Birth of Marine Snow Aggregates

Agglomerates of organic matter called marine snow form in the upper mixed layer of the ocean as a result of primary production, thanks to the phytoplankton. These aggregates form, sink and remineralize creating an emergent flux profile as a function of depth in the ocean called the Martin curve, the micro-physics of which remains hitherto unknown. We recently discovered that marine snow is a multiphase comet-shaped particle that consists of mucus and particulate organic matter [R. Chajwa et al. arXiv:2310.01982 (2023)]. To understand the formation of these aggregates, we numerically study how the multiphase structures spontaneously form in Stokesian suspension in the non-linear regime of number-density perturbations; and find merging and fracture dynamics at long times with a steady state size distribution. We corroborate these findings with experiments in a fluidized bed geometry.