Bioavailability assessment of metals from a nickel mining residue in the gastrointestinal tract of Oreochromis niloticus in vivo.

Mining to obtain ferronickel by the pyrometallurgical process involves a calcination stage that generates a highly metallic solid dust. This study evaluated the bioavailability of metals from calcination dust after being ingested by Oreochromis niloticus. Chemical analysis was performed on the whole body and histological analysis was performed on the gills and gastrointestinal tract of fish to evaluate potential bioaccumulation. After 96 h of exposure to the dust, gill tissue contained a small amount of particulate matter, while the gastrointestinal tract was filled with the material, generating high values of metals in the fish whole body chemical analysis. However, after 15 and 30 days in clean water, both the gills and gastrointestinal tract were nearly devoid of particles and metal concentrations in the fish whole body had largely returned to baseline levels.