Vertical flux of trace elements associated with lithogenic and biogenic carrier phases in the Southern Ocean

• Published in: Global Biogeochemical Cycles
• Main Authors: Blain, S., Planquette, Helene, Obernosterer, I., Guéneuguès, A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2022
• Subjects: trace element; export; trace metal; southern ocean; diatoms; faecal pellets; Southern Ocean
• Online Access: https://archimer.ifremer.fr/doc/00770/88197/93752.pdf; https://archimer.ifremer.fr/doc/00770/88197/93753.pdf; https://doi.org/10.1029/2022GB007371; https://archimer.ifremer.fr/doc/00770/88197/

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.