Evaluation of the Fluoride Retardation Factor in Unsaturated and Undisturbed Soil Columns
Bibliographic record
Abstract
Fluorides deposited on the soil surface near aluminum smelters represent a risk for ground water contamination. This study was conducted to evaluate F retention in soils sampled near an aluminum smelter. The F retardation factor ( R ) was evaluated at different depths in four coarse‐textured soils by percolating a Br and F solution under steady‐state conditions through 26 unsaturated and undisturbed soil columns. The convective‐dispersive equation (CDE) and convective‐lognormal transfer function (CLT) models were used to evaluate R , using Br and F breakthrough curves (BTCs) and F accumulation profiles evaluated with oxalate‐extractable F (F ox ). Following percolation of 4.0 to 13.7 pore volumes of F solution through the soil columns, F BTCs were obtained in 5 out of 26 columns. In the other columns, all F remained in the soil profiles, indicating higher F retention. When R was evaluated using F accumulation profiles, the CDE‐evaluated retardation factor ( R CDE ) was consistently higher than the one evaluated with the CLT ( R CLT ), by as much as 111%. This was explained by a difference in the models' behavior near the soil surface. The retardation factor varied among soils and depths by a 20‐fold factor, from 4.4 to 91. The highest retardation factors were obtained in slightly acid and neutral soils. The retardation factor was lower in strongly acid and alkaline soils. The large range of R values obtained and its influence on the velocity of F movement in the soil show that R is one of the critical factors controlling the risk of ground water contamination by F.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| 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 teacher head, 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".