Impacts of Deep Water Structuring on Seabed Pollution Levels: Evidence from Radiogenic Isotopes (Pb-Sr-Nd) in Surface Sediments Along the Reykjanes Ridge (Southern Iceland)
Bibliographic record
Abstract
Significant proportions of debris containing pollutants are present in remote and unknown areas of the deep seabed. Although identified amongst the top threats to marine ecosystem and human health, the mechanisms that particulate materials entered rapidly these deep ocean systems are still matter of debate. This study use depicting radiogenic isotopes (Sr, Nd, Pb) to question the relationship between the seabed sediment contamination levels and ambient stratification in the North Atlantic Ocean. On this basis, we studied sedimentary inputs and related mechanisms from more recent sequences collected at three locations representing different deep-sea hydrodynamics along the Reykjanes Ridge. Sm-Nd concentrations, as well as Sm-Nd-Sr-Pb isotopic compositions, were determined in digested and purified fraction of the sediment cores by Thermal Ionization Mass Spectrometry (TIMS). The Sm-Nd-Sr-Pb data simply reflect the scale of the perturbation of upper part (0-15 cm) of the sequences, which is much more pronounced in east flank than crossing and west bordering ridge areas. The Pb-Pb systematics show that the intensity of water mass mixing modulates degree of contamination and induced the modal transport of detrital components. As consequence of ambient stratification in this region, two major transport processes of pollutant downwards to the sediments are proposed: (i) sediments entrainment in the eastern flank and over ridge axis primarily dominated by vertical flux of particulates controlled by repackage and dislocation by strong mechanical mixing; and (ii) in the west flank, advection of abyssal waters, due to well-stratified mixing layer, provides particulates from the NEADW1 and DSOW.
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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 | 0.005 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.003 |
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".