High methane levels in the Nord Stream leak area

The scientific expedition on the Nord Stream leak from the University of Gothenburg has arrived home. The researchers found that methane levels near the leak site were about 1,000 times higher than normal, but it is too early to draw any conclusions from the discovery. The researchers brought back piles of samples for analysis.

After five days at sea, the Skagerrak research vessel returned home to Gothenburg. A hastily organized expedition to the source of the Nord Stream in the Baltic Sea is over, and the researchers are satisfied with their efforts.

“Everything went incredibly well, considering the short preparation time. In less than 48 hours, we got the right researchers and equipment on board,” says Katarina Abrahamsson, a marine chemist from the University of Gothenburg and the expedition’s coordinator.

German scientists helped

The methane leak was discovered on September 26, and methane has continued to leak into the water since then. It was critical for researchers to get to the area quickly to measure the effects of this large discharge and collect important data, Abrahamson says. In 54 hours, the expedition took 100–200 water samples.

“In order to map the distribution of methane in the water, we had 20 different measurement locations approximately 9-18 kilometers apart. We were assisted by researchers and equipment from the Alfred Wegener Institute in Germany. They have the knowledge to separate pipeline methane from what happens in nature,” says Katarina Abrahamson.

What did you see?

“In the water samples, we saw that methane levels were 1,000 times higher than normal. In addition, the distribution pattern of methane from the leak was complex and difficult to interpret. This may be because we could not measure the entire release because the vessel was only allowed to enter Swedish waters. We just didn’t have time to ask for permission in Denmark,” says Katarina Abrahamsson.

Methane gas is dissolved in water, but when it reaches the surface, it turns back into gaseous form and is released into the atmosphere. How long elevated methane levels persist in the Baltic Sea depends on currents and when the leak stops.

Unclear effect on marine flora and fauna

It is not yet clear what impact this high level of methane might have sea ​​inhabitant. For example, there are bacteria in water that can oxidize methane gas grow and multiply.

“During the expedition, I filtered water samples to see if these types of bacteria grow when methane levels are elevated in the water,” says Karina Bunze, a marine biologist at the University of Gothenburg.

Could this affect biological life in the Baltic Sea?

“It’s autumn now, and it will soon be the low season for phytoplankton and zooplankton. This can affect the food web at the local level if these methane-some bacteria grow at the expense of other species of plankton. But we cannot predict the results. Before we can draw any conclusions, we have to do a DNA analysis of the contents of the water samples,” says Karina Banze.

Skagerrak is now back in Gothenburg, and researchers have a gigantic workload ahead of them. Before anything can be said with certainty about the long-term effects of Nord Stream emissions on marine flora and fauna, water samples and measurements need to be analyzed and discussed. But researchers are already making plans for new expeditions to the waters east of Bornholm.

“Now we need to get an overview of our results and then summarize them in an original scientific paper. With luck, it can be published before the end of the year,” says Katarina Abrahamson.