Surface-subsurface hydrologic exchange and nutrient dynamics in a groundwater-fed stream, Bauman Creek, Ontario, Canada
Bibliographic record
Abstract
The stream-riparian-aquifer interface plays a major role in the regional flow of nutrients and contaminants due to a strong physical-chemical gradient that promotes the transformation, retention, elimination or release of biogenic elements. To better understand the effects of the near-stream zones on stream biogeochemistry, we conducted a field study on a small groundwater-fed stream located in the rare Charitable Research Reserve, Cambridge, Ontario, Canada. This study focused on monitoring the spatial distributions of nutrient elements in the riparian and hyporheic zones. Several piezometer nests were installed near stream to obtain data on the groundwater chemistry and sampled from May 2013 to May 2014. In addition to piezometer groundwater sampling, a series of passive (diffusion) water samplers, known as peepers, were installed along longitudinal and lateral transects centered on the stream during the Summer of 2013. Equilibrium time of peepers was determined in the laboratory to be ~28 days. The spatial and temporal variation in surface water and groundwater chemistry (carbon, nutrients) was observed between locations. Notably, groundwater upwelling along the stream resulted in distinctly different groundwater types and associated nitrate concentrations between small distances in the riparian zone (<4m). Notably, high concentrations of nitrate (13.5 mg l-1 NO3--N) were observed in deep groundwater and surface water. The flux of nitrate to the receiving Grand River ranged from 47 kg N d-1 in July and August to over 133 kg N d-1 in October. After the upstream source of the stream surface water concentrations of nutrients (nitrate, ammonium, sulfate and carbon) did not significantly change before the stream outlet. Although reduction of nitrate and sulphate were reported in the riparian zone of the stream, this did not significantly influence the chemistry of the adjacent stream water. Also, minimal retention in the hyporheic zones limited reduction of reactive compounds (NO3- and SO4-2) within the stream channel. This study suggests dissolved organic carbon (DOC) and residence time of water in the hyporheic zone and in surface water limited denitrification.
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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 | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".