Estudos de adsorção de mercúrio elementar gasoso em solos: influência de características químicas e/ou mineralógicas

Abstract

This work aimed to study the adsorption of gaseous elemental mercury (Hg) in soils of strategically important areas (with and without anthropogenic activity) and with different physicochemical characteristics. By diffraction ray-x, was identified Quartz (SiO2), kaolinite (Al2Si2O5(OH)4) and smaller amounts of hematite (Fe2O3), periclase (MgO), Manganosite (MnO) Anatase (TiO2). Using the analysis by fluorescence ray-x was obtained the content of some metals (mainly Fe, Al and Mn). Was employed a direct mercury analyzer (DMA-80) being obtained concentration ranges for the fraction of < 2 mm 43 ± 2 g kg-1 to 413 ± 25 g kg-1 and the fraction of <0.063 mm 144 ± 5 g kg-1 at 590 ± 3 g kg-1. Pearson's analysis showed significant correlation with mainly Fe2O3 (r = 0.62) and MnO (r = 0.53). To evaluate the gaseous elementary Hg adsorption on soils, the samples were subjected to an atmosphere saturated metal during different periods of time and after incubation and the amount of Hg Total adsorbed, as well as species of Hg, were determined using a DMA. The adsorption of gaseous mercury in soils varied depending on the soil type, 13-2236 times. Among the characteristics of soil responsible for mercury adsorption stood out the iron oxides and manganese which were significantly correlated with the amount of Hg adsorbed (Mn, r = 0.97) and (Fe, r = 0.94). Speciation using DMA shows that Hg adsorbed in soils may be present both oxidized and reduced. The results indicate that the Mn present in the samples is one of the most important abiotic factors for the adsorption of Hg, and probably help in gaseous elemental mercury oxidation process in contact with the ground. This fact has to contribute to a better understanding of key processes of geochemical cycle Hg, worth mentioning that the gaseous elemental mercury emissions to the atmosphere have increased because of human activities such as burning of forests and amalgam Hg-Au in gold mining.