Chemicals from mine contaminate lake
“Sea conditions” in inland lake
The fog clears on Salminen, a wilderness lake near the Talvivaara nickel mine in the eastern community of Sotkamo. The picturesque landscape could be straight out of a nature book, but the smell on the shore suggests that the lake is not in good shape.
“It smells here as if someone had soiled himself”, says Leo Schroderus, chairman of the Jormaskylä-Korholanmäki cooperative as he looks at the lake, which covers an area of seven hectares.
Waste water from Talvivaara has brought so much sodium sulphate into the lake that the water in the lake has turned into brine. The sulphate has also reduced the oxygen content of the water, adding to the foul odour.
“Heavier, salty water has settled at the bottom of the lake, and normal mixing of the water does not take place”, says environmental geologist Ilkka Haataja of the Kainuu Centre for Economic Development and the Environment.
Normally, water at the bottom of a lake rises to the surface, and oxygen-rich water sinks to the bottom in the spring. In Salminen, and in the Baltic Sea, there is an invisible thermocline layer between the layers of water and the inversion does not take place, leading to a shortage of oxygen at the bottom.
The Talvivaara Mining Company is looking into the feasibility of pumping out the contaminated and oxygen-free water from the bottom.
“The company has made analyses at the lake. According to model calculations there are 24,000 cubic metres of salty water, which is about ten per cent of the entire water mass in the lake”, Ilkka Haataja says.
“The water could be pumped back to the mine area, but no decisions have been made, as studies are still under way”, says Talvivaara’s environment director Veli-Matti Hilla.
“This is the first time in Finland that someone has managed to create sea conditions in an inland lake”, says special researcher Jouni Lehtoranta of the Marine Research Centre of the Finnish Environment Institute. He feels that the existence of a miniature Baltic Sea is actually interesting from the point of view of marine research.
Lehtoranta says that an oxygen-free, dense layer of salt water will gradually change the flora and fauna of the wilderness lake.
“A large amount of sulphate must have entered the lake, as it has become so salty that a thermocline layer has formed”, Lehtoranta says.
Sodium sulphate gets into the waste water when lye is used to neutralise the smell of hydrogen sulphide at the mine.
The company has permission to dump treated waste water into the lake.
From Salminen, the water flows via the lakes Kivijärvi and Kalliojärvi toward the Oulujärvi waterway.
Emissions from Talvivaara can also be felt in waters in North Savo.
Waste water from the mine may also have affected ground water in villages near the Talvivaara mine.
“In the summer the water in the well of our home became cloudy. The water has always had much iron in it, and it has been cleaned with ozone, but now manganese has also been detected in the well water. The water is not recommended for use in the home”, says Maija-Leena Pirhonen, whose summer home is five kilometres from the mine.
Pirhonen says that the problem has also been noted in other wells in the area.
Finnish Environment Institute (SYKE)