Selective Log of Scientific Papers | 2020

[1] Clayton et al., 1990 – Effects of Advancing Freeze Fronts on Distributions of Fine-grained Sediment Particles in Seawater and Freshwater

Summary (4/30). This work discusses an experimental study of sediment (dirt) particles in water as it freezes. It assumes some level of mixing has occurred sufficient enough for the sediment to be suspended in the water. The experiment is performed in a small tube with insulated edges to simulate natural scenarios. The authors track the change in salinity and sediment distribution in the ice. The findings suggest salinity removal is higher for slower freeze rates, and the same appears to be true for the sediment. However, sediment much less sediment is removed than salt, with 94% remaining in the ice. Finer particles migrated further than coarser sediment particles.

Discussion. This study says a lot of interesting things, but it is important to note the authors do not touch on mechanisms or venture to guess why sediment particles act different than salt. To me, it implies further dependence on particle size which is reflected by the distribution of sediment by size. Does this suggest HCN (or other organic molecules) will be less resistant to removal than salt? Is the difference in particle sizes significant enough to matter for HCN as it does with sediment used?

Addendum. I think it is safe to equate dissolved molecules (i.e. solutes) with suspended particles. I found this interesting virtual lab that helped me conceptualize the idea. It shows how water will break down salt into the atoms it is made of, perhaps with a slight charge. Alternatively, sugar will break down but only into individual sugar molecules. Fundamentally, these are still particles suspended in the water. We might imagine that the inter molecular forces are more important than larger particles, but fundamentally, they are just particles suspended in water. Therefore, the basics physics should still be applicable. For more on the physics, see the next paper (Remble and Worster 1999).

Further reading: Corte 1962; Reimnitz and Kempema 1979, 1987;

[2] Remble and Worster 1999 – The interaction between a particle and an advancing solidification front

Intro Summary (5/1). I am still reading through this but I wanted to start by reviewing the basic mechanism here as an introduction to the paper (as defined in the paper). When an ice surface approaches a particle in the liquid, the distance (H) between the two shrink. As it gets within a critical distance, intermolecular forces (e.g. van der Waals interactions) come into play and force the two apart. Whether the particle becomes entrapped depends on whether the ice front velocity exceeds a critical velocity that is essentially faster than the particle will move due to these forces. This was known prior to this paper, and this paper explores the idea further. I’ll summarize the entire paper after I finish it, but for now I want to discuss this idea as it relates to my project.

Schematic diagram of a freezing front impinging upon
a foreign particle. From paper. Explanation in text above.

Summary (5/11). This work uses the fundamental physics of particle entrapment to calculate critical solidification velocities (i.e. how fast the water freezes) needed to trap a particle of a given size. They consider the effects of different scenarios of inter molecular forces and briefly consider the effect of buoyancy on the process. As a particle approaches the ice interface, thermomolecular pressures repel the particle. However, within one particle diameter, the process is slowed. Once the solidification velocity reaches a critical point, the particle will become entrapped. The critical velocity is inversely related to the particle radius (e.g. larger particles move slower). Significant buoyancy differences will effect the forces at play, either hindering or encouraging particle entrapment.

Discussion. This is an interesting look at the role of intermolecular forces in this process. I want to look back at Buffo et al. (2018 and 2020) to see if 1) he references this paper and 2) how it relates to his work. I know I’ve seen van der Waals interactions mentioned in the code at the very least. Worster et al. mention that particles with different conductivity will react differently, so I need to think about the conductivity of organics vs water (probably closer than salt?). There is another point in here where Worster says that the higher thermal gradients promote particle repulsion, but that seems to conflict with sea ice observations which suggests thermal gradients are a major factor. This is also only mentioned in passing, so I don’t know what to make of it. My main take away is to investigate intermolecular forces more closely and the role they play.

Further Reading. Israelachvili 1992; Sen et al., 1997; Dash et al., 2006

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