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Recovery of rare earth elements from bauxite residues of lateritic versus karstic origin was explored at a pH ranging between 2.7 and 4.5 using a mixture of citric acid and citrate in water. Dissolution yields of up to 82 % for lanthanum and 62 % for yttrium were achieved with excellent selectivity toward iron (a selectivity factor of up to 4200), the main element of bauxite residues. An experimental Box-Behnken statistical design identified the concentration of citric acid/citrate and temperature as key factors controlling the dissolution yield and selectivity of rare earth elements. Observed differences in dissolution yields and selectivity as a function of origin were attributed to differences in the speciation of rare earth elements in the two bauxite residues. It is therefore possible to draw an “à la carte” graph that identified the optimum citric acid/citrate concentrations and dissolution temperatures for dissolution yields and selectivity for the two BRs. This work provides fundamental knowledge for the future development of sustainable processes for the recovery of rare earth elements from bauxite residues derived from bauxites of different origin.

Copyright of Türkiye Jeoloji Bülteni is the property of TMMOB JEOLOJI MUHENDISLERI ODASI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• GRACE observations and GLDAS data are used to obtain total water storage (TWS) components for an endorheic basin in central Turkey. • Contrary to expectation, the impact of soil moisture on TWS anomaly is found to be larger than that of groundwater. • TWS anomaly time series indicate a significant decline, implying that the basin is losing more water than it is gaining. • The groundwater storage system of the basin responds to precipitation in a relatively short time period (6 months). Water budget components of endorheic basins of semi-arid and karstic characters are difficult to assess. In this study, we attempt to estimate the water budget components of the Konya Endorheic Basin (KEB), which is a semi-arid, karstic basin in central Anatolia, using The Gravity Recovery and Climate Experiment mission (GRACE) observations and Global Land Data Assimilation System (GLDAS) data over the period 2002-2019. We also investigate the trends and sub-trends in the time series of the hydrometeorological parameters. The results indicate that the available water potential in the basin has a decreasing trend over the study period. Precipitation and evapotranspiration show increasing trends in the basin, however, the other hydrometeorological parameters demonstrate decreasing trends. Both Terrestrial Water Storage Anomaly (TWSA) and groundwater level decrease significantly (20.21 mm/yr and 122.34 mm/yr, respectively). The dry 2008 and subsequent wet year created a hydrological breaking point in the time series. The weights of soil moisture and groundwater storages are relatively large amongst the TWSA components (49.61% and 33.12%, respectively). The surface water storage anomaly comes at the third place with a 14% weight. It is assessed that the groundwater storage system responds to precipitation with a delay of 6 months. Limestone zones respond more sharply to groundwater depletion than alluvial zones. It should be noted that the GRACE and GLDAS data could be used together to successfully estimate the water budget components for sustainable management of the limited water resources of the basin. [ABSTRACT FROM AUTHOR]

A new bromeliad species of the genus Catopsis Mez is described in this work. This species is recognized as endemic from Cañon del Sumidero National Park, Chiapas, Mexico. The main character of the new species is its stoloniferous/ rupicolous habit, being similar in size and rosette shape to Catopsis morreniana; it differs from the latter species by its monoecious plants, with slender, simple or once-branched inflorescences. [ABSTRACT FROM AUTHOR]

A checklist of arrenurids of Mexico is presented, including three new records from the Yucatan Peninsula. We provide updated descriptions of Arrenurus mexicanus, A. (Megaluracarus) colitus, and A. (Megaluracarus) marshalli. Additionally, four new species of the subgenus Megaluracarus and one of Dadayella are described by using integrative taxonomy: Arrenurus (Megaluracarus) eduardoi n. sp., characterized by a large, thorn-shaped hump in the middle dorsal shield; Arrenurus (Megaluracaurus) federicoi n. sp., with large pores in the body, including the idiosoma; Arrenurus (Megaluracarus) ecosur n. sp., with a peculiar pattern of setation in the legs; Arrenurus (Megaluracarus) beatrizae n. sp., with a short cauda with two pairs of lateral notches, and Arrenurrus (Dadayella) cristinae n. sp., characterized by a male cauda with two falcate setae. Non-destructive methods allowed the taking of scanning electron microscope images and DNA sequencing of the designed type material. All new species have a divergence using the DNA mitochondrial gene COI from 21.1% to 28.6% within them. With these records and descriptions, the number of Arrenurus registered for Mexico increases to 42, most of them from a single locality. [ABSTRACT FROM AUTHOR]

