Compound specific isotope analysis to evaluate in situ transformation of a complex mixture of substituted chlorobenzenes in a pilot constructed wetland system
Bibliographic record
Abstract
Constructed wetlands can be a suitable remediation technique for the treatment of industrial contaminants via transfer (i.e., non-destructive) and transformation (i.e., destructive) processes. Providing direct evidence of in situ transformation using concentrations and biogeochemical parameters alone is challenging. Compound specific isotope analysis (CSIA) is a widely used tool to assess in situ transformation of contaminants based on changes in their stable isotope signatures. In this work, we evaluated the potential of CSIA to identify and possibly quantify the in situ transformation of six NO2- and NH2-chlorobenzenes in complex aqueous samples from a pilot constructed wetland system. No significant changes in δ13C, i.e., ≤2‰ were observed for any of the target compounds despite the contaminant concentration decreased by more than 99% between the inlet and outlet of the system. Using multi-element CSIA of carbon, hydrogen, and nitrogen and laboratory-derived isotope enrichment factors, we successfully identified and quantified the extent of in situ transformation of 2,3-dichloroaniline (2,3-DCA) in the pilot constructed wetlands. The isotopic trends provide evidence for aerobic biotransformation as a dominant pathway in the surface flow planted wetlands; whereas sorption was identified as the likely process in planted and unplanted upflow gravel bed wetlands during the initial wetland operation periods. Another major contaminant from the NO2-chlorobenzene group, i.e., 2-chloronitrobenzene (2-CNB), showed negligible δ13C, and small δ2H (±20‰) and δ15N (±2‰) isotope fractionation. No laboratory-controlled CSIA studies are yet available for 2-CNB biotransformation to characterize transfer and transformation processes. This study highlights the applicability of CSIA as a quantitative tool for 2,3-DCA in dynamic environmental conditions of wetlands and the need for pathway-specific isotope enrichment factors for the successful CSIA application of other target compounds.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".