How does the interaction between photosynthetic organisms in the ocean's surface and its large-scale circulation govern the cycling of nutrients in the sea?

As an isotope geochemist with a strong interest in global-scale ocean biogeochemistry, I use stable isotope tracers to study this interaction, in research that has been funded by the Swiss National Science Foundation with support from the US National Oceanic and Atmospheric Administration.

My research in Prof. Jorge Sarmiento's ocean biogeochemistry group at Princeton combines observational isotopic data with ocean general circulation model studies to gain a process-based understanding of the controls on oceanic stable isotope distributions, specifically the stable isotopes of silicon, an element that is vital to the growth of siliceous phytoplankton such as diatoms. These simulations demonstrate that the isotopic composition of silicon dissolved in seawater bears integrative information on how large-scale nutrient transport interacts with locally enhanced biological productivity to produce the oceanic Si distribution.

In other research funded by the National Aeronautics and Space Administration, I collaborate with Carolina Dufour and Ivy Frenger in Prof. Sarmiento's group to study the physical processes that control the upwelling, transport and subduction of nutrients and carbon in the Southern Ocean.

Results from an ocean general circulation model simulation (MOM3 P2A) that deconvolves Si into its preformed and regenerated components. The plots show the isotopic composition of total dissolved Si and these two components at a model depth of ~2000m. From the modelling study of de Souza et al. (2014).