Assessing the Origin of Sulfate Deposition at the Hubbard Brook Experimental Forest
Bibliographic record
Abstract
Abstract The geographical and chemical origin of SO 2− 4 deposition has become a concern, because anthropogenic S emissions have influenced the biogeochemistry of forested ecosystems and surface waters. Our aim was to evaluate the origin of SO 2− 4 in bulk precipitation at the Hubbard Brook Experimental Forest (HBEF), New Hampshire. We analyzed 26 years of archived bulk precipitation samples for sulfur stable isotopes. We compared the δ 34 S values with anthropogenic SO 2 emissions, the relative contribution of sea salt aerosols (as the SO − 4 /Na + ratio in precipitation), and temperature and solar radiation effects on the long‐term patterns of δ 34 S values. The long‐term pattern of δ 34 S values in bulk precipitation could be explained partly by the relative contribution of marine SO 2− 4 or solar radiation but not by temperature variation or anthropogenic SO 2 emissions. The high variability of the δ 34 S values of various fossil fuels makes it difficult to use stable S isotopes for identifying whether changing fossil fuel use is affecting the δ 34 S values in bulk precipitation. The seasonal pattern of δ 34 S values in bulk precipitation (significantly higher values in the winter than the summer) may be explained by the temperature dependence of the isotopic shift during SO 2− 4 formation in the atmosphere. A greater relative contribution of marine SO 2− 4 during the winter also may have contributed to the higher δ 34 S values in the winter. Previous investigations may have overestimated the role of biogenic emissions in affecting the δ 34 S pattern.
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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 | 0.001 | 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) | 0.009 | 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".