TOMSK, March 27. /TASS/. Scientists say that methane emissions in the Laptev Sea in the Arctic continue for 5,000 years. The gas migrates into the atmosphere and affects global warming, Russia's Ministry of Education and Science told TASS.
"Scientists of the Tomsk Polytechnic University together with other experts have studied sedimentary minerals, authigenic carbonates, formed in various methane deposits on the Laptev Sea's shelf and continental slope. The obtained data helped the scientists to determine the duration of methane emissions in the Arctic, which affect global warming," the ministry said.
Marine sediments and underlying rocks contain methane, and it can migrate through faults, cracks and pore spaces and may exit into the water column, and further on into the atmosphere, creating methane seeps (areas where gas seeps to the surface). Such phenomena occur in different regions of the World Ocean, like for example, in the Arctic Ocean. In places where methane appears, microbes oxidize the gas, and this process results in formation of carbonate minerals. They remain in sediments even after methane emissions stop.
According to Alexey Ruban, associate professor at the Engineering School of Natural Resources' Geology Department, scientists have found most carbonates in the Barents Sea, the Laptev Sea and the Chukchi Sea. They studied samples from three sections of the Laptev Sea, two of which are located on the outer relief (sea depths of 64 and 72 meters), and one - on the continental slope (at a depth of 294 meters). This research is important for the Laptev Sea with its complex geology, high seismicity, the recent shelf flooding, and a variety of gas release conditions.
"The obtained age of studied samples suggests that the methane discharge in the Laptev Sea continues at least for about 5,000 years. Moreover, our results indicate recurring episodes of carbonate formation, which may reflect the intermittent or pulsating nature of methane intake. On the outer shelf, such episodes date back about 5,000 and 2,600 years, whereas on the continental slope they appeared about 2,700 and 2,100 years ago. Emissions of methane-containing fluids in various parts of the Laptev Sea could be caused by several, partially interrelated, factors, including tectonic fault activity, degradation of underwater permafrost and seismic events," the scientist said.
The study involved specialists of the University's Engineering School of Natural Resources' Geology Department, as well as experts of the St. Petersburg State University and of the Ilyichev Pacific Oceanology Institute of the Far Eastern Branch of the Russian Academy of Sciences. Results are published in the Marine Geoscience and Energy Resources journal. The project was supported by a grant from the Russian Science Foundation.