Geochemical determination of anthropogenic sources of elevated chloride in groundwater and surface water across various land uses of an urbanizing watershed
Bibliographic record
Abstract
Chloride concentrations in natural surface and groundwaters of the Western Lake Ontario Basin are rising, surpassing guidelines for the protection of aquatic organisms. Thus far the observed increases of chloride have been attributed primarily to the application of winter de-icing salts on an increasing impervious area. To develop effective best management practices for chloride application, a complete understanding of the sources of anthropogenic chloride is required. Continuous monitoring and discrete sampling were performed at four research sites within the Credit River Watershed for one hydrological year. To determine sources of chloride, geochemical and isotopic source characterization techniques were applied, including Cl/Na ratios, Cl/Br ratios, deuterium, iodine, artificial sweeteners, tritium, and helium analysis. The highest chloride concentrations in surface and groundwater samples occurred during the winter at the two urban sites. Cl/Na plots suggest that three of the four sites were impacted by road salt to varying extents. Cl/Br ratios revealed further sources including wastewater, and landfill leachate at the most urbanized site. These sources were further confirmed using analysis of deuterium, iodine, tritium-helium and artificial sweeteners. The findings of this study indicate that various anthropogenic sources of chloride must be considered and can be discerned using geochemical and isotopic techniques.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.000 | 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".