Two new species of water mites of the family Lebertiidae, Lebertia (Brentalebertia) micropalpis sp. n. and Lebertia (Lebertia) pesici sp. n., are described and illustrated. Specimens of these two species have been collected from the upper part of the Köprüçay River, Antalya Basin, western Anatolian Karstic Plateau, Turkey [ABSTRACT FROM AUTHOR]

A checklist of arrenurids of Mexico is presented, including three new records from the Yucatan Peninsula. We provide updated descriptions of Arrenurus mexicanus, A. (Megaluracarus) colitus, and A. (Megaluracarus) marshalli. Additionally, four new species of the subgenus Megaluracarus and one of Dadayella are described by using integrative taxonomy: Arrenurus (Megaluracarus) eduardoi n. sp., characterized by a large, thorn-shaped hump in the middle dorsal shield; Arrenurus (Megaluracaurus) federicoi n. sp., with large pores in the body, including the idiosoma; Arrenurus (Megaluracarus) ecosur n. sp., with a peculiar pattern of setation in the legs; Arrenurus (Megaluracarus) beatrizae n. sp., with a short cauda with two pairs of lateral notches, and Arrenurrus (Dadayella) cristinae n. sp., characterized by a male cauda with two falcate setae. Non-destructive methods allowed the taking of scanning electron microscope images and DNA sequencing of the designed type material. All new species have a divergence using the DNA mitochondrial gene COI from 21.1% to 28.6% within them. With these records and descriptions, the number of Arrenurus registered for Mexico increases to 42, most of them from a single locality.

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Trichomycterus rosablanca is described as a new troglobitic catfish species from caves in southeastern Santander, Colombia. These caves are drained by the Carare River of the Magdalena River basin. The new species is characterized by the advanced condition in the typical troglomorphisms found in other congeneric cave-dwelling species, such as absence of eyes and pigmentation. Trichomycterus rosablanca is diagnosed by the following putative autapomorphies: 1) presence of a circular foramen in the main body of the interopercle, dorsal to the interopercular plate supporting the odontodes, and 2) presence of a single sensory pore in the posteriormost section of the infraorbital canal. Trichomycterus rosablanca can be distinguished from all known Trichomycterus species from Colombia by having the supraorbital canal interrupted in the nasal section, resulting in the pattern of s1, s2, s3, and s6 sensory pores, and the lachrimal/antorbital bone not enclosing the anteriormost section of the infraorbital canal. The genetic distinctiveness of Trichomycterus rosablanca is confirmed by GMYC and genetic distance method analyses of the cytochrome C oxidase subunit I gene sequence. The description of this species places Colombia as the second most diverse country in the continent in terms of number of cave fish species and calls the attention on the conservation efforts needed to guarantee the permanence of this remarkable diversity of hypogean fishes.

