Infrared characterization of water uptake by low‐temperature Na‐montmorillonite: Implications for Earth and Mars
Bibliographic record
Abstract
A large fraction of atmospheric mineral aerosol is composed of clays, such as smectites. Smectites are known to expand upon addition of water, and thus their properties in the atmosphere may vary strongly with relative humidity (RH). Here we report on the adsorption of water to Na‐montmorillonite, a smectite clay. We probe the water uptake under conditions representative of the Earth's troposphere, as well as those relevant for the surface of Mars, of which montmorillonite is a proposed component. Using a vacuum chamber equipped with transmission Fourier transform infrared spectroscopy, we find that Na‐montmorillonite contains 10% water by mass at temperatures from 212 K to 231 K at 50% RH. Surprisingly, the water uptake by Na‐montmorillonite is almost as great as that of deliquesced ammonium sulfate. We also find that although water adsorption to Na‐montmorillonite depends strongly on RH, there is not a strong dependence on absolute temperature. In addition, we find the time required for the clay to become saturated with water decreases with increasing water vapor pressure and is much shorter than suggested in previous studies. We discuss the implications of these results for the Earth's troposphere and the potential role of montmorillonite in the Martian hydrologic cycle.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".