末次冰期以来阿拉伯海底层水体氧含量变化及其驱动因素

Changes in bottom water oxygen level of the Arabian Sea and the driving factors since the Last Glacial Period

  • 摘要: 末次冰期以来阿拉伯海水体氧含量变化在时空上具有显著的差异。目前对其空间变化规律及主导因素尚缺乏系统的研究,尤其缺乏对千年尺度上深层水氧含量变化过程及其控制因素的综合分析。本文基于阿拉伯海中部深水区WIND-CJ06-6与WIND-CJ06-13两个岩芯的XRF岩芯扫描结果,结合前人已发表的指示阿拉伯海水体氧含量变化数据,重建了末次冰期以来千年尺度阿拉伯海不同海域和深度的水体氧含量变化历史并分析了其驱动因素。阿拉伯海水深小于1 500 m的水体在千年尺度上的氧含量变化受到表层初级生产力和中层水流通性的共同控制,但在不同时期主导因素不同;在B/A(Bølling–Ållerød)到YD(Younger Dryas)期间,阿拉伯海西北部表层生产力显著高于同时期其他海域,导致了中层水体的氧含量在西北部降低而在其他海域增高的空间差异。阿拉伯海水深大于1 500 m的水体氧含量在末次冰期以来整体上受北大西洋深层水(NADW)强弱的控制,在LGM(Last Glacial Maximum)到HS1(Heinrich stadial 1)阶段则受到南大洋通风增强的影响,水体氧含量显著升高。

     

    Abstract: Variations in the oxygen content of water column in the Arabian Sea since the Last Glacial Period have significant differences in space and time. However, regarding the spatial variation patterns and dominating factors, systematic studies are scarce, especially on the mechanism of changes in oxygen content in deep water and the controlling factors on a millennial scale. Based on XRF core scanning results from two cores, WIND-CJ06-6 and WIND-CJ06-13, in the central deep water of the Arabian Sea and previously published data, we reconstructed the processes and analyzed the drivers of the variations in oxygen content in the Arabian Sea in different areas and depths on millennial scale since the Last Glacial Period. Results show that the variations in oxygen content in the Arabian Sea in water depths less than 1500 m on the millennial scale are controlled jointly by the surface primary productivity and mesopelagic water fluxes, and the dominant factors varied in different periods. Surface productivity in the northwestern part of the Arabian Sea was significantly higher than that in the rest of the sea during the transition period from B/A (Bølling-Ållerød) to YD (Younger Dryas) events, resulting in spatial difference: the oxygen content in the intermediate water was high in the NW Arabian Sea but low in the rest of the sea. The oxygen content in water column in the Arabian Sea at depths greater than 1500 m was mainly controlled by the strength of the North Atlantic Deep Water (NADW) since the Last Glacial Maximum (LGM), and the oxygen content in water was significantly increased due to enhanced ventilation in the Southern Ocean from the LGM to the HS1 (Heinrich Stadial 1) stage.

     

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