Abstract The Nd isotopic compositions (eNd) of mixed planktonic foraminifera have been analyzed in two sediment cores collected in the Nile deep-sea fan in order to reconstruct past eNd of the Eastern Mediterranean Deep Water (EMDW) and to assess the relative contributions of Nile discharge and Modified Atlantic Water (MAW) inflow to the Eastern Mediterranean Sea hydrology, as well as their potential control on anoxic events over the last climatic cycle. The two foraminiferal eNd records are similar and display an increase in eNd values during the African Humid Periods. Superimposed on this precession-forced variability (insolation received by the Earth at low latitudes), the record of variations in foraminiferal eNd indicates a 2-unit decrease in eNd during the interglacial Marine Isotope Stages (MIS) 5 and 1 compared to glacial MIS6, 4, 3 and 2. The eNd results suggest that the long-term glacial to interglacial changes in Nd isotopic composition of EMDW were not entirely induced by variations in Nile River discharge and Saharan dust inputs. Decreases in eNd during MIS5 and MIS1 interglacials indicate an increase in the contribution of unradiogenic MAW to the eastern Mediterranean Sea related to high sea-level stands and greater seawater exchange between the North Atlantic and Mediterranean basins. In addition, radiogenic seawater eNd values observed during African Humid Periods (and sapropel events) are associated with an intensification of Nile discharge and an increase in residence time of deep-water masses in the eastern Mediterranean Sea, which induces an increase in the interaction between deep-water masses and radiogenic sediments along the margin of the eastern Mediterranean Sea. Results confirm that an intensification of the hydrological exchanges between the western and eastern Mediterranean basins during high sea-level stand and the subsequent higher proportion of Atlantic Water in the Levantine Basin may have preconditioned the eastern Mediterranean Sea to sapropel depositions during the last climatic cycle.

中文翻译：

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从有孔虫中的钕同位素推断出的最后一个气候循环期间东地中海水文的变化

摘要 为了重建东地中海深水 (EMDW) 过去的 eNd 并评估尼罗河的相对贡献，在尼罗河深海扇中收集的两个沉积岩芯中分析了混合浮游有孔虫的 Nd 同位素组成 (eNd)。排放和修改后的大西洋水 (MAW) 流入东地中海水文，以及它们对最后一个气候循环中缺氧事件的潜在控制。两个有孔虫的 eNd 记录相似，并显示在非洲湿润期 eNd 值有所增加。叠加在这种进动强迫变化（地球在低纬度接收的日照）上，有孔虫 eNd 的变化记录表明，与冰期 MIS6 相比，间冰期海洋同位素阶段 (MIS) 5 和 1 期间 eNd 减少了 2 个单位， 4、3 和 2。eNd 结果表明，EMDW 中 Nd 同位素组成的长期冰期到间冰期变化并不完全是由尼罗河流量和撒哈拉沙尘输入的变化引起的。MIS5 和 MIS1 间冰期期间 eNd 的减少表明非放射性 MAW 对东地中海的贡献增加，这与高海平面和北大西洋和地中海盆地之间更大的海水交换有关。此外，在非洲湿润期（和腐泥事件）观察到的放射性海水 eNd 值与尼罗河排放的加剧和地中海东部深水团的停留时间增加有关，这导致了之间相互作用的增加地中海东部边缘的深水团和放射性沉积物。