Concentrations and total mass storage of fine sediment, potentially toxic elements (PTEs) and phosphorus in the channel bed of an urban river: a multi-year study
Bibliographic record
Abstract
Abstract Purpose Given the rapid growth of people living in urban and peri-urban areas, this study examined the downstream trends in concentrations and determined the total storage of potentially toxic elements (PTEs) and phosphorus (P) associated with fine-grained sediment (0.45 to 63 µm) stored in the channel bed of an urban river. Materials and methods Samples were collected from seven sites along McMillan Creek (watershed area = 55 km 2 ) in the city of Prince George, British Columbia, Canada, between 2010 and 2016 using a resuspension approach. Grabs samples were also collected from two key tributaries and a large culvert. Results and discussion Some elements (e.g., As, Mn and P) decreased in a downstream direction due to inputs from agricultural sources in the headwaters, while others (e.g., Cr, Cu, Pb and Zn) increased downstream reflecting inputs from urban sources in the lower part of the watershed. Several PTEs increased significantly due to a large culvert which supplied road-deposited sediment (RDS) and other urban materials. In some cases (e.g., As, Mn, Zn) PTE concentrations exceeded Canadian sediment quality guidelines (SQGs) for the protection of aquatic organisms. While concentrations were similar for most years, they were elevated in 2016 which may reflect higher rainfall prior to sample collection. The average total storage of fine-grained sediment in the channel bed of McMillan Creek was 155 t (4198 g m −2 ), while for PTEs this ranged from 0.01 kg (0.0002 g m −2 ) for Hg to 1130 kg (30.7 g m −2 ) for Mn. Conclusions The channel bed of an urban river stored large amounts of fine sediment, PTEs and P, with concentrations that exceeded SQGs for some elements. Given the expected increase of people living in urban and peri-urban areas, more studies are required to assess the impacts of this growth on the amount and quality of fine-grained sediment stored in urban rivers.
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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 | 0.001 | 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".