Diffusive and advective flux measurements of trichloroethene from soil into a building: a case study
Bibliographic record
Abstract
In order to validate some assumptions and calculations of Johnson and Ettinger's model, a mapping of measured VOC fluxes in a heavily contaminated building was undertaken. To this end, both advective and diffusive flux measurements were carried out under real conditions. Diffusive fluxes were measured with flux chambers recording the initial concentration rise during the first minutes. The results showed high diffusive fluxes and considerable spatial heterogeneity, even at a distance of a few meters. A novel method, described in this article, was used to measure advective fluxes. It appears that the majority of these fluxes originate from two cracks close to poles. Measurements confirmed that diffusive fluxes are independent of the indoor-outdoor pressure differential, whereas advective ones are strongly influenced by the pressure differential. At the building scale, the mass balance is validated, as the variation in concentration within the building can be predicted by the measured fluxes and air exchange rate. However, we show that the order of magnitude of the diffusion coefficient through the slab is particularly high, outside the range of conventionally accepted values. In this building, diffusive fluxes, independent on pressure differences, are clearly dominant while in Johnson and Ettinger's model, the fluxes through the slab depend on the crack surface and vary with pressure. • Advective and diffusive fluxes of TCE into a contaminated house were measured. • Diffusive fluxes exceeded advective despite of active air ventilation. • We found high slab diffusion coefficients and highly localized advective fluxes. • Measurements contradict basic assumptions made in the Johnson & Ettinger model.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".