Chemicals used for washing oil canisters are believed to be behind the deaths of thousands of fish in Vammala in the southwest of Finland.

   

The company where the spill is believed to have originated, specialises in cleaning and repainting used oil barrels. Last week, large vessels with a volume of one cubic metre that had been used for the storage of sulphonic acid had been washed at the installation out of doors.

Large numbers of dead fish

were found in the river Sammunjoki which runs through Vammala and Huittinen. On Friday, dead fish were seen at a fish farm in Sammaljoki, a tributary of Sammunjoki. The monetary damage at the fish farm is expected to reach about FIM 150,000.

   

The owner of the fish farm, Juhani Jokela has made a criminal complaint about the foaming water to Vammala police.

   

"On Friday, experts of the Pirkanmaa Environment Institute came to take water samples. Reportedly the pH level of the water was high, but more precise results will come next week. The toxic foamy water has already gone past Vammala and it is moving downstream somewhere around Huittinen", Jokela says.

   

Jokela, who has raised fish in the river for stocking purposes for 30 years, has never experienced anything like this. The foaming water killed tens of thousands of asp less than one year old, as well as thousands of two-year-old rainbow trout. Also killed by the poisonous water were a number of large rainbow trout.

   

The damage could have been much worse, however. Jokela notes that it is fortunate that the natural food pools had already been filled with water, and the fish in those pools were not affected by the spill.

Public health officials

have been taking samples of the river water, and are warning farmers to keep domestic animals from drinking the suspect water.

   

A frothy chemical solution is a typical cause of fish deaths. It raises the pH level so high that the fish cannot get enough oxygen. A fish’s gills are very sensitive to changes in the acidity of water", says eco-toxicologist Juha Pekka Hirvi of the research laboratory of the Finnish Environment Institute.

   

In the slow-flowing river Sammunjoki, pollutants can move along the flow for long distances without being diluted by the river water to any considerable degree. Local people described the foamy water as a plug of poison that moved forward in the river.

   

Hirvi says that water contamination is mainly the result of human activity. Excessive plant growth caused by phosphorous and nitrogen compounds can lead to oxygen depletion and massive deaths of fish. The main sources of nitrogen and phosphorous are household sewage and the runoff from fields using agricultural fertilizers.

   

Environmental toxins, mainly heavy metals and organic compounds, are emitted by industry, mining, as well as runoff from landfills and household sewage. The most likely cause of the Vammala emergency was an organic cleaner.