Graduate Program in Environmental Engineering, Federal University of Ouro Preto, Campus Universitário Morro do Cruzeiro, s/n, Ouro Preto, MG, 35400-000, Brazil.
Department of Geological Engineering, Escola de Minas, Federal University of Ouro Preto, Campus Universitário Morro do Cruzeiro, s/n, Ouro Preto, MG, 35400-000, Brazil.
Environ Sci Pollut Res Int. 2020 Feb;27(4):4365-4375. doi: 10.1007/s11356-019-07119-1. Epub 2019 Dec 12.
The rupture of the Fundão dam released about 39 million m of tailings into the Rio Doce/Brazil. The sediment load increase in the affected rivers has become a concern. As such, this article provides recent information about the region. In addition, based on past studies in the region, it shows the magnitude and dynamics of the environmental impacts caused by the rupture of the dam on the bottom sediments. Sediment samples in different seasonal periods were collected at eleven sampling stations located along the Gualaxo do Norte River, the first tributary of the Rio Doce affected by the environmental disaster. These sediments underwent physical, chemical, and granulometric analyses for their organic, metal, and semimetal content. The contamination factor and the enrichment factor of the samples also were calculated. To evaluate the anthropogenic contributions to sediment metal concentrations, reference values (regional background values) for the Gualaxo do Norte River were used. The results indicate that, in the sampling stations not affected by the disaster, the concentrations of the metals and semimetals reflect the geology of the Quadrilátero Ferrífero. However, in the area affected by the environmental disaster, there were changes in the chemical and physical properties of the bottom sediment, mainly in the concentrations of iron, organic matter, and fine sediment fractions. This was reflected in the contamination factors and enrichment factors calculated for the sediments of the sampling stations. Iron and manganese concentrations in sediments are much higher than other rivers in the world that are unaffected by mining activities. The observed changes in the bottom sediments of the river suggest a need for constant monitoring of the iron because the iron oxide minerals present in silt and clay have a high adsorption capacity. In the long term, these factors may contribute to the decrease of the quality of these sediments and consequently of the waters and biota present in these environments.
丰当大坝的溃坝将约 3900 万立方米的尾矿排入了巴西的里约杜塞（Rio Doce）。受影响河流的泥沙负荷增加已成为一个关注点。因此，本文提供了该地区的最新信息。此外，根据该地区过去的研究，本文展示了大坝溃坝对底泥造成的环境影响的规模和动态。在不同的季节，在受环境灾难影响的里奥杜塞的第一条支流瓜拉苏斯-多斯北河（Gualaxo do Norte River）的 11 个采样站收集了沉积物样本。这些沉积物经历了物理、化学和粒度分析，以确定其有机、金属和类金属含量。还计算了样品的污染因子和富集因子。为了评估人为因素对沉积物金属浓度的贡献，使用了瓜拉苏斯-多斯北河的参考值（区域背景值）。结果表明，在未受灾难影响的采样站，金属和类金属的浓度反映了四边形铁矿区的地质情况。然而，在受环境灾难影响的地区，底泥的化学和物理性质发生了变化，主要是铁、有机物和细颗粒沉积物分数的浓度发生了变化。这反映在计算得出的采样站沉积物的污染因子和富集因子中。沉积物中的铁和锰浓度远高于世界上其他不受采矿活动影响的河流。河流底泥的这些变化表明，需要对铁进行持续监测，因为淤泥和粘土中的氧化铁矿物具有很强的吸附能力。从长远来看，这些因素可能会导致这些沉积物的质量下降，从而影响这些环境中的水和生物。
