Quantifying Methane Oxidation in Cover Soils of the Vancouver Landfill Using the Stable Isotope Technique
Bibliographic record
Abstract
The stable isotope technique is a methodology that allows for the quantification of biologically oxidized methane (CH4) in a landfill cover. In this methodology, the oxidized fraction of methane is calculated based on the isotopic signature of the emitted CH4, the preference degree of methanotrophic bacteria in consuming methane with lighter isotopes and the isotopic signature of methane within anaerobic zone of the landfill. This study was conducted in four separate operational phases of the Vancouver landfill (VLF). These four phases were grouped into two areas based on the characteristics of the soil used as interim and/or final cover. Methane emission rates were measured using a flux chamber technique. The methane samples, which was collected from the landfill’s anaerobic zones, the flux chambers, and aerobic soil incubations test, were analysed for isotopic signature. δ13C values for methane generated in the VLF ranged between -54‰ and -58‰. All CH4 samples collected from flux chambers were enriched in 13C with δ13C values ranging between -35‰ to -56‰. The overall average oxidation fractionation factor (αox) at the VLF was 1.0266 ± 0.0037 at 25 °C. Methane oxidation ranged from 3 to 73% with mean values of 28% and 34% for two different areas of the landfill. Results suggested that the overall methane oxidation percentage, for a region with similar climatic conditions to Vancouver, may be considered more or less constant throughout the year. As our objective was to compare different sections and cover soil types across the landfill, the use of chambers to capture emitted methane was deemed appropriate. Keywords: Landfill, LFG, methane emission, methanotrophy, methane oxidation, stable isotope.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| 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 teacher head, 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".