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El diseño de redes basado en la modelización del flujo subterráneo es unaherramienta básica en la monitorización de las aguas subterráneas. La ideaprincipal es la optimización de tiempo y recursos durante las operaciones demonitorización, con la obtención de datos de calidad en cantidad suficientepara los estudios a realizar, especialmente en terrenos contaminados. Esesencial calibrar adecuadamente el tiempo invertido en el diseño de la red demonitorización y adecuarlo a los resultados esperados.En el mercado se encuentran innumerables programas que permiten abordar el problema, tanto de pago como gratuitos; de entre todos ellos el OWL se muestra como una herramienta sencilla, que permite una primera aproximación al problema del diseño de redes de control. En la presente comunicación se muestra mediante un caso de estudio las ventajas, inconvenientes y limitaciones que ofrece el programa, comparándolo con otros disponibles en el mercado.La zona estudiada es un terreno contaminado que fue ocupado por una instalación industrial por mas de 70 años en el noroeste de España, en el que se tratado de optimizar la red de monitorización de las aguas subterráneas, con elfin de maximizar la calidad de los datos con un mínimo de pozos de control.

En la actualidad, el conocimiento sobre la hidrología de las cuencas carboníferas y su relación con la explotabilidaddel CBM es inexistente. Localmente, su importancia es evidente por la necesidad de deprimir el nivel piezométricocon el objeto de favorecer la desorción del gas contendido en la capa de carbón. Sin embargo, exceptuando estaasociación, pocas asociaciones se han establecido entre el régimen hidrogeológico y la explotabilidad del CBM. Losprocesos geoquímicos inherentes con las condiciones de generación y yacimiento del metano modifica la calidad delagua subterránea a un tipo distintivo que es fácilmente reconocible. La firma geoquímica del agua producida durante la extracción del CBM puede ser un criterio útil en las evaluaciones preliminares de prospectos cuando amplios conjuntos de datos estén disponibles. Esto puede ser importante, sin embargo, en el diseño y duración de los ensayos de bombeo y en la selección de los consiguientes emplazamientos de los pozos de explotación.

En el mundo anglosajón se ha bautizado como "Efecto NIMBY" a un fenómeno acentuado en los últimos años. Estas siglas corresponden a la frase "Not In My BackYard", traducido en castellano como "no en mi patio trasero". La paradoja de este fenómeno reside en que los ciudadanos quieren las comodidades de las sociedades modernas, perono desean en las cercanías de sus domicilios cualquier posible molestia derivada de ellas. En este trabajo se profundizara en las causas efectos y posibles soluciones que el efecto NIMBY tiene en la minería.

En Asturias yacen materiales que están contrastados como generadores de hidrocarburos, aunque la acumulación enrocas almacén tradicionales no ha sido muy favorable. Se exploró fundamentalmente en la plataforma costera y lospozos suministraron numerosos indicios de gas y de petróleo. Pero los indicios de hidrocarburos en Asturias sonanteriores. Desde antiguo se sufre la presencia de gas grisú (metano, con trazas de etano, etcétera) en las minas decarbón y, en especial, en el yacimiento de la Cuenca carbonífera Central Asturiana (CCCA). En las rocas encajantes y en las capas de carbón se ha observado, asimismo, la presencia de aceites minerales, destilados o condensados, restos de parafinas, ozoqueritas, etcétera. Todas estas manifestaciones de hidrocarburos sólidos, líquidos y gaseosos demuestran que los materiales carboníferos y mesozoicos constituyen una roca madre.

In Asturias, diverse geochemical anomalies of As of anthropic origin are located. Some of them are associated with Hg orphan mines. There are many studies that characterize these sites from an environmental point of view, analyzing in turn the risks associated with As and Hg contamination both in sediments and in soils and waters.This work focuses on the analysis of the electrokinetic decontamination of soils with high contents in As. Based on the data obtained from the laboratory on different materials in previous works, it has been sought to combine these with current laboratory and field work to infer the environmental and technical implementation implications of the As mobility in sediments and soils.

