Microplastics and other Anthropogenic Contaminants: from Source to Sink in the Canadian Environment
Bibliographic record
Abstract
Anthropogenic particles (AP), including microplastics and microfibers, are a ubiquitous contaminant in the environment. Due to the mounting evidence of their persistence, accumulation and toxicity, the sources, release pathways and fate of AP warrant further investigation in order to identify and develop effective mitigation efforts. This thesis aims to (1) investigate the abundance and composition of AP assemblages in environmental sinks, (2) explore environmental transport pathways for AP in the Canadian environment, (3) assess AP sources and release pathways; and (4) explore opportunities for diverting these releases to the environment. This thesis documents anthropogenic microfibers, including those composed of natural and semi-synthetic materials, as a major component of AP contamination in the Canadian environment. Further, this work shows, for the first time, that fractionation of AP occurs as particles are transported from sources to remote environments. Evidence from sediment samples indicates that fractionation occurs such that microfibers, particularly those composed of anthropogenically-derived natural and semi-synthetic materials, undergo long-range transport to remote areas whereas, non-fibrous particles tend to settle closer to source regions. As a result, microfibers from blue jeans, the world’s most popular garment, have similar abundance in Arctic sediments as in sediments from populated urban source regions. This work provides further evidence supporting the use of washing machine filters for mitigating microfiber emissions from laundering. This thesis also shows that secondary, external dryer filters can be an effective means for diverting releases of microfibers during laundering. By expanding investigation to include semi-synthetic and natural textile fibers and advancing methods for the confident enumeration and identification of microfibers in environmental samples, this thesis has led the shift in our scientific understanding of what constitutes AP contamination, and specifically microfiber pollution.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.008 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".