Abstract. We present downcore records of redox-sensitive authigenic uranium (U) and manganese (Mn) concentrations based on five marine sediment cores spanning a meridional transect encompassing the Subantarctic and the Antarctic zones in the Southwest Indian Ocean covering the last glacial cycle. These records signal lower bottom water oxygenation during glacial climate intervals and generally higher oxygenation during warm periods, consistent with climate-related changes in deep ocean remineralised carbon storage. Regional changes in the export of siliceous phytoplankton to the deep-sea may have entailed a secondary influence on oxygen levels at the water-sediment interface, especially in the Subantarctic Zone. The rapid reoxygenation during the deglaciation is in line with increased ventilation and enhanced upwelling after the Last Glacial Maximum (LGM), which, in combination, conspired to transfer previously sequestered remineralised carbon to the surface ocean and the atmosphere, contributing to propel the Earth’s climate out of the last ice age. These records highlight the yet insufficiently documented role the southern Indian Ocean played in the air-sea partitioning of CO₂ on glacial-interglacial timescales.

中文翻译：

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自上次冰期以来，印度洋西南部的底部水氧合变化是增加呼吸碳储量的指标

摘要。我们提供了基于五个洋沉积物核心的氧化还原敏感性自生铀（U）和锰（Mn）浓度的下层记录，这些核心沉积物跨过子午线，涵盖了西南印度洋的南极和南极地区，覆盖了上一个冰川周期。这些记录表明，在冰川气候间隔期间底层水的氧合较低，而在温暖时期通常较高的氧合，这与深海再矿化碳储量中与气候有关的变化一致。硅质浮游植物向深海出口的区域变化可能会对水-沉积物界面（尤其是亚南极带）的氧气含量产生二次影响。冰川消融期间的快速补氧与增加的通风和增强的上冰川期（LGM）之后的上升流相一致，结合起来，这些气体共同企图将以前封存的再矿化碳转移到海面和大气中，从而将地球的气候推向了最后一个冰河时期。这些记录突显了印度洋南部在CO的气海划分中所起的作用，但尚未得到充分的文献记载。₂在冰川间时间尺度上。