RIO DOCE, BRAZIL – The collapse of two dams at a Brazilian mine has cut off drinking water for quarter of a million people and saturated waterways downstream with dense orange sediment that could wreck the ecosystem for years to come.
Nine people were killed, 19 are still listed as missing and 500 people were displaced from their homes when the dams burst at an iron ore mine in southeastern Brazil on Nov. 5.
The sheer volume of water disgorged by the dams and laden with mineral waste across nearly 500 km is staggering: 60 million cubic meters, the equivalent of 25,000 Olympic swimming pools or the volume carried by about 187 oil tankers.
President Dilma Rousseff compared the damage to the 2010 oil spill by BP PLC in the Gulf of Mexico and Environment Minister Izabella Teixeira called it an “environmental catastrophe.”
Scientists say the sediment, which may contain chemicals used by the mine to reduce iron ore impurities, could alter the course of streams as they harden, reduce oxygen levels in the water and diminish the fertility of riverbanks and farmland where floodwater passed.
Samarco Mineração SA, a joint venture between mining giants Vale SA and BHP Billiton and owner of the mine, has repeatedly said the mud is not toxic.
But biologists and environmental experts disagree. Local authorities have ordered families rescued from the flood to wash thoroughly and dispose of clothes that came in contact with the mud.
“It’s already clear wildlife is being killed by this mud,” said Klemens Laschesfki, professor of geosciences at the Federal University of Minas Gerais. “To say the mud is not a health risk is overly simplistic.”
As the heavy mud hardens, Laschesfki says, it will make farming difficult. And so much silt will settle along the bottom of the Rio Doce and the tributaries that carried the mud there that the very course of watershed could change.
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