Mercury speciation in environments impacted by gold-mining activities

In Amazonia, anthropogenic activities like Artisanal and Small-scale Gold Mining (ASGM) have been involved in Hg pollution but the exact extend of contamination is difficult to assess. A binary mixing model with Hg isotopic composition is commonly used to show the contribution of anthropogenic Hg in river sediments and soils. However, some of higher concentrated samples, expected to contain mainly anthropogenic Hg do not follow this binary model. On the other hand, other samples following this model show high degree of contamination but with low Hg concentrations which it is not consistent with the literature. Consequently, the accuracy of this binary model is questioned. In this project we propose to study Hg speciation in various samples related to ASGM. We aim to investigate Hg oxidative state and bearing phases to refine our understanding of Hg mobility from tailings and pristine sources in order to have a better insight of the isotopic composition.