Quantification and speciation of mercury in soils from the Tripuí Ecological Station, Minas Gerais, Brazil

Abstract

Contents of total mercury, organic carbon, total sulfur, iron, aluminum and grain size and clay mineralogy were used along with Pearson's correlation and Hg thermal desorption technique to investigate the presence, distribution and binding behavior of Hg in soils from three depths from the Tripuí Ecological Station, located near Ouro Preto, Minas Gerais State, Brazil. The soils studied had predominantly medium and fine sand texture (0.59-0.062 mm), acid character and Hg contents ranging from 0.09 to 1.23 microg/g. The granulometric distribution revealed that Hg is associated with coarse sand (2-0.59 mm) and silt and clay (<0.062 mm) and presents similar Hg concentrations in both fractions. Mercury distribution in soil profiles showed that Hg was homogeneously distributed throughout the depths at most sites. Hg thermal desorption curves show that mercury occurs not only as Hg2+ predominantly bound to organic components in most of the samples, but also in the form of cinnabar in some. Pearson's correlation confirmed that mercury is associated with organic matter and sulfur and possibly with sulfur-bearing organic matter in most samples.

Interaction of Soil and Mercury as a Function of Soil Organic Carbon: Some Field Evidence

“…4 show a positive trend, indicating increase in THg and MeHg concentrations with increasing f oc in the soil. Similar findings have been reported earlier for different study sites (Palmieri et al 2006;Shi et al 2005;Cai et al 1999;Rae and Aston 1982). It is known that soil organic carbon enhances the capacity of the soil to bind metals (Bolt and Bruggenwert 1976).…”

Preliminary results of detailed geochemical study of mercury at the ancient ore roasting site P{enk (Idrija area, Slovenia)

“…In general Hg concentrations in all three studied profiles show a gradual decrease with depth which is in accordance with the decrease in organic matter content. This behaviour, Preliminary results of detailed geochemical study of Hg at the ancient mercury ore roasting site P{enk ... which was observed in several studies (BIESTER et al, 2002, PALMIERI et al, 2005 indicates that retention of Hg is strongly related to organic matter content, which is the highest in uppermost soil layer. However, the increase of Hg content from the topsoil layer to the highest value in the depth range from 15-35 cm in profile P1-1 and 20-30 cm in profile P3 could imply that adsorption of Hg to mineral soil components is as much or even more important than binding of Hg to organic matter content.…”

Sustainable remediation of mercury contaminated soils by thermal desorption

“…Authors mentioned above Bombach et al 1994;Palmieri et al 2006;Windmoller et al 1996) gave theoretical values of temperature at which some Hg forms are desorbed from soils. The results obtained in the present work are discussed according to them.…”

“…The furnace was opened to take samples at each temperature waiting until the temperature was below 40°C due to the nature of volatile compounds. Both the ramp rate to reach each target temperature and the corresponding hold time were 1 h. This ramp of temperature was chosen considering the literature which shows the thermal desorption curves of standard Hg compounds and the theoretical desorption temperatures for Hg associated to different fractions Bombach et al 1994;Palmieri et al 2006;Windmoller et al 1996).…”

“…A typical thermal desorption unit for Hg removal operates at temperatures from 320 to 700°C (United States Environmental Protection Agency (US EPA) 2007), and it is one of the few methods that are effective for very high Hg concentrations (Xu et al 2015). There are previous preliminary studies that have demonstrated the viability of the Hg release at temperatures between 127 and 600°C (Chang and Yen 2006;Chang et al 2009;Matsuyama et al 1999;Navarro et al 2009Navarro et al , 2014Palmieri et al 2006). Hg will be released at different temperatures depending on the phase to which it is linked (Navarro et al 2009(Navarro et al , 2014.…”