Expedition on board the RV “Papanin” from 2 to 10 August 2021
The expedition within the framework of the programme “Investigation of the role of atmospheric deposition on aquatic and terrestrial ecosystems of the Lake Baikal basin, identification of sources of atmospheric pollution” was carried out from 2 to 10 August on board the RV “Papanin”.
The aim of the expedition was the parallel complex experimental studies of the rhythms of hydrochemical and hydrobiological processes of gas exchange in the littoral zone near the Bolshie Koty settlement (the research station of Limnological Institute) as well as at different sites of the littoral and pelagic zones of the southern basin of Lake Baikal in summer.
The planned fieldwork was completely fulfilled. The conducted studies revealed that the concentration of dissolved oxygen at the stations averaged 11.5 mg/dm3, with the minimum values near the Tankhoy station and the maximum values near Marituy Cape.
The pH value at the stations corresponded to the study season; the maximum value was recorded near Tankhoy. Thirty samples were taken for further determination of the concentrations of nutrients, organic matter and chlorophyll a.
In the diurnal drift (Kadilny-Listvyanka) at a distance of 20 km from the coast, the CO2 partial pressure in the surface water was Pw = 261 ppm with SD = 5.2 ppm, and in the near-water atmosphere – Pа = 391 ppm with SD = 8.5 ppm. Hence, there was an obvious release of carbon dioxide from the atmosphere to the water surface. The СН4 partial pressure in the surface water was Pw=5 ppm with SD= 4.2 ppm, and in the near-water atmosphere – Pа = 1.9 ppm with SD = 002 ppm. Hence, there was a weak release of methane into the atmosphere. These data are rather comparable with the values of parallel measurements in the coastal zone at Baikal Atmospheric Limnological Observatory.
Similar methane concentrations in the surface water and atmosphere were observed at the Marituy station and near Kadilny Cape, but the maximum values of the CH4 partial pressure in the surface water were recorded near the Tankhoy settlement: Рw = 14 ppm with SD = 0.2 ppm, and in the near-water atmosphere – Pа = 1.9 ppm with SD = 0.02 ppm, indicating the significant increase in methane flux into the atmosphere.