Oceanic oxygen reconstructions of the last glacial period are needed to understand the mechanisms of glacial deep ocean carbon storage and to validate climate model simulations. However, existing bottom-water oxygen (BWO) reconstructions are ambiguous due to limitations of each paleo-BWO proxy. Here we present data on three proxies for BWO: benthic foraminiferal surface porosity, benthic foraminiferal iodine/calcium (I/Ca), and authigenic uranium (aU), from globally distributed core-top samples, and we evaluate the potential advantages and limitations of these BWO proxies on global and regional scales. All three proxies are most sensitive to changes at relatively low BWO concentrations (<∼50 µmol/kg). Data from globally-distributed core tops confirm that foraminiferal surface porosity is correlated with BWO between 0 and 100 µmol/kg. Our analysis further confirms that benthic surface porosity is predominantly controlled directly by BWO rather than other potential functionalities of surface pores such as organic carbon uptake and respiratory CO₂ release. Low benthic I/Ca can identify low BWO (<50 µmol/kg), whereas higher benthic I/Ca values are not associated with specific BWO, possibly due to additional dependence of I/Ca on temperature, salinity, carbonate ion concentration, or water mass mixing at higher BWO. The relationship between aU and BWO is regionally dependent. In the Arabian Sea, variable aU enrichments occur only within the Oxygen Minimum Zone (OMZ), driven by high export production and organic matter fluxes to the sediment. Finally, we combine foraminiferal surface porosity, I/Ca and aU to generate the first quantitative glacial-Holocene BWO reconstructions using a sediment core taken from within the modern Arabian Sea OMZ. All three proxies consistently suggest BWO < 50 μmol/kg in the shallow Arabian Sea during the last ∼30 kyr, with relatively higher BWO during the glacial period than the Holocene. A comparison with the benthic carbon isotope gradient proxy (Δδ¹³C) confirms that Δδ¹³C over-estimates BWO in low-oxygen settings possibly due to sediment diagenesis impacts. Our study provides new insights on the merits and limitations of these BWO proxies and confirms the importance of multi-proxy reconstructions for more reliable paleo-BWO estimates.

需要对末次冰期的海洋氧气进行重建，以了解冰期深海碳储存的机制并验证气候模型模拟。然而，由于每个古 BWO 代理的限制，现有的底水氧（BWO）重建是模棱两可的。在这里，我们展示了 BWO 的三个代理数据：底栖有孔虫表面孔隙度、底栖有孔虫碘/钙 (I/Ca) 和自生铀 (aU)，来自全球分布的岩心顶部样品，我们评估了以下方法的潜在优势和局限性这些 BWO 代理在全球和区域范围内。所有三个代理对相对较低的 BWO 浓度（<~50 µmol/kg）的变化最敏感。来自全球分布的岩心顶部的数据证实，有孔虫表面孔隙度与 BWO 相关，介于 0 和 100 µmol/kg 之间。₂发布。低底栖 I/Ca 可以识别低 BWO (<50 µmol/kg)，而较高的底栖 ​​I/Ca 值与特定 BWO 无关，可能是由于 I/Ca 对温度、盐度、碳酸根离子浓度或在较高 BWO 下的水团混合。aU 和 BWO 之间的关系因地区而异。在阿拉伯海，受高出口产量和沉积物有机物通量的驱动，不同的 aU 富集仅发生在最低氧区 (OMZ) 内。最后，我们结合有孔虫表面孔隙率、I/Ca 和 aU，使用取自现代阿拉伯海 OMZ 内的沉积物核心生成第一个定量的冰河全新世 BWO 重建。在过去 ∼30 kyr 期间，所有三个代理均一致表明浅阿拉伯海的 BWO < 50 μmol/kg，冰期的 BWO 比全新世高。与底栖碳同位素梯度代理的比较（Δδ¹³ C) 证实 Δδ ¹³ C 高估了低氧环境中的 BWO，这可能是由于沉积物成岩作用的影响。我们的研究为这些 BWO 代理的优点和局限性提供了新的见解，并证实了多代理重建对于更可靠的古 BWO 估计的重要性。