Garimpo e o mercúrio no rio Madeira: uma breve revisão

Abstract

NATURAL AND ANTHROPOGENIC CAUSES OF MERCURY IN THE MADEIRA RIVER. This study delves into the environmental impact of mercury (Hg) in the Madeira River, encompassing the historical aspects of gold mining, the risks of hydroelectric dams, and the biogeochemical cycles of mercury in the Amazon region through data collection and bibliographic and documentary research. Since the 1980s, intense gold mining activities in the Madeira River have propelled the release of mercury into the environment. This practice has resulted in the contamination of soil, watercourses, and the aquatic food chain. The Santo Antônio and Jirau dams, constructed on the Madeira River, pose another threat to the mercury issue. The reservoirs of these dams have flooded areas with high mercury concentrations accumulated during the gold rush, potentially enhancing mercury methylation and its entry into the food chain. Mercury exhibits a complex biogeochemical cycle involving atmospheric, terrestrial, and aquatic compartments. Elemental mercury (Hg0) present in the atmosphere is oxidized and deposited onto the Earth's surface and oceans. In the aquatic environment, inorganic mercury (Hg2+) can be converted into methylmercury (MeHg) by bacteria, becoming highly toxic and bioaccumulative in the food chain. Exposure to mercury, primarily through the consumption of contaminated fish, can cause severe human health consequences, affecting the central nervous system, kidneys, cardiovascular system, and fetal development. The presence of mercury in the Madeira River poses a significant environmental and public health challenge. Implementing rigorous measures for mercury contamination control and monitoring is crucial. Collaboration among environmental enforcement agencies, hydroelectric power plant companies, and local communities is essential. Additionally, partnerships with research institutions are paramount to fostering a broader dialogue on the perils of mercury across different scales and environments, considering the Madeira River's history of environmental damage. The environmental impact of mercury in the Madeira River demands a comprehensive approach encompassing historical considerations, current threats, and future actions. By acknowledging the intricate relationship between gold mining, hydroelectric dams, and mercury biogeochemistry, stakeholders can work collaboratively to mitigate mercury contamination and protect the health of the river ecosystem and the communities that depend on it.