Evolución hidroquímica del lago minero de Aznalcóllar, Sevilla

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, Departamento de Geodinámica, leída el 02/07/2010.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEProQuestpu

La corta inundada de Aznalcóllar y su uso como vertedero de residuos mineros (Sevilla, España)

Desde su cierre en 1995 y el accidente de la balsa de lodos en 1998, la corta minera de Aznalcóllar ha sido utilizada como vertedero de diversos materiales, como los suelos contaminados retirados del área del río Guadiamar o residuos mineros de estériles, lodos piríticos y cenizas de tostación de pirita. La corta minera está parcialmente inundada y contiene un lago ácido (pH 2,7) con un volumen de ~6 Mm3 de agua enriquecida en metales y sulfato. Las investigaciones detalladas realizadas en la mina durante estos últimos años, han demostrado que los vertidos y la entrada de aguas ácidas de mina están modificando de manera notable la calidad del agua del lago. La mayor afección a la calidad del agua del lago de Aznalcóllar se debió al vertido de 1,4 Mm3 de una escombrera de pirita, entre 2005 y 2006. La disolución oxidativa de este mineral ha causado (i) un consumo total de oxígeno disuelto, (ii) un aumento notable de la conductividad eléctrica (de 8,6 a 12 mS/cm), (iii) una fuerte acidificación (pH de 4,2 a 2,7) y un calentamiento debido al carácter exotérmico de la oxidación de la pirita. A pesar de la ausencia de los agentes que oxidan a la pirita en el lago, como O2 y Fe (III) (Fe (III) <5 % Fetotal), la pirita continúa oxidándose con un incremento de las concentraciones de SO4 2- y Fe. [ABSTRACT] Since its closure in 1995 and the subsequent failure of the slurry deposit dam in 1998, the Aznalcóllar pit has been used as a disposal site for diverse metal-rich materials, such as the polluted soils removed during the cleaning-up of areas along the Guadiamar river together with waste rock, pyrite sludge and ashes deriving from pyrite roasting. At present the pit is partly flooded with a highly acidic (pH 2.7) lake holding some 6 Mm3 of metal- and sulphate-rich water. Detailed research undertaken in the area during recent years has proved that the dumping of wastes and the inflow of acidic mine waters are having a dramatic effect on the quality of the water in the lake. The greatest effect upon the Aznalcóllar lake water was due to the dumping of 1.4 Mm3 of pyritic wastes during 2005 and 2006. The oxidative dissolution of this mineral has resulted firstly in the total consumption of dissolved oxygen, secondly, a notable increase in electric conductivity (from 8.6 to 12 mS/cm), thirdly, considerable acidification (from pH 4.2 to 2.7) and finally, heating due to the exothermic character of pyrite oxidation. Despite the almost total lack of oxidizing agents such as O2 and Fe(III) (Fe(III)<5% Fetotal) in the pit lake, pyrite continues to oxidize, producing a concomitant increase in SO4 2- and Fe.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Changes in stratification and iron redox cycle of an acidic pit lake in relation with climatic factors and physical processes

Nuestra Señora del Carmen (NSC) mine pit located in the northwest of Huelva province in the Iberian Pyrite Belt has been entirely flooded for several decades. The pit lake dimensions are 110 m×80 m, with a depth of 34 m and a volume of 79,500 m3. Lake water is acidic (average pH 2.7) with high concentrations of sulfate (8.5 g/L), magnesium (1.0 g/L) and metals (Fe 760 mg/L, Al 230 mg/L, Mn 88 mg/L and Cu 29 mg/L). As with the majority of mining lakes of the Iberian Pyrite Belt, this lake develops chemical stratification (meromictic lake) but unlike the rest, it has occasionally showed circulation throughout the entire water column at the beginning of some winters, displaying total homogenization (holomictic lake). The lake regains chemical stratification during periods of high precipitation due to freshwater runoff contribution from the basin (ectogenic meromixis). Furthermore, another unusual period of mixing was observed in the summer period. Evapoconcentration of the warmer upper layer has been identified as the reason for the chemical destabilization observed in the water column. This work presents the processes (evapoconcentration), parameters (temperature and electric conductivity) and climatic factors (runoff, precipitation and wind) that influence the development of chemical stratification or mixing of the water column in the lakeInstituto Geológico y Minero de España, Españ

