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Abstract

Gold mining has been one of the driving factors for some of the settlements in Mato Grosso and for its enormous population growth. Poconé, a municipality located in the extreme north of the Pantanal, has been the particular target of these events and has been marked, both socially and environmentally, by changes in mining technologies. In the 1980s, the political and economic situation in Brazil resulted in a floating population of around 10,000 miners in the area surrounding Poconé. Mining activities during that time left behind enormous amounts of waste contaminated with mercury, which had been used indiscriminately in the amalgamation of gold dust. Metallic mercury used in this process is relatively immobile and only slightly toxic. However, toxic mercury ions (Hg2+) can be released, e.g., by rain, and, under favourable conditions, methylated on land or in bodies of water, thereby entering the food web. Consequently, gold- mining activities have led to intense environmental degradation through (i) landscape destruction and morphological changes in affected water bodies, (ii) the release of mercury into the environment, and (iii) the entrance of mercury into food webs. Nonetheless, mining remains an important part of the Poconé economy, although it is more regulated than in the 1980s and 1990s. For example, companies involved in gold extraction must comply with the “terms of conduct” imposed by the State Department of the Environment. Despite these measures, environmental concerns are and will continue to be relevant in the area of Poconé – until existing regulations aimed at reducing mercury emissions and recovering contaminated sites are fully implemented.