FACTORS CONTROLLING THE SILICON ISOTOPE COMPOSITION OF DISSOLVED SILICATE AND BIOGENIC SILICA IN THE PERUVIAN UPWELLING
The stable silicon (Si) isotope composition (δ30Si) of dissolved silicic acid (Si(OH)4) and of biogenic silica reflects changes in nutrient utilization and biogeochemical cycling in the present and past ocean. Here we present dissolved and biogenic Si isotope signatures at shelf stations in the upwelling area off Peru to better understand the different processes influencing Si isotope distributions. Primary productivity in this upwelling area is dominated by diatoms, which preferentially incorporate the lighter 28Si when building their frustules. This leaves the corresponding seawater enriched in heavier 30Si. Previous studies suggest that the fractionation factors accompanying this process are species dependent and that the Si isotope signature off Peru is strongly influenced by water mass mixing mainly due to upwelling resulting in less fractionated surface water signatures. To disentangle these different processes information on the Si isotope composition of the dissolved and particulate phases will be compared.
Grasse, P., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, firstname.lastname@example.org
Brzezinski, M. A., University of California Santa Barbara, Germany, email@example.com
Frank, M., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, firstname.lastname@example.org
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall
Presentation is given by student: No