The Suspended Sediment and Metals Load from the Mariana's Tailing Dam Failure to the Coastal Sea

ABSTRACT We present an assessment on the sediment flux caused by the tailing dam failure at Mariana, Minas Gerais Estate, Brazil. Field data of water level, water flow, and suspended sediment concentrations (SSCs) were obtained during the period from 21 November to 5 December 2015, when the muddy waters reached the coast. A rating curve of the coastal tidal signal was built, allowing a robust estimate of the flow at the mouth of the Doce River. Together with SSC data, early sediment delivered to the coastal sea was of 15 × 104 t, what may account for only 0.5% of the total material remobilized at the accident site. This accounted for >25 000 t of Fe and between 1 and 4 t of other trace metals, such as Co, Ni, and Zn. Integr Environ Assess Manag 2020;16:661–668. © 2020 SETAC RESUMO É apresentada uma avaliação do fluxo de sedimentos causado pela ruptura da represa de resíduos em Mariana, MG. Dados de campo de nível da água, fluxo e concentração de sedimentos em suspensão (CSS) foram obtidos durante o período de 21‐Novembro até 5‐Dezezembro, 2015, quando as águas barrentas chegaram na costa. Uma curva chave de descarga resolvendo o nível da maré costeira foi elaborada permitindo uma estimativa robusta da descarga fluvial na desembocadura do Rio Doce. Com valores de descarga e CSS, obtivemos que a exportação inicial de sedimentos para a costa foi de 15 × 104 ton, o que contabiliza por somente 0,5% do total de material remobilizado no local do acidente. Isto contabiliza >25,000 tons de Fe e entre 1 e 4 toneladas de outros metais traço, tais como Co, Ni e Zn. Integr Environ Assess Manag 2020;16:661–668. © 2020 SETAC KEY POINTS First assessment ever made on the arrival of the slurry caused by a dam failure to the sea. Only a fraction (~0.5%) of the total material released by the dam failure was exported by the initial arrival of the slurry. The amount of Fe exported accounted for >25 000 t and between 1 and 4 t of other trace metals, such as Co, Ni, and Zn.