Using NdSr isotopes in suspended sediments in the Abrolhos coral-reef (SW Atlantic, Brazil) to assess potential contamination from the 2015 Fundão dam collapse.

The Abrolhos bank is home of the richest coral reef system of the Southwestern Atlantic, where endemic coral species are found. It has been reported that Abrolhos' corals are under intense stress due to increasing of Marine Heat Waves during the last decades. Additionally, anthropic interventions along the adjacent coastal regions are a factor of concern since they contribute to the increase in the sediment load and to organic debris input in the reef domain. In November 2015, the collapse of the Fundão mining tailings dam resulted in the release of approximately 50 million m3 of iron oxide and quartz-rich slurry into the Doce River. Aiming at using a fingerprint of the tailings and to assess the presence of traces of the Fundão dam material from this event on the Abrolhos bank, this work presents new 87Sr/86Sr and 143Nd/144Nd isotope ratios of marine suspended sediment samples collected between 2016 and 2020 from a network of sediment traps throughout the reef and complementary suspended material at sea. In parallel, we monitored meteo-oceanographic parameters and modeled surface marine currents as an attempt to identify the sediment transport between the Doce River mouth and Abrolhos bank. The r isotopes were used as provenance proxies based on the fact that minerals and rocks tend to have specific isotopic signatures reflecting their own geological derivation. In this context, the isotopic ratios of various potential regional sources for the sedimentation in Abrolhos bank were evaluated. Our monitoring and isotopic measurements indicate that Doce River signatures are detected at Abrolhos bank, following the seasonal Doce River discharge at sea. Isotopic signature of Doce River at Abrolhos bank was also observed during the austral winter (July-August) when cold fronts migrate at the Brazilian coast with higher frequency and energy.

Bees and the Environmental Impact of the Rupture of the Fundão Dam.

The environmental consequences associated with the Fundão tailings dam failure in Mariana, Minas Gerais, Brazil on 5 November 2015 are still being investigated. Bees are the main pollinators believed to be most affected by the accident because they occur throughout the area affected by the dam rupture and build their nests in the soil. In this study, we evaluated the richness of different bee species in areas affected and not affected by the accident and measured the concentration of different metals on the pollen basket, or corbicula, located on the hind legs of Apis mellifera. Diversity indices were similar and there was no statistical difference in the diversity of bees sampled when comparing the sites affected and not affected by the tailings mud, either before or after the dam rupture. It is possible that the similarity is due to nearby forests that may be serving as areas of refuge. The levels of Al, Cu, Cd, Hg, and Pb in A. mellifera suggest no change in the level of metals in pollen collected by the bees that can be attributed to the rupture of the dam. Integr Environ Assess Manag 2020;16:631-635. © 2020 SETAC.

As consequências ambientais da ruptura da barragem de Fundão, ocorrida em Mariana, Minas Gerais, Brasil, em 5 de novembro de 2015, ainda estão sendo investigadas. As abelhas, principal grupo de polinizadores, podem ter sido afetadas direta e indiretamente, uma vez que a maioria das espécies constrói seus ninhos no solo. Neste estudo, avaliamos a riqueza de espécies de abelhas nas áreas afetadas e não afetadas e medimos a concentração de metais pesados nas corbículas de Apis mellifera, espécie que ocorre em toda a área afetada pela ruptura da barragem. Os índices de diversidade foram semelhantes e não houve diferença estatística na diversidade de abelhas amostradas quando comparamos locais afetados e não afetados pela lama de rejeitos após o rompimento da barragem. É possível que a semelhança se deva a florestas próximas que possam estar servindo como áreas de refúgio. Os resultados mostraram a presença de Al, Cu, Cd, Hg e Pb em A. mellifera. Nossos resultados indicam que não há efeito da contaminação de metais pesados nas abelhas devido à ruptura da barragem. Integr Environ Assess Manag 2020;16:631-635.

Far-reaching cytogenotoxic effects of mine waste from the Fundão dam disaster in Brazil.

On November 2015, one of Brazil's most important watersheds was impacted by the mine waste from Fundão dam collapse in Mariana. The mine waste traveled over 600 km along the Doce River before reaching the sea, causing severe devastation along its way. Here we assessed trace element concentrations and cytogenotoxic effects of the released mine waste. Water samples were collected along the Doce River ten days after the disaster in two impacted sites and one non-impacted site. Sampling points were located hundreds of kilometers downstream of the collapsed dam. Water samples were used for trace element quantification and to run an experiment using Allium cepa to test cytogenotoxicity. We found extremely high concentrations of particulate Fe, Al, and Mn in the impacted sites. We observed cytogenotoxic effects such as alterations in mitotic and phase indexes, and enhanced frequency of chromosomal aberrations. Our results indicate interferences in the cell cycle in impacted sites located hundreds of kilometers downstream of the disaster. The environmental impacts of the dam collapse may not only be far-reaching but also very likely long-lasting, because the mine waste may persist in the Doce River sediment for decades.

Dispersal and attenuation of trace contaminants downstream of the Ajka bauxite residue (red mud) depository failure, Hungary.

This paper identifies the spatial extent of bauxite processing residue (red mud)-derived contaminants and modes of transport within the Marcal and Rába river systems after the dike failure at Ajka, western Hungary. The geochemical signature of the red mud is apparent throughout the 3076 km² Marcal system principally with elevated Al, V, As, and Mo. Elevated concentrations of Cr, Ga, and Ni are also observed within 2 km of the source areas in aqueous and particulate phases where hyperalkalinity (pH < 13.1) is apparent. Although the concentrations of some trace elements exceed aquatic life standards in waters (e.g., V, As) and fluvial sediments (As, Cr, Ni, V), the spatial extent of these is limited to the Torna Creek and part of the upper Marcal. Source samples show a bimodal particle size distribution (peaks at 0.7 and 1.3 µm) which lends the material to ready fluvial transport. Where elevated concentrations are found in fluvial sediments, sequential extraction suggests the bulk of the As, Cr, Ni, and V are associated with residual (aqua-regia/HF digest) phases and unlikely to be mobile in the environment. However, at some depositional hotspots, association of As, Cr, and V with weak acid-extractable phases is observed.