Environmental exploration studies requires working with many geochemical variables; these geostatistical variables require treatment prior to their representation and subsequent analysis . Until recently, geostatistical treatment and representation programs did not permit the realization of anállisis and consultations or there was a complex process. A GIS tool currently has a friendly interface and is very comfortable working with them. In this case studydifferent geochemical data types (water, soil, air) and coverages (geology, land use, soils, topography, etc.) are assembled together. The geochemical indicator was monitored in several springs, and the aquifer’s hydrodynamic behavior was performed using mathematical and simulation models.

At the Nalón River estuary (Asturias, Northern Spain), the occurrence of Hg is due to historical mining activity which has resulted in environmental issues of great concern. Although several studies have investigated the sediment compartment regarding Hg contamination, no information is currently available on the fate of Hg and MeHg in the water column. Considering different hydrodynamic/seasonal conditions, water samples were collected along the estuary to evaluate Hg and MeHg distribution and partitioning behaviour between solid and aqueous phases. The complementary effect of the river discharge and tidal currents contributed to the prevalence of the dissolved (4.02 ± 1.33 ng L−1) or particulate (8.37 ± 4.20 ng L−1) Hg under different conditions of discharge in summer and autumn, respectively. Conversely, particulate MeHg prevailed when the river flow was low, especially at the estuary mouth (25.8 ± 19.1 pg L−1) and most likely due to the resuspension of fine particles promoted by a stronger tidal current. In comparison with the total Hg concentration, extremely low amounts of dissolved and particulate MeHg were observed, and strong interactions between MeHg and organic carbon highlighted a negligible risk of increased mobility and potential bioaccumulation of MeHg.

La minería del mercurio en Asturias ha sido la segunda más importante en España, localizándose en la cuenca alta del río Nalón. Las actividades mineras y metalúrgicas que se llevaron a cabo durante más de 100 años han sido la causa de que importantes cantidades de mercurio hayan afectado al medioambiente próximo a las minas. El mercurio presente en labores mineras, escombreras, y otras instalaciones clausuradas, ha sido dispersado principalmente en forma particulada, a través de los cauces fluviales de la región y transportado lejos de las fuentes, alcanzando el estuario del río Nalón y el medio costero. El estuario del Nalón, como zona de transición del sistema fluvial más importante del norte de España, es un ecosistema de gran valor ecológico el cual, ha sido el receptor final de gran parte de la contaminación minera. En el medio estuarino, diferentes compartimentos ambientales muestran concentraciones anómalas de mercurio lo que refleja la capacidad detransporte del medio fluvial y la baja degradación de este elemento, cuya permanencia temporal y extensión geográfica ha afectado a zonas alejadas de las áreas mineras. De entre los diferentes compartimentos ambientales, el medio sedimentario es el más afectado, mostrando importantes anomalías en las concentraciones del elemento, tanto en superficie como en profundidad. La afección sufrida a lo largo de décadas ha quedado registrada en la secuencia sedimentaria y ha permitido identificar la importante contribución de la minería de mercurio. Actualmente, a pesar de que las actividades mineras cesaron hace más de 60 años, la atenuación natural no ha sido suficiente para disminuir la afección sobre el medio. Por otra parte, los estudios sobre biota han detectado la presencia de mercurio, demostrando que se ha producido una transferencia de este elemento entre diferentes compartimentos ambientales, convirtiendo al mercurio en un contaminante global en el estuario.