Bauxite residues (BRs) are highly alkaline wastes generated during alumina production from bauxite ore. Billions of tons have been accumulating worldwide for more than 100 years, they are stored in various forms, and pose environmental and societal issues. At the same time, BRs are promising secondary sources for the production of critical metals including rare earth elements (REEs). However, knowledge on REE speciation is lacking, and is consequently an obstacle to the development of large-scale extraction process. This study analyses the influence of origin of the bauxite ore (lateritic or karstic), the storage conditions and storage time on the properties of ten BR samples, with a particular focus on the speciation of yttrium, which is used as a proxy to identify the behaviour of heavy REE. A multi-scale approach linked yttrium speciation and the origin of the bauxite ore whereas no major variation was observed as a function of storage conditions or ageing of the BRs. Yttrium is mainly found in the form of xenotime phosphate particles in BRs of lateritic origin, while in karstic BRs, the majority of yttrium is probably adsorbed or incorporated into other minerals including iron oxyhydroxide and hydroxyapatite minerals., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The transition between the Middle Atlas and the Sais Basin contains a sequence of alluvial fans from the Plio-Quaternary period. These fans are mostly made up of debrites and are found resting unconformably on top of carbonate beds from the Jurassic Period. This location provides a key case study for investigating the primary processes of aggradation, as well as the secondary processes that alter alluvial fan deposits. Alluvial fans are developed through primary processes that occur intermittently over time, resulting in both active and inactive sectors. Internal and external organization of the deposits is, however, partially influenced by secondary processes that can cause mechanical, chemical, and/or biochemical changes, making the comprehension of alluvial fan development processes more complex. In this study, we investigated fan development processes by examining five lithostratigraphic logs and seven sedimentary facies in eight alluvial fans that have merged together. The findings indicate that debris flows were the main driver of fan development, with some contribution from sheet floods and mud-flows. In addition, the study suggests that secondary processes, including mechanical, chemical, biochemical, and diagenetic processes, have had a substantial impact on sediment deposition. The mechanical processes include brittle deformation, incision, reworking, and desiccation. On the other hand, the chemical and/or biochemical processes are evidenced by paleosol and calcrete development, as well as cementation, micritization, dissolution, development of porosity, oxidation, recrystallization, epigenesis, and neoformation. These processes would have been influenced by hydrological, hydrogeological and karstic factors, which are closely linked to the generally semi-arid climatic conditions punctuated by wet phases. • Alluvial fan deposits in the Middle Atlas-Sais Basin transition zone are mainly debris flow-derived. • Diagenetic versus primary processes' impact on alluvial fans in a karstic context. • Secondary mechanical and chemical/biochemical processes prevail in the inactive sectors of alluvial fans. • Biological activity controls the formation of calcretes and diagenetic processes (cementation, micritization, dissolution). • Climate, tectonics, karstification, and hydrogeology (autocyclic and allocyclic factors) govern secondary processes. [ABSTRACT FROM AUTHOR]

The need for a better understanding of factors controlling the variability of soil water content (θ) in space and time to adequately predict the movement of water in the soil and in the interphase soil-atmosphere is widely recognised. In this paper, we analyse how soil properties, surface cover and topography influence soil moisture (θ) over karstic lithology in a sub-humid Mediterranean mountain environment. For this analysis we have used 17 months of θ measurements with a high temporal resolution from different positions on a hillslope at the main recharge area of the Campo de Dalías aquifer, in Sierra de Gádor (Almería, SE Spain). Soil properties and surface cover vary depending on the position at the hillslope, and this variability has an important effect on θ. The higher clay content towards the lower position of the hillslope explains the increase of θ downslope at the subsurface horizon throughout the entire period studied. In the surface horizon (0-0.1 m), θ patterns coincide with those found at the subsurface horizon (0.1-0.35 m) during dry periods when the main control is also exerted by the higher percentage of clay that increases downslope and limits water depletion through evaporation. However, in wet periods, the wettest regime is found in the surface horizon at the upper position of the hillslope where plant cover, soil organic matter content, available water, unsaturated hydraulic conductivity (Kunsat) and infiltration rates are higher than in the lower positions. The presence of rock outcrops upslope the θ sampling area, acts as runoff sources, and subsurface flow generation between surface and subsurface horizons also may increase the differences between the upper and the lower positions of the hillslope during wet periods. Both rock and soil cracks and fissures act disconnecting surface water fluxes and reducing run-on to the lower position of the hillslope and thus they affect θ pattern as well as groundwater recharge. Understanding how terrain attributes, ground cover and soil factors interact for controlling θ pattern on karst hillslope is crucial to understand water fluxes in the vadose zone and dominant percolation mechanisms which also contribute to estimate groundwater recharge rates. Therefore, understanding of soil moisture dynamics provides very valuable information for designing rational strategies for the use and management of water resources, which is especially urgent in regions where groundwater supports human consume or key economic activities.

