Transport of hexavalent chromium in the vadose zone by capillary and evaporative transport from chromium ore processing residue
Bibliographic record
Abstract
Column tests were conducted to evaluate the transport of Cr from underlying chromium ore processing residue (COPR) through the vadose zone in capped and uncapped scenarios and to determine if an asphalt cover system is a viable containment strategy. Four large (140 mm diameter) columns and one small (50 mm diameter) column were filled with COPR underlying a silty sand. Wet–dry cycling (representing precipitation events) induced suction gradients in the uncapped columns. At termination, the uncapped columns contained 10–120 mg/kg Cr on the surface (background Cr level, 8.3 mg/kg), and the capped columns had Cr concentrations equal to background levels, indicating that the capped surface limited Cr migration to the surface. The smaller column was constructed to study the evaporative transport of Cr by simulating a heat source (i.e., sunshine) to increase suction. Soil specimens from the surface of the small-diameter, uncapped column were as high as 410 mg/kg Cr(VI) after 4 weeks. A series of numerical analyses was conducted to interpret and validate the experimental results and to quantify Cr(VI) transport through composite asphalt caps. Through column testing and numerical analysis, in a controlled condition, Cr was found to migrate from COPR in the vadose zone by evaporation and capillary rise, but a controlled, capped condition effectively limited Cr migration.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".