Adsorption of Free Lead (Pb <sup>2+</sup> ) by Pedogenic Oxides, Ferrihydrite, and Leaf Compost
Bibliographic record
Abstract
Iron oxides and organic matter have a high capacity to adsorb Pb and concomitantly maintain a low free Pb 2+ activity in solution. It is, therefore, important to assess the adsorption capacity of naturally occurring materials and evaluate their potential to reduce toxicity. The free Pb 2+ activity was measured in the solution in equilibrium with ferrihydrite (a synthetic Fe oxide), two field‐collected pedogenic amorphous oxides, and leaf compost. The experiment used a factorial design varying total Pb loading and solution pH. The results show that ferrihydrite was more efficient in lowering Pb aqueous concentration than the two pedogenic oxides. Furthermore, of the two pedogenic oxides examined, a higher Pb 2+ activity was maintained in solution at equilibrium with the most crystalline phase, which also has a lower surface area relative to the other adsorbents. Leaf compost maintained a significantly higher free Pb 2+ activity, relative to the various oxides. The experimental data could be fitted to a semi‐mechanistic model predicting free Pb 2+ activity as a function of total Pb loadings and pH, with R 2 varying from 0.77 to 0.92.
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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".