Incorporation of Multi-Elements Into Diatom Frustules in the Scotia Sea, Antarctica, Since the Last Glacial Maximum

Abstract

The glacial-interglacial cycle of elements and the linkage with biological production is very important. Nonetheless, records on incorporation of elements into diatom frustules are very poor in the Southern Ocean where diatom productivity is very high. As a result, there is a big gap in our understanding of elemental cycles in association with biological production and the controlling mechanisms. Here, we documented concentrations of major, trace, and rare earth elements of diatom frustules in two cores collected from the Southern Ocean since the Last Glacial Maximum to understand changes of incorporation of these elements into diatom frustules and to investigate mechanisms for changing incorporation. We found that there are three types of glacial-interglacial variation patterns. Most elements showed increased (decreased) concentrations during the glacial period (interglacial) with decreased (increased) diatom production in the surface water following the variation pattern of magnetic susceptibility, whereas P, Ge, and Sb showed the opposite trend following the variation pattern of biogenic opal. Li, Ni, Ag, W, U, and I showed no clear glacial-interglacial variation pattern. These different variation patterns imply that elemental incorporation into diatom frustules are also different according to elements. Our results revealed that biologically mediated removal of most elements from surface water to deep-sea is comparable between glacial (low diatom production with high elements assimilation) and interglacial (high diatom production with low elements assimilation) periods in the Southern Ocean. However, more removal of P, Sb, and Ge in the surface water by diatoms occurs during interglacial periods in the Southern Ocean. Concentrations of multi-elements within diatom frustules were documented from the Southern Ocean since the Last Glacial Maximum (LGM) Most elements were assimilated/incorporated into diatoms synchronously: high (low) during glacial (interglacial) periods P, Ge, and Sb showed low incorporation into diatom frustules during the LGM but increased during the Holocene