Vertical flux of trace elements associated with lithogenic and biogenic
carrier phases in the Southern Ocean.
Trace elements (TE) are tracers of multiple biotic and abiotic processes
in the ocean and some of them are essential for marine life. Vertical
export by particles is a major removal process of a large fraction of TE
from the surface ocean. However, the seasonal export dynamics and its
controlling factors, critical for the understanding of the internal TE
cycling, remain poorly constrained. Here, we report and discuss the
seasonal export of 15 TE in sinking particles collected by a sediment
trap deployed in a highly productive region of the Southern Ocean.
Basalt material was the main carrier phase for the export flux of 9 TE,
and its dynamic was characterised by a strong decrease over time. TE
export driven by biological carriers such as diatom spores and
vegetative cells added pulsed seasonal dynamics to the lithogenic
signal, while the contribution of fecal pellets was less variable over
the season. For each TE, we were able to decipher the biological carrier
phases that represent the most dominant export pathway. We discuss this
partitioning with regards to the known metabolic functions of the
different trace metals or TE of biological interest.