Explotación De Minas

Background: An essential requisite for controlling and monitoring mercury in the environment is to identify its species in different types of soils and sediments, as this will help not only to establish its mobility in the environment and ecosystem and the degree of its toxicity, but also to establish the source of contamination. The objective of this work was to identify the origin of mercury in beach sands and soil taken from a coastal region with previously high mining and industrial activity by characterizing the mercury species using the technique known as thermal desorption (HgTPD). Results: Apart from quartz, the main mineral species identified in the raw sands and soil were calcite, fluorite and barite. The concentration of mercury ranges from 5 to 23 µg g −1 , and although it is distributed in different proportions in the function of the size, thermal desorption profiles demonstrated that the mercury species present in the samples do not vary with the mercury concentration and the particle size. By means of HgTPD, mercury oxide (HgO) was identified in the beach sands, whereas mercury sulfide (HgS) was found in the soil sample taken from the vicinity of the beach. Complementary methodologies foster the HgTPD conclusions and verify that mercury is present mostly in insoluble stable (HgS) or low-mobility (HgO) forms in the samples studied. Analyses by ICP-MS after sequential extraction and HPLC separation of mercury species show that inorganic mercury is the predominant form in the samples. Conclusions: The technique HgTPD is a very useful tool to ascertain the origin of mercury in contaminated beach sands and shoreline soils. In the particular area studied in this work, the species identified indicate that previous mining activity was the source of the mercury and rule out the possibility that contamination is derived from coal combustion activities ongoing in the region.

An environmental forensic study was developed in a former industrial area in southern Spain. Previous information about the site revealed arsenic and hydrocarbons affection exceeding soil screening levels. A full characterisation of arsenic affection was thus performed. In this regard, the bioavailable fractions, arsenic speciation and grain-size distribution were determined. Two different polluted types of soils/fillers were identified. The first one is affected by non-bioavailability As(V) concentrations on the finer fraction, and the other one is affected by As(III) and As(V) with higher bioavailability than the other case, affecting all grain-size fractions homogeneously. Notably the textures are very heterogeneous within the site. On the other hand, hydrocarbons affection was also studied. Cuantitative and cualitative organic analyses revealed the presence of organic products with differing degree of degradation (naphthas). An additional microbiological study revealed regular m...

By the end of 2002, the shoreline of the Cantabrian Sea had been severely contaminated by the Prestige fuel oil spill. As a result, coastal sediments were affected with a heavy and viscous hydrocarbon mixture and, initially, waste was removed by hot pressurized water washing. However, some specific sites were considered for biotreatment where grain-size sediment and other factors made mechanical removal ineffective or inappropriate. Therefore, the aim of this work was to select bioremediation procedures for cobble and pebble sediments at Bahinas Beach (Asturias, Spain). Laboratory, pilot, and full-scale experiments were carried out to select nutrient sources, surfactants, and other bioremediation amendments to be applied as part of a novel on-site bioremediation approach vs. in situ bioremediation. Simple microbiological control and chemical determinations were made to monitor these two procedures. First, a classic approach of in situ bioremediation was tested with the direct application of S-200 (a new oleophilic fertilizer), which achieved hydrocarbon depletion higher than 30% of linear alkanes and aromatics after 60 days of cobble-pebble treatment. On the other hand, the design and subsequent implementation of on-site bioremediation achieved not only better results in shorter periods of treatment (40% of global hydrocarbon depletion after 30 days), but also reduced viscosity of the fuel residues adhering to the sediments, thereby enabling a secondary water washing to complete cleaning of cobbles and pebbles.

Soil in a brownfield contaminated by pyrite ashes showed remarkably high concentrations of several toxic elements (Hg, Pb, Zn, Cu, Cd, and As). Initially, we assessed various physical, chemical and mineralogical properties of this soil. The data obtained, and particularly multivariate statistics of geochemical results, were useful to establish the predominant role of the soil organic matter fraction (6%) and iron oxyhydroxides in the binding of heavy metals and arsenic. In addition, we studied the viability of soil washing techniques to reduce the volume of contaminated soil. Therefore, to concentrate most of the contaminants in a smaller volume of soil, the grain-size fraction below 125 m was treated by hydrocycloning techniques. The operational parameters were optimized by means of a factorial design, and the results were evaluated by attributive analysis. This novel approach is practical for the global simultaneous evaluation of washing effectiveness for several contaminants. A concentration factor higher than 2.2 was achieved in a separated fraction that contained less than 20% of the initial weight. These good yields were obtained for all the contaminants and with only one cycle of hydrocycloning. Hence full-scale soil washing is a plausible remediation technique for the study site.

Soils geochemical data was assessed with different Bayesian network approaches. • A Bayesian Risk Index (BRI) for assessing soil contamination was constructed. • BRI's spatial patterns were constructed throughout geostatistical modeling. • Clusters of high PTEs cm, concentration are overlapping an agriculture zone. • Metallurgical plant's emissions are the main source of soils pollutants.

The circular economy seeks to minimize the use of raw materials and waste generation. In this context, here we addressed the use of dunite mining tailings and subproducts to stabilize metal(oid)s in polluted soils. We first characterized the dunite mining tailings and subproducts, and a paradigmatic polluted soil in depth to determine their chemical and mineralogical properties. Experimental trials using Brassica juncea L. were performed to evaluate the impact of the two materials on vegetation growth, edaphic properties and pollutant stabilization yields. To this end, the plants were grown over 75 days in 1 kg pots containing the polluted soil amended with the dunite materials. Notably, both amendments caused a dramatic decrease in the available Zn and a moderate reduction in available Cu, Cd and Pb. In contrast, the concentration of available As was not modified. The cation exchange capacity (CEC) was improved by treatment with the amendments, allowing an increase in the biomass h...

