An estimation of mercury concentrations in the local atmosphere of Almadén (Ciudad Real Province, South Central Spain) during the twentieth century.

We show the first estimations of long-term (100 years, 1900 to 2000) total gaseous mercury concentrations (TGM) in the urban area of Almadén. The estimation was carried out by comparing data on known metallic mercury production with measured TGM concentrations. The estimated diurnal background level ranges from 60 to 120 ng m(-3) and corresponds to periods when the metallurgical complex (cinnabar roasting plant) was shut down. The average TGM concentration during the period from 1900 to 2000 was about 600 ng m(-3) (with peaks above 1,200 ng m(-3)). Additionally, a 24-h-based TGM monitoring program has highlighted significant differences between the diurnal and nocturnal concentrations, particularly during the warmer months. In this regard, given that the average nocturnal to diurnal ratio is 2.12, we suggest that the average nocturnal concentrations must have exceeded 1,200 ng m(-3), and peak nocturnal concentrations could have reached levels up to 2,400 ng m(-3). Our estimations indicate that most parts of the town of Almadén were generally exposed to TGM concentrations in air that exceed the World Health Organization air quality guideline for Hg (1,000 ng m(-3)) for countryside and urban areas.

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.

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, [Formula: see text]), 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.

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.

Mercury accumulation in soils and plants in the Almadén mining district, Spain: one of the most contaminated sites on Earth.

Although mercury (Hg) mining in the Almadén district ceased in May 2002, the consequences of 2000 years of mining in the district has resulted in the dissemination of Hg into the surrounding environment where it poses an evident risk to biota and human health. This risk needs to be properly evaluated. The uptake of Hg has been found to be plant-specific. To establish the different manners in which plants absorb Hg, we carried out a survey of Hg levels in the soils and plants in the most representative habitats of this Mediterranean area and found that the Hg concentrations varied greatly and were dependent on the sample being tested (0.13-2,695 microg g(-1) Hg). For example, the root samples had concentrations ranging from 0.06 (Oenanthe crocata, Rumex induratus) to 1095 (Polypogon monspeliensis) microg g(-1) Hg, while in the leaf samples, the range was from 0.16 (Cyperus longus) to 1278 (Polypogon monspeliensis) microg g(-1) Hg. There are four well-differentiated patterns of Hg uptake: (1) the rate of uptake is constant, independent of Hg concentration in the soil (e.g., Pistacia lentiscus, Quercus rotundifolia); (2) after an initial linear relationship between uptake and soil concentration, no further increase in Hg(plant) is observed (e.g., Asparagus acutifolius, Cistus ladanifer); (3) no increase in uptake is recorded until a threshold is surpassed, and thereafter a linear relationship between Hg(plant) and Hg(soil) is established (e.g., Rumex bucephalophorus, Cistus crispus); (4) there is no relationship between Hg(plant) and Hg(soil )(e.g., Oenanthe crocata and Cistus monspeliensis). Overall, the Hg concentrations found in plants from the Almadén district clearly reflect the importance of contamination processes throughout the study region.