Atmospheric Transport Pathways of Oxidized Mercury at Storm Peak Laboratory
Bibliographic record
Abstract
Mercury is a global pollutant and neurotoxin that bioaccumulates via the food chain and is harmful to the nervous system. Elemental mercury (Hg0) is relatively inert in the atmosphere compared to its oxidized state (HgII). Atmospheric deposition is a major source of mercury to the ecosystem; therefore, atmospheric oxidation makes mercury more bioavailable. This study expands on past work to characterize atmospheric transport regimes of HgII measured at the continental, high-elevation Storm Peak Laboratory (SPL) in Steamboat Springs (3,220m asl). Hourly-averaged measurements of Hg0 and HgII, criteria gases (CO, NOx, O3, SO2), and meteorological measurements from March 12, 2021 to October 10, 2021 and from March 1, 2022 to May 31, 2022 were used to characterize air mass composition and origin at this location. Cluster analysis was applied to hourly 10-day air mass back trajectories, generated using Global Data Assimilation System (GDAS) input meteorology and the Hybrid Single Particle Lagrangian Integrated Transport (HYSPLIT) model. Trajectories were initiated from the location of SPL (40.455°N, 106.744°W) with a starting height of 1000m AGL, determined to closely represent the typical atmospheric pressure at the lab (675 mb). Cluster output was merged with the hourly measurement data to determine if concentrations of Hg0, HgII, and other trace gases were statistically different between transport regimes and by season. The back-trajectories showed prevailing westerlies for the measurement periods, consistent with previous analyses of local wind measurements at SPL. In spring 2021, the highest mean concentration of HgII was associated with northerly transport from continental Canada as well as transport from the north-central Pacific, whereas in both spring 2021 and 2022 trans-Pacific transport was associated with comparably high levels of HgII. These clusters also had the lowest mean concentrations of Hg0, consistent with oxidation chemistry as a source of HgII measured at SPL. For the summer and fall periods, the highest mean HgII concentrations were associated with shorter distance westerly transport. Across all seasons, enhanced HgII concentrations occurred in dry air masses suggestive of free tropospheric origin, and similar transport patterns were found consistent with past research at high-elevation sites.
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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 | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".