Turkey hosts essential bauxite deposits, typically of the karstic-type. The most economically important bauxite deposits of Turkey form in the Seydişehir-Akseki region of the central Taurides Mountains. The Mortaş and Doğankuzu deposits are the most important deposits in that region. The bauxite beds contain boehmite, hematite, rutile, smectite, quartz, diaspore, calcite, pyrite, marcasite and goethite. Brown to red-colored bauxite minerals are massive, oolitic – pisolitic textured. The Seydisehir schists could be possible parent rocks of bauxites, and have unearthed acidic source (mostly granite) with hornblende and plagioclase minerals. The schists were compositionally mature with minimal alkali feldspar sediments. The Mortaş deposit is 400 m long and up to 40 m thick; it averages 10 m thick. It has about 5 million tons of ore reserves, with ~50 percent Al2O3. The Doğankuzu bauxite deposit is situated 2 km southwest of the Mortaş deposit, with 14.9 million metric tons of ore at 61 percent Al2O3. The Doğankuzu ore was deposited on a fault-controlled karst surface of Cenomanian limestone succession, which was overlain by 5- to 10-cm-thick Santonian limestones. The bauxite has been mined by the Seydişehir aluminum factory, which was founded in 1973, and privatized in 2005. The plant is capable to produce 65.000 ton liquid aluminum per year, around 15% of Turkey’s Aluminum demand.

Trichomycterus rosablanca is described as a new troglobitic catfish species from caves in southeastern Santander, Colombia. These caves are drained by the Carare River of the Magdalena River basin. The new species is characterized by the advanced condition in the typical troglomorphisms found in other congeneric cave-dwelling species, such as absence of eyes and pigmentation. Trichomycterus rosablanca is diagnosed by the following putative autapomorphies: 1) presence of a circular foramen in the main body of the interopercle, dorsal to the interopercular plate supporting the odontodes, and 2) presence of a single sensory pore in the posteriormost section of the infraorbital canal. Trichomycterus rosablanca can be distinguished from all known Trichomycterus species from Colombia by having the supraorbital canal interrupted in the nasal section, resulting in the pattern of s1, s2, s3, and s6 sensory pores, and the lachrimal/antorbital bone not enclosing the anteriormost section of the infraorbital canal. The genetic distinctiveness of Trichomycterus rosablanca is confirmed by GMYC and genetic distance method analyses of the cytochrome C oxidase subunit I gene sequence. The description of this species places Colombia as the second most diverse country in the continent in terms of number of cave fish species and calls the attention on the conservation efforts needed to guarantee the permanence of this remarkable diversity of hypogean fishes. [ABSTRACT FROM AUTHOR]

Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method in all European Union member states. One of the criteria used to establish GPZs is to define contributing catchment areas (CCAs). This methodology has been applied to the Sierra de Cañete, a region comprising a carbonate aquifer in the province of Malaga, Spain. The tools used to define CCAs are hydro-chemical and isotopic characterizations, namely water isotopes (i.e., ²H, 18O and tritium) and the isotopes of dissolved sulfates (i.e., 34S and 18O). Traditionally, the Sierra de Cañete aquifer has been divided into six sectors. Hydro-chemical and isotopic characterization differentiated between two large areas in the carbonate aquifer. The southern part presents younger water that is the result of faster recharge and that shows a high level of karstification, while the northern area has a slower flow, and recharge is produced over several years. In addition, the northern part is hydraulically connected to an alluvial aquifer (i.e., Llanos de Almargen) that borders the Sierra de Cañete to the north. This aquifer has high levels of pollution due to agricultural and livestock activities carried out in the Llanos de Almargen area. This pollution is transmitted to the carbonate aquifer when groundwater depletion occurs. Therefore, the Sierra de Cañete GPZ needs to be extended to include the Llanos de Almargen aquifer. [ABSTRACT FROM AUTHOR]

