据介绍，重力驱动的“海雪”下沉将碳封存在海洋中，构成了调节地球气候的关键生物泵。由于这些聚集体的生物丰富性和缺乏对其沉积物理的直接观察，对这一现象的机械理解模糊不清。
研究人员利用野外设置的无标度垂直跟踪显微镜，对从沉积物捕集器中新收集的海雪聚集体进行微流体动力学测量。该观察揭示了迄今为止未知的彗星状形态，这种形态是由下沉聚集体周围透明的外聚合物晕轮的流体-结构相互作用产生的。
这些看不见的彗尾减缓了单个粒子的速度，大大增加了它们的停留时间。基于这些发现，研究团队构建了一个降阶模型，用于这些黏液嵌入的两相颗粒的Stokesian沉积，为预测性理解海雪铺平了道路。
附：英文原文
Title: Hidden comet tails of marine snow impede ocean-based carbon sequestration
Author: Rahul Chajwa, Eliott Flaum, Kay D. Bidle, Benjamin Van Mooy, Manu Prakash
Issue&Volume: 2024-10-11
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.
DOI: adl5767
Source: https://www.science.org/doi/10.1126/science.adl5767