Background

Human actions derived from industrial activities, agriculture and domestic sewage are among those responsible for the pollution of the environment by toxic metals (Biondo, 2008). Mercury occurs in the environment combined with other elements and naturally in different chemical species with distinct solubility, reactivity and toxicity. Occurring in volcanoes and mercury mines, which are responsible for emissions of mercury in the order of 2700-6000 tons/year (Micaroni et al. 2000). In the Amazon, it is also used in mines in the amalgamation of gold (Au-Hg) (Figura 1), where a quantity of metallic mercury (Hg0) is released upon rivers and soils by the handling in insecure situations, and through the outdoor burning process, which releases element's vapor to the atmosphere, that leads to the aquatic ecosystem contamination.

Figure 1. Direct contact with mercury in the Amalgamation of gold process.

In Amazon rivers, about 3000 tons of mercury are available and can be bioconverted in its most toxic forms for living beings, through methylation - the addition of the radical CH3 – of mercury, bioaccumulative properties are acquired by its high affinity to animal tissues (Souza and Barbosa, 2010). The mercury methylation is a crucial step to its entry in the aquatic food chain organisms, because of it riverside communitiesA traditional pupulation that resides in the rivers proximities and they have the artisanal fishing as main food supplying activity. are the main affected by contaminated fish ingestion.