Carbon and Hydrogen Isotope Fractionation of Benzene, Toluene, and <i>o</i> ‐Xylene during Chemical Oxidation by Persulfate
Bibliographic record
Abstract
Abstract Experiments were performed to investigate the carbon and hydrogen isotope fractionation of benzene, toluene, and o ‐xylene (BTX) during chemical oxidation by unactivated persulfate at two concentrations (8 and 20 g/L). Carbon enrichment ( ϵ C ) values of −1.7 ± 0.1‰ for benzene, −0.64 ± 0.1‰ for toluene and −0.36 ± 0.04‰ for o ‐xylene were obtained. No significant hydrogen enrichment ( ϵ H ) was observed for benzene, while the hydrogen enrichment for toluene and o ‐xylene were −20 ± 3‰ and −23 ± 2‰, respectively. The dual isotope plot (Δδ 13 C vs. Δδ 2 H) for benzene and o ‐xylene revealed a distinct fractionation trend compared to the majority of the biodegradation data compiled from the literature; however, no unique trend was observed for toluene. The significant carbon and/or hydrogen enrichment, and the distinct trend observed on the dual isotope plot suggest that compound specific isotope analysis (CSIA) can potentially be used to monitor the chemical oxidation of BTX by persulfate, and to distinguish treatment areas where persulfate or biodegradation reactions are occurring for benzene and o ‐xylene.
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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) | 0.001 | 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".