Reconstructing the Oxygen Depth Profile in the Arabian Sea During the Last Glacial Period
Reconstructing the Oxygen Depth Profile in the Arabian Sea During the Last Glacial Period
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DOI：
10.1029/2023pa004632
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发表时间：
2023-06
影响因子：
3.5
通讯作者：
Wanyi Lu;K. Costa;D. Oppo
中科院分区：
文献类型：
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作者：
Wanyi Lu;K. Costa;D. Oppo
重建冰川海洋中最小含氧带（OMZs）的强度和深度边界有助于我们了解OMZs对气候变化的响应。虽然许多努力推断更好的氧化的冰川阿拉伯海OMZ的定性指标，氧化和冰川OMZ的垂直范围没有很好地量化。在这里，我们介绍了阿拉伯海岩心深度剖面中的冰川-全新世氧气重建，水深从600米到3,650米。我们估计冰川氧浓度底栖有孔虫表面孔隙度和底栖碳同位素梯度重建。与现代阿拉伯海相比，冰川氧浓度在较浅的OMZ（<1 000米）中高出约10-15 μmol/kg，在较深的OMZ（1 500 - 3 650米）中低5-80 μmol/kg。我们的研究结果表明，在冰川阿拉伯海的OMZ是稍好的氧合，但仍在上1,000米。我们建议，在最后一次冰期的阿拉伯海OMZ的氧化的小的增加是由于较弱的上层海洋分层引起的较强的冬季季风风，加上由于较低的温度增加氧的溶解度，抵消了更多的氧气消耗的影响导致较高的初级生产力。海洋环流的大规模变化也可能有助于冰川阿拉伯海OMZ更好的通风。
Reconstructing the strength and depth boundary of oxygen minimum zones (OMZs) in the glacial ocean advances our understanding of how OMZs respond to climate changes. While many efforts have inferred better oxygenation of the glacial Arabian Sea OMZ from qualitative indices, oxygenation and vertical extent of the glacial OMZ is not well quantified. Here we present glacial‐Holocene oxygen reconstructions in a depth transect of Arabian Sea cores ranging from 600 to 3,650 m water depths. We estimate glacial oxygen concentrations using benthic foraminiferal surface porosity and benthic carbon isotope gradient reconstructions. Compared to the modern Arabian Sea, glacial oxygen concentrations were approximately 10–15 μmol/kg higher in the shallow OMZ (<1,000 m), and 5–80 μmol/kg lower at greater depths (1,500–3,650 m). Our results suggest that the OMZ in the glacial Arabian Sea was slightly better oxygenated but remained in the upper 1,000 m. We propose that the small increase in oxygenation of the Arabian Sea OMZ during the last glacial period was due to weaker upper ocean stratification induced by stronger winter monsoon winds coupled with an increase in oxygen solubility due to lower temperatures, counteracting the effects of more oxygen consumption resulting from higher primary productivity. Large‐scale changes in ocean circulation may have also contributed to better ventilation of the glacial Arabian Sea OMZ.