Due to increases in gold prices, illegal small-scale mining have intensified in the Brazilian Amazon in the last few years. With significant environmental and health impacts associated with mining, the socio-economic repercussions are complex and thus difficult to assess.
In this study, researchers present a framework for assessing the costs associated with impacts of small-scale gold mining. They created a value transfer formula based on the extent of mining activities and impacts from deforestation, erosion and mercury contamination, and presented a case study applying the framework to mining activities in the Tapajós Basin in the Brazilian Amazon.
First, they estimated the productivity of the mines to derive the total area of impact. From this they assessed the impacts of deforestation both in terms of restoration costs and value of ecosystem services including forest products, climate regulation and species richness. To quantify the latter, the authors used GBIF-mediated occurrences of plants, mammals, reptiles and birds in the municipal of each mining site. They finally considered costs associated with land degradation and mercury contamination.
In non-monetary values, mining activities in the Tapajós Basin impacted more than 4,500 hectares in order to produce ~7,800 kg of gold, requiring 20 kg of pure mercury for the extraction. They estimated that 370,000 people were at risk for mercury ingestion, resulting in 700 heart attacks and 32 children born with intellectual disability every year.
For the year 2020, the total socioeconomic costs of illegal gold mining in the region was USD 1 billion, equivalent to USD 136,000 per kilo of extracted gold. With an average gold price of USD 56,800 per kg, the societal costs are more than double the benefits illegal miners may derive from its extraction.