Multi-proxy paleoenvironmental study of Lake Ontario coastal lagoons: Frenchman’s Bay and Lynde Creek, Ontario
Bibliographic record
Abstract
European settlement (between 1770 and 1850 CE) and urbanization in the mid-20th century resulted in the rapid degradation and disruption of Lake Ontario watersheds and coastal wetland environments. This study assessed the impacts of historic land use changes and urbanization on sediment and water quality in two coastal lagoons in the eastern Greater Toronto Area: Lynde Creek (LC) and Frenchman’s Bay (FB). Twelve short sediment cores (0.5-2 m) were collected in both lagoons to determine the thickness and distribution of contaminated sediments, using a range of environmental proxies (ITRAX micro-XRF elemental geochemistry, magnetic susceptibility, testate amoebae, loss-on-ignition, AMS 14C, 210Pb chronology). Lithochemofacies were identified by principal component analysis and hierarchical clustering of elemental data. The lagoon stratigraphy consists of a lowermost package of Late Holocene interbedded sand and peat (2 500- 600 14C YBP) overlain by a distinctive ~1-1.5 m thick, organic muddy silt unit (ca. ~1850), representing the European Settlement Layer (ESL). PCA revealed 10 distinctive lithochemofacies representing ESL and underlying natural wetland (NW) deposits. The ESL lower boundary is defined by a rapid increase in magnetic susceptibility and terrigenous elements (Si, K, Ti, Fe, Zr), and lower organic content. The ESL is a basin-wide marker in Frenchman’s Bay and Lynde Creek, signalling the onset of European land clearance, soil erosion and enhanced delivery of terrigenous elements to coastal environments. The transition is also tracked by an increase in Cucurbitella tricuspis, recording increasing basin eutrophication. The onset of urbanization in the mid-20th century is indicated in FB by an upward increase in heavy metals (Zn, Pb), C. tricuspis and elevated calcium (Ca), chlorine (Cl). LC lagoon shows similar elemental trends but with a lower relative abundance of heavy metals. The widespread extent and thickness of the contaminant-impacted layer highlight the need for further assessment and monitoring of lagoon sediment and water quality.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".