A preliminary assessment of mercury, methylmercury and other potentially toxic elements in largemouth bass (Micropterus salmoides) from the Almadén mining district

A preliminary assessment of mercury and methylmercury concentrations in largemouth bass (Micropterus salmoides) from the Almadén mining district reveals alarmingly high levels, with total mercury ranging between 0.47 and 7.61 mg/kg wet weight, and methylmercury constituting 79.7 to 92.1% of total mercury—among the highest ever recorded in this species. The study, conducted along a 34 km transect of the Valdeazogues River, found that mercury concentrations peak at a decommissioned open pit lake (El Entredicho) and decrease steadily downstream. While selenium levels are also elevated, the Se/Hg molar ratio and HBV Se index suggest low risk for most specimens, except for smaller, younger fish from highly contaminated sites. Other potentially toxic elements (As, Pb, Zn, Sb, Cu) showed no concerning values despite the area's history of polymetallic mining.

Barquero, J. I., Hidalgo, J. J., Esbrí, J. M., Higueras, P., & García-Ordiales, E. (2024). A preliminary assessment of mercury, methylmercury and other potentially toxic elements in largemouth bass (Micropterus salmoides) from the Almadén mining district. Environmental Geochemistry and Health, 47(1). https://doi.org/10.1007/s10653-024-02326-3