in promoting groundwater protection?

The term ‘aquifer pollution vulnerability’ was first coined by Margat (1968), and subsequently given a working definition plus a practical tool-box in the mid-1980s by the US Environmental Protection Agency (EPA) through DRASTIC (Aller et al. 1987) and by WHO and the Pan American Health Organization (PAHO) through GOD (Foster 1987; Foster and Hirata 1988). The concept attempted to represent the sensitivity of an aquifer to being adversely affected at any given point by an imposed contaminant pressure (or load) from the land surface. It being possible to:

Modeling spatiotemporal impacts of hydroclimatic extremes on groundwater recharge at a Mediterranean karst aquifer

Karst aquifers provide large parts of the water supply for Mediterranean countries, though climate change is expected to have a significant negative impact on water availability. Recharge is therefore a key variable that has to be known for sustainable groundwater use. In this study, we present a new approach that combines two independent methods for karst recharge estimation. The first method derives spatially distributed information of mean annual recharge patterns through GIS analysis. The second is a process-based karst model that provides spatially lumped but temporally distributed information about recharge. By combining both methods, we add a spatial reference to the lumped simulations of the process-based model. In this way, we are able to provide spatiotemporal information of recharge and subsurface flow dynamics also during varying hydroclimatic conditions. We find that there is a nonlinear relationship between precipitation and recharge rates resulting in strong decreases of recharge following even moderate decreases of precipitation. This is primarily due to almost constant actual evapotranspiration amounts despite varying hydroclimatic conditions. During the driest year in the record, almost the entire precipitation was consumed as actual evapotranspiration and only little diffuse recharge took place at the high altitudes of our study site. During wettest year, recharge constituted a much larger fraction of precipitation and occurred at the entire study site. Our new method and our findings are significant for decision makers in similar regions that want to prepare for possible changes of hydroclimatic conditions in the future.

The Triassic palaeogeographic transition between the Alpujarride and Malaguide complexes. Betic–Rif Internal Zone (S Spain, N Morocco)

Abstract Various tectonic units situated between the Malaguide and Alpujarride complexes (in the Betic–Rif Internal Zone, S Spain and N Morocco) present Triassic successions sharing features of both complexes the presence of which indicates a transitional domain. These units (which we term Intermediate units) are situated preferentially near the external limit of the Betic–Rif Internal Zone, generally adapted to the shape of the Arc of Gibraltar. The palaeogeography of this area is reconstructed on the basis of the general geometric position of these units and their relationships with equivalent domains in the western Mediterranean, the scarce existing palaeomagnetic data and the directions of tectonic displacement. The most problematic reconstructions concern those units on the N border of the Betic–Rif Zone, as they have significant clockwise rotations (up to 200°), S and SE tectonic displacements, and a different geometric distribution from the rest of the units. We conclude that in general the transition between the Malaguide and Alpujarride complexes was gradual, the Malaguide domain located S of the Alpujarride, with the intermediate units lying, evidently, between the two complexes.

Application of geochemistry and radioactivity in the hydrogeological investigation of carbonate aquifers (Sierras Blanca and Mijas, southern Spain)

The chemical characteristics, 3 H contents and radioactivity of groundwaters from the Sierras Blanca and Mijas (Southern Spain) have been studied in relation to the chemical composition and radioactivity of the aquifer host rocks, and the residence time of the water. The Sierras Blanca and Mijas are made up of calcitic and dolomitic marbles of Triassic age. The groundwaters that drain the calcitic marbles (which outcrop principally in the western Sierra Blanca) have less mineralization, which descreases quickly with recharge (as does the 3 H content), and the gross alpha and beta activities are below detection limit. This is due to the short residence time of water inside the aquifers which are conduit flow systems. The waters of the dolomitic marbles (eastern Sierra Blanca and Sierra Mijas) have higher and less variable mineralization and contain greater concentrations of Mg 2+ , SiO2 and SO 2ˇ 4 (ions normally associated with slow flows). The 3 H contents are more uniform with time (indicating an older age) and there is detectable natural radioactivity, because the waters have a longer residence time in the aquifers, which

Characterisation of dissolved organic matter in karst spring waters using intrinsic fluorescence: relationship with infiltration processes.