Modificaciones ambientales en el humedal del Parque Nacional de Las Tablas de Daimiel propiciadas por la actividad de especies exóticas invasoras

Iberian Association of Limnology. Conference (20ª. 2018. Coimbra)Instituto Geológico y Minero de España, Españ

Hidrología del humedal del Parque Nacional de Las Tablas de Daimiel (Ciudad Real, España)

Iberian Association of Limnology. Conference (20ª. 2018. Coimbra)Instituto Geológico y Minero de España, Españ

Acid rock drainage in Nevado Pastoruri glacier area (Huascarán National Park, Perú): hydrochemical and mineralogical characterization and associated environmental implications

The generation of acid rock drainage (ARD) was observed in an area of Nevado Pastoruri as a result of the oxidative dissolution of pyrite-rich lutites and sandstones. These ARDs are generated as abundant pyrite becomes exposed to atmospheric conditions as a result of glacier retreat. The proglacial zone contains lagoons, springs, streams and wetlands, scant vegetation, and intense fluvioglacial erosion. This work reports a comprehensive identification and the results of sampling of the lagoons and springs belonging to the microbasin, which is the headwaters of the Pachacoto River, as well as mapping results based on the hydrochemical data obtained in our study. The physical properties and water chemistry of 12 springs and 22 lagoons from the proglacial zone are also presented. Water springs are far from being chemically uniform, with pH and EC values ranging between 2.55–6.42 and 23–1110 μS/cm respectively, which suggests a strong geologic control on water chemistry. Fe-SO4 −2 concentrations confirm the intense process of pyrite oxidative dissolution. Many of the lagoons are affected by ARD, with low pH (~ 3), and high EC (256–1092 μS/cm) values when compared with unaffected lagoons (EC between 7 and 59 μS/cm), indicating a high degree of mineralization. The affected lagoons show higher concentrations of SO4 2− and SiO2, and elements as Fe, Al, Mg, Mn, Zn, Co, and Ni, which are related to the alteration of pyrite and the dissolution of aluminosilicate minerals. Schwertmannite-goethite appears to be the most important mineral phases controlling the Fe solubility at a pH of 2–3.5. Moreover, they act as a sorbent of trace elements (As, Sb, V, Pb, Zn, Cr), which is an efficient mechanism of natural attenuation. Despite of this, the water flowing out from the basin is acid (pH 3.1) and contains significant concentrations of Fe (0.98 mg/L) and Al (3.76 mg/L) that confer mineral acidity to water. The Pachacoto River located 5.5 km downstream from this point showed a strong natural attenuation, with a pH of 6.9 and low concentration of metals. This mitigating process is possible due to (i) the formation of precipitates that retain toxic elements and (ii) the mixing with natural waters that promote dilution, which favor the increase of pH until circumneutral conditions.Instituto Geológico y Minero de España, EspañaDepartamento Académico de Ciencias Ambientales, Universidad Nacional Agraria de la Selva, PerúCentro de Astrobiología, Instituto Nacional de Técnica Aeroespacial, EspañaCentro de Astrobiología, Consejo Superior de Investigaciones Científicas, Españ

Hidroquímica y parámetros físicos potencialmente relacionados con la ausencia de vegetación sumergida en las Tablas de Daimiel

