The evolution of intermediate circulation in the northern Indian Ocean since the last deglaciation has been reconstructed from two marine cores located at intermediate depths off the southern tip of India (MD77‐191) and in the northern Bay of Bengal (BoB) (MD77‐176). Benthic foraminiferal δ¹³C, seawater carbonate ion concentration ([CO₃²⁻]) estimated from the Sr/Ca, and paleotemperature reconstructed on the basis of the Mg/Li of aragonite benthic species Hoeglundina elegans were used to trace the evolution of past intermediate‐deepwater masses and to constrain ocean‐atmosphere exchanges during the two‐stage increase in atmospheric CO₂ across the last deglaciation. The intermediate water [CO₃²⁻] was mainly affected by changes in the ocean alkalinity inventory, associated with the modulation of atmospheric CO₂ on glacial‐interglacial timescales. Higher benthic foraminiferal δ¹³C, depleted [CO₃²⁻], and decreased benthic‐planktonic ¹⁴C age offsets at intermediate water depths suggest a release of deep‐sea CO₂ to the atmosphere through the Antarctic Intermediate Water (AAIW) in the Southern Ocean during the 17–15.2 and 12.6–10.5 cal kyr BP time intervals. In addition, the decreased H. elegans Mg/Li record seems to reflect an increased contribution of cold water mass during the 17–15.2 and 12.6–11.9 cal kyr BP intervals and throughout the Holocene. In contrast, two warm events occurred in the 15–13.3 and 11–10.3 cal kyr BP time intervals. During the late Holocene, a decrease in the intermediate water [CO₃²⁻] indicates a contribution to atmospheric CO₂ rise since 8 cal kyr BP, due to the depleted global ocean alkalinity and/or the variations in surface productivity (at least for MD77‐191).

中文翻译：

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根据底栖有孔虫Hoeglundina elegans的新元素比率记录推断，自上次冰消期以来的北印度洋环流

自最后一次冰消以来，北印度洋中部环流的演变是由位于印度南端（MD77-191）和孟加拉湾北部（BoB）（MD77-176）中间深度的两个海心重建的）。底栖有孔虫δ ¹³ C，海水碳酸根离子浓度（[CO ₃ ^2- ]）从SR /钙估计，和古温度重建文石海底物种中，Mg / Li的基础上Hoeglundina线虫被用来跟踪过去的演变在最后一次冰消期间大气CO ₂的两阶段增加过程中，中间深水团块和海洋-大气交换受到限制。中间水[CO ₃ ^2-]主要受海洋碱度清单变化的影响，这与大气CO ₂在冰川间时间尺度上的调节有关。更高底栖有孔虫δ ¹³ C，耗尽[CO ₃ ^2- ]，和降低的底栖-浮游^14个Ç年龄偏移在中间水深建议深海CO的释放₂通过南极中层水（AAIW）在向大气南海在17–15.2和12.6–10.5 cal kyr BP时间间隔内。此外，线虫的减少Mg / Li记录似乎反映了在17–15.2和12.6–11.9千卡的BP间隔以及整个全新世期间，冷水质量的增加。相反，在15-13.3和11-10.3 cal kyr BP时间间隔内发生了两次暖事件。晚全新世期间，在中间水的减少[CO ₃ ^2- ]指示大气CO贡献₂自8 CAL KYR BP上升时，由于耗尽全球海洋碱度和/或用于在表面生产率的变化（至少MD77-191）。