Mercury Behavior in a Tropical Environment: The Case of Small-Scale Gold Mining in Poconé, Brazil

Abstract

An estimated 50 tons of mercury (Hg) have been emitted by gold miners in the Bento Comes river basin, in the municipality of Poconb, Brazil, since the 1980s. Since the mid-l990s, the state agency for environmental protection, FEMA (FundaGZo Estadual do Meio Ambiente de Mato Grosso), has enforced regulations to reduce Hg emissions to air and water and has also implemented an environmental assessment program. The objectives of this study were to evaluate efforts to reduce emissions of Hg to air and water from nine improved amalgamation centers, and to assess the pollution level in sediment at 25 sites around PoconC.In spite of the fact that retorts were used, results showed large emissions of Hg when burning amalgam, resulting in Hg air concentrations above the limit for occupational air (50 pg/m3) at all centers except one. Keeping washing water in closed systems and dumping residues in specially prepared sites reduced Hg emissions to watercourses. The average Hg concentration of fine sediments (<74 pm) in the Bento Gomes river basin was 104 ng Hg/g dry weight, three to four times higher than the background level; large amounts of Hgcontaminated sediments are re-suspended during the rainy season. In conclusion, present emissions to local watercourses have been efficiently reduced, but the use of retorts in improved amalgamation centers has not adequately reduced Hg emissions to air, which is why the use of Hg remains an occupational and environmental problem.Environmental Practice 6: 121-134 (2004) he activities of small-scale gold miners (garimpeiros de

Sustainability Agenda for the Pantanal Wetland: Perspectives on a Collaborative Interface for Science, Policy, and Decision-Making

“…Risks of contamination due to the use of the mercury from gold mining have been reported over two decades (Nogueira, Nascimento, Silva, & Junk, 1997;Tu¨mpling, Wilken, & Einax, 1995;Vieira, Alho, & Ferreira, 1995). In tropical wetlands, the rate of biomagnification of the mercury in the trophic web is high (Da Silva & Estanislau, 2015;Oliveira, Hylander, & e Silva, 2004;Vieira et al, 1995). Signs of this process have been already found in the Pantanal (e.g., Callil & Junk, 2009;Ceccatto et al, 2016;Del Lama, Rocha, Jardim, Tsai, & Frederick, 2011;Fonseca, Malm, & Waldemarin, 2005;Hylander et al, 2000;May Junior et al, 2017;Pietro-Souza et al, 2017;Vieira et al, 2011).…”

Origin and consumption of mercury in small-scale gold mining

“…A recent study of nine Amalgamation Centers in Brazil, all using retorts, revealed that the retorts managed to keep the ambient Hg levels below the occupational safety limit at only one center [44]. This should be mentioned when retorts are promoted, in order to avoid giving the mining community the false impression that exposures would be easily and completely eliminated.…”

Implications of the Minamata Convention on Mercury for informal gold mining in Sub-Saharan Africa: from global policy debates to grassroots implementation?

“…For decades, concerns about mercury contamination in the global food supply -especially fish -have led to a burgeoning body of literature on mercury's effects on human health and the environment (Oliveira et al, 2004;Passos and Mergler, 2008). The toxic risks of mercury pollution have been examined in depth both in terms of risks experienced by populations living near local emission sources as well as more dispersed transboundary pollution (Bose-O'Reilly et al, 2010;Taylor et al, 2005;Telmer and Veiga, 2008;Tomicic et al, 2011).…”