During the first stage of the ‘Trans Arctic 2019' expedition, soil vapour surveys of the Barents Sea bed sediments have been carried out, and material collected for palaeoclimatic reconstructions. This was done by Associate Professor of St Petersburg University Aleksei Krylov together with colleagues from the Scientific Research Institute for Geology and Mineral Resources of the Ocean (Federal State Budgetary Institution VNIIOKEANGEOLOGIA).

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Photo: AARI archive

In the first stage of research, the scientists look for methane whose presence in sediments might indicate fossil fuel deposits. Besides exploration of oil and gas deposits, the scientists have a more fundamental task: to study the process and mechanism of methane release into the atmosphere. ‘Methane is one of the most effective greenhouse gases. Its presence in the ocean can be as a result of various activities of microorganisms or an indicator of fossil fuel deposits. Oxidation or generation of methane in bed sediments often leads to the formation of carbonate nodules. By studying the isotopic composition of carbonate materials, it is possible to identify the origin of carbon in its crystal lattice. So, we know exactly whether the presence of a particular carbonate indicates some underground process, deposit or just a result of some bacterial activity,’ explained Aleksei Krylov, Associate Professor of St Petersburg University.

The Arctic Ocean, however, is a very unique place as low temperatures prevent the formation of carbonate deposits. Instead, there are unique minerals such as ikaite (СаСО3*6Н2О). It only exists at low temperature, but transforms the moment scientists try to bring it to the surface. Besides ikaite, scientists explore iron and manganese carbonates.

In order to conduct palaeoclimatic research the scientists have used a specially developed sampling device – a four-metre direct-flow gravitation tube which breaks through bed sediments under its own weights and collects samples for further research. Collected materials will help scientists conduct a thorough analysis of the precipitation regime in the Arctic Ocean.

As the geological and mineral composition of main Arctic archipelagos is thoroughly studied, we can identify the origin of minerals in bed sediments. We can also say how much time it took for them to be delivered to a particular place. Eventually, it is possible to tell whether these minerals were brought by seasonal or palaeocrystic ice.

Aleksei Krylov, Associate Professor of St Petersburg University

According to Aleksei Krylov, ice and icebergs are one of the ways to shift geological material in the region. They can transfer minerals and debris significant distances. He said, ‘There are three basic climate regimes for accumulating sediments and forming bed deposits: interglacial, glacial and deglaciation periods. Each period is characterised by a different speed of bed deposit formation. By examining bed sediments, it is possible to describe climate conditions during the period when these deposits were formed.’

In future, the results obtained will be useful for climatologists engaged in modelling the reduction of Arctic sea ice.

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Photo: AARI archive