A geochemical characterization of southwestern Ontario's breathing well region
Bibliographic record
Abstract
A physical and geochemical characterization has been completed for a 1400 km2 breathing well zone in a Middle Devonian, karstic carbonate aquifer system in southwestern Ontario. Breathing wells are unusual because they draw in or emit large volumes of air, in response to fluctuations in atmospheric pressure. This behavior causes gas exchange between the atmosphere and the subsurface and quite commonly the expelled gases are depleted in oxygen and enriched in carbon dioxide. To better understand this unique atmosphere-geosphere connection, geochemical, hydraulic, and barometric data were used to investigate the interconnectivity within the breathing well zone. Regionally, 102 sites were sampled for groundwater chemistry characterization, and 10 wells located within the breathing well zone were monitored monthly over one year. Spatial and time series analyses reveal that most wells affected by the breathing well phenomena are drilled through the Dundee Formation and finished in the underlying Lucas Formation. The results suggest that a significant amount of unsaturated void space exists within the Lucas Formation, and that hypoxic, high CO2 gases are generated by several processes and emitted during low atmospheric pressure periods. Locally, groundwater shows remarkable chemical and isotopic stability over the 1 year monitoring period, which suggests a very large degree of storage in the aquifer. Regional distributions of groundwater facies types are strongly influenced by local hydrogeological conditions and consist dominantly of Na-Ca-HCO3, Ca-Mg-HCO3, Ca-Sr-HCO3, and Ca-Mg-SO4-types. The groundwater composition includes detectable levels of dissolved oxygen and elevated concentrations of sulphate. Sulphur isotopic data indicate that the sulphate results from two endmember processes: evaporite dissolution and oxidation of metallic sulphides. Evidence for the latter process also includes elevated concentrations of iron and trace metals including Zn, Pb, Cu and Ag. Very high strontium up to 80 mg/L comes from the dissolution of celestite (or celestine; SrSO4) in the absence of gypsum. This provides insight on the solution-karstification process that appears to have formed the breathing well system and may provide a tool for mapping the system in areas to the north where void space is saturated and air exchange is prevented.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".