The explosion that blasted a hole in the underwater Nord Stream gas pipeline sprang up long-buried toxins at levels sufficient to threaten marine life for more than a month, site analysis suggests. .
Last September, a series of four explosions ruptured the Nord Stream 1 and 2 gas pipelines that run from Russia to Germany near the Danish island of Bornholm in the Baltic Sea, releasing more than 100,000 tons of methane into the ocean. and released into the atmosphere. It’s not clear who was behind the explosion, but recent speculation puts a pro-Ukrainian group responsible.
Beneath a dramatic spectacle of bubbles erupting from the sea, the explosion threw sediment from the seafloor and returned it to the water column. Given that the explosion occurred near a historic chemical warfare dump site, we were concerned that the consequences could not be overlooked. Second World War. They set out to find out how these chemicals affect marine life.
blast impact
The researchers used decades of monitoring data of sediments in the Bornholm Basin’s active shipping area and hydrological models of sediment transport to calculate the effects of the explosion. The power of each blast is estimated to be equivalent to the blast. 500 kilograms of TNT. Their model showed that an explosion occurring at a depth of about 70 meters ejected a total of 250,000 tons of sediment reaching 30 meters below sea level. Sanderson and his colleagues looked at known concentrations of various contaminants in the sediment, including the biocide tributyltin (TBT), heavy metals and chemical warfare agents, to see what was stirring. .
They calculated how much of each contaminant would become bioavailable and calculated the toxicity threshold for the sediments. Resuspension of more than 5.8 milligrams of sediment per liter of seawater was predicted to be harmful to marine life. The team found that contaminants in the sediment, such as lead and TBT (an endocrine disruptor used to protect the hull), accounted for most of the toxicity. Only lead and TBT were responsible for 75% of the toxicity.
The sediment hoisted up by the Node Stream 1 explosion contained pollutants above the safe level threshold for 15 days at depths between 95 and 53 meters. For the Nord Stream 2 pipeline, the threshold was exceeded for 34 days at water depths of 78-42 meters. In total, the blast contaminated 11 cubic kilometers of seawater for over a month.This work, which is under peer review in a journal, has been published as a preprint.1.
“impressive modeling”
“This is an impressive modeling effort,” says Rodney Forster, a marine scientist at the University of Hull, UK. Also, the team’s calculations for the dispersion of the sediment plume clearly show that the sediment never reached the surface. “That explains why, aside from the bubble plume, we don’t see any visible suspended sediment plumes in post-event satellite imagery,” Forster adds.
The effects of pollutants on marine life will not be apparent for months, if not years. But Sanderson is concerned about some of the animals in the area. Of the contaminated sediments, he said that “the presence of high concentrations over extended periods of time over large areas could have a very large impact” on cod stocks. It’s not good news for us,” he says. A gust of wind occurs at the end of the cod spawning season, and the eggs float to the depths reached by the agitated sediment. Sanderson speculates that the physical weight of sediments could be another problem for eggs.
Other animals that could be affected include porpoises, which are estimated to number only 500 left in the Baltic Sea. Losing even one affects this population. The blast may have deafened the porpoise’s hearing, impairing its ability to communicate.
According to Sanderson, the team’s research shows that sediment content needs to be addressed, along with any activity that stirs up the seafloor, such as installing pipelines and wind turbines and fishing. “There are also environmental impacts of conflict, which also need to be clarified,” he adds.
