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The Castilseras reservoir is geographically located in the south-central part of the Almadén Hg mining district (Ciudad Real, South-Central Spain). This reservoir collects rainwaters, mine water drainage and leachate from spoil heaps from four of the most important decommissioned Hg mines of the district (Las Cuevas, El Entredicho, Nueva- and Vieja Concepción). As consequence of its special hydrological conditions, artificial reservoirs can be considered important barriers, which significantly alter the natural solid phase transport. These basins promote sedimentation processes becoming significant repository of sediments and of heavy metals associated to them. Moreover, the specific physico-chemical conditions found in these reservoirs, as compared to flowing waters, may induce the development of biologically mediated transformations of inorganic Hg into different and more toxic Hg species for the environment such as methylmercury. Therefore, sediments of the reservoir can be seen as sink and/or source of contaminants and their ecological risk assessment should be a priority in order to know the environmental quality of the fluvial compartment. In this work, we report the results of the studies of contents, species and potential risk of Hg in the Castilseras reservoir sediments, determined using different techniques to assess its role in the aquatic environment of the reservoir. Results showed that Total Hg (THg) values range between 2.49-17.30 µg g-1, decreasing from the upper reservoir area to the dam and significantly exceed legal toxic reference values such as EPA severe effect level (2 µg g-1). Moreover, Organic Hg values up to 10.30 ng g-1 increase their contents in the flow direction, where the highest value was measured from the deepest sampling point near the dam, suggesting methylation processes associated with the deep. On the other hand, a four steps Sequential Extraction Procedure (SEP) was accomplished to determine the availability of the mineral phases to incorporate Hg species into the aquatic ecosystem. Results showed that the non-residual fraction of Hg, which can be seen as indicator of the potential environmental risk, range between 19 and 58% suggesting an important anthropogenic origin of Hg. Considering only the extracted percentages in the most labile step of the SEP, recovery percentages range from 5 to 27%, showing that the risk varies from low to moderate. These results suggest that Castilseras reservoir is heavily contaminated by mercury, and this structure may play an important role as sink and source of Hg in the aquatic environment, generating a potential environmental risk.

El Entredicho is a cinnabar open-pit mine located in the Almadén mining district (Ciudad Real, Spain). It is the second most important mine within the district, since it has produced 290,000 flasks of mercury (Hg) during its short period of activity (1978-1997). Mining operations created a large hole reaching a maximum of 92 m depth, which was purposely flooded with waters from the Valdeazogues River in 2004. Today, this open-pit lake is only fed by runoff waters and as a consequence, the water column has remained isolated during the last ten years, thus creating an unique environmental laboratory for studying the effects of interactions between freshwaters and permanently flooded cinnabar ore rocks. This research focuses on a preliminary characterization of Hg abundance and partitioning in the water column of El Entredicho open-pit to depict possible effects of physical and biogeochemical factors on element distribution and speciation. The main physico-chemical parameters of freshwaters were recorded using an Ysi CTD 6920V2 in five selected points. Water samples were collected at the deepest point by means of a Niskin bottle and were analysed using ICP-MS technique. In the water column, partitioning of Hg varies with depth, being most important the dissolved fraction (DHg) (0.45µm) represents the main fraction. PHg concentration increases with depth (0.059-0.137 µg l-1), peaking at 55 m depth (0.174 µg l-1). Vertical variability for DHg and PHg appears to be similar down to 55 m depth. Below 55 m, DHg quickly decreases to concentrations lower than those detected at the surface (0.175 vs 0.125 µg l-1) suggesting the existence of different mechanism governing Hg partitioning at this stage of the water column. During field works, physicochemical parameters showed a sharp chemocline starting at 46 m depth. In the chemocline, temperature (Tº) quickly increases from 8.57 to 10.17 ºC as conductivity (Cond.) from 854 to 2684 µS cm-1 whereas dissolved oxygen (DO) decreases from 9.81 to 9.20 mg l-1 in only one meter. Then, Tº, Cond. and pH remain constant, whereas DO and redox potential decrease with depth (0.61 mg l-1 and 56.5 mV, respectively). The bottom layer seems to behave like a “biochemical reactor” playing an important role in the Hg partitioning between water and cinnabar rocks. Future research should be addressed to this compartment.

