Event-Based Atmospheric Precipitation Uncovers Significant\nEven and Odd Hg Isotope Anomalies Associated with the Circumpolar\nVortex
Bibliographic record
Abstract
The determination of the mass-independent fractionation\nof even\nHg isotopes (even-MIF, Δ<sup>200</sup>Hg) in atmospheric samples\nadds another intriguing feature to the Hg isotope system. Despite\nour lack of sufficient experimental verification and the momentary\nabsence of a valid mechanism to explain its occurrence, even-MIF could\nbe instrumental in understanding the cycle and deposition of atmospheric\nHg. In contrast to slightly positive Δ<sup>200</sup>Hg values\n(<0.30‰) frequently observed in most atmospheric samples,\nlarge Δ<sup>200</sup>Hg values (up to 1.24‰) determined\nin precipitation from Peterborough (Ontario, Canada) stand out and\ncould provide valuable information for the origin of the even-MIF\nmystery. We now report a systematic analysis of high-resolution rainfall\nand snowfall samples collected in winter during cold weather at Peterborough,\nCanada. Dissolved and particulate Hg both displayed large variations\nof odd-MIF (from −0.93‰ to 2.02‰ for Δ<sup>199</sup>Hg), which may result from long-range transportation, as\nthe negative odd-MIF in particulate Hg is likely a result of long-distance\ntransport of arctic atmospheric Hg(II). Dissolved Hg revealed significant\neven-MIF values (from 0.25‰ to 1.19‰ for Δ<sup>200</sup>Hg) and a negative relationship between Δ<sup>200</sup>Hg and Δ<sup>204</sup>Hg, which provide further evidence for\nthe previously proposed conceptual model of Δ<sup>200</sup>Hg.\nDisconnected odd-MIF and even-MIF trends were detected in sequentially\ncollected precipitation samples, which further suggests different\nsources or mechanisms for Δ<sup>199</sup>Hg and Δ<sup>200</sup>Hg. Particularly, the high Δ<sup>200</sup>Hg values\nhighlight the transport of stratospheric Hg through a polar vortex\nto the sampling region, stimulating further systematic investigation.\nThe new Δ<sup>200</sup>Hg data for particulate Hg add to existing\ninformation on atmospheric Hg(II) worldwide, suggesting a global distribution\nof Hg characterized by even-MIF in the atmosphere, and further constrain\nthe model of atmospheric Hg deposition.
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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) | 0.002 | 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".