Hidden comet-tails of marine snow impede ocean-based carbon sequestration

Gravity-driven sinking of "marine snow" sequesters carbon in the
ocean, constituting a key biological pump that regulates earth's
climate. A mechanistic understanding of this phenomena is obscured by the
biological richness of these aggregates and lack of direct observation of
their sedimentation physics. Utilizing a scale-free vertical tracking
microscopy in field setting, here we present micro-hydrodynamic
measurements of freshly collected marine snow aggregates from
sediment-traps. Our observations reveal hitherto unknown comet-like
morphology, arising from fluid-structure interactions of transparent
exopolymer halo around sinking aggregates. These invisible comet-tails
slows down individual particles, dramatically increasing their residence
time. Based on these findings, we construct a reduced order model for the
Stokesian sedimentation of these mucus-embedded two-phase particles,
paving the way towards a predictive understanding of marine snow.