Talvivaara’s mine in Sotkamo, Northern Finland, has had a devastating impact on the ecology of nearby lakes.
The Environmental Change Research Unit (ECRU) of the University of Helsinki has reported that emissions from the zinc and nickel mine have transformed the lakes completely into stratified pools of salt water with all but lifeless bottoms.
ECRU drew its conclusions based on an examination of sediment samples collected from the bottom of Lake Kivijärvi, one of the two lakes used by the mining company to discharge waste water from the mine area. The water column of the lake has been affected by a number of sewage leaks and discharge from the mine since 2008.
“The diversity of species has collapsed and the algal populations characteristic of forest lakes have been replaced with species that thrive in brackish water,” says Jan Weckström, one member of the research group at ECRU.
ECRU also reports that the crustacean species found in the lake have also changed dramatically due the sewage leaks and discharges. The heavy metals and other pollutants contained in the sewage water have affected the diet of the species.
Talvivaara released unprocessed waste waters into the surrounding waterways several times – both on purpose and out of necessity – since 2008. The most damaging leak occurred in 2012, when roughly 1.2 million cubic metres of water with high salt and metal concentrations was released from a pond used to store water at the mine. Roughly 240,000 cubit metres of the water ended up outside the mine area.
ECRU believes its findings to be important because they suggest salinisation may be the single greatest threat to waterways surrounding metal mines.
“Acid mine drainage has traditionally been considered one of the most serious unsolved environmental problems associated with mines, but one should also pay close attention to the ecological problems of salinisation,” states Atte Korhola, the professor in charge of the research group.
The Finnish government established a special-purpose company to take over the mining operation from Talvivaara in 2015. The special-purpose company, Terrafame, is currently discharging its processed waste water into Lake Nuasjärvi.
Terrafame has estimated that the environmental risks associated with the mining operation have decreased and asked that its annual sulfate discharge quota be raised to 20,000 tonnes.
Veli-Matti Hilla, the head of sustainable development at Terrafame, told Helsingin Sanomat that the stratification and the consequent lack of oxygen in the basins of the lake has been caused by the operations of Talvivaara.
He also estimated that the stratification is unlikely to occur in Lake Nuasjärvi.
Aleksi Teivainen – HT
Photo: Kimmo Rauatmaa – Lehtikuva