Determination of Rare Earth Elements (REEs) in the waters and sediments of El Hito Lake and its drainage basin was carried out. Distribution maps for REEs concentrations show increasing values in the lake sediments from the center to the eastern edge reaching 166.5 mg/kg. In the drainage basin, higher values were observed with a maximum of 350.9 mg/kg in the southern part. Concentrations in the water were considerably lower with a maximum value of 1.3 µg/L. Ce, La and Nd were the most abundant elements. When normalized REE concentrations against NASC (North American Shale Composite), a positive anomaly of Eu in the water and of Nd in the sediments (lake and basin) was observed. The (La/Gd)NASC and (La/Yb)NASC ratios determined the predominance of light REE (LREE) over medium (MREE) and heavy REE (HREE) Se llevó a cabo el estudio de Tierras Raras (REEs) del agua y los sedimentos de la Laguna de El Hito así como de su cuenca de recepción. Los mapas de distribución de las concentraciones de REE en los sedimentos de la laguna mostraron valores crecientes desde el centro hacia el margen este alcanzando 166,5 mg/kg. En la cuenca se midieron valores más elevados llegando hasta 350,9 mg/kg en la mitad sur. Los valores en el agua fueron notablemente inferiores, con un máximo de 1,3 µg/L. El elemento más abundante fue el Ce seguido del Nd. Se normalizaron las concentraciones de REEs frente a las del NASC (North American Shale Composite), observándose una anomalía positiva de Eu en el agua, así como de Nd en los sedimentos (laguna y cuenca). Mediante los índices (La/Gd)NASC y (La/Yb)NASC se determinó el predominio de las REEs ligeras (LREEs) frente a las medias (MREE) y pesadas (HREE)

Determination of Rare Earth Elements (REEs) in the waters and sediments of El Hito Lake and its drainage basin was carried out. Distribution maps for REEs concentrations show increasing values in the lake sediments from the center to the eastern edge reaching 166.5 mg/kg. In the drainage basin, higher values were observed with a maximum of 350.9 mg/kg in the southern part. Concentrations in the water were considerably lower with a maximum value of 1.3 µg/L. Ce, La and Nd were the most abundant elements. When normalized REE concentrations against NASC (North American Shale Composite), a positive anomaly of Eu in the water and of Nd in the sediments (lake and basin) was observed. The (La/Gd)NASC and (La/Yb)NASC ratios determined the predominance of light REE (LREE) over medium (MREE) and heavy REE (HREE), Se llevó a cabo el estudio de Tierras Raras (REEs) del agua y los sedimentos de la Laguna de El Hito así como de su cuenca de recepción. Los mapas de distribución de las concentraciones de REE en los sedimentos de la laguna mostraron valores crecientes desde el centro hacia el margen este alcanzando 166,5 mg/kg. En la cuenca se midieron valores más elevados llegando hasta 350,9 mg/kg en la mitad sur. Los valores en el agua fueron notablemente inferiores, con un máximo de 1,3 µg/L. El elemento más abundante fue el Ce seguido del Nd. Se normalizaron las concentraciones de REEs frente a las del NASC (North American Shale Composite), observándose una anomalía positiva de Eu en el agua, así como de Nd en los sedimentos (laguna y cuenca). Mediante los índices (La/Gd)NASC y (La/Yb)NASC se determinó el predominio de las REEs ligeras (LREEs) frente a las medias (MREE) y pesadas (HREE)

The Almadén district constitutes the largest and probably the most intriguing mercury concentration in the world. This paper reports the first lead isotope compositions of cinnabar from the district. Whole samples and stepwise leaching cinnabar aliquots display relatively homogeneous isotopic compositions (206Pb/204Pb = 18.112 - 18.460; 207Pb/204Pb = 15.635 - 15.705; 208Pb/204Pb = 38.531 - 38.826). Taken together with Jébrak et al. (2002) pyrite lead isotope results, the new cinnabar isotopic data defines a steep array trend on the 207Pb/204Pb - 206Pb/204Pb diagram, suggesting a mixed contribution from both ancient upper continental crust and (enriched mantle derived) magmatic sources for the ores of the Almadén Hg deposits

The Almadén district constitutes the largest and probably the most intriguing mercury concentration in the world. This paper reports the first lead isotope compositions of cinnabar from the district. Whole samples and stepwise leaching cinnabar aliquots display relatively homogeneous isotopic compositions (206Pb/204Pb = 18.112 - 18.460; 207Pb/204Pb = 15.635 - 15.705; 208Pb/204Pb = 38.531 - 38.826). Taken together with Jébrak et al. (2002) pyrite lead isotope results, the new cinnabar isotopic data defines a steep array trend on the 207Pb/204Pb - 206Pb/204Pb diagram, suggesting a mixed contribution from both ancient upper continental crust and (enriched mantle derived) magmatic sources for the ores of the Almadén Hg deposits

Nine new S isotope analyses are presented of which 8 are from the Las Cuevas deposit. They are compared with data from literature. The different deposits of the district (and the three orebodies of the Almadén deposit) are characterised by a specific range of a34S values

Nine new S isotope analyses are presented of which 8 are from the Las Cuevas deposit. They are compared with data from literature. The different deposits of the district (and the three orebodies of the Almadén deposit) are characterised by a specific range of a34S values

