The environmental impacts of one of the largest tailing dam failures worldwide

TLDR

Heavy rain episodes will likely cause enhanced erosion, remobilization, and transport of contaminated particles, sustaining high inputs of suspended particulate matter and metals for years to come and threatening ecosystem services. The study assessed the impacts of the SAMARCO iron tailing spill along more than 650 km of the Doce River by determining toxic metal concentrations. Analysis of the spill revealed elevated suspended sediment loads (up to 33 000 mg L⁻¹) and widespread deposition along the Doce basin, with high transport of dissolved Fe, Ba, and Al, extreme enrichment of Hg, Co, Fe, Ni, and other metals in sediments, and concentrations of iron, arsenic, mercury, and manganese exceeding quality guidelines, indicating a high likelihood of adverse ecological effects from the dam failure and associated mining activities.

Abstract

The impacts of the SAMARCO iron tailing spill along more than 650 km, between the dam and the plume of the Doce River in the Atlantic, were assessed by the determination of toxic metals. The tailing spill caused a substantial increase in suspended sediment loads (up to 33,000 mg L-1), in addition to large depositions of waste along the Doce basin. The highest estimated transport of dissolved metals was observed for Fe (58.8 μg s-1), Ba (37.9 μg s-1) and Al (25.0 μg s-1). Sediments reached the highest enrichment factors (EFs) for Hg (4,234), Co (133), Fe (43), and Ni (16), whereas As (55), Ba (64), Cr (16), Cu (17), Mn (41), Pb (38) and Zn (82) highest EFs were observed for suspended particulate matter (SPM). Iron, As, Hg, Mn exceeded sediment quality guidelines. Therefore, the risk of occurrence of adverse effects is highly possible, not only due to the dam failure, but also due to the Fe mining and the artisan Au mining. Heavy rain episodes will likely cause enhanced erosion, remobilization, and transport of contaminated particles, sustaining high inputs of SPM and metals for the years to come and threatening the ecosystem services.