Oxygen pumps for healthier coastal waters

Tvärminne Zoological Station and the Department of Economics and Management at the University of Helsinki are participating in the Proppen project – which involves the archipelago being oxygenated with the aid of pumps.

Marko Reinikainen

The idea behind the three-year joint Nordic project, which is being coordinated in Finland by the Finnish Environment Institute, is to test whether pumping water from the surface layer can improve oxygen levels in the oxygen-deficient bottom-most layer. The pumps are used in the Stockholm archipelago and at Sandöfjärden in the Ekenäs archipelago, where the oxygen deficiency has been noticeable for over 20 years.

According to Marko Reinikainen, adjunct professor at Tvärminne Zoological Station and participant in the project, this method may be an effective way of reducing the internal burden.

“What happens in the oxygen-deficient areas is that eutrophying substances present in the sea bed, primarily phosphorus, are released. The release of phosphorus leads to the water being fertilised from within.”

In order to achieve the desired results, it is important to ensure that the pumping is not made too fast. One possible risk is hydrogen sulphide rising to the surface.

“The results from the first year show that the pumping is fulfilling its purpose. If the research model functions and is cost-effective, it may be possible in the long term to employ the pumps more widely in the Baltic.”

By visualising the project at laboratory level, Tvärminne researcher Magnus Lindström and researchers from the Finnish Environment Institute have produced a model of what happens in connection with pumping.

“We dye the water that is pumped down to the bottom-most layer, and this allows us to track how the oxygen disperses,” explains Lindström.

The pumping will continue during the early summer, and it is hoped that this will supply the sea bed with sufficient oxygen for the entire summer.

“But our biggest hope, naturally, is that the burden will be reduced in our archipelago, so that we don’t need to provide “artificial respiration” for the sea,” concludes Reinikainen.

To find out more about the Proppen project, visit »»

Text & photo: Nathalie Edman

Translation: AAC Global

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