A Continental and Marine-Influenced Tree-Ring Mercury Record in the Old Crow Flats, Yukon, Canada
Bibliographic record
Abstract
Gaseous elemental mercury (Hg0) concentrations in the atmosphere have been increasing due to anthropogenic activities since the onset of colonial mining in the 17th century. However, accurate measurements of atmospheric Hg, including temporal trends, are mostly limited to recent decades. Natural environmental archives including tree rings show promise for reconstructing atmospheric concentrations of Hg0. In this paper, we present a new white spruce (Picea glauca) tree-ring Hg record (1696–2005) from the Old Crow Flats in northern Yukon. The record we present shows an increase in tree-ring Hg concentration (a proxy for gaseous Hg0 concentration) between 1748 and 1990 at a rate of +3.3% per year. A decrease in measured Hg is observed at the end of the record between 1990 and 2005, which may reflect the success of international regulations to reduce emissions including Hg. When compared with two other sites (a continental and marine location) in northwest Canada, there is not only some coherence in Hg trends at the regional scale but also some unique differences, suggesting that the location may influence atmospheric Hg0 available for assimilation. Further local factors within a site, such as soil moisture, may also affect the efficiency of this uptake. Results from this study highlight the need to better understand intra-site and inter-site differences in measured tree-ring Hg, and we recommend the continued development of a spatially resolved tree-ring Hg network in the northern boreal forest. Such records will be useful for developing better atmospheric Hg and global Hg models.
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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 | 0.000 | 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".