The Almadén Hg deposits are associated with deeply altered magmatic rocks, which main features are briefly described here. Geochemical, including isotopic, data on these rocks suggest that they are derived from deep mantelic sources. The volcanic units underwent low-pressure alteration processes, probably related to the geothermal evolution of the district along with the magmatic activity (Silurian-Devonian). As a conclusion, this magmatism could have been the responsible for the mobilisation of mercury concentrated in the district deposits Se describen en el presente trabajo las características de las rocas magmáticas con las que aparecen relacionadas las mineralizaciones de mercurio del distrito de Almadén, y los procesos de alteración que las afectan. Los datos geoquímicos e isotópicos referidos a estas rocas indican que proceden de fuentes mantélicas profundas. Las unidades volcánicas sufrieron procesos de alteración a baja presión, probablemente relacionados con la evolución geotérmica del distrito durante el propio periodo de actividad del magmatismo (Silúrico-Devónico). Se concluye que este magmatismo puede haber sido el responsable de la movilización del mercurio que constituye los yacimientos del distrito

The Almadén Hg deposits are associated with deeply altered magmatic rocks, which main features are briefly described here. Geochemical, including isotopic, data on these rocks suggest that they are derived from deep mantelic sources. The volcanic units underwent low-pressure alteration processes, probably related to the geothermal evolution of the district along with the magmatic activity (Silurian-Devonian). As a conclusion, this magmatism could have been the responsible for the mobilisation of mercury concentrated in the district deposits, Se describen en el presente trabajo las características de las rocas magmáticas con las que aparecen relacionadas las mineralizaciones de mercurio del distrito de Almadén, y los procesos de alteración que las afectan. Los datos geoquímicos e isotópicos referidos a estas rocas indican que proceden de fuentes mantélicas profundas. Las unidades volcánicas sufrieron procesos de alteración a baja presión, probablemente relacionados con la evolución geotérmica del distrito durante el propio periodo de actividad del magmatismo (Silúrico-Devónico). Se concluye que este magmatismo puede haber sido el responsable de la movilización del mercurio que constituye los yacimientos del distrito

This study concerns the geochemical characteristics of deposited particles in an urban area -namely the urban area of the mining and industrial city of Puerto llano. This falls with in the context of environmental systems, notably those concerned with atmospheric pollution in urban areas. In this case, particles transported in the air and deposited on the ground, are the agents which polluty the atmosphere

After seven years of experience in a project, controlled from its beginning by the C.O .U. (University Orientation Academic Year) coordination group of Castilla-La Mancha University, now we present the results of the modifications for the subject "Geology " recommended by the Education & Science Ministry in the program development and the university entrance examinations

Different ocurrences of basic-ultrabasic rocks ranging in age from Precambrian to Mesozoic reveal that intraplate magmatism is a suitable target for exploration of Ni-Cu-PGE ores (and locally, Hg ores'). Long travels o f these magmas across the continental crust favours the assimilation of enclosing siliceous rocks, promoting their saturation in sulfur and segregation of immiscible sulfide melts. This can generate a primary Ni-Cu-PGE ore which can be remobilized and reconcentrated during later hydrothermal or tectonometamorphic processes. The latter are obviously more probable in old than in young rocks, thus explaining the current association of world-grade, Ni-Cu-PGE deposits to Precambrian and Paleozoic rocks

Different ocurrences of basic-ultrabasic rocks ranging in age from Precambrian to Mesozoic reveal that intraplate magmatism is a suitable target for exploration of Ni-Cu-PGE ores (and locally, Hg ores'). Long travels o f these magmas across the continental crust favours the assimilation of enclosing siliceous rocks, promoting their saturation in sulfur and segregation of immiscible sulfide melts. This can generate a primary Ni-Cu-PGE ore which can be remobilized and reconcentrated during later hydrothermal or tectonometamorphic processes. The latter are obviously more probable in old than in young rocks, thus explaining the current association of world-grade, Ni-Cu-PGE deposits to Precambrian and Paleozoic rocks

This study concerns the geochemical characteristics of deposited particles in an urban area -namely the urban area of the mining and industrial city of Puerto llano. This falls with in the context of environmental systems, notably those concerned with atmospheric pollution in urban areas. In this case, particles transported in the air and deposited on the ground, are the agents which polluty the atmosphere

New petrographic and chemical data on the Garlitos pluton and other associated igneous rocks in the Almadén area have shown a high-K calc-alkaline character and clear simiarities with other calc-alkaline granitoids, in particular the lithotypes dominant in the Los Pedroches batholith. Similarities include petrographical, mineralogical and chemical features, as well as a number of metamorphic xenoliths, suggesting that igneous rocks were generated from similar sources and emplaced through similar crustal segments.