Structure and Origin of the Underwater Plume Near Sevastopol

Bondur V. G., Ivanov V. A., Dulov V. A., Goryachkin Yu. N., Zamshin V. V., Kondratiev S. I., Lee M. E., Mukhanov V. S., Sovga E. E., Chukharev A. M.

In 2015—2016, comprehensive research was conducted on the underwater plume observed from outer space near Sevastopol in the area of the deep-water runoff. In ship expeditions vertical hydrological profiles, current velocity profiles and optical characteristics of water were obtained on the grid of stations, and water samples were taken for chemical and microbiological analysis. In-situ studies were accompanied by surveys from various satellites. It is reliably shown that the plume is a layer of turbid water, stretched along the coast for a distance of several kilometers and localized at the depth of the pycnocline. Plume can be observed from Space in the visible range when the pycnocline rises up to the sea surface. An analysis of the data indicates that the existence of the plume is a consequence of emergency state of the underwater pipe of the wastewater discharge system, which is confirmed by the results of satellite image analysis. An estimate of location of the probable break of pipeline is obtained. In the area of the source of pollution, detachment of the pieces of turbid waters from the main layer and their lifting to the sea surface was revealed. Chemical composition of turbid waters corresponds to the sewage one. The existence of a plume near the coast leads to unfavorable ecological consequences, in particular, the concentration of ammonium ions in the plume region is 2 times higher than the maximum permissible level, and microbiological analyses indicates destabilization of the microbial community and destructive processes in phytoplankton caused by pollution.

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