Institute of Geosciences, University of Campinas, PO Box 6152, 13083-970, Campinas, Sao Paulo, Brazil.
Institute of Science and Technology, São Paulo State University, Sao Jose Dos Campos, São Paulo, Brazil.
Environ Pollut. 2021 Mar 1;272:116014. doi: 10.1016/j.envpol.2020.116014. Epub 2020 Nov 9.
One of the worst socio-environmental disasters to mark the history of Brazil and the world occurred in November 2015 and involved the mining sector. The collapse of the Fundao dam released approximately 43 million m³ of iron ore tailings, which moved downstream to reach the Doce River. This resulted in the contamination of water, soil, and sediments along the entire course of the river, which also affected its mouth in the Atlantic Ocean. Four years after the disaster, several socio-environmental problems continue to persist in the affected areas. In this context, the reservoirs built along the Doce River deserve special attention as they are artificial environments that are highly vulnerable to changes in water parameters. This study aims to determine water quality indicators of these reservoirs using remote sensing data and image processing methods, including semi-analytical algorithms, to comprehend the progress of eutrophication processes. Operational land imager/Landsat-8 data (from 2013 to 2019) were used to map the suspended particulate matter (SPM), euphotic zone (Z) and chlorophyll-a (Chl-a) before and after the collapse. The results showed significant changes in SPM and Z in the reservoirs after the collapse. Non-conformity of these parameters is observed even now, and they tend to intensify during rainy periods when resuspension processes of sediments occur. Moreover, there has been an increase in the eutrophication of reservoirs as noticed by the significant increase in Chl-a after the disaster, especially in January, July, and August.
巴西乃至世界历史上最严重的社会环境灾难之一发生在 2015 年 11 月，涉及矿业部门。万德山尾矿坝的溃坝释放了约 4300 万立方米的铁矿石尾矿，这些尾矿顺流而下，到达多斯雷斯河。这导致了整条河流及其在大西洋的入海口的水、土壤和沉积物受到污染。灾难发生四年后，受影响地区仍存在着许多社会环境问题。在这种情况下，多斯雷斯河沿岸建造的水库尤其值得关注，因为它们是高度易受水参数变化影响的人工环境。本研究旨在利用遥感数据和图像处理方法（包括半分析算法）来确定这些水库的水质指标，以了解富营养化过程的进展。使用操作陆地成像仪/陆地卫星-8 数据（2013 年至 2019 年），在溃坝前后绘制悬浮颗粒物（SPM）、透光带（Z）和叶绿素-a（Chl-a）图。结果表明，溃坝后水库的 SPM 和 Z 发生了显著变化。即使现在，这些参数也存在不一致，而且在发生沉积物再悬浮过程的雨季，它们往往会加剧。此外，还观察到水库富营养化程度的增加，这是由于灾难后 Chl-a 显著增加，尤其是在 1 月、7 月和 8 月。
