Intercalibration studies of short‐lived thorium‐234 in the water column and marine particles
Bibliographic record
Abstract
Intercomparision of 234 Th measurements in both water and particulate samples was carried out between 15 laboratories worldwide, as a part of GEOTRACES inter‐calibration program. Particulate samples from four different stations namely BATS (both shallow and deep) and shelf station (shallow) in Atlantic and SAFE (both shallow and deep) and Santa Barbara station (shallow) in Pacific were used in the effort. Particulate intercalibration results indicate good agreement between all the participating labs with data from all labs falling within the 95% confidence interval around the mean for most instances. Filter type experiments indicate no significant differences in 234 Th activities between filter types and pore sizes (0.2–0.8 µm). The only exception are the quartz filters, which are associated with 10% to 20% higher 234 Th activities attributed to sorption of dissolved 234 Th. Flow rate experiments showed a trend of decreasing 234 Th activities with increasing flow rates (2‐9 L min −1 ) for > 51 µm size particles, indicating particle loss during the pumping process. No change in 234 Th activities on small particles was observed with increasing flow‐rates. 234 Th intercalibration results from deep water samples at SAFe station indicate a variability of < 3% amongst labs while dissolved 234 Th data from surface water at Santa Barbara Station show a less robust agreement, possibly due to the loss of 234 Th from decay and large in‐growth corrections as a result of long gap between sample collection and processing.
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".