Analysis of the distribution and transport of mercury in rivers under mining operations with applications to the Caroní river basin
Article
Baselice, A, García, R, Saavedra, I et al. (2002). Analysis of the distribution and transport of mercury in rivers under mining operations with applications to the Caroní river basin
. 17(2), 83-95.
Baselice, A, García, R, Saavedra, I et al. (2002). Analysis of the distribution and transport of mercury in rivers under mining operations with applications to the Caroní river basin
. 17(2), 83-95.
This article presents the mathematical bases that govern the transport and distribution of three basic mercury species (elemental, divalent and methylmercury) in aquatic environments, involving sources, input paths, toxicity, and the kinetic transformation of each species. The theoretical analysis that governs the physicochemical behavior of mercury together with the analysis of available mercury data from the Caroní River are used to formulate a model for mercury pollution in this river. Due to the high adsorption of mercury to solid particles, organic and inorganic phases may be associated with suspended and bed load sediment transport and to high molecular weight organic matter and, consequently mercury mobility is determined by the geochemical composition and morphology of the particles. Data from the Caroní River shows that mercury concentrations in water are below the maximum recommended by the US Environmental Protection Agency (EPA). However, in extensive mining activity zones, it is possible to find values higher than 12 μg/l in water and 20 μg/Kg in bottom sediments. Besides, levels in the fine sediment fraction increase with distance from the source. Even though the measured data correspond to total mercury, due to the hydraulic and water quality characteristics of the Caroní River, it is reasonable to assume that most of the total mercury is in dissolved phase and is divalent mercury associated with the dissolved organic carbon or to inorganic ligands. Furthermore, the metilmercury production is low due to high dissolved oxygen concentration in the river.
