Hidden Comet-Tails of Marine Snow Impede Ocean-based Carbon Sequestration

Chajwa, R., Flaum, E., Bidle, K. D., Van Mooy, B., & Prakash, M. (2024). Hidden comet tails of marine snow impede ocean-based carbon sequestration. Science, 386(6718), eadl5767.

Link: https://www.science.org/doi/abs/10.1126/science.adl5767

• Abstract

  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 phenomenon is obscured by the biological richness of these aggregates and a lack of direct observation of their sedimentation physics. Utilizing a scale-free vertical tracking microscopy in a field setting, we present microhydrodynamic 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 halos around sinking aggregates. These invisible comet tails slow down individual particles, greatly increasing their residence time. Based on these findings, we constructed a reduced-order model for the Stokesian sedimentation of these mucus-embedded two-phase particles, paving the way toward a predictive understanding of marine snow.