High levels of methane have been found in the Nord Stream outflow area

A scientific expedition carried out by University of Gothenburghas found high levels of methane in the Nord Stream outflow area.

The team spent five days at sea on the research vessel Skagerak. Despite the hastily organized expedition, the researchers were able to detect rising levels of methane.

They found that levels near the leak were about 1,000 times higher than normal; however, it is too early to draw conclusions from the discovery.

“Everything went incredibly well, considering the short time to prepare. In less than 48 hours, we got the researchers and equipment we wanted on board,” said Katarina Abrahamsson, a marine chemist at the University of Gothenburg and coordinator of the expedition.

Methane levels spread throughout the water

The methane gas leak was discovered on September 26 and has continued to leak into the water ever since, raising methane levels. This meant it was essential for researchers to get to the area quickly so they could measure the effects of the leak. The team collected a lot of important data by taking 100-200 water samples in about 54 hours.

“To map the distribution of methane in the water, we had 20 different measurement locations at approximately nine to 18 kilometer intervals. We had researchers and equipment from the Alfred Wegener Institute in Germany to help us. They have the knowledge to separate the methane in the pipeline from what occurs naturally,” Abrahamson explained.

She continued: “In the water samples we could see that methane levels were up to 1,000 times higher than normal. Furthermore, the distribution pattern of methane from the leak was complex and difficult to explain. A reason for this may be that we could not measure the entire leak as the ship was only allowed to enter Swedish waters. We just didn’t have time to ask permission from Denmark.”

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

Could a gas leak affect biological life in the Baltic Sea?

The researchers revealed that it is not clear what kind of effect the gas may have on marine life. For example, there are bacteria in water that can oxidize methane gas, causing it to grow and multiply.

“I filtered water samples during the expedition to see if there is now growth of these types of bacteria when there are elevated levels of methane in the water,” explained Karina Bunse, a marine biologist at the University of Gothenburg.

Bunse continued, “It is autumn now and it will soon be low season for phytoplankton and zooplankton. This can affect the local food web if these methane-eating bacteria grow at the expense of other plankton species. But we cannot predict the results. Before we can draw any conclusions, we need to do DNA analyzes of the contents of the water samples.”

Now that the Skagerrak ship has returned to Gothenburg, the research team has a huge workload to take on. Before they can conclude the long-term effects of high methane levels in the Nord Stream on marine life, they must analyze and discuss the water samples and measurements.

Abrahamson concludes: “We now need to get a review of our results and then summarize them in an initial scientific paper. With any luck this could be published before the end of the year.

The team is already planning a second expedition, this time intending to explore the waters east of Bornholm.