Eduardo CesarOne of the banks of the Gualaxo do Norte River: the brown area marks the highest point reached by the slurry from the tailings damEduardo Cesar
Researchers from the Independent Environmental Impact Analysis Group (GIAIA) did something unusual for a scientific expedition during nine days of travel to the region affected by the tailings that escaped from the Samarco dam in November 2015. From the collection points—situated from Mariana, in Minas Gerais State out to the mouth of the Doce River in Espírito Santo State—they brought back more samples of water and sediments than they could use themselves. They also gathered material for teams from the Fisheries Institute of São Paulo, the Federal University of São Carlos (UFSCar), São Paulo State University (Unesp), the University of São Paulo (USP), and the University of Brasília (UnB), parties that were interested in taking part in the analyses.
Another peculiarity of the group: “We want to release the data as quickly as possible through the website and on the group’s Facebook page,” says André Santos, a professor at UFSCar in Sorocaba. On the morning of March 31, 2016, the second day of the expedition, as he talked about the group, he was helping arrange in Styrofoam boxes the pots of water and sediment samples that had been collected at the foot of rapids on the Gualaxo do Norte River, the first river to be affected by the slurry that leaked from the reservoir. “Our Facebook followers are demanding to see the results of the analyses and the expeditions,” added biologist Flávia Bottino, also from UFSCar.
This mode of operation reflects the history of the group. In November 2015, shortly after the dam breached, Dante Pavan, business consultant and USP-trained biologist, commented on his Facebook page that the situation was “too serious for us to simply keep sharing the news.” He said he was going into the field at his own expense to record environmental impacts and asked whether anyone else was willing to go with him. An initial group was formed quickly and included Pavan, Viviane Schuch, a biologist from the Federal University of São Paulo (Unifesp), Flávia Bottino, and Alexandre Martensen, another USP-trained biologist.
In order to cover the expense of the trips made to collect materials for analysis, Pavan’s friend, architect Dino Zammataro, set up a group financing company that raised about R$90,000, almost twice the amount expected, from donations by 1,473 individuals and companies. Expenses for the trips and purchase of materials for analyses are promptly listed on the group’s website. One limitation, Pavan acknowledges, is that because the participants are volunteers, progress depends on how much free time each of them can commit to the effort.
Six months after the accident, little has changed on one of the riverbanks alongside the rapids on the Gualaxo do Norte River: the edges of a forest expose fallen or leaning trees, an indication of the force of the torrent of slurry. In the dry mud mixed with earth on the other bank, grass and beans are beginning to sprout. The seeds were planted by the mining company to restore the soil and keep the residues from re-entering the river. It was the beginning of environmental recovery efforts for the Doce River basin that Environment Minister Izabella Teixeira said in early April 2016 would probably take about 15 years.
The planting of grasses and legumes is “part of an emergency plan and implementation is being monitored by government agencies,” reported the Brazilian Institute of the Environment and Renewable Natural Resources (IBAMA) in an email. “Permanent recovery depends on more accurate diagnoses that have not yet been made, such as the depth of the tailings at each segment of the affected rivers,” the communiqué adds.
“We cannot wait for the forests alongside the rivers to re-establish themselves naturally,” comments Soraya Botelho, a professor of forest restoration at the Federal University of Lavras (UFLA) in Minas Gerais. She warned of the risk that the grasses could grow too high and slow the development of other plants that could help restore the lost forested areas on the riverbanks. She argues that it is important to identify the plant species that can grow in that kind of soil, which is very different from the natural soil.
Sergius Gandolvi, a forestry restoration laboratory researcher at USP’s Luiz de Queiroz College of Agriculture (ESALQ), suggests two additional steps. The first is to isolate the polluted segments of the rivers and remove the residues from the riverbed. These could be deposited at nearby sites and covered with native vegetation. The second step would be to carve out canals parallel to the main river in order to capture and distribute the water from rivers that have not been degraded, water that could also be used for rural irrigation.
Experts from the USP Institute for Technological Research (IPT) propose that riverbank erosion be controlled by the building of platforms, barriers, and ditches to prevent the tailings from getting back into the rivers. “Control measures could be implemented before final protection actions are taken, such as the planting of legumes,” says Omar Yazbek Bitar, a geologist from the Institute. “We need to tailor specific solutions for each section of the river.” The IPT team also suggests to the Office of the Prosecutor for the Public Interest of Minas Gerais that floating barriers be installed, using so-called geotextile blankets to keep the sediments in suspension before the water is captured and sent to the water treatment plants in different cities.
