Time-sequence development of metal(loid)s following the 2015 dam failure in the Doce river estuary, Brazil

In the context of the Doce river (Southeast Brazil) Fundao dam disaster in 2015, we monitored the changes in concentrations of metal(loid)s in water and sediment and their particulate and dissolved partitioning over time. Samples were collected before, during, and after the mine tailings arrival to the Doce river estuary (pre-impact: 12, 10, 3 and 1 day; acute stage: tailing day - TD and 1 day after - DA; chronic stage: 3 months and 1 year post-disaster). Our results show that metal(loid) concentrations significantly increased with time after the disaster and changed their chemical partitioning in the water. 35.2 mg Fe L-1 and 14.4 mg Al L-1 were observed in the total (unfiltered) water during the acute stage, while aqueous Al, As, Cd, Cr, Cu. Fe, Mn, Ni, Pb, Se and Zn concentrations all exceeded both Brazilian and international sale levels for water quality. The Al, Fe and Pb partitioning coefficient log (K-d) decrease in the acute stage could be related to the high colloid content in the tailings. We continued to observe high concentrations for Al, Ba, Cd, Cr, Cu, Fe, V and Zn mainly in the particulate fraction during the chronic stage. Furthermore, the Doce river estuary had been previously contaminated by As, Ba, Cr, Cu, Mn, Ni and Pb. with a further increase in sediment through the tailing release (e.g. 9-fold increase for Cr, from 3.61 +/- 2.19 mu g g(-1) in the pre-impact to 32.16 +/- 20.94 mu g.g(-1) in the chronic stage). Doce river sediments and original tailing samples were similar in metal(loid) composition for Al, As, Cd, Cr, Cu, Fe, V and Zn. As a result, these elements could be used as geochemical markers of the Fundao tailings and considering other key parameters to define a baseline for monitoring the impacts of this environmental disaster. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study monitored changes in metal(loid) concentrations in water and sediment after the Fundao dam disaster in Brazil. Results showed significant increases in metal(loid) concentrations over time, with alterations in their chemical partitioning in water. High concentrations of various metals were observed both in water and sediment, indicating the ongoing impact of the disaster on the environment.