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Thermal release analysis of mercury species in contaminated soils was performed by temperature controlled continuous heating of the samples in a furnace coupled to an Atomic Absorption Spectrophotometer (AAS). It was shown that this method allows the identification of different redox states of Hg-species through their characteristic releasing temperature ranges. The method was applied to Hg-contaminated samples from an inactive chlor-alkali production plant in former East Germany (GER), and from a gold mining area in Pocon6, Mato Grosso, Brazil (BRA), as well as synthetic soil samples obtained by spiking pre-heated soil matrices (GER and BRA) with the following mercury species: Hg °, Hg2C12, HgC12, HgO and HgS.The samples GER, in general, frequently showed the presence of Hg 2+ probably bound to humic substances, in the case of samples with higher total carbon content. Only in highly contaminated samples (>3000 ppm of mercury) was Hg ° the predominant species. The samples BRA more frequently showed the presence of mercury species in the lower oxidation states, i.e. Hg 1+ in combination 0 with Hg . The method allows observing changes in Hg-speciation in the samples with time, mainly changes among the oxidation states Hg U, Hg 1+ and Hg 2+.The treated GER matrix showed a stronger tendency to oxidise Hg-species than the BRA treated matrix, in which only added Hg ° is partially oxidised to Hg 1+ and Hg 2+. In contrast, the BRA matrix 2+ 1+showed a pronounced tendency to reduce spiked Hg to Hg . This may be the reason for the presence of Hg 1+ in the majority of original BRA samples. The method appears to be very useful to study speciation of mercury and its dynamics. It can be used as a tool for monitoring mercury oxidation states and/or reactions of mercury in soils.

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