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Se analizaron in situ y en el laboratorio, variables físicas y químicas informativas de la calidad de agua subterránea de 14 pozos ubicados en el área de mayor uso de agua dulce de la isla Cozumel, Quintana Roo, México durante un ciclo anual (noviembre 2007 a octubre 2008). Se contrastaron los valores obtenidos con la normatividad nacional e internacional de calidad de agua para uso potable; contribuyendo con información que por un lado permitió determinar áreas con mejor calidad de agua y por otro, evaluar el comportamiento de las variables a escala temporal. Con una prueba de Kruskal-Wallis (p

In the karstic regions of the South of France, caves were used as water source during the Late Neolithic. Different strategies of water collection were put in place, the most frequent being the positioning of very large ceramic containers under trickle points. Functional studies, and more specifically use-wear analysis, are seldom used approaches applied to ceramic assemblages and the identification of post-depositional processes remains a major challenge that affects interpretation, particularly in karstic contexts. In the case of Le Claux, this approach shed light on a possible storage of acid liquid, that was potentially fermented. This paper aims both to contribute to the discipline of use-wear studies applied to ceramic material by offering a new method to differentiate natural and man-made wears, and to offer a better understanding of cave activities in the Late Neolithic of the South of France. • The function of Neolithic cistern-caves is renewed by a use-alteration analysis on pots. • A new method to differentiate ceramic use-alteration from natural and post-depositional alterations is proposed. • Use-wear of ceramic vessels from a cave context may reveal the production of acid fermented liquids. [ABSTRACT FROM AUTHOR]

Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method in all European Union member states. One of the criteria used to establish GPZs is to define contributing catchment areas (CCAs). This methodology has been applied to the Sierra de Cañete, a region comprising a carbonate aquifer in the province of Malaga, Spain. The tools used to define CCAs are hydro-chemical and isotopic characterizations, namely water isotopes (i.e., 2H, 18O and tritium) and the isotopes of dissolved sulfates (i.e., 34S and 18O). Traditionally, the Sierra de Cañete aquifer has been divided into six sectors. Hydro-chemical and isotopic characterization differentiated between two large areas in the carbonate aquifer. The southern part presents younger water that is the result of faster recharge and that shows a high level of karstification, while the northern area has a slower flow, and recharge is produced over several years. In addition, the northern part is hydraulically connected to an alluvial aquifer (i.e., Llanos de Almargen) that borders the Sierra de Cañete to the north. This aquifer has high levels of pollution due to agricultural and livestock activities carried out in the Llanos de Almargen area. This pollution is transmitted to the carbonate aquifer when groundwater depletion occurs. Therefore, the Sierra de Cañete GPZ needs to be extended to include the Llanos de Almargen aquifer.

Wetlands in semiarid regions have received less attention than wetlands in humid-temperate areas, and the limited amount of information has resulted in little regulatory recognition. A comprehensive map of the saline wetlands that occur in karstic depressions in the semiarid region of Monegros, NE Spain, was developed from historical data, topography, and surveys of vascular flora. Playa-lakes and other saline depressions are expressions of solution dolines largely founded on groundwater dynamics and favored by the limestone and gypsum-rich substrate. Substrate composition, groundwater dynamics, and the network of infilled valleys are key factors in the distribution of the wetlands. In spite of the anthropogenic imprint, wetlands morphometrics are the expression of geological processes. Significant correlations were found between basin area and depth, and between elongation and substrate composition. The predominantly subelongated shape of the Monegros saline wetlands (MSW) reflects their origin and a geometry strongly influenced by fractures. Grouping the MSW based on geological and vegetation features, provide a predictable relationship of surficial processes with the occurrence of otherwise complex and undetectable hydrological connectivity. Our ten geology-based Groups showed a high intra-group variation in depth, elongation, and vegetation cover. The eight vegetation-based categories mirror the gradation in flooding frequency and the soil salinity of MSW. The significant contrasts existing in-between the groups of wetlands and the disclosure of their causal factors provides a functional perspective at the landscape scale. This approach will help to monitor the ongoing environmental alterations associated with new on-farm irrigation developments.

