Examinando por Autor "Higueras, Pablo"

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A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: Separating fads from facts
(Springer, 2013) Higueras, Pablo; Oyarzun, Roberto; Kotnik, Joze; Esbrí, José María; Martinez-Coronado, Alba; Horvat, Milena; Lopez-Berdonces, Miguel Ángel; Llanos, Willians; Vaselli, Orlando; Nisi, Barbara; Mashyanov, Nikolay; Ryzov, Vladimir; Spiric, Zdravko; Parichev, Nikolay; McCrindle, Rob; Feng, Xinbin; Fu, Xuewu; Lillo, Javier; Loredo, Javier; Garcia, María Eugenia; Alfonso, Pura; Villegas, Karla; Palacios, Silvia; Oyarzun, Jorge; Maturana, Hugo; Contreras, Felicia; Adams, Melitón; Ribeiro-Guevara, Sergio; Niecenski, Luise Felipe; Giammanco, Salvatore; Huremovic, Jasna
Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, Hggas0), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m-3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m-3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m-3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au-Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical-chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans
Determinants of exposure to mercury in hair from inhabitants of the largest mercury mine in the world
(Elsevier, 2011-03-31) Díez, Sergi; Esbrí, José María; Tobias, Aurelio; Higueras, Pablo
Mercury exposure of the local population was assessed in two areas of the Almadén mercury mining district, Spain, which has been the world's largest producer of this element. Two groups, who are exposed to different sources of mercury, from a point source in Almadén and a diffuse source hundreds of kilometres away in the same region, were studied. Total mercury (THg) in human hair ranged from 0.20 to 9.35mgkg-1 and the mean value was 2.64mgkg-1. About 87% of subjects had THg levels in excess of the EPA reference dose (RfD=1.0mgkg-1), while a high percentage (68%) of them live in Almadén. There was a clear increase in hair Hg with reported fish consumption and the highest mean hair mercury level was 4 times the RfD in a group who had reported the highest consumption of fish. For the whole group, there was a significant effect of age, gender and fish consumption in relation to Hg concentration in the hair. Nevertheless, when both groups were tested separately by means of a multivariate regression model, there was significant exposure in those living near the mine area. Several factors such as age, gender and fish consumption remained statistically significant and were associated with THg. The main conclusion is that people living close to the hot spot are more impacted by mercury than people living further away. The intake of Hg through consumption of fish is an important parameter for Hg exposure; however, in the case of people living close to the hot spot, their levels are related to the highly Hg-impacted living environment.
Distribution of gaseous Hg in the Mercury mining district of Mt. Amiata (Central Italy): A geochemical survey prior the reclamation project
(Elsevier, 2013) Vaselli, Orlando; Higueras, Pablo; Nisi, Barbara; Esbrí, José María; Cabassi, Jacopo; Martinez-Coronado, Alba; Tassi, Franco; Rappuoli, Daniele
The Mt. Amiata volcano is the youngest and largest volcanic edifice in Tuscany (central-northern Italy) and is characterized by a geothermal field, exploited for the production of electrical energy. In the past Mt. Amiata was also known as a world-class Hg district whose mining activity was mainly distributed in the central-eastern part of this silicic volcanic complex, and particularly in the municipality of Abbadia San Salvatore. In the present work we report a geochemical survey on Hg0 measurements related to the former mercury mine facilities prior the reclamation project. The Hg0 measurements were carried out by car for long distance regional surveys, and on foot for local scale surveys by using two LUMEX (915+ and M) devices. This study presents the very first Hg0 data obtained with this analytical technique in the Mt. Amiata area. The facilities related to the mining areas and structures where cinnabar was converted to metallic Hg are characterized by high Hg values (>50,000ngm-3), although the urban center of Abbadia San Salvatore, few hundred meters away, does not appear to be receiving significant pollution from the calcine area and former industrial edifices, all the recorded values being below the values recommended by the issuing Tuscany Region authorities (300ngm-3) and in some cases approaching the Hg background levels (3-5ngm-3) for the Mt. Amiata area.
