Silicon Cycle in the Mediterranean and Black Seas: An Isotopic Approach (SiCyMBSIA)

The SiCyMBSIA (Silicon Cycle in the Mediterranean and Black Seas: An isotopic approach) project will be carried out by Dr.

Diksha Sharma, an experienced researcher at the Centre National de la Recherche Scientifique (CNRS) in France under the supervision of Prof. Damien Cardinal.

This project aims to unravel the intricate biogeochemical silicon (Si) cycling in the Mediterranean Sea (MS) and the Black Sea (BS). These two distinct marine environments offer unique opportunities for scientific exploration.

The MS, with its unique oceanic characteristics, diverse ecosystems, and trophic regimes, provides an excellent opportunity for climate change research. Diatoms, an important phytoplankton group, play a crucial role in primary production and carbon export in this region. However, our understanding of their Si sources and limitations remains incomplete.

By employing stable silicon isotopes (30Si) to analyze dissolved silicic acid and biogenic silica in the deep biogenic silica maxima and deep chlorophyll-a maxima layers, this project will quantify the role of diatoms and Si as nutrients and investigate processes governing dissolved silicic acid concentrations and biogenic silica dissolution in the intermediate and deeper layers of the MS.

Along with this, understanding the seasonal pattern of exported biogenic silica from sediment traps will also be a novel aspect of this project. In contrast, the BS, characterized by its anoxic conditions and complex stratification, presents a unique challenge.

This project will delve into the Si uptake by diatoms, sub-surface remineralization, and biogenic silica release through 30Si analyses, shedding light on nutrient-driven diatom growth and biogenic silica production through hypoxic, anoxic, and H2S rich deep environments of the BS.

Ultimately, this project promises to make a significant contribution to the international GEOTRACES programme and enhance our comprehension of Si cycling in these critical marine ecosystems.