Biochar‐induced formation of Zn–P‐phases in former sewage field soils studied by P <i>K</i>‐edge XANES spectroscopy
Bibliographic record
Abstract
Abstract Biochar is proposed as a soil amendment for metal immobilization. Studies on former sewage field soils have indicated that biochar addition immobilized Zn, probably by the precipitation of Zn phosphates. Direct evidence of the presence of these mineral phases was still lacking. We investigated the colloidal precipitate obtained after ultracentrifugation of the soil‐water extract a biochar particle and a corresponding bulk soil sample from a sewage field soil that had been amended with 5% (w/w) biochar by P K‐edge XANES spectroscopy. The P K‐edge XANES spectrum of a colloidal precipitate visually resembled spectra of a synthetic Zn phosphate [Zn3(PO4)2] and of hopeite (Zn[6]Zn2[4]PO4·4H2O). Spectra evaluation by principal component analysis (PCA) and linear combination fitting (LCF) confirmed the presence of Zn‐P‐phases in the colloidal precipitate and, to a lesser extent, in the biochar and bulk soil sample. The P speciations varying in differently sampled soil compartments point to a small‐scale heterogeneity of the biochar‐induced P transformation processes.
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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".