Three underwater robots are monitoring the environmental impact of the gas leaks from the Nord Stream pipelines.

Deployed by the University of Gothenburg in Sweden, the ‘glider’ robots from the Voice of the Ocean foundation (VOTO) are helping analyse chemical changes and the effect of the leaking methane gas on marine life.

The remote-controlled underwater robots will move around the ocean and record water data continuously for the next 15 weeks, researchers said.

“The robots can give us measurements over a series of time about how the chemistry and quality of the water is affected by the natural gas leak,” said oceanographer Bastien Queste at the University of Gothenburg.

VOTO has had two gliders in the area since March 2021, functioning as ‘ocean observatories’ and constantly measuring the water quality. The robots descend to the bottom and then return to the surface, repeating that move over a pre-set distance. The latest measurement data is sent to the researchers via satellite every time the glider is at the surface.

The previous project means ‘plenty’ of data is already available from the area affected by the Nord Stream gas leaks, the researchers said. The natural gas pipelines were hit by explosions on 26 September in a suspected case of sabotage, releasing gas near the Danish island of Bornholm.

One of the three additional robots that was dropped into the sea last week has been equipped with a special sensor from manufacturer Alseamar, measuring the change in methane content.

“Last week's expedition provided valuable data and a snapshot of the state of the ocean immediately after the leakage occurred. With the new robots in place, we receive continuous reports on the state of the water near the Nord stream pipeline leaks. They are deployed solely for this purpose”, said Queste.

“The point is that we get measurements from the water over a long period of time and over a larger area. We can see how long it takes for the methane to disappear and how the aquatic environment reacts over time. The response in the sea is often delayed. It may take days or weeks before we see a change.”

The underwater robots that are usually deployed there can also contribute important data as they measure salinity, temperature, oxygen content and the amount of chlorophyll.

“Together with the new robots and the expedition's measurements, we researchers will have solid scientific documentation of the impact of the Nord Stream leak. When we add it all up, we have a good picture of both the immediate and the delayed effects. With gliders that continuously measure, we will be able to better understand the processes that were observed then”, said Queste.

The team is also planning a further trip to the Baltic Sea with the larger unmanned vessel Ran, which can measure carbon dioxide and nitrate levels in the water.

extracted from IMechE website, read more here

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