The Minas Gerais Research Foundation (FAPEMIG) and the Espírito Santo Research Foundation (FAPES) issued a R$6.6 million Request for Proposals to obtain proposals for short-term implementation of measures to promote the recovery of the soil, water, and biodiversity and identify and reduce the economic and social impacts on inhabitants of the Doce River Basin. The selected proposals should be announced shortly.
Eduardo CesarA lifeless river: the rapids on the Gualaxo RiverEduardo Cesar
After the best methods of environmental restoration have been selected, the next step is to determine who will be in charge of implementation. Target of a civil class action suit seeking R$20 billion for the environmental and social damages caused to the region, Samarco has threatened to leave the state of Minas Gerais, which is not something city officials of Mariana want to see. They resent the drop in tax revenues that resulted from suspension of the company’s operations in November 2015. Despite the disaster, the mining company enjoys quiet support among some of the population. A luncheonette in the commercial center of Mariana displays a small poster on one of the tables. It says “#Samarco Stay#. Signatures collected here.”
Acid water
The leakage of 32 million cubic meters of slurry containing tailings has exacerbated the condition of rivers that had already been degraded by the continuous discharge of sewers and mining waste, as well as the loss of forests that protected their banks. “The Doce River Basin is now the most heavily impacted in Brazil,” says Pavan, based on the field and laboratory work done by GIAIA.
On the morning of March 31, 2016, wearing rubber boots and jumpsuit, standing in yellowish water up to his knees, Márcio Vicente, a professor of biology in college-preparatory courses, collected sediments from the river bottom while Bottino, also in boots, held a multiparametric probe in the shape of a champagne bottle. A long cable stretched from the probe to the monitor held by Vinicius Rodrigues as he read the physical and chemical characteristics of the water while standing on a firm patch of the steep riverbank. Trained in environmental monitoring, Rodrigues observed that the water at that point, just below the rapids, had a pH of 5.5 and was more acid than at the first sampling point near a wooden bridge over the Gualaxo do Norte River, not polluted by the tailings.
“Because it’s acid and loaded with metals, this water can cause contact dermatitis,” says Natália Guimarães, who has a degree in pharmacy. She had gone into the field for the first time, to collect samples for her master’s degree advisor Vivian Santos, a professor at the University of Brasília (UnB) who had conducted initial analyses of the concentrations of metals. Evaluations of the samples from the first expedition indicated high levels of iron, aluminum, manganese, zinc, and arsenic, which helped make the water something to be avoided, as Guimarães had already confirmed when a colleague brushed a wet glove against her arm, causing her pale skin to become red and irritated within seconds.
Eduardo CesarBottino examines the water and Vicente collects sedimentsEduardo Cesar
The turbidity was still high: just below the rapids it varied from 490 to 500 Nephelometric Turbidity Units (NTU), much lower than the 15,000 recorded in November 2015, but still higher than the 25 NTU recorded in the clear water from the first collection point.
The excess of solid particles in the water prevents the entry of light, which is essential to the performance of photosynthesis and survival of micro and macroscopic aquatic plants. And without plants there are no animals. “For now, in the parts of the rivers closest to the dam, the ones that received the tailings, we are not seeing a single living thing,” says Luciana Menezes, a researcher from the Fisheries Institute who had examined the microorganisms from the river bottom.
The village of Bento Rodrigues, the first to be hit by the mass of slurry, indicates that it was not only the river that died. Very few walls were still standing at houses that had lost their roofs in a community where about 300 people used to live. The former village soccer field was occupied by an accumulation of tailings, surrounded by a stone dike built recently by the mining company. Technical personnel from IBAMA and the Office of the Prosecutor for the Public Interest of Minas Gerais claim that dikes like this one are not efficient in containing the excess sediment and could break apart in heavy rain.
Because reservoirs further along the Doce River in the municipalities of Rio Doce, Governador Valadares, and Aimorés, in Minas Gerais, and Baixo Guandu, in Espírito Santo were holding back the sediment, the water was gradually becoming clearer. Researchers observed the reappearance of phyto- and zooplankton and heard reports from fishermen that the fish are coming back, although they are still scarce. “Near the river mouth, the tailings moved into the alluvial floodplains and cacao plantations, spreading out more than in the mountainous areas of interior Minas Gerais State,” Pavan says. “Only the very fine orangey sediments reach the sea, where they penetrate deeply into the sand in the rivers and on the beaches.”
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