Influence of groundwater discharge on stream chloride concentrations in mixed urban land use sub-watersheds receiving road salt applications
Bibliographic record
Abstract
Freshwater salinization from elevated chloride (Cl) concentrations is a major threat to aquatic ecosystems in cold climate urban areas. Rising Cl levels in urban streams in summer suggest groundwater discharge is an important and increasing contributor, yet its role is poorly quantified. This study examines the influence of groundwater discharge on spatial and seasonal variations in Cl concentrations in three urban streams. Two approaches are used: (1) analysis of Cl concentration–discharge ( C–Q ) data over a 24-month period, and (2) assessment of longitudinal stream Cl and radon-222 inferred groundwater discharge patterns across seasons and flow conditions. Negative C–Q relationships in summer suggest groundwater is likely the dominant source of Cl, while flatter relationships during winter indicate decreased groundwater influence. Longitudinal data reveal that local groundwater contributions and surrounding land use changes can cause high spatial and temporal variation in Cl concentrations in small streams. For instance, stream Cl concentrations increased where high groundwater discharge coincided with urban land use, in contrast to declines observed in forested areas. Dilution in larger streams lessened the impact of groundwater discharge on stream Cl levels with substantial increases observed in an urbanized high groundwater discharge area in a small stream (>800 mg/L), but only minor increases observed in a larger stream (<30 mg/L). The findings indicate that sampling only at sub-watershed outlets may miss localized hotspots, potentially underestimating Cl contamination risks. More detailed spatial and temporal monitoring is essential to properly assess and manage urban freshwater salinization.
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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 | 0.000 |
| 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 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".