Changing nitrogen deposition with low δ<sup>15</sup>N−NH<sub>4</sub> <sup>+</sup> and δ<sup>15</sup>N−NO<sub>3</sub> <sup>−</sup> values at the Experimental Lakes Area, northwestern Ontario, Canada
Bibliographic record
Abstract
Ammonium deposition at the International Institute for Sustainable Development Experimental Lakes Area (IISD–ELA), in northwestern Ontario, Canada, has doubled in the last 45 years and thus is no longer among the low nitrogen (N) deposition sites in North America. This may be related to the concurrent intensification of Manitoba agriculture to the west and upwind of the ELA. Large increases in ammonium deposition at the ELA were important in driving the observed trend and increased the NH 4 + to NO 3 − ratio of input to aquatic and terrestrial systems. Stable isotope analyses of two years of bulk (wet and dry) atmospheric deposition revealed very large ranges in δ 15 N−NH 4 + (22‰ range), δ 15 N−NO 3 − (18‰), and δ 18 O–NO 3 − (19‰). Few other δ 15 N−NH 4 + , δ 15 N−NO 3 − , and δ 18 O–NO 3 − values have been published for Canadian precipitation. Increases in δ 15 N of NH 4 + and NO 3 − in July occurred with increases in total N deposition. The wide range and seasonal trends of δ 15 N and δ 18 O values in ELA precipitation mean that studies characterizing N inputs to watersheds and lakes require an ongoing and comprehensive annual sampling regime. Global trends of declining δ 15 N of N deposition evident in lake sediment records may be a result of increases in NH 4 + deposition with lower δ 15 N−NH 4 + values. Similarly, the relationship in Lake Superior between increasing NO 3 − and lower δ 15 N−NO 3 − values may be explained by increased atmospheric deposition of N with low δ 15 N values.
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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) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| 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; both teacher heads agree on what is shown here.
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".