Could Large-Scale Oxygen Pumps Fix the Baltic Sea's Dead Zones?

denmark and baltic sea

Image from NASA

It seemed like just yesterday geo-engineering was one of those taboo subjects you couldn't touch with a ten foot pole. Now, though still far from being widely embraced, it has been recognized by many governments and reputable research institutions as a potential last ditch alternative to conventional climate mitigation strategies. One consequence has been that more and more scientists have been turning to these highly unconventional methods as a way to address other seemingly intractable problems, like dead zones.

baltic sea

Image from elsamuko

A team of researchers at the University of Gothenburg, for example, is considering a proposal to install hundreds—if not thousands—of pumps in the Baltic Sea (dubbed the world's "most damaged sea" in a recent WWF report) that would pipe in oxygen-rich water at depth. The hope is that they would eliminate the massive dead zones that have been plaguing the region for years. (Seven of the world's ten largest dead zones are found in the Baltic Sea.)

The pilot project, called "Box," and funded by the Swedish Research Council Formas and the Swedish National Environmental Protection Agency (to the tune of SEK 20 million, or about $2.6 million), will begin operating within the coming months.

Though the Baltic Sea is typically characterized by large summer algal blooms—the result of high phosphate levels (which fuel eutrophication)—the scientists noticed a lull during the 1990s that coincided with a marked decline in its phosphorus content; the cause, they believe, was a more pronounced thermocline that increased the Baltic's oxygen content down to a depth of 120 meters.

Might it be possible then, they mused, to relieve the Baltic's eutrophication symptoms (so-called because of its extremely low oxygen content) by pumping in a steady supply of cold, oxygen-rich water? Mixing oxygen-rich bodies of water at depth could help keep the water column well-aerated, which, in turn, would prevent the formation of its dead zone. The pilot project's main objective will be to see whether it is possible to keep the Baltic in a high oxygen state—something that, given all the other factors at play (current movement, basin dynamics, marine life, etc), could prove extremely tricky.

This is how Anders Stigebrandt, a professor of earth sciences at the University of Gothenburg and Box's director, described it:

We are going to investigate how you succeed in retaining the phosphorus in the bottom sediment under different external circumstances, with and without artificial oxygenation, in two coastal basins. Among other things we will be using the prototype of a wind-driven pump, but we will also investigate how a full-scale pump system in the Baltic proper might be designed.

Via ScienceDaily
More about dead zones and the Baltic Sea
Lithuanian Man to Swim Across Baltic Sea for the Environment
Ocean "Dead Zones" Increasing: 400 Oxygen-Deprived Areas Now Exist

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