From analysis of spectrophotometric properties of dissolved organic matter (OM) and the hydrochemical responses of some karst springs under different hydrologic conditions, an assessment of the origin and transfer pathway of OM present in karst spring waters, from soil and epikarst toward the spring, has been conducted for three karst aquifers in southern Spain: Alta Cadena, Sierra de Enmedio and Los Tajos. Intrinsic fluorescence (excitation-emission matrices or EEMs), together with major water chemistry (electrical conductivity, temperature, alkalinity, Cl⁻, Mg⁺²) and P(CO₂) along with natural hydrochemical tracers (TOC and NO₃⁻, have been monitored in 19 springs which drain the three karst aquifers examined in this study. The spring water EEM spectra indicate that fulvic acid-like substances, produced in the soil as a consequence of the decomposition of OM, are the dominant fluorophores, although some of the OM appears to originate from in situ microbiological activity but could be indicative of contamination present in recharge waters from livestock. During each recharge event, TOC and NO₃⁻ concentrations increased and variations in fluorescence intensities of peaks attributed to fulvic acid-like compounds were observed. In areas with minimal soil development, spatial and temporal variations in the fluorescence intensity of fulvic acid-like substances and other fluorophores derived from microbiological activity, together with other hydrochemical parameters, provide insights into the hydrogeological functioning of karst aquifers and the infiltration velocity of water from soil and facilitate assessment of contamination vulnerability in these aquifers.

Combined use of natural and artificial tracers to determine the hydrogeological functioning of a karst aquifer: the Villanueva del Rosario system (Andalusia, southern Spain)

Analysis of natural responses of karst springs provides information on the behavior of the aquifers they drain. Detailed monitoring and qualitative and quantitative analyses of natural responses, and environmental—total organic carbon (TOC), NO3−, Cl− and intrinsic fluorescence—and artificial (fluorescent dye) tracers, in the water drained by Villanueva del Rosario spring (southern Spain), suggest the existence of a conduit flow system with rapid flows and very short transit times of water through the aquifer. This is in agreement with uranine and eosin breakthrough curves and with simple numerical models done using these data. However, due to the low capacity for natural regulation, not all the recharge effects are simultaneously transmitted to the spring water; given a single input, the system modulates and transfers hydrodynamic variations faster than variations of chemical composition and of water temperature. Additionally, time lags between maximum concentrations of natural and artificial tracers show that the global system response (including diffuse infiltration) is faster and more sensitive than that produced from infiltration concentrated at a single point on the surface (sinkholes).RésuméL’analyse des réponses naturelles des sources karstiques fournissent une information sur le comportement des aquifères qu’elles drainent. Un suivi détaillé et des analyses qualitatives et quantitatives des réponses naturelles, et des traceurs environnementaux—carbone organique total (COT), NO3−, Cl− et fluorescence intrinsèque—et artificiels (colorants fluorescents), dans l’eau drainée par la source de Villanueva del Rosario (Sud de l’Espagne), suggère l’existence d’un système d’écoulement dominé par des conduits avec des écoulements rapides et des temps de transit très courts de l’eau au sein de l’aquifère. Ceci est en accord avec les courbes de restitution de l’uranine et de l’éosine et avec des modèles numériques simples utilisant ces données. Cependant, à cause de la faible capacité de régulation naturelle, tous les effets de la recharge ne sont pas transmis simultanément à la source, considérant une contribution unique, le système module et transfère les variations hydrodynamiques plus vite que les variations de la composition chimique et de la température de l’eau. De plus, les décalages dans le temps entre les concentrations maximums des traceurs naturels et artificiels montrent que la réponse globale du système (y compris l’infiltration diffuse) est plus rapide et beaucoup plus sensible que celle produite par l’infiltration concentrée au niveau d’un point singulier d’introduction en surface (pertes).ResumenEl análisis de las respuestas naturales de manantiales kársticos informa sobre del comportamiento de los acuíferos que drenan. El muestreo detallado y los análisis cualitativos y cuantitativos de las respuestas naturales, y los trazadores ambientales—carbono orgánico total (TOC), NO3−, Cl− y fluorescencia natural—y artificiales (colorantes fluorescentes), en el agua drenada por el manantial de Villanueva del Rosario (sur de España), sugiere la existencia de un sistema de conductos con flujos rápidos y tiempos de tránsito del agua muy cortos a través del acuífero. Esto está de acuerdo con las curvas de concentración de la uranina y la eosina y con los modelos numéricos simples realizados usando estos datos. Sin embargo, debido a la baja capacidad de regulación natural, no todos los efectos de la recarga son transmitidos simultáneamente al agua del manantial; ante una entrada, el sistema modula y transfiere las variaciones hidrodinámicas más rápidamente que las variaciones en la composición química y en la temperatura del agua. Adicionalmente, los retardos temporales entre las concentraciones máximas de trazadores naturales y artificiales muestran que la respuesta global del sistema (incluyendo la infiltración difusa) es más rápida y más sensible que aquella producida a partir de la infiltración concentrada en un solo punto en la superficie (sumidero kárstico).摘要岩溶泉自然反应分析提供了其含水层的行为信息。(西班牙南部)Villanueva del Rosario泉自然反应的详细监测及定量和定性分析、水中的环境(总有机碳(TOC)、 NO3−、 Cl− 及内荧光)及人工(荧光染料)示踪剂显示存在着通过含水层的快速流动管道水流系统及很短的过渡时间。这与荧光素钠和曙红突破曲线一致,也与用这些数据做的简单数值模型一致。然而,由于自然调节能力很低,并不是所有的补给影响同时传到泉水;考虑到单一的输入项,系统调整和传输水文动力变化的速度比化学组分和水温变化要快。另外,天然和人工示踪剂最大含量之间的时滞显示,全球系统反应(包括弥散渗入)比集中在地表一个点(落水洞)产生的渗入更快、更敏感。ResumoA análise das respostas naturais de nascentes cársicas fornece informações sobre o comportamento dos aquíferos que drenam. A monitorização detalhada realizada, bem como os resultados de análises qualitativas e quantitativas das respostas naturais e ambientais—carbono orgânico total (COT), NO3−, Cl− rescência intrínseca—e com traçadores artificiais (corante fluorescente) na água drenada pela nascente de Villanueva del Rosario (sul de Espanha), sugerem a existência de um sistema de escoamento da água no aquífero efetuado por condutas com fluxos rápidos e tempos de percurso muito baixos. Esta análise está de acordo com os dados obtidos com curvas de traçadores de uranina e de eosina, e com modelos numéricos simples feitos usando esses dados. No entanto, devido à baixa capacidade de regulação natural, nem todos os processos de recarga são transmitidos simultaneamente à água de nascente; considerando uma única entrada, o sistema modela e transfere variações hidrodinâmicas mais rapidamente do que as variações da composição química e da temperatura da água. Além disso, os lapsos de tempo entre as concentrações máximas de marcadores naturais e artificiais mostram que a resposta do sistema global (incluindo infiltração difusa) é mais rápida e mais sensível do que a produzida a partir de infiltração concentrada num único ponto na superfície (algar).

