School of Geosciences, University of Edinburgh, Edinburgh, UK.
School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK.
Nat Commun. 2020 Mar 24;11(1):1534. doi: 10.1038/s41467-020-15101-6.
Changes in ocean circulation and the biological carbon pump have been implicated as the drivers behind the rise in atmospheric CO across the last deglaciation; however, the processes involved remain uncertain. Previous records have hinted at a partitioning of deep ocean ventilation across the two major intervals of atmospheric CO rise, but the consequences of differential ventilation on the Si cycle has not been explored. Here we present three new records of silicon isotopes in diatoms and sponges from the Southern Ocean that together show increased Si supply from deep mixing during the deglaciation with a maximum during the Younger Dryas (YD). We suggest Antarctic sea ice and Atlantic overturning conditions favoured abyssal ocean ventilation at the YD and marked an interval of Si cycle reorganisation. By regulating the strength of the biological pump, the glacial-interglacial shift in the Si cycle may present an important control on Pleistocene CO concentrations.
海洋循环和生物碳泵的变化被认为是过去冰川消退期间大气 CO 上升的驱动因素；然而，所涉及的过程仍不确定。先前的记录表明，在大气 CO 上升的两个主要间隔期间，深层海洋通风存在分区，但对 Si 循环的不同通风的后果尚未得到探索。在这里，我们提出了来自南大洋的硅藻和海绵中硅同位素的三个新记录，这些记录共同表明，在冰川消退期间，深部混合导致硅供应增加，在年轻的干旱期（YD）达到最大值。我们认为，南极海冰和大西洋翻转条件有利于 YD 时的深海通风，并标志着 Si 循环重组的一个时期。通过调节生物泵的强度，Si 循环的冰期-间冰期变化可能对更新世 CO 浓度产生重要控制。
