Tree-Ring Nitrogen Isotopes Reflect Anthropogenic NO<sub><i>X</i></sub> Emissions and Climatic Effects
Bibliographic record
Abstract
Anthropogenic emissions of atmospheric nitrogen have increased over the last century, but the monitoring of nitrous oxide concentrations is only recent. Can trees from temperate regions be used to infer past changes in nitrogen cycles? To considerthis question, we investigate nitrogen isotope (delta15N) ring series from pine and beech trees near Montréal, and beech specimens of Georgian Bay Islands. The delta15N values show coherent intertree and interspecies trends, independent of the sapwood-heartwood transition zones, implying that these results reflect local environmental conditions. At both sites, short-term isotopic fluctuations correlate directly with precipitation and inversely with temperature. Long-term isotope decreases of 1.5 to 2 per thousand suggest progressive changes in soil nitrogen after 1951. In Georgian Bay, an additional important change is inferred on the basis of a 1.5 per thousand increase initiated after 1971. At both sites, long-term series correlate with a proxy for NOx emissions. We propose that the contrasted long-term delta15N changes of Montreal and Georgian Bay reflect deposition of NOx emissions from cars and coal-power plants, with higher proportions from coal burning in Georgian Bay. This research suggests that tree-ring delta15N series may record both, regional climatic conditions and anthropogenic perturbations of N cycles.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Science and technology studies | 0.001 | 0.005 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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".