Fluid flow and solute transport phenomena in fractured and karstic aquifers remain an open issue that calls the attention of numerous researchers belonging to different disciplinary fields as far as the aspects linked both to shallow and to deep phenomena are concerned. The hydrogeologic knowledge of these phenomena proves to be of high importance especially if considered in relationship with water resource exploitation, with the problems linked to contamination and the ones linked to urban and industrial development of the territory. In the examined area, characterized by a dismissed contaminated site, the realization of the landfill has required the development of a 3D flow model supported by a detailed local scale geologic model in order to evaluate the effects on groundwater flow and subsequently on contaminant propagation. The results of the flow model prove to be coherent with the fractured and karstic nature of the site in that they show at higher depths the presence of a subterranean stream channel that would speed up pollutant propagation. The obtained results represent the fundamental basis to implement a transport model that will permit to achieve a more in depth knowledge of the subsoil transport phenomena, and therefore to optimize any anthropic intervention that can involve the site. [ABSTRACT FROM AUTHOR]

Abstract: Karstic areas in Yucatan are very permeable, which allows contaminants to move rapidly into the aquifer. In the present study, we evaluated gene expression of vitellogenin (VTG) and cytochrome P-450 1A (CYP1A) in caged juvenile zebrafish deployed for 15 days in 13 different water bodies, cenotes and aguadas, throughout karstic region of the Yucatan peninsula. Gene expression was evaluated using qRT-PCR. Results indicated induction of VTG in 7 water bodies with respect to reference cage. The highest relative VTG expression, about 3000 times higher than reference cage, was found in an aguada close to a cattle farm. CYP1A induction with respect to reference cage was observed in 3 water bodies, all of them located near villages or used for tourist activities. Pollutants and biomarkers of effect should be monitored in these water bodies in order to have a better understanding of the actual levels of pollutants that are present at Yucatan’s aquifer and the potential risk to human and environmental health. [Copyright &y& Elsevier]

In earlier studies involving simulation of the Fergus River flows in Ireland, the conceptual Soil Moisture Accounting and Routing (SMAR) model had been found to consistently outperform a number of black-box models. Subsequently, in investigating any loss of flow through this catchment's subsurface karstic features, it was verified from the overall long-term water balance that such losses were substantial. This raised the awkward question of why the volume-conservative SMAR model had performed so well on this considerably non-conservative catchment. Further analyses revealed that, to compensate for the excess volume of total runoff generated by the model's conservative water balance component, the memory length of the surface runoff response function had been unrealistically curtailed in the optimization process, effectively truncating that function and thereby violating the conservation property of the routing process. This embarrassing revelation called for reconsideration of the model structure to account more sensibly for actual losses, while still achieving high model efficiency. This paper highlights not only the discovery of the karstic Fergus catchment as a “hydrological monster”, in the context of the SMAR model, but also why conservative models perform poorly in such cases. In an attempt to “tame the monster”, better simulation of the observed flows was achieved by conceptually adapting the SMAR model, in a pragmatic empirical manner, by simply modifying its water balance component. Citation Goswami, M. & O'Connor, K. M. (2010) A “monster” that made the SMAR conceptual model “right for the wrong reasons”. Hydrol. Sci. J. 55(6), 913-927. [ABSTRACT FROM AUTHOR]

