An inverse modelling approach to constrain 7Be cycling in the subpolar North Atlantic
Bibliographic record
Abstract
Beryllium-7 is a short-lived cosmogenic radionuclide that has been used as a tracer of atmospheric deposition at the sea surface and of physical processes in the upper ocean. These applications generally assume that (i) the fraction of marine 7 Be in particulate form is negligible, and/or (ii) the interactions between the particulate and dissolved forms of 7 Be in seawater can be neglected. In this study, we test different steady-state models of upper ocean 7 Be cycling from measurements of total 7 Be and particulate 7 Be activities collected at two stations of the GEOVIDE cruise in the subpolar North Atlantic (May–June 2014). The most complete model includes vertical advection , vertical diffusion, gravitational settling, radioactive decay , atmospheric deposition , and the reversible exchange between dissolved 7 Be ( 7 Be d ) and particulate 7 Be ( 7 Be p ). This model reproduces the measured 7 Be activities at both stations to within their uncertainties (±1 standard deviation). In the East Greenland-Irminger Current (station 51/60), models that do not consider adsorption and/or desorption can still reproduce the measured activities, while in the southern Labrador Sea (station 69) models that neglect reversible exchange or desorption poorly fit the data. Thus, 7 Be d at station 51/60 could have been supplied entirely by surface deposition, whereas 7 Be d at station 69 originated at least partly from the release of particulate 7 Be into solution. The subsurface 7 Be p maxima, present at both stations, seem to require a flux of 7 Be between particles and solution at station 69 but not at station 51/60. At both stations, most of the total 7 Be deposited at the ocean surface was removed by radioactive decay , with at most 5% removed by sinking of 7 Be p , suggesting that reversible exchange can be neglected in applications of total 7 Be as a tracer for atmospheric deposition. However, reversible exchange is important to consider in applications of 7 Be d as a deposition tracer, with a maximum bias of 40% when reversible exchange is neglected. The steady state assumption does not alter our results regarding the solid-solution exchange of 7 Be, but it does result in a significant bias when deriving atmospheric 7 Be tot deposition fluxes from water column 7 Be tot inventories. Overall, our findings suggest that reversible exchange could significantly influence the oceanic cycling of 7 Be at some locations, and should not be systematically neglected when using 7 Be d as an oceanic tracer.
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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 | 0.016 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.016 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.000 |
| Research integrity | 0.000 | 0.003 |
| 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 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".