The scientific expedition to the Nord Stream leak from the University of Gothenburg has arrived back home. The researchers discovered that the methane levels near the leak were about 1,000 times higher than normal, but it’s too early to draw any conclusions from that discovery. The researchers have brought back heaps of samples to analyse.

After five days at sea, the research vessel Skagerak is back home in Gothenburg. The hastily organised expedition to the Nord Stream leaks in the Baltic Sea is over.

Nord Stream is a pair of offshore natural gas pipelines in Europe that runs under the Baltic Sea from Russia to Germany. It comprises the Nord Stream 1 (NS1) pipeline running from Vyborg in northwestern Russia, near Finland, and the Nord Stream 2 (NS2) pipeline running from Ust-Luga in northwestern Russia near Estonia. Both pipelines run to Lubmin in the northeastern German state of Mecklenburg-Vorpommern. Each pipeline comprises two pipes, denoted A and B, each of the four pipes being approximately 1,200 kilometres (750 mi) long and with approximate diameters of 1,220 millimetres (48 in). The combined capacity of the four pipes is 110 million cubic metres per annum (3.9 billion cubic feet per annum) of natural gas

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

“Given the reports of explosions and the statistical unlikelihood of three accidents occurring on the same day, sabotage seems certain.” Sergey Vakulenko Shock and Awe: Who Attacked the Nord Stream Pipelines?

Katarina Abrahamsson, marine chemist at the University of Gothenburg, and coordinator for the expedition, explained:

“In order to map the spread of the methane in the water, we had 20 different measurement locations at intervals of approximately 9–18 kilometres. At our assistance, we had researchers and equipment from the Alfred Wegener Institute in Germany. They have the knowledge to separate the pipeline methane from what occurs naturally.

“In the water samples, we could see that the methane levels were up to 1,000 times higher than normal. Also, the distribution pattern of the methane from the leak was complicated and difficult to explain. A reason for this could be that we couldn’t measure the entire discharge, because the vessel was only permitted to go in Swedish waters. We simply didn’t have time to seek permission from Denmark.” 

Methane gas is dissolved in water, but when it reaches the surface, it transforms back to gas form and is emitted into the atmosphere. For how long the elevated levels of methane remain in the Baltic Sea depends on the currents, and when the leakage stops. It is unclear what kind of effect these high methane levels could have on marine life. For example, there are bacteria in the water that can oxidize methane gas to grow and multiply.

The water samples and measurements will now be analysed which is a considerable amount of work.

Nord Stream issued a Press Release : “The pressure in both lines of the Nord Stream 1 gas pipeline stabilised as of Monday, October 3, 2022. Nord Stream AG is unable to inspect the damaged sections of the gas pipeline due to the lack of earlier requested necessary permits.

“In particular, according to the Swedish authorities, a ban on shipping, anchoring, diving, using of underwater vehicles, geophysical mapping, etc. has been introduced to conduct a state investigation around the damage sites in the Baltic Sea.

“According to information received from the Danish authorities, the processing time of the Nord Stream AG request for the survey may take more than 20 working days.

“Nord Stream AG remains in close contact with relevant authorities.

“Moreover, the owner of the appropriately equipped survey vessel chartered by Nord Stream AG still doesn’t have “green light from Norwegian Ministry of Foreign Affairs” to depart.”