Climate driven changes in Lake Baikal during the late Pleistocene and Holocene are revealed as large systematic variations in the abundance of total organic carbon (TOC) and disulfide (pyritic) sulfur, and sulfur isotope (δ34S) values in a sediment core from the Selenga delta region of the lake. Beginning in the late Pleistocene, enhanced primary production, accumulation of organic matter, and microbial-sulfate reduction led to carbon and pyritic sulfur maxima in middle Holocene sediments. A large negative shift in the pyritic-sulfur isotope δ34S values in the late Pleistocene indicates an increase in sulfate and probably other major ions and nutrients from terrestrial runoff, reflecting warmer, wetter conditions. TOC and diatom abundance show corresponding increases. Positive shifts in δ34S at about 12.5 and 10 kyr BP indicate a decrease in sulfate availability, suggesting cooler, dryer periods and possibly enhanced lake stratification with limited deep-water renewal. A decrease in the abundance of pyritic sulfur and positive δ34S values in the late Holocene apparently resulted from a decline in riverine sulfate input, reflecting a shift to drier continental conditions.
Spiker et al. (Fri,) studied this question.