The new method does not require any chemical agents and can be applied even in winter time.
Researchers from the Tomsk State University (TSU) have developed a new technology of clearing lake ecosystems of oil, the TSU press service reports. Experiments have proved that it decreases oil content in water by 35 to 40 times.
"The main technical solutions were tested when carrying out clearing actions on the Schuchie Lake (the Komi Republic), where 157 tons of oil managed to be lifted from the bottom and removed", - the press release informs.
The new method is as follows: a punched hose is submerged onto the bottom of a reservoir to jet air under excessive pressure in the place of oil accumulation. As a result, oil rises to the surface and sticks to the border between two phases, those of air and liquid. In summer time it is collected into a primary settler to be afterwards sent to floating pools with sorbents, and in winter time it is removed through a channel laid down right in ice.
The technology offered by the TSU is best of all suitable for lakes with stony, clay or sandy bottoms. It makes it possible to remove not only bottom deposits of oil, but also clear the entire water column, without any limitations as per the reservoir depth. The method does not require any chemical agents and can be used even in winter time, when vegetative processes in lakes are slowed down and thus intervention into life of the underwater world is minimum.
"In spring and summer fish and hydrobionts actively breed, that is why it is better to carry out any clearing works during a cold season, - Dr Sci Danil Vorobyov, one of the method's developers and the director of the TSU Biological Institute explained. - We also need to consider  the fact that lots of Russia's polluted lakes are in hard-to-reach spots, which can be reached and transport the oil removed only on a winter road. For such reservoirs the subglacial method of clearing is the only possible option".
When getting into a reservoir, oil at first gets accumulated on a water surface, but gradually gathers mineral particles, loses its buoyancy and settles onto the bottom. It can stay there for decades, killing evrything alive in the area and thus inevitably leads to decrease in recreational and fishery value of a reservoir. Preliminary experiments have shown that this new method of water clearance can stop these negative processes: in several years after oil pumping out the number of fish development anomalies was considerably reduced.
The  Biological Institute of the TSU has secured patents for winter and summer versions of the invention. After a number of additional experiments oil industry workers who are already interested in this technology will get an opportunity to apply it. The research data is published in the journal Water Practice & Technology.