Examinando por Autor "Oyarzun, Roberto"

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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
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