RESUMO
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.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Mercúrio/análise , China , Cidades , Coleta de Dados , Europa (Continente) , Mineração , África do Sul , América do Sul , Erupções VulcânicasRESUMO
This paper presents a short-term monitoring study of total gaseous mercury (TGM) in air, and exposure to airborne mercury. The evaluation was carried out in polluted mining sites (El Callao, Venezuela), where for decades mercury has been used in diverse stages of gold mining activities. The contamination is mainly due to emission of Hg0 during gold amalgamation and burning, which can cause direct human health risks. Total gaseous mercury (TGM) in air was analysed in mill, jewellery and indoor house sites, and at different heights (height profiles near the surface) at polluted and not polluted sites. Mercury concentration in air was measured with a portable mercury analyser (Lumex Ra-915+). Time weighted average mercury (TWA) was calculated for the evaluation of mercury exposure. TWA values ranged between 0.28 microg m(-3) and >100 microg m(-3). These measurements were done during sunny and dry days. In the case of mills and gold workshops, the values were over the limit recommended by the World Health Organization to exposure (25 microg m(-3)) and NIOSH limit (50 microg m(-3)). Indoors in a house, the air Hg average value was 2.58 microg m(-3) exceeding EPA (0.3 microg m(-3)) and ATSDR (1 microg m(-3)) guidelines. The mercury concentration at different height profiles, varied between 1766 microg m(-3) and 0.014 microg m(-3). Mercury height profiles were described by a power function model of the form c(Hg) = ah(-b), where a parameter describes the magnitude of Hg emission. For polluted sites there was a significant correlation between a and Hg in soil or Hg emission from soil to air, while b is only significantly correlated with air temperature. An air and soil mercury measurement transect was carried out at a mill site up to a distance of 1000 m, and it was observed that the air mercury concentration decreases with increasing distance from the mill site, and inversely to Hg soil content.
Assuntos
Mercúrio/toxicidade , Poluentes Atmosféricos , Poluentes Ocupacionais do Ar , Monitoramento Ambiental/métodos , Poluentes Ambientais , Gases , Intoxicação por Mercúrio/etiologia , Mineração , Exposição Ocupacional , Temperatura , Venezuela , VolatilizaçãoRESUMO
El contenido de mercurio en muestras de suelos provenientes de El Callao, Estado Bolívar, Venezuela, fue determinado por digestion en agua regia y cuantificación por el método del vapor frío-absorción atómica (CVAAS), y por determinación directa en la matriz sólida por pirólisis y preconcentración en el analizador automático de mercurio AMA-224 (AMA). Los niveles de Hg en las muestras analizadas estuvieron en los intervalos de 0,05 a 17,31 mg/kg para CVAAS y de 0,050 a 20,066mg/kg para AMA. Las mayores concentraciones de Hg se detectaron en las áreas de molinos, donde es empleado para amalgamar el oro. La exactitud de la técnica AMA fue estimada por el análisis de rocas de referencia (US Geological Survey) comprobándose que la técnica es de exactitud y precisión satisfactorias. Se comprobó que ambas técnicas producen resultados equivalentes sin que se produzcan errores sistemáticos