Atmospheric mercury emissions from polluted gold mining areas (Venezuela)

Abstract

Soil, waste rock and mud from mercury-gold amalgamation mining areas of El Callao (Venezuela) are highly enriched in Hg (0.5-500 microg g(-1)) relative to natural background concentrations (<0.1 microg g(-1)). Mercury fluxes to the atmosphere from twelve polluted sites of this area were measured in situ (6 a.m. to 8 p.m.) using a Plexiglas flux chamber connected to a portable mercury analyzer (model RA-915+; Lumex, St. Petersburg, Russia). Mercury fluxes ranged between 0.65 and 420.1 microg m(-2) h(-1), and the average flux range during the diurnal hours was 9.1-239.2 microg m(-2) h(-1). These flux values are five orders of magnitude higher than both reported world background Hg fluxes (1-69 ng m(-2) h(-1)) and the regional values, which are in the range 2-10 ng m(-2) h(-1). The flux results obtained in this study are, however, similar to those measured at Hg polluted sites such as chloro-alkali plants or polymetallic ore mining districts (>100,000 ng m(-2) h(-1)). The results from this study also show that Hg emissions from the soil are influenced by solar radiation, soil temperature and soil Hg concentration. Our data suggest that solar radiation may be the dominant factor affecting Hg degrees emission since the major species of mercury in polluted soil is Hg degrees (85-97% of total Hg). The simple release of Hg degrees vapor is probably the dominant process occurring with incident light in the field. The apparent activation energy for mercury emission indicates that the volatilization of mercury mainly occurred as a result of the vaporization of elemental mercury in soil. The degree of Hg emission differed significantly among the soil sites studied, which may be due to variations in soil texture, organic matter content and soil compaction.

Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela

“…This chemical form of mercury is very important with regard to environmental risks, since its low reactivity prevents mobilization in soils and waters. By contrast, its high vapour pressure provides a high Hg flux (soileair), up to 420 mg m À2 h À1 in the mining areas (Garcia-Sanchez et al, 2006), contributing significantly to the local atmospheric pollution and may be to the global Hg cycle.…”

“…The main factors that determine total gaseous mercury (TGM) levels in the ambient air are Hg speciation and its concentration in topsoil. Moreover, TGM in the air is also related to soil temperature, soil moisture, solar radiation, rainfall, and wind direction and speed Engle and Gustin, 2002;Liu et al, 2002;Garcia-Sanchez et al, 2006).…”

Mercury in soils and plants in an abandoned cinnabar mining area (SW Spain)

“…The main factors that determine the total gaseous mercury (TGM) in the ambient air are Hg speciation and concentration in topsoil. Moreover, TGM in the air is also related to soil temperature, soil moisture, solar radiation, rainfall and wind direction and speed [11][12][13][14][15][16][17][18][19][20][21]. The wind direction and intensity influence gaseous Hg dispersion, while temperature influences its production [2].…”

Metalotioninas en <i>Perna viridis</i> (Bivalvia: Mytilidae): variación estacional y su relación con la biología reproductiva

“…Los mayores niveles de Mts en los ejemplares de de Río Caribe podrían estar asociados a los mayores índices de condición presentados por los mejillones de esta zona, que además de estar influidas por los parámetros físico-quími-cos y biológicos ya planteados anteriormente y que caracterizan a la zona como un centro de alta productividad primaria, en relación a Chacopata existe un aporte fluvial de materia en suspensión que puede aportar niveles significativos de metales producto de las industrias de metalurgia y explotación minera (García-Sánchez et al 2006, Rojas et al 2009). …”