Reduced river flows in Brazil, as global warming intensifies the drought there, mean more damage from a burst dam, scientists say

by Jan Rocha, Climate News Network, November 22, 2015

SÃO PAULO – Climate change has had no direct role in Brazil's worst-ever environmental disaster, but its effects could make a bad situation even worse.

Scientists believe the soil may take centuries to recover from the accident, which released millions of tons of iron ore waste into the River Doce in Brazil's southeastern state of Minas Gerais. Many plant and animal species have been wiped out locally.

Some fear that the drought that affects most of Brazil and has already reduced river volumes (which many attribute to the changing climate) could prevent the river from fully dispersing the toxic matter.

Minas Gerais means General Mines – the mountainous region was once famous for its goldmines, worked by slaves. Today most mines produce iron ore for export to China.

On November 5th, 2015, an earthen dam at the Samarco mine containing tailings (waste from the ore) collapsed, sending a tidal wave of mud and water roaring through the nearby village of Bento Rodrigues, sweeping away men, women and children. At least 11 people were killed, and 12 are still missing.

The mining company had rejected a recommendation to install a warning siren, saying it was unnecessary, because they could call or text people on their mobile phones.

Deadly tide

Over fifty million cubic meters of toxic sludge then swept down the valley and into the Rio Doce. The river, whose name means Sweet, became instead a lethal expanse of stinking orange-brown water, instantly killing every living organism in it and contaminating the water supply of a dozen towns and cities along its course, one of them with over 200,000 inhabitants (Governador Valadares).

As the sludge made its way slowly downstream, leaving behind a desolate landscape of dead fish and animals, uprooted trees, and a thick layer of solidified mud, scientists said this was Brazil’s worst-ever environmental disaster.

“The loss of habitat is enormous, and the damage to the ecosystem is irreversible,” said Marcus Vinicius Polignano, an environmental health lecturer at the Federal University of Minas Gerais.

“In addition to iron ore and other metals, the mud, which invaded houses and fields, brought sewage, pesticides and dead animals, which accelerate the production of algae and bacteria.”

So far, the government has fined Samarco, the administrator of the dam (which is joint-owned by two of the world’s mining giants, the Brazilian Vale and the Anglo-Australian BHP-Billiton), about US$60 million for environmental damage. The company has agreed to pay a further US$300m to repair damage to the ecosystem.

But the true cost of revitalizing the river and the basin's biodiversity is expected to run into billions of dollars. The company has not yet provided a complete list of the minerals in the mud, apart from iron ore and manganese.

Removal impossible

As inquiries into the cause of the dam burst continue, scientists say there could also be lead, cadmium, zinc and mercury, but nobody knows for sure. They fear Rio Doce’s low volume means a lot of the mud will end up as silt on the riverbed, instead of being carried downstream and dispersed into the ocean.

In August, river levels dropped so low that the river did not reach the sea, but ended up trickling into a sandbank; in some places, it was only 3 cm deep.

Polignano believes the quantity of tailings in the water is so great that local ecosystems will be unable to recover.

“It is irreversible. They talk of remedying the situation, but in the case of this mud in the river, it is impossible; there is no way of removing it from there.”

Marcos Freitas is from the International Virtual Institute of Global Change at COPPE, the center for engineering research at Federal University of Rio de Janeiro.

He describes the layer of mud, which covers a 30-km radius around the dam, as a sterile “floor of iron, a no man's land,” covering the fields where animals grazed and crops grew.

Biologist Andre Ruschi, director of an environmental research center in the river basin, says: “There are animal and plant species there that we can consider extinct as from today. It is the biggest environmental disaster in the history of the country.”

For the Krenak Indians, who live on the banks of the contaminated river and now have to rely on deliveries of drinking water and  food, it is much worse than that. Chief Leomir Cecilio de Souza says: “The river was everything for us, not just water, and fish, but a source of survival and culture.”

“Since the time of our ancestors, the river maintained our people. It was sacred. But now it is dead.”

As the tide of mud makes its way slowly downstream, the environmental authorities have begun urgent efforts to prevent major damage to the rich marine life at the mouth of the Rio Doce.

The Brazilian navy has joined teams of specialists from IBAMA, the government environment agency, to try to install the type of barriers used to contain oil spills in order to protect the mangrove swamps. Volunteers have been digging up hundreds of sea turtle eggs buried in the sand to move them to safe beaches and help them hatch.

Fish evacuated

The disaster has prompted desperate plans to try to save the region's biodiversity, much of it unique. Local fishermen have been scooping up fish and moving them to lakes before the toxic tide kills them.

World-famous photographer Sebastião Salgado, who was already involved in an ambitious project to restore the now deforested region he grew up in, has proposed a plan to revitalize the area.

Local authorities are talking about a special fund, with money from the mining companies. A group of scientists are raising their own funds to carry out independent studies of the situation and work out how they can restore the Rio Doce basin.

But there is concern about nearly 200 similar earthen dams holding mine waste that could also be at risk, two of them next to the dam that ruptured. NGOs and environmentalists are calling for a tightening-up of mining regulations, instead of present efforts to relax them.

For this they blame the close relationship between mining companies and politicians. Last year, the companies were reported to have spent over US$7m funding politicians’ election campaigns.

There is concern that, despite the River Doce disaster, the result of their lobbying could be a new mining code that benefits rather than regulates the sector.