Microplastic fate and behaviour in model freshwater mesocosms
Bibliographic record
Abstract
Microplastics (plastic particles <5.0 mm in diameter) have been detected in freshwater ecosystems worldwide, yet little is known about the fate and behaviour in Canadian freshwater systems. Knowledge gaps include the influence of ice formation, water quality (i.e., nutrients enhancing both biofilm and filamentous algae growth), and the presence of aquatic plants (cattails) on fate and behaviour of microplastics. I conducted two field-based mesocosm studies at the Prairie Wetland Research Facility at the University of Manitoba. The first mesocosm study was a long-term 622-day study where five different microplastic types (foams, films, fragments, microbeads and fibres) were added to understand long-term microplastic fate and behaviour during distinct seasons and overwintering. The second study was a short-term 251-day study using model constructed freshwater mesocosms where both films and fibres were added to understand whether nutrients, cattails and overwintering affected microplastic fate and behaviour. In both studies, distinct open water seasons (spring, summer, fall), over wintering and subsequent spring melt of ice lead to unique behaviours of different types of microplastics i.e., resuspending, and settling. In the second study, I found that biofilm and filamentous algal growth were enhanced by the nutrient addition were the likely drivers of microplastic settling and resuspension behaviour in the mesocosms through biofouling, defouling (biofilms) and trapping microplastics as enhanced filamentous algal growth occurs. Overall, substrate may not be the ultimate sink for microplastics as previously thought, as microplastic behaviour (e.g., aggregation, biofouling), and characteristics of the aquatic ecosystem (e.g., climate, ice crystal formation, and water temperature-density effects) will add to the complexities of microplastic behaviours and will determine their ultimate fate in freshwater ecosystems. This thesis has begun to advance our understanding of microplastic fate and behaviour in Canadian freshwater systems, their cyclical/seasonal dynamics, biofilm as a driver of microplastic behaviour, resuspension/settling dynamics due to ice formation and subsequent melting, and the potential for floating wetlands using cattails as a bioremediation technique.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".