Evaluation of mercury stress in plants from the Almadén mining district by analysis of phytochelatins and their Hg complexes
(American Chemical Society, 2014) Dago, Ángela; Gonzalez, Inmaculada; Ariño, Cristina; Martinez-Coronado, Alba; Higueras, Pablo; Diaz-Cruz, José; Esteba, Miguel
To evaluate plant response to Hg stress, glutathione, phytochelatins, and their Hg complexes were analyzed using HPLC with amperometric detection in samples of Asparagus acutifolius grown in the Almadén mining district (Ciudad Real, Spain), one of the most Hg-contaminated sites in the world. Soils of the Almadén mining district, and specifically from the Almadenejos zone, are highly contaminated, with some zones having values above 4,000 μg Hg g-1 soil. Although soils have an extremely high concentration of mercury, generally less than 2% is available for plants, as is shown by various soil extractions simulating bioavailability. In plants, Hg concentration increases depending on the content of Hg in soils. In addition, Hg levels in roots are higher than in aerial parts, which is a strategy of plants for protecting their more sensitive aerial parts from the deleterious effects of metal stress. The total content of phytochelatins (PCs) and their complexes are directly related with the amount of mercury in soils. These findings highlight the important role of thiol compounds and their metal complexes in capturing and fixing Hg from soils, giving plants the capacity to deal with the heavy metal toxicity of polluted soils. © 2014 American Chemical Society.
Industrial and natural sources of gaseous elemental mercury in the Almadén district (Spain): An updated report on this issue after the ceasing of mining and metallurgical activities in 2003 and major land reclamation works
(Elsevier, 2013) Higueras, Pablo; Esbrí, José María; Oyarzun, Roberto; Llanos, Willians; Martinez-Coronado, Alba; Lillo, Javier; Lopez-Berdonces, Miguel Ángel; Garcia-Noguero, Eva Maria
Two events during the last decade had major environmental repercussions in Almadén town (Spain). First it was the ceasing of activities in the mercury mine and metallurgical facilities in 2003, and then the finalization of the restoration works on the main waste dump in 2008. The combination of both events brought about a dramatic drop in the emissions of gaseous elemental mercury (GEM) to the atmosphere. Although no one would now call the Almadén area as 'mercury-free', the GEM levels have fallen beneath international reference safety levels for the first time in centuries. This has been a major breakthrough because in less than one decade the site went from GEM levels in the order of "tens of thousands" to mere "tens" nanogram per cubic meter. Although these figures are per se a remarkable achievement, they do not mark the end of the environmental concerns in the Almadén district. Two other sites remain as potential environmental hazards. (1) The Las Cuevas mercury storage complex, a partially restored ex-mining site where liquid mercury is being stored. The MERSADE Project (LIFE-European Union) has tested the Las Cuevas complex as a potential site for the installation of a future European prototype safe deposit of surplus mercury from industrial activities. Despite restoration works carried out in 2004, the Las Cuevas complex can still be regarded as hotspot of mercury contamination, with high concentrations above 800μgg-1 Hgsoil and 300ngm-3 Hggas. However, as predicted by air contamination modeling using the ISC-AERMOD software, GEM concentrations fade away in a short distance following the formation of a NW-SE oriented narrow plume extending for a few hundred meters from the complex perimeter. (2) Far more dangerous from the human health perspective is the Almadenejos area, hosting the small Almadenejos village, the so-called Cerco de Almadenejos (CDA; an old metallurgical precinct), and the mines of La Nueva Concepción, La Vieja Concepción and El Entredicho. The CDA is an old metallurgical site that operated between 1794 and 1861, leaving behind a legacy of extremely contaminated soils (mean concentration=4220μgg-1 Hg) and GEM emissions that in summer can reach levels up to 4,000-5,000ngm-3. Thus the CDA remains the sole 'urban' site in the district surpassing GEM international reference safety levels. In order to prevent these emissions, the CDA requires immediate action regarding restoration works. These could involve the full removal of soils or their permanent capping to create an impermeable barrier.
