Investigating the spatial and temporal distribution of microplastics in the Fraser River and Burrard Inlet (British Columbia, Canada)
Bibliographic record
Abstract
Metropolitan areas, such as Metro Vancouver, are major contributors to microplastic (MP) pollution in adjacent receiving water bodies, including the Fraser River and Burrard Inlet (BC, Canada). Through tidal exchange and hydrological events, these MPs may be exported to the Strait of Georgia (SoG) and eventually to the North Pacific Ocean. Yet, MPs spatiotemporal variability within these dynamic riverine systems and shallow-sided fjords is not well understood. To address this knowledge gap, MPs (>10 µm) were examined at multiple depths in the Fraser River (0.5 and 6 m) and Burrard Inlet (0.5, 30, and 60 m) from January to November 2024, using a newly constructed multichannel MPs sampling apparatus and adapted McLane large-volume pumps. To elucidate potential sinks of MPs in Burrard Inlet, the vertical distribution of MPs in a sediment core was determined. To advance current MP processing efforts, a novel method was developed to extract and quantify MPs from various environmental matrices. Findings revealed pronounced seasonal patterns in the distribution of MPs in the Fraser River and Burrard Inlet. Highest MP concentrations were observed in springtime, and attributed in the Fraser River to the freshet, and in Burrard Inlet to the influx of freshwater from the North Shore mountains snowmelt coupled with the Fraser River freshet inputs through First Narrows. MPs in the Fraser River and Burrard Inlet were primarily small (< 100 µm, ~ 63% of the total MPs), and fragments (85% of the total). In Burrard Inlet, MPs concentrations (mean ± SE) were 58 ± 6 particles per cubic meter of water (MP particles m-3), with no significant difference (p > 0.05) among mean MP concentrations in all three depths (0.5, 30 and 60 m). In the Fraser River, mean MP concentrations were 81 ± 19 MP particles m-3, with concentrations significantly higher at 6 than 0.5 m (p < 0.05), associated with faster water velocities and sediment resuspension. The Fraser River exports 9.88 trillion MPs to the SoG annually, with 64% exported during the spring freshet. This study provides valuable insight for predicting MPs behavior in complex and dynamic coastal and riverine systems.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.000 |
| 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".