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TSU is exploring a swamp river saturated with dissolved carbon

Elena Fritz

The staff of the TSU Bio-Geo-Clim laboratory, with the support of the Russian Science Foundation, is studying the climate-regulating role of the Siberian rivers Ob and Lena, and in particular, assessing their contribution to the formation of the greenhouse effect. Researchers recently began work on the river Ket, which is a tributary of the Ob and originates in carbon-rich marshes. At the new site, scientists conducted a sampling to measure the concentration of dissolved carbon in water, and in addition, they will estimate the extent of its release into the atmosphere. Samples will be analyzed by five research centers in Russia and France.

- The subject of dissolved carbon in the context of global warming is worrying many countries, especially those that are below sea level, says Sergey Vorobyov, a researcher at Bio-Geo-Clim. - The reason is that emissions of this element are increasing, in part because of melting of the permafrost, which stores large stocks of dissolved carbon. Rivers also make a significant contribution to these processes because they accumulate this element and transport it to the world's oceans. How large their role is in the formation of the greenhouse effect is not precisely known; large-scale studies have not previously been conducted.

The scientists are exploring three large objects—the Lena, Ob and its tributary the Ket. The latter, according to Sergey Vorobyov, is interesting in that it collects water from the watershed areas, where there are many raised bogs. They contain a large amount of dissolved hydrocarbons and methane, which fall into the Ket from the water intake.

In order to determine the volume of gas emissions from the river surface and measure their concentration in water, an expedition was organized under the supervision of Oleg Pokrovsky, the head of the laboratory Bio-Geo-Clim, a scientist at TSU and the Observatory of Midi-Pyrenees (Toulouse, France). Scientists went by boat from the Sochur River—the tributary Ket to the inflow of the Ket into the Ob in the area of Kolpashevo; at the same time an automated system took measurements of indicators every five minutes. Researchers took dozens of samples of water and suspended matter that falls into the river from the marshy watersheds. Geochemical, microbiological, and metagenomic analysis of samples will be carried out by several research centers.

The research results will help to obtain comprehensive data on the river. Along with the saturation of greenhouse gases, sources will be identified from which water enters the Ket (marshes, atmosphere, and others), and consortia of organisms living in the river will be studied. This is important for tracking the further dynamics of the ecosystems' state and their transformation. In August 2019, scientists will once again follow the selected route and conduct repeat sampling at the same sites, to increase the objectivity of the data.

- Such studies are carried out on the Lena and Ob, - explains Sergey Vorobyov. –The Lena has no floodplain, and the Ob, on the contrary, has a very large one—in the spring it can reach a width of up to 60 kilometers. In the spring, a large amount of organic matter gets into the river, which decomposes, which leads to a sharp increase in the concentration of dissolved carbon and methane. Comparative analysis of the two rivers will allow us to calculate the role of the floodplains in climate regulation and evaluate their cumulative contribution to the saturation of the oceans with greenhouse gases.

Provided by Tomsk State University