Impactos ambientais da mineração aluvionar de ouro na bacia do rio Boia – Amazonas

Abstract

The constant increase in the price of gold in the international market stimulated in Brazil the resumption and growth of artisanal mining of this metal, alluded to in the form of garimpos. The gold extraction process, in this model, operates with rudimentary techniques and methods that cause significant environmental damage. Obtaining ore, in this context of normative and technological precariousness, is based on a process that is deeply dependent on mercury, which, in unsuspecting mining situations, becomes a worrying source of chemical environmental contamination by heavy metals. This research aims to present a methodology that gathers information from multi-source remote sensors, field work and chemical analysis by x-ray fluorescence to qualify and quantify the environmental impacts caused by alluvial gold mining in the Boia River basin. The evaluation of environmental contamination by heavy metals was extended to the Western Amazon, using samples discarded from the gold amalgamation process and mercury recovery. A total of 1466 sites with deep environmental degradation were mapped in the Boia river basin that obliterate the fluvial geomorphology features and cause silting. Mercury contamination in Amazonian environments progresses as mining spreads along the rivers, even reaching remote regions driven by the high price of gold. Regional sources of mercury-contaminated material were identified, especially in the Japurá River, with the capacity to contaminate millions of liters of drinking water daily. The inefficiency and ineptitude of preventive and supervisory action is mainly the result of the absence of the State in many areas with great logistical challenges and incipient legislation.