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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Biological and environmental changes in Lake Baikal during the late Quaternary inferred from carbon, nitrogen and sulfur isotopes
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Biological and environmental changes in Lake Baikal during the late Quaternary inferred from carbon, nitrogen and sulfur isotopes

机译：从碳，氮和硫同位素推断第四纪晚期贝加尔湖的生物和环境变化

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摘要

An 8-m continuous sediment core, approximately 250-ky-old at the bottom, from Academician Ridge in Lake Baikal, has been analyzed for the stable isotopes of carbon, nitrogen and sulfur, in order to study the paleoclimatic and paleobiological changes that occurred in the Eurasian continental interior. These isotopic changes are closely related to changes in vertical lake-water circulation between glacial and interglacial periods. Sedimentary organic carbon in cool periods is more enriched in ~(13)C (-23.8‰ on average) than that in warm periods (-27.0‰ on average). The 13C-enrichment of organic carbon suggests a decrease of land-derived organic matter influx to the lake, less precipitation, and loss of terrestrial vegetation around Lake Baikal in cool periods. Pyrite in high total sulfur/total organic carbon (TS/TOC) layers shows strong depletion in ~(34)S (-20.8‰ to -32.4‰) during climate transitions from glacial to interglacial periods at the beginning of oxygen isotope stages (OIS) 1, 5 and 7. The ~(34)S-depleted pyrite indicates augmentation of dissimilatory sulfate reduction by sulfate reducing bacteria (SRB) at the sediment–water interface. Enhancement of aqueous sulfate concentrations and limitation of oxygen circulation to the surface sediments might also occur in the climate transition periods. The δ~(15)N values of total nitrogen increase abruptly by ～2‰ just after the δ~(34)S negative peaks, which may result from low nutrient concentrations in the euphotic zone associated with water circulation changes in Lake Baikal.
机译：为了研究发生的古气候和古生物学变化，对贝加尔湖院士岭一个8 m连续沉积岩心（底部约250 ky，底部）进行了碳，氮和硫的稳定同位素分析，在欧亚大陆内部。这些同位素变化与冰川期和冰川间期之间的垂直湖水循环变化密切相关。寒冷时期的沉积有机碳比温暖时期的沉积碳富集在（13）C处（平均为-23.8‰）。 13C富集的有机碳表明，在凉爽的时期，贝加尔湖周围的陆生有机质流入湖水减少，降水减少以及陆地植被的损失。在从氧同位素阶段开始的冰期到间冰期的气候过渡期间，高总硫/总有机碳（TS / TOC）层中的黄铁矿在〜（34）S（-20.8‰至-32.4‰）中显示出强烈的消耗。 ）1、5和7。〜（34）S贫化的黄铁矿表明，沉积物-水界面处的硫酸盐还原细菌（SRB）增加了异化硫酸盐还原。在气候过渡时期，硫酸盐水溶液浓度的增加和氧气对地表沉积物的循环限制也可能发生。紧接δ〜（34）S负峰之后，总氮的δ〜（15）N值突然增加〜2‰，这可能是由于贝加尔湖水循环变化引起的富营养区低养分含量所致。

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