Diurnal behavior of the carbon dioxide flux and change in the isotopic ratio δ~(13)C in surface and near-bottom water in littoral of Lake Baikal

摘要

Lake Baikal is one of the unique natural environments in Siberia which, to a large extent, affects the state of the nature in this region. The processes of gas exchange in the "water-atmosphere" system have been studied in Lake Baikal since 2002. The main purpose of the integrated investigations of exchange of carbon-containing gases in the water-atmosphere system in Lake Baikal is to study the contribution of physical, chemical, and biological components of the process and their interrelation with the intensity and rhythms of the fluxes. In 2013, the integrated measurements in the littoral area of Baikal were complemented with studies of the diurnal dynamics of isotopic ratio δ~(13)C in the surface and near-bottom water, which were not yet performed in Baikal before. In this work, we analyze first results of the joint analysis of CO_2 fluxes in the "atmosphere - water surface" system and δ~(13)C, obtained in August 2013 in the littoral area of South Baikal. It is shown that d~(13)C markedly increases in the surface waters at daylight time. In nighttime period, there takes place a reverse process, when δ~(13)C of the surface water approaches δ~(13)C, which is recorded for near-bottom water.