Department of Biodiversity, Evolution and Environment, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
Integr Environ Assess Manag. 2022 Mar;18(2):528-538. doi: 10.1002/ieam.4495. Epub 2021 Aug 2.
The biggest world tailing dam rupture occurred in Brazil in 2015, releasing approximately 32 million m of iron tailings in the Doce River watershed, along its 660 km trajectory, reaching the Atlantic Ocean. This disaster significantly altered water and soil properties, increasing the soil metal contents, mainly iron concentration. Little is known about the concentration of toxic elements in plants grown in these areas. Brachiaria decumbens stands out as the most cultivated grass in the affected areas and is widely used for cattle grazing. This study verified the metal contents in soils and in samples of B. decumbens grown in the initial pathway of the debris flow. It was noted that the tailing deposition altered the substrate chemically, increasing Fe by 181% and reducing Zn soil contents by 188%. However, the metal contents in the forage grass were below the toxic limit for cattle feed. In addition, the results suggest that the natural geological characteristics of the region also influenced the metal contents in plants since those plants grown in nonaffected areas also showed high metal concentrations. The impacted area soils had a slightly basic pH, which can reduce the metal availability. Considering that, in the future, these soils would return to their natural acid state, the metal contents in plants grown in the affected regions could probably increase. Thus, long-term studies are needed to ensure the food safety of the forage production in these areas. Integr Environ Assess Manag 2022;18:528-538. © 2021 SETAC.
2015 年巴西发生了全球最大的尾矿坝溃坝事件，约 3200 万立方米的铁尾矿排入多斯雷斯流域，沿着 660 公里的河道到达大西洋。这场灾难极大地改变了水和土壤的特性，增加了土壤中的金属含量，主要是铁浓度。人们对这些地区生长的植物中有毒元素的浓度知之甚少。垂穗披碱草是受影响地区种植最广泛的草种，广泛用于放牧牛群。本研究检测了泥石流初始路径上土壤和垂穗披碱草样本中的金属含量。结果表明，尾矿沉积使基质的化学成分发生了变化，铁含量增加了 181%，锌含量减少了 188%。然而，饲料草中的金属含量低于牛饲料的毒性限值。此外，结果表明，该地区的自然地质特征也影响了植物中的金属含量，因为生长在未受影响地区的这些植物也表现出了较高的金属浓度。受影响地区的土壤呈微碱性，这可能降低了金属的有效性。考虑到这些土壤将来会恢复其自然的酸性状态，受影响地区生长的植物中的金属含量可能会增加。因此，需要进行长期研究以确保这些地区饲料生产的食品安全。《综合环境评估与管理》2022 年；18 卷：528-538 页。© 2021 SETAC。