The capacity of graphene oxide nanoparticles (nGOx) to reduce or increase As and metals availability in polluted soils was compared with that of zero valent iron nanoparticles (nZVI). The nanomaterials used in this study were characterized by X-ray techniques, CHNS-O analysis, dynamic light scattering, and microscopy procedures such as atomic force microscopy. To assess the capacity of these materials to immobilize pollutants, field samples of two soils were treated with nZVI and nGOx at a range of doses (0.2%, 1% and 5%). Availability tests were then performed. nGOx effectively immobilized Cu, Pb and Cd, but mobilized As and P (even at low doses), in the latter case irrespective of the simultaneous presence of high concentrations of metals. In turn, nZVI promoted notable immobilization results for As and Pb, a poorer result for Cd, and an increased availability for Cu. Soil pH and EC have been slightly affected by nGOx. On the whole, nGOx emerges as a promising option for mobilizat...

A bioslurry reactor was designed and used to treat loamy clay soil polluted with polycyclic aromatic hydrocarbons (PAHs). To this end, biostimulation alone, or combined with bioaugmentation with two bacterial strains (Rhodocccus erythropolis and Pseudomonas stuzeri) previously isolated from the polluted site, was applied. The PAH concentrations decreased notably after 15 days in all of the treatments. The concentrations of the two- and three-ring compounds fell by >80%, and, remarkably, the four- to six-ring PAHs also showed a marked decrease (>70%). These results thus indicate the capacity of bioslurry treatments to improve, notably, the degradation yields obtained in a previous real-scale remediation carried out using biopiles. In this sense, the remarkable results for recalcitrant PAHs can be attributed to the increase pollutants’ bioavailability achieves in the slurry bioreactors. Regarding bioaugmentation, although treatment with R. erythropolis led to a somewhat greater ...

The demand for soils for recreational uses, gardening, or others in urban and periurban areas is increasing, and thus the presence of polluted technosols in these areas requires nature-based in situ remediation technologies. In this context, the capacity of three amendments, namely zero valent iron nanoparticles (nZVI), compost and a mixture of compost and biochar, to immobilise As in a polluted technosol simultaneously cultivated with Lolium perenne L. were tested and compared. The characteristics of the soil were comprehensively characterised by chemical and X-ray analysis to determine As contents, distribution, and mineralogy. As mobility was evaluated by the RBA methodology and then potential human health risks, both carcinogenic and non-carcinogenic, were assessed in all treatments. The nZVI treatment reduced risks due to the As immobilisation obtained (41% As decrease, RBA test), whereas the organic amendments did not imply any significant reduction of the RBA values. As to so...

El diseño de una BD relacional se puede abordar de dos formas distintas:  Obteniendo el Esquema Relacional directamente a partir de la observación de nuestro Universo del Discurso según lo captamos en nuestro análisis del mundo real.  Realizando el proceso de diseño en dos fases, obtener un Esquema conceptual (por ej. usando el Modelo Entidad/Relación) y transformando este en un Esquema Lógico Relacional. Al utilizar cualquiera de los dos métodos anteriores, el diseñador puede cometer fallos en la percepción del mundo real o en la transformación del Esquema E/R al esquema relacional. Esto tendrá como consecuencia una falta de fidelidad del esquema obtenido con respecto a la realidad que se pretende representar y dará lugar a una serie de problemas en la Base de Datos, tales como:  Redundancias.-datos que se repiten continua e innecesariamente por las tablas de las bases de datos. Cuando es excesiva es evidente que el diseño hay que revisarlo, es el primer síntoma de problemas y se detecta fácilmente  Ambigüedades.-Datos que no clarifican suficientemente el elemento al que representan. Los datos de cada fila podrían referirse a más de un ejemplar de esa tabla o incluso puede ser imposible saber a qué ejemplar exactamente se están refiriendo. Es un problema muy grave y difícil de detectar.  Pérdida de información.-Normalmente debido a dependencias funcionales. Más adelante se explica este problema. Se arreglan fácilmente siguiendo una serie de pasos concretos.  Aparición de estados no válidos en el mundo real: anomalías de Inserción, Borrado y Modificación.-El hecho de que al insertar un solo elemento haya que repetir tuplas en una tabla para variar unos pocos datos. O que eliminar un elemento suponga eliminar varias tuplas necesariamente (por ejemplo que eliminar un cliente suponga borrar seis o siete filas de la tabla de clientes, sería un error muy grave y por lo tanto un diseño terrible)  Incapacidad para representar ciertos hechos.  Incoherencia de la información. El principio fundamental reside en que las tablas deben referirse a objetos o situaciones muy concretas, relacionados exactamente con elementos reconocibles de forma inequívoca. Cada fila de una tabla representa inequívocamente un elemento reconocible en el sistema. La mayor parte de problemas se agravan si no se sigue un modelo conceptual y se decide crear directamente el esquema relacional. En ese caso, el diseño tiene una garantía casi asegurada de funcionar mal. La Teoría de la Normalización permite analizar un esquema detectando en él posibles problemas y facilitando su transformación al proporcionar relaciones más estructuradas que los eviten.