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The rupture of the Fundão dam in Brazil released tons of mining tailings into the Doce River Basin (DRB). This investigation aimed to determine the bioaccumulation of metals in soft tissues of the bivalve Corbicula fluminea exposed to sediments collected in the DRB in four periods (just after, 1, 3, and 3.5 years after the dam rupture). In the exposure bioassays, the concentrations of Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in sediments and bivalve soft tissues were quantified. The concentration of some elements (As, Cd, Mn, and Al) in sediments exceeded the federal limits or regional backgrounds at some sampling sites, but their concentrations tended to decrease over time. However, higher concentrations of many elements were detected in the winter of 2019. Several elements were detected in C. fluminea soft tissues, but the bioaccumulation factors were generally low or not related to those elements associated with the ore tailings, evidencing that the bioavailability of metals to bivalves, in laboratory conditions, was limited. Integr Environ Assess Manag 2024;20:87–98. © 2023 SETAC Key Points: The bivalve Corbicula fluminea exposed to sediments collected in the Rio Doce after the Fundão dam failure generally showed low bioaccumulation of metals, as evidenced by the low bioaccumulation factors; some bioaccumulated elements, such as Cu, were not related to the ore tailings.The concentrations of metals and As were high after the dam rupture, and the levels of As, Cd, Mn, and Al in sediments exceeded the federal limits or regional backgrounds at some sampling sites, but their levels tended to decrease over time.The concentrations of metals and As in soft tissues of C. fluminea did not correlate with the respective levels in the sediments, suggesting limited bioavailability of metals or the organisms' ability to cope with metals and metalloids. [ABSTRACT FROM AUTHOR]

Specialized acidophilic bacteria and archaea are able to extract valuable metals such as copper, gold, cobalt, nickel, zinc, and uranium from sulfide ores. This process is known as bioleaching and its application in the mining industry as biomining. Laboratory studies also demonstrated bioleaching of oxide ores such as laterites and of mining residues such as mine tailings as well as metal recycling from waste (secondary mining). Metals being leached have to be recovered from acidic polymetallic solutions (mine and process waters) which is possible via biosorption or biomineralisation. [ABSTRACT FROM AUTHOR]

The carbonation of chrysotile and nickel mining residues was studied under ambient laboratory conditions to assess their response under various potential field conditions (pore saturation, watering episodes, temperature, CO2 diffusion, and dissolved oxygen) and to a variety of natural and chemical enhancers (sulfide minerals, brucite, chelate ligands, ionic liquids, and carbonic anhydrase enzyme). Watering of the residues to achieve partial pore saturation was critical for optimal ambient CO2 sequestration by mediating magnesium leaching and CO2 absorption, and by favouring diffusion of gaseous CO2 in pores deep inside the residues. Increasing temperature stimulated CO2 uptake whereas dissolved oxygen triggered undesirable oxidative precipitation and passivation by iron (III) hydroxides. The latter effect was attenuated through addition of depassivation chelates, which impeded iron precipitation and enhanced carbonation under ambient conditions. Pyrite and pyrrhotite, as natural acid generators, failed to improve ambient carbonation by fostering iron passivation to the detriment of mining residue dissolution whereas the use of carbonic anhydrase inhibited formation of magnesium carbonates. Ionic liquids were found suitable for magnesium extraction under alkaline conditions but inefficient for inducing carbonate precipitation. The lower rate of carbonation with hydrophobic ionic liquid-water mixtures was ascribed to a slower gas-liquid mass transfer of CO2 to the liquid, which primarily prompted a loss of gas-liquid interfacial area due to viscous effects and bubble coalescence. [ABSTRACT FROM AUTHOR]