In collaboration with PIs in Applied Math (Richard McLaughlin and Roberto Camassa) and Marine Sciences (Carol Arnosti), we have been examining the effect of density stratification on the sinking flux of marine snow particles to the deep ocean, which drive biological hotspots and play a major role in the ocean carbon cycle (funded by the NSF Collaborations in Mathematics and Geosciences program). The sinking of marine snow is an important component of the ocean carbon pump, which removes CO2 from the surface ocean through phytoplankton growth and subsequent export to the deep ocean.

As follow-up to this work, we received a grant from the NSF Chemical Oceanography program to study diatom particle aggregation in turbulent flows. This project, termed AFT (Aggregate Formation in Turbulence), aims to improve models of particle aggregation in the ocean surface layer following large phytoplankton blooms, currently the major unknown factor determining the efficiency of the carbon pump. This project is in collaboration with Adrian Marchetti from UNC Marine Sciences, Kai Ziervogel from the University of New Hampshire, and Jenny Prairie from the University of San Diego.

Rotating_Grid_schematic

 

Experimental setup of the aggregate formation experiments in which advanced imaging will be used to track particle transport and aggregation in a rotating grid-stirred turbulence tank.

 

particle_agg

An example series of images from a preliminary aggregate formation experiment demonstrating the 3D tracking of two marine particles encountering one another and forming a larger aggregate.