Congreso Ibérico sobre Agua subterránea, medio ambiente, salud y patrimonio (2018. Salamanca)La recuperación hídrica del humedal del Parque Nacional de las Tablas de Daimiel en 2010, tras un largo periodo de sequía (2006-09) que desecó el humedal, trajo consigo la recuperación del ecosistema acuático y presencia de aguas cristalinas y amplios tapices de carófitas (Chara spp.) en el fondo. En el año 2011 tiene lugar un cambio en el aspecto del agua y se observa una pérdida gradual de la vegetación sumergida junto con un aumento de la turbidez en el agua, además de un incremento en la población de peces bentónicos. Durante 2015-16 el Instituto Geológico y Minero de España (IGME) diseña una amplia red de muestreo, para estudiar la calidad del agua del humedal y su entorno, incluyendo las aguas superficiales y subterráneas. El objetivo del muestreo era conocer si el aspecto anómalo que presentaba el humedal junto con la pérdida de la biodiversidad, podía estar inducido por la entrada de contaminantes. Tras el estudio de la calidad del agua se pudo afirmar que las concentraciones de los compuestos químicos inorgánicos (iones mayoritarios, elementos traza y metales), orgánicos (herbicidas y plaguicidas) y nutrientes no superaban los valores máximos recogidos en las legislaciones medioambientales vigentes y se descartó que la situación actual se debiera principalmente a la contaminación de las aguas. Lo que sí se pudo constatar es una alta población de peces bentónicos que parece que está generando un fuerte impacto en el medio acuático. Los trabajos en el humedal de Las tablas de Daimiel se han retomado durante 2018, a través de un proyecto que está llevando a cabo el IGME con el apoyo de la Fundación Biodiversidad. El objetivo del trabajo es evaluar las causas que han llevado al humedal a alcanzar un estado de aguas turbias y sin vegetación bentónica. Con tal fin se están estudiando una serie de variables que pueden incidir en el desarrollo de las carófitas (hidroquímica del agua superficial y subterránea, nutrientes, turbidez, fitoplancton y radiación solar), y la influencia que tiene sobre las mismas, la abundante población de peces que ha sido identificada, que incluye varias especies exóticas invasoras (Lepomis gibbosus, Ameiurus melas y Cyprinus carpio), conocidas por su alta capacidad de modificar el medio.Instituto Geológico y Minero de España, Españ

Hydrogeological researches in karstic lakes in the center of the Iberian Peninsula: two study cases

[EN] The study of two groups of lakes or lagoons of karstic origin in the interior of the Iberian Peninsula is presented. They are two of the most interesting protected natural spaces of karstic nature in Spanish territory: The Ruidera Lakes Natural Park, located between the provinces of Ciudad Real and Albacete; and the Natural Monument of the Lagoons of Cañada del Hoyo, located in Cuenca province. Both present very interesting geomorphological evolutions and hydrogeological functionings. The research analyzes the anthropic influence on the natural functioning of the lakes/lagoons with the objective of recovering the Natural Area conditions prior to the anthropogenic impact, thus returning the hydrological systems to a morphological and functional state as close as possible to their original state.Peer reviewe

Mineral microbial precipitation of subseafloor fluids at the submarine Tagoro Volcano hydrothermal system (El Hierro, Spain)

[EN] Microbial organisms are known to participate in the (bio)mineralization and (bio)precipitation of certain compounds as found in hydrothermal vents. This includes metabolic processes acting directly on the precipitate formation (iron-oxidation, sulfate-reduction) or indirectly by the acceleration of mineralization promoted by the presence of microbial cells that act as nucleation sites, such as for opal-A. Here, we present the findings of different microbial precipitation processes at a novel low-temperature and shallow-water hydrothermal system at the summit of the Tagoro volcano (80–120 m water depth). This system is characterized by seafloor and basanite-hornitos covered by Fe-flocculate deposits, with micro-cracks and degasification vesicles filled mostly by pyrite and covered by sulfur-oxidizing bacterial mats.This research has been partially funded by the Spain’s Recovery and Resilience Plan included in the MINECRITICAL project “Strategic critical metals for the energy transition” (C17.I7).Peer reviewe