23/11/2015
Brazil dam toxic mud reaches Atlantic via Rio Doce estuary
A wave of toxic mud travelling down the Rio Doce river in Brazil from a collapsed dam has reached the Atlantic Ocean, amid concerns it will cause severe pollution.
The waste has travelled more than 500km (310 miles) since the dam at an iron mine collapsed two weeks ago.
Samarco, the mine owner, has tried to protect plants and animals by building barriers along the banks of the river.
Workers have dredged the river mouth to help the mud flow out to sea fast.
The contaminated mud, tested by the
water management authorities, was found to contain toxic substances like
mercury, arsenic, chromium and manganese at levels exceeding human
consumption levels.
Samarco has insisted the sludge is harmless.
In an interview with the BBC, Andres
Ruchi, director of the Marine Biology school in Santa Cruz in Espirito
Santo state, said that mud could have a devastating impact on marine
life when it reaches the sea.
He said the area of sea near the mouth of the Rio
Doce is a feeding ground and a breeding location for many species of
marine life including the threatened leatherback turtle, dolphins and
whales.
“The flow of nutrients in the whole food
chain in a third of the south-eastern region of Brazil and half of the
Southern Atlantic will be compromised for a minimum of a 100 years,” he
said.
The magazine Chemistry World quotes Aloysio da Silva Ferrao Filho, a researcher at the respected Oswaldo Cruz Foundation, as saying that the impact has been severe in the river itself.
“The biodiversity of the river is completely lost, several species including endemic ones must be extinct.”
Samarco has erected 9km of temporary
floating barriers similar to those used at sea during oil spills in the
river to try to hold back the mud from river banks and to protect flora
and fauna from the mud.
One concern is that because the mud is high in iron ore and silica it will set hard as concrete when it dries out.
At the mouth of the river, the company has been using heavy equipment to remove sand banks and dredge so that the mud, when it reaches the sea, can flow out as fast as possible and be diluted quickly.
It is the fish and turtle breeding
season at this time of year. Local people have been helping get fish
into tanks and have been collecting turtle eggs to incubate.
In the meantime, Samarco says it is
doing repairs on two other dams it uses to hold waste water which is
says are at risk of collapsing.
Eleven people were killed and 12 are missing – presumed dead – in the disaster.
Samarco is owned by mining giants, Vale, from Brazil, and the Anglo-Australian company, BHP Billiton.
It has agreed to pay the Brazilian government 1bn (£170m; $260m) compensation.
The money will be used to cover the initial clean-up and to offer compensation to families.
(Via BBC)
Nenhum comentário:
Postar um comentário