Migration of Colloids through Nonfractured Clay-Rich Aquitards
Bibliographic record
Abstract
This study examined characteristics and controls on diffusive transport of colloids through nonfractured, clay-rich glacial till. The range in molecular weight (M(w) of the colloids tested (five polymers and three natural dissolved organic carbons) was 910-15 450 Da. Hydrodynamic diameters increased from 1.45 to 6.05 nm, and aqueous diffusion coefficients decreased from 2.6 x 10(-10) to 6.3 x 10(11) m2 s(-1) with increasing M(w). All colloids were subjected to diffusion testing using undisturbed core samples placed in double reservoir diffusion cells. All colloids decreased in concentration with time in the spiked reservoirs. Concentrations in the receiving reservoirs increased for only the four smallest colloids. The lack of breakthroughs for larger colloids was attributed to straining. Transport modeling using data from colloids exhibiting breakthrough shows effective diffusion coefficients and tortuosity factors decrease from 1.5 x 10(-10) to 6.5 x 10(-11) m2 s(-1) and from 0.6 to 0.3, respectively, with increasing M(w). The effective porosities are slightly less than total porosity (0.31). Our data suggest diffusive transport through clay-rich aquitards is limited to colloids with mean diameters < 2-2.2 nm and that measuring the diameter of dissolved organic carbon from nonfractured clay-rich aquitards may be an effective method to estimate effective pore throat diameters of these media.
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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 | 0.001 | 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".