Oxygen isotope composition of diatoms from Lake Kotokel (southern Siberia, Russia)@en

This is a diatom oxygen isotope record from Lake Kotokel (southern Siberia, Russia), with implications for responses of the lake system and its environment to global change over the past 46 cal. ka BP. The δ¹⁸O diatom values vary between +23.7 and +31.2‰ over the record. The results present mainly diatom assemblages of summer blooming periods, except for the time span between 36 and 32 cal. ka BP, when the isotopic signal records mainly a shift from summer to spring blooming conditions. Possible water temperature changes only partly explain the changes in the isotopic record. The observed isotopic patterns are mainly produced by isotope changes in lake water in response to variations in air temperature, hydrology, and atmospheric circulation in the region. During Marine Isotope Stage (MIS) 2 (Last Glacial maximum), high δ¹⁸O diatom resulted from rapid evaporation and low fluvial inputs. The relatively high δ¹⁸O diatom values during the first half of MIS 1 (Holocene interglacial) suggest an increased portion of summer precipitation associated with southern/southeastern moisture transport. The decrease in δ¹⁸O diatom values during the second half of MIS 1 is due to the overall hemispheric cooling and increased moisture supply to the area by the Atlantic air masses. The Lake Kotokel record provides an example of complex interplay among several climatic/environmental controls of δ¹⁸O diatom during the Late Pleistocene and the Holocene.本数据集为俄罗斯西伯利亚南部科托克尔湖（Lake Kotokel）的硅藻氧同位素记录，旨在揭示过去46校准千年距今（calibrated kiloyears before present, cal ka BP）期间该湖泊系统及其生态环境对全球变化的响应。本记录中硅藻δ¹⁸O值的变化范围为+23.7‰至+31.2‰。除36~32校准千年距今时段外，本记录的硅藻组合主要对应夏季水华期的群落特征；该时段的同位素信号则主要记录了水华期从夏季向春季的转变过程。单纯的水体温度变化仅能部分解释本同位素记录的波动特征。观测到的同位素分布模式主要源于区域气温、水文条件以及大气环流变化所引发的湖水同位素组分改变。在海洋同位素阶段（Marine Isotope Stage，MIS）2（末次冰盛期）期间，高硅藻δ¹⁸O值由快速蒸发与河流输入量减少共同导致。海洋同位素阶段1（全新世间冰期，Holocene interglacial）前半段的硅藻δ¹⁸O值相对偏高，表明该时期夏季降水占比提升，且水汽输送主要来自南部/东南部区域。海洋同位素阶段1后半段的硅藻δ¹⁸O值呈下降趋势，这一现象源于全球半球尺度的整体降温以及大西洋气团向该区域输送的水汽量增加。科托克尔湖记录为晚更新世至全新世期间硅藻δ¹⁸O值受多重气候与环境因子复杂交互作用影响提供了典型案例。