Measurement of <sup>238</sup> U/ <sup>235</sup> U ratio in black spruce seedlings to fingerprint the source of uranium taken up by black spruce trees as a biogeochemical sampling medium
Bibliographic record
Abstract
This study explored the measurement of 238 U/ 235 U ratios in black spruce seedlings as a tracer to investigate the origin of U taken up by this biogeochemical sampling media. Inductively coupled plasma quadrupole mass spectrometer (ICP-QMS) and neutron activation (NAA) analyses of the 238 U/ 235 U ratios in the total digested (HF/HNO 3 -aqua regia) portions of substrates (soil and peat) treated with 200 ml aliquots of 100, 250, and 400 mg/l of aqueous solutions of depleted uranium (DU) exhibited a substantial deviation from the accepted natural value of 137.88. Similarly, the measured 238 U/ 235 U ratios in stems of seedlings grown in the DU-dosed substrates ranged from 174 to 210 and are linearly correlated with the dose of DU applied. The elevated 238 U/ 235 U ratio in the seedlings suggests that U taken up by the plants is derived predominantly from the labile DU components in water rather than the component adsorbed onto mineral phases in the substrate. Consequently, it was concluded that the U contents in vegetation used as a biogeochemical sampling medium are derived from the labile components in groundwater and/or surface water. The precision and accuracy of the measured ratios were compared with the 238 U/ 235 U ratios of in-house granite and uraninite reference samples.
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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 | 0.000 |
| 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) | 0.000 | 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".