Three underwater robots monitor Nord Stream’s environmental impact

Three underwater robots in the Baltic waters around the leaks on the Nord Stream gas pipelines have been deployed to follow how chemistry and life in the sea changes over time due to the large release of methane gas, according to a statement by the University of Gothenburg published on Friday.

Between 56,000 and 155,000 tonnes of methane were released into the atmosphere as a result of the Nord Stream break, making it one of the highest methane emissions ever measured from a single site, reported NewScientist.

Recording water data

The robots are being monitored through research vessel Skagerak and are created with the help of the Voice of the Ocean foundation (VOTO). The devices are remote-controlled and are set to move around the sea and record water data continuously for the next 15 weeks.

“They are called gliders and are provided by VOTO, who also manages their operation. 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.

The robots are not entirely new. Two of them have been around since March 2021 to measure the water quality non-stop. The robots go down to the bottom and then turn up to the surface where they send the latest measurements to researchers via satellite.

In addition, one of the three additional robots that was dropped into the sea last week has been equipped with a special sensor to be able to measure the change in the methane content over the next 15 weeks.

“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,” added 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.”

How the water is affected by the leak

Researchers collect important data from the underwater robots that are usually deployed to measure salinity, temperature, oxygen content and the amount of chlorophyll. This information completes the picture of how the water in the Baltic Sea is doing after the gas leak.

“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,” concluded Queste.

Last week, the US Navy said it would process sonar signatures provided by Sweden and Denmark to try and figure out what happened in the Nord Stream attack. This process may lead to an understanding of what was in the area at the time of the pipelines’ suspected sabotage and therefore what caused it.