Environmental and human health risk of potentially toxic elements in residues from artisanal cassiterite and monazite mining areas in the Amazon
Rare earth elements, chemical properties, bioavailability, metals and metalloids, pollution indice
The mineral exploration is essential for global economic development. In the Amazon region, artisanal mining predominates and is carried out on a large scale, with little concern for environmental impacts and human health. This is mainly due to the release of significant amounts of potentially toxic elements (PTEs) (represented here by metals and metalloids) and rare earth elements (REEs). In Chapter 1, the objectives were to quantify the concentrations of Rare Earth Elements (REEs) and estimate environmental and human health risks in artisanal mining areas of cassiterite and monazite in the Amazon region, as well as to understand the dynamics of this risk over time after exploitation. Environmental and human health risks were evaluated in waste materials (sterile and tailings) from three artisanal mining areas of cassiterite and monazite, considering the time of exploitation. In Chapter 2, the objective was to quantify the concentrations of PTEs and estimate environmental contamination and pollution in cassiterite artisanal mining areas in the Amazon region. Environmental and human health risk indices were estimated for PTEs with concentrations above the quality reference value for the state of Pará. The concentrations of REEs and PTEs were quantified through alkaline fusion and ICP-MS. The results were used to calculate pollution indices, environmental risk, and human health risks. The residues from monazite and cassiterite exploitation caused an increase in REE and PTE concentrations, significant enrichment, and a high contamination factor by PTEs and REEs. Waste from active and recently deactivated mines showed high ecological risk. The results indicate that artisanal mining of cassiterite and monazite has the potential for contamination and enrichment by PTEs and REEs. The considerable bioaccumulation in forage plants indicates a high potential risk in a municipality that is the largest producer of cattle in the country. From these results, we can conclude that monitoring and remediation measures should be taken by state environmental authorities.