The deformation of marine snow enables its disaggregation in simulated oceanic shear
The deformation of marine snow enables its disaggregation in simulated oceanic shear
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DOI：
10.3389/fmars.2023.1224518
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发表时间：
2023-07
影响因子：
3.7
通讯作者：
Yixuan Song;A. Burd;M. Rau
中科院分区：
文献类型：
--
作者：
Yixuan Song;A. Burd;M. Rau
了解水动力对团聚体大小和结构的影响是预测水环境中质量输运的关键。颗粒的聚集理论已经建立，但我们对变形过程、生物结合力及其对水生聚集体破碎的影响的了解仍然有限。为了更好地理解破碎过程和附着力，我们在实验室中对硅藻和微塑料聚集体进行了破碎实验。我们捕捉到大量的事件显示变形和随后破碎的振荡剪切流这些聚集体。聚苯乙烯和聚乙烯团聚体表现出明显的破碎强度，并提供了硅藻团聚体生物结合强度的比较上限和下限。此外，我们采用了一个力平衡模型，利用拉格朗日应力历史和形态来评估粒子簇内的吸引相互作用。我们发现，聚集体的分形结构导致破碎强度随尺寸的幂律，并且时间积分应力控制了整个破碎过程。我们还发现，聚集体通过剪切暴露的变形而减弱，使其在非常低的剪切速率下解体，这是海洋环境的典型特征。
Understanding the effect of hydrodynamics on aggregate size and structure is key to predicting mass transport in the aquatic environment. Aggregation theory of particles is well established but our knowledge of deformation processes, biological bonding forces, and their effects on fragmentation of aquatic aggregates is still limited. To better comprehend fragmentation processes and adhesion forces we implemented breakup experiments with diatom and microplastic aggregates made in the laboratory. We captured a substantial number of events showing deformation and subsequent fragmentation of these aggregates in an oscillatory shear flow. Polystyrene and polyethylene aggregates showed distinct fragmentation strengths and provided comparative upper and lower limits to the biological bonding strength of the diatom aggregates. Additionally, we employed a force balance model to evaluate attractive interactions within clusters of particles using the Lagrangian stress history and morphology. We found that the fractal structures of aggregates led to a power law of breakup strength with size and that time-integrated stress governed the overall fragmentation process. We also found that the weakening of the aggregates through deformation with shear exposure enabled their disaggregation at very low shear rates typical of the ocean environment.