In order to counteract mercury pollution, due to gold recovery practices, in situ strategies are required. In this study, some physico-chemical additions were tested, in different environmental compartments, to verify their potential to mitigate mercury contamination. Results indicate that the addition of sulfide reduces chemical methylation of Hg(II), but enhances the solubility of Hg 0. The use of oxides, phosphate, and organic matter may be effective in the immobilization of Hg(II), depending upon Hg speciation. Calcium was effective in counteracting the solubility enhancement of Hg 0 promoted by the presence of Aldrich humic acid.