Multiple sources of pollutants reaching the Doce River in southeastern Brazil basin and their impact on benthic Diptera (Chironomidae) biology.

The collapse of the Fundão Dam, in the Rio Doce Basin (DRB), released tons of metal-rich waste that spread across the basin and reached the sea. Chemicals present in tailings and other sources located along the DRB can influence benthic organisms such as Chironomidae (Diptera). This study aimed to investigate the consequences of subchronic sediment exposure (sampled in the 2019 dry season) from different segments (six sites) of the DRB on Chironomus sancticaroli larvae. Then, the survival rate, development, and intracorporeal inorganic chemical elements were evaluated. Larval survival was significantly reduced after exposure to all six sediments, ranging from 49 to 78%. The development time of larvae were significantly reduced when exposed to sediments, especially in the Upper DRB where the presence of adults was observed earlier. High levels of metals related to mining activities, such as Cd, Fe, and Mn, were detected in larvae, especially in those exposed to upper DRB sediments. Copper and zinc presented the highest biota-sediment bioaccumulation values. The results revealed the impact of complex mixtures of substances from different origins in aquatic macroinvertebrates, reinforcing the need to prevent inorganic and organic chemical elements from multiple sources from reaching rivers.