Sampling high to extremely high Hg concentrations at the Cerco de Almadenejos, Almadén mining district (Spain): The old metallurgical precinct (1794 to 1861 AD) and surrounding areas
(Elsevier, 2011) Martinez-Coronado, Alba; Oyarzun, Roberto; Esbrí, José María; Llanos, Willians; Higueras, Pablo
The Cerco de Almadenejos (CDA) is an old metallurgical site located in the province of Ciudad Real (Spain) that operated between 1794 and 1861. The metallurgical precinct was built for the roasting of the Almadén and Almadenejos cinnabar ore to extract Hg metal. A previous pilot geochemical study of soils at the CDA had already shown extremely high concentrations of Hg. To analyze the extent and intensity of contamination, we planned and executed a geochemical survey to cover the CDA and the surrounding areas. The survey covered soils, air, and plants. The planning involved the design of two sampling grids in order to obtain a comprehensive picture of potential environmental hazards in the area: 1) a detailed sampling grid centred on the metallurgical precinct (n=16 samples; area=3.6×104m2); and 2) a less detailed sampling grid planned to determine the extension of contamination beyond the metallurgical site (n=35 samples; area=1.2×106m2). After variogram modelization of geochemical data, the kriging plots showed that contamination, even if centred at the precinct, extends beyond the site, with Hg concentrations of up to 2200 times those of uncontaminated soils (world baseline). The detailed study of the soils from the precinct shows an extremely high mean concentration of 4220μgHg g-1 (4.2×105 times baseline concentration). In turn, these highly polluted soils induce strong emissions of Hg(g), with concentrations of up to 970ng Hg m-3. The study of the edible wild asparagus Asparagus acutifolius shows extremely high concentrations of mercury in roots (0.6-443μgg-1) and stems (0.3-140μgg-1). The data indicate that the study area constitute a hot spot of contamination and is a potential health/environmental hazard for the inhabitants of Almadenejos, livestock, and wild life, that requires immediate action via remediation procedures
Time variations of gaseous and reactive mercury in the industrial area of Puertollano (south-central Spain). Temporal cycles with marked variations
(Elsevier, 2016) Martinez-Coronado, Alba; Esbrí, José María; Higueras, Pablo
Puertollano (48,086 inhabitants) is the largest industrial city in the Castilla-La Mancha region (South-Central Spain). The city is located some 250 km South of Madrid; it was an important coal mining site during the last century and today it is the location of one of the most important Spanish oil refineries and the only refinery located away from the coast. Nowadays the area (which mainly includes the Ojailen valley) has a large open pit coal mine (Encasur), two power plants (Eon and Elcogas) and a petrochemical complex (Repsol) located S and SE from the town. These industries give rise to a complex scenario in terms of mercury emissions to the atmosphere: Repsol, Elcogas and Eon act as discrete sources, while coal mine and dumps acts as a general, diffuse source. The mercury contents in Puertollano town and the related industrial area were characterized during 2010 and 2011 by acquiring stationary data of Gaseous Elemental Mercury (GEM), Reactive Gaseous Mercury (RGM), meteorological parameters and other atmospheric contaminants (NO, NO2, SO2, benzene, toluene, xylene, ozone and PM10). In addition, several Total Gaseous Mercury (TGM) mobile surveys were carried out covering the Ojailen valley.Total Gaseous Mercury (TGM) in the whole valley was in the range 0-24 ng m-3 in all surveys, while higher levels were found near to the coal mine and in the vicinity of a coal power plant that employs clean technology (Elcogas).Tekran data showed low GEM levels during 2010-2011 (1.81 ng m-3 on average), while lower GEM levels were measured during autumn and summer, and maximum levels in spring (7.32 ng m-3 on average). RGM measurements were 0.0088 ng m-3, i.e., significantly lower than background levels in the USA and Europe (0.04 ng m-3). Concentrations of these mercury species' were higher during summer (0.0117 ng m-3).Multiple regression analysis was carried out and good relationships between GEM levels, meteorological parameters and other pollutants were identified. The best GEM predictors were temperature, relative humidity and NO2, whereas the best predictors for RGM were GEM, temperature and ozone. RGM variations seem to be explained predominantly by photoxidation processes, with GEM availability and transport processes of secondary importance.