Insights on mercury and energy consumption from in-situ measurements of artisanal gold mining in Brazilian Amazon rainforest

Abstract The Tapajós River basin in Brazil is one of the worlds most affected regions by artisanal gold mining (ASGM). Its environmental problems include the release of mercury, deforestation and energy consumption. However, measures to recover mercury with the help of so-called retorts have now become standard. Although most mines are not open to outsiders, in a comprehensive survey we determined mercury use in 47 sites. Our survey shows that 1.7 kg of mercury are used per kg of gold extracted, whereas with the use of retorts only about 0.19 kg of mercury are lost. Nevertheless, this means an annual release of at least ≈2.5 tonnes of mercury for the region. ASGM also contributes to climate change through energy consumption. ASGM releases about 16,000 kg of CO2 equivalent per kg of gold. ASGM is thus in a similar range as industrial gold mining but performs significantly worse than recycling gold.