Methane in the atmosphere and surface water of Lake Baikal

Abstract

Long-term observation series of the methane content in the near-water atmosphere and in water in the coastal zone of Lake Baikal are analyzed. The measurements were carried out in the Baikal Atmospheric-Limnological Observatory (BALO SB RAS, which is a part of the Resource Sharing Center “Atmosfera”). A steady increase of the methane content in the atmosphere by about 12 ppb per year is observed. The average diurnal methane content in March 2021 (the last measurement cycle) was 2.012 ppm. For the period of ling-term observations, the measured partial methane pressure in the surface water always exceeded that in the atmosphere. This fact indicates that this part of Lake Baikal is a source of methane into the atmosphere. For the coastal zone, the average value of methane flux from water was 380μgСН₄ m^-2 day¹ . The observed increased methane concentration in the near-bottom layer indicates the predominance of bottom methanogenesis. Our data show that the increment rate of dissolved methane in surface water of Lake Baikal is 0.015 μgCH₄/l per year.