Four boreholes drilled at depths ranging from 9 to 27 m and retrieved from the Nalon estuary (Asturias, northern Spain) were investigated to assess the impact of the historical human footprint on the sedimentary sequence. Analytical measurements of grain size, geochemical composition (major and trace elements), and stable Pb isotopic ratios were performed. Two different sections of the sedimentary profile were identified throughout the sedimentary sequence using Pb isotopic ratios and then corroborated with grain size characteristics and As, Hg, Pb and Zn concentrations. The upper sediment layer of the boreholes (variable depth ranging between 3 and 9 m) exhibited an increase in 208Pb/206Pb ratios and a decrease in 206Pb/207Pb ratios, whereas, in the deepest layers, these ratios remained unchanged. These variations reflected the anthropogenic input of Pb into estuarine sediments, which can be attributed to mining activities when compared to Pb isotopic ratios from coal mined in the region. The anthropogenic input can be also noted on the basis of the variability of the trace element concentrations with depth. The enrichment factors of As (max 7.5), Hg (max 45.4), Pb (max 10.3), and Zn (max 8.6), calculated using local geochemical background values helped distinguish the impact of intense anthropogenic activities, which can be attributed to mining exploitation in the Nalon River drainage basin. Despite the closure of several of these mines during the second half of the 20th century, geochemical characteristics have revealed the ongoing input of As, Hg, Pb, and Zn into the coastal zone. Thus, the legacy of contamination from these elements, mainly from leaching slags and tailing dams, is still being recorded in estuarine sediments and requires careful scrutiny on the part of local authorities in terms of its possible effects on the aquatic biota.

Sediments contaminated by Hg and As from two historical mining areas have been deposited in the Nalon estuary (Asturias, northern Spain) since 1850. Total mercury (Hgtotal) concentrations in the sediments range from 0.20 μg g−1 to 1.33 μg g−1, most of it in the form of sulphides. Concentrations of methylmercury (303.20–865.40 pg g−1) are up to two orders of magnitude lower than the concentration of Hgtotal. Total As concentration (Astotal) is enriched compared to the background level for the area. The relative abundance of As(V) on As(III) in the sediments ranges from 97.6% to 100%, whereas inorganic Hg accounts for more than 99% of the total Hg. The occurrence of the most toxic species, inorganic As(III) and organic methylmercury, seem to be related to redox conditions together with the amounts of sulphur which act as natural barriers which inhibit the biological and chemical speciation processes. Despite the high amounts of Hg and As present in the sediments, their transference to the water column appear to be limited thus converting sediments in an effective sink of both elements. Special attention should be paid to potential variations of the environmental conditions which might increase the element mobility and exchange between sediments and the water column.

The extensive extraction activity of mercury ores in Asturias (northwest Spain), also rich in As and Sb, has impacted the Nalon river estuary. The objective of this research was to assess the historical evolution of As-Hg-Sb accumulation in the salt marsh sediments of this area. For this purpose, sediment cores were collected from two different salt marshes (eastern and western river banks) in the estuarine environment to evaluate the degree of anthropogenic enrichment and the geochronology of As-Hg-Sb accumulation. Core subsampling was performed by cutting 2-cm-thick slices of sediments. The subsamples were then analysed for several physical and chemical parameters. Sedimentation rate was assessed by measuring short-lived radionuclides (excess 210Pb and 137Cs). Pre-mining levels of As-Hg-Sb were observed at core depths below 50 cm. In the less extended salt marsh (eastern river bank), maximum As-Hg-Sb concentrations of 87.48, 3.66, and 5.75 μg·g−1, respectively, were found at the core top as a consequence of long-term mining activity in the area. The vertical distribution of As-Hg-Sb was influenced by the single-point contamination sources, whereas grain-size variability and diagenetic remobilisation did not seem affected. Geochronological measurements showed that the depositional fluxes of As-Hg-Sb were influenced by anthropogenic input after 1900, when mining activity in the area was most intense. Hg mining ceased in 1969; however, the corresponding core profiles did not show a drastic decreasing trend in element fluxes, implying that the river drainage basin retains some “memory” of contamination which affects riverine sediments. A preliminary gross estimation of total As-Hg-Sb “trapped” in the Nalon river salt marsh sediments amounted to approximately 18.7, 1.0, and 0.7 t, respectively. These morphological structures suffer erosive processes, thus representing a potential source of these elements associated with sediments; consequently, management conservation and monitoring of salt marshes should be taken into consideration from this environmental point of view.