Hydrochemical dynamics of TOC and NO 3 − contents as natural tracers of infiltration in karst aquifers

Analysis of Total Organic Carbon (TOC) and NO3− contents in the water at six springs in the province of Malaga (Southern Spain), sampled under different hydrologic conditions, revealed two different hydrochemical behaviour patterns for these natural tracers of infiltration. TOC content increased during every recharge period, following the rapid arrival of water infiltrating through the soil. On the other hand, NO3− content only rose during the first flood episodes (normally in autumn), and fell during the winter and spring ones. This difference is consequence of the distinctive biogeochemical kinetics of nitrogen with respect to organic carbon, both in the soil and within the aquifer. Unlike the mineralisation undergone by TOC from the surface to the spring, the NO3− ion remains in the aquifer almost unaffected, due to the oxidizing conditions prevailing within the karst medium, which do not allow its denitrification and favour its preservation within the saturated zone. In non-polluted aquifers, TOC and NO3− have a common origin in the soil and can be used to determine infiltration processes and the hydrogeological functioning of karst aquifers. Their different hydrochemical evolution provides information about mineralization and degradation processes of organic matter within karst aquifers, which can be used to validate the vulnerability to contamination in this type of medium.

Factors controlling groundwater salinization and hydrogeochemical processes in coastal aquifers from southern Spain

In detrital coastal aquifers, seawater and surface water may interact with groundwater in multiple ways. Understanding the interference of water fluxes in this type of environment is essential to effectively manage the groundwater resources in water-stressed regions, such as the Mediterranean coastal fringe. In this research, the characterization of the main hydrogeochemical processes and the interaction between surface water and groundwater in the Marbella-Estepona coastal aquifers (southern Spain) have been carried out by means of the combined use of different hydrogeochemical indicators along with isotope data. The results show that the diversity of source lithologies (peridotite, carbonate and/or metapelitic) substantially conditions the groundwater geochemistry. The analysis of ionic deltas made it possible a preliminary screening of the geochemical reactions that occur in the Marbella-Estepona aquifers, while the Discriminant Analysis allowed for a consistent classification of sampled groundwater types. The dissolution of calcite and dolomite determines the chemical composition of the groundwater from the eastern sector that are more conditioned by the rainwater infiltration. The dissolution of magnesium-bearing minerals (predominantly forming peridotite rocks) is observed in groundwater samples from the western and central sectors, whose chemical composition showed a greater influence of surface water. The spatial analysis of rCl-/Br- in groundwater has permitted to corroborate that saline intrusion is negligible, hardly affecting to its original water quality. The irregularly distributed recharge by precipitation (seasonal effect) and the atmospheric circulation of cloud fronts (coastal/continental effect) explains why most of groundwater sampled is isotopically impoverished with respect to the rainfall signature. The isotope approach also suggests the hydraulic relationship between surface water and groundwater in the study site. A deeper knowledge of spatial hydrogeochemical variations in coastal groundwater and the influence of water sources over them are crucial for a sustainable groundwater management and global change adaptation in equivalent Mediterranean water-stressed regions.