Abstract: Lacustrine and tufa deposits from Laguna de Taravilla (Iberian Range, Guadalajara province, Spain, 40°39′ N, 1°59′ W, 1100 m a.s.l.) have been analyzed using sedimentological, mineralogical, geochemical and palynological techniques. A preliminary chronological framework is presented, based on U/Th, 14C AMS, 210Pb and 137Cs analyses. The lacustrine–tufa system developed in a hanging tributary valley of the Upper Tajo River and is composed of a large perched springline tufa build-up, and a barrage tufa dam that impounds Laguna de Taravilla. The Taravilla tufa stable-isotope compositions are similar to other examples in central and southern Spain and they plot in the same field as other lowland European stream tufas. These values are coherent with the range of isotopic compositions measured in the Taravilla spring and lake water. Several sediment cores retrieved from the Laguna de Taravilla have been dated with 14C AMS and analyzed using a multiproxy approach including magnetic properties, sedimentology, geochemistry, stable isotopes, palynology and ostracode assemblages. Sedimentary facies analyses show the dominance of clastic depositional processes in the lacustrine depositional system and suggest the potential of the sequences as palaeoflood records. Sands and coarse silts reflect periods of increased alluvial activity of the inlet. The dominance of clastic depositional processes and the input of detrital carbonate hinder the use of lake mud stable-isotope compositions as environmental indicators. Phases of increased tufa growth occurred during the Late Pleistocene (Last Glacial to Interglacial transition from oxygen isotopic stage 6 to 5) and during the Late Glacial and Early Holocene. Although the Taravilla chronology does not allow a detailed analysis of flood frequency, the reconstructed evolution is coherent with the palaeoflood history of the Tajo River for the last 2000 years, particularly with an increase during the last 500 years. The increase in flood frequency coincides with other evidence of wetter and colder climate and environmental change in Central Spain and in Europe during the Little Ice Age. [Copyright &y& Elsevier]

The overexploitation of the world's biomes for natural products calls for the prioritization of biologically important ecosystems for conservation. Here we show that limestone karats are "arks" of biodiversity and often contain high levels of endemism. Humans have exploited karsts for a variety of products and services, but unsustainable practices have caused population declines and extinctions among site-endemic taxa. Limestone quarrying is the primary threat to karat biodiversity in Southeast Asia, where quarrying rates exceed those in other tropical regions. Several socioeconomic, political, and scientific issues undermine the stewardship of these karsts. Mitigation of these problems will involve (a) better land-use planning to prevent karst resources from being exhausted in developing regions, (b) comprehensive assessments of a karat's economic and biological value before development, (c) improved legislation and enforcement to protect karat biodiversity, and (d) increased research and activities to promote public awareness of the importance of karats and the threats facing them. [ABSTRACT FROM AUTHOR]

Karstic aquifers can be particularly vulnerable to both pollution from surface activities and large-scale dewatering from mineral winning operations. This is because of the enhanced vertical and lateral flow paths, resulting from the dissolution of carbonate species by rainfall. Often this process results in the development of voids that can range in size from several centimetres to several tens of metres. To date, groundwater vulnerability maps for England and Wales, including karst areas, have been produced using a methodology that does not consider the presence of karst features. The uncertainties that are presented by the potential for pollution by the presence of water-carrying conduits in karst areas, where there are proposed or existing limestone quarries, require new techniques for detecting and delineating underground cave systems. In order for any mapping technique to provide an acceptable assessment of vulnerability, the location and spatial distribution of high permeability flow paths need to be established. Of the available geophysics techniques that may allow for the identification of such features, microgravity and resistivity imaging are likely to be the most successful. Microgravity surveying has the potential to identify the presence and location of such voids, and with the integration of electrical tomographic work, can provide 'targets' for the location of monitoring boreholes. Whilst these techniques are intensive and may not be cost effective on a regional scale, they do have the potential to provide high-resolution data over smaller areas, which would be invaluable to any site or area-specific assessment of vulnerability. [ABSTRACT FROM AUTHOR]