Assessment of Groundwater Quality in Artisanal and Small-Scale Gold Mining (ASGM) Communities in Quimistán, Santa Bárbara-Honduras

Resumen

Artisanal and Small-Scale Gold Mining (ASGM) in Quimistán, Santa Bárbara, takes place within a geological setting dominated by metamorphic rocks associated with auriferous hydrothermal systems that naturally contain potentially toxic elements, such as arsenic. In this context, artisanal ore-processing practices primarily mercury amalgamation and the reprocessing of tailings through cyanide-based leaching interact with pre-existing geogenic conditions, increasing the vulnerability of the aquifers used by the communities of Santa Cruz Minas and La Mina for drinking water, productive activities, and mining operations. To establish a baseline of groundwater quality, a sampling campaign was conducted during the 2025 rainy season at 17 water supply sources. Total, free, and WAD cyanide were analyzed, along with metals, metalloids, and physicochemical parameters. The results were assessed using a Water Quality Index adapted to ASGM contexts, which revealed a heterogeneous and predominantly impaired condition of the resource: one source classified as good, eleven as fair, four as marginal, and one as poor. Arsenic concentrations exceed the maximum permissible value in several sources (0.02–2.456 mg/L), while nickel also shows exceedances at multiple sites. In addition, electrical conductivity exceeds regulatory limits in most of the evaluated sources, indicating high mineralization. Overall, the results reflect the combined influence of geogenic processes and anthropogenic pressures associated with ASGM and underscore the need for prior treatment, continuous monitoring, and preventive water resource management in territories with similar geological and mining conditions.