Fluxes and Composition of Particulate Matter in the Water Column of South Baikal (between March 2015 and March 2016)

Abstract

Abstract —The paper provides the results of experiments with sediment traps in the deep-water part of the South Basin of Lake Baikal (depth of 1366 m), installed from March 2015 to March 2016 in order to study recent sedimentation within the lake. We present new data on total fluxes of particulate matter and fluxes of biogenic components (SiO2biog, Сorg, and Ntot) at different depths of the water column both for the whole year and for individual periods of the year. Diatom analyses were carried out for all obtained samples. The total flux of sedimentary material averaged 94.9 g/m2/y; the average fluxes of SiO2biog, Сorg, and Ntot were 23.9, 11.6, and 0.94 g/m2/y, respectively. The molar C/N ratio varies from 11 to 21 and indicates a predominance of allochthonous material in almost all samples. Maximum fluxes of sedimentary matter were recorded from 20 June to 20 July 2015. This period corresponds to the bloom of diatoms of the species Synedra acus. This species amounts to >94% of the total diatom content in all samples taken during this year. The recent predominance of Synedra acus in the water column, as well as in the surface bottom sediments of South Baikal, is probably due to the climate warming.