Photodissolution of copper from resuspