Sea in bubbles. A massive methane leak near the Baltics baffled scientists

Scientists made a strange discovery during their expedition to the Landor Trench, the deepest point of the Baltic Sea. A research team discovered a large-scale leak of methane, a greenhouse gas, at a depth of about 400 meters, covering an area of ​​about 20 square kilometers, Live Science writes.

This discovery surprised the team: What was especially incredible was that greenhouse gas bubbles in this large area, the size of 400 football fields, rose higher in the water column than the researchers expected.

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According to the study’s author, Marcelo Coetzer, professor of environmental science at Linnaeus University in Sweden, he and his team were surprised to discover that the water column was “literally boiling” in an area of ​​20 square kilometers.

Note that on the shallow seafloor near the shore, methane bubbles arise from decaying organic matter, but in deeper water they tend to disperse by diffusion, meaning no bubbles form. As a result, most of the methane remains in the deepest waters of the sea, but the new leak behaves counterintuitively.

By observing this large-scale leak of greenhouse gases, scientists have concluded that there is a completely different mechanism by which methane is delivered to the bottom of the Baltic Sea, according to Coetzer. The team also says they were surprised that methane bubbles could rise so high in the water column.

Typically, methane dissolves in water as the bubbles approach the surface, causing them to shrink until they disappear completely. According to Coetzer, the maximum height scientists can expect will be no more than 50 meters above the ocean floor. But the reality turned out to be different: In the Landsort Depression, greenhouse gas bubbles reached an incredible 380 meters. In fact, they were only 20 meters short of reaching the sea surface.

The study’s authors don’t know exactly why this happens, but they suggest that a weaker microbial filter, a layer of bacteria that lives in sediments and absorbs 90% of the methane produced by decomposition, is partly responsible. Coetzer notes that, as a rule, in the ocean the thickness of this filter can reach several meters, but in the Baltic Sea it is only a few centimeters.

Another possible cause is human activities. Fertilizers used on land are thought to contribute to algal blooms when released into the sea. When they die, organic matter is added to the sediment, but methane-eating bacteria also like to eat this matter, which only increases the amount of greenhouse gases approaching the surface.

The team also notes that the methane leak could be caused by large amounts of sediment deposited there due to natural currents. But one way or another, today researchers cannot find an answer to the question of what causes such a large-scale methane leak and why gas bubbles behave so strangely.

Note that the water at the bottom of the Baltic Sea contains higher levels of methane, so gas bubbles are likely to rise higher. This may also explain why methane bubbles come so close to the sea surface.

The team is currently preparing for a second expedition to the deepest point of the Baltic Sea and hopes their results will shed light on such strange phenomena.

Previously Focus He wrote that methane not only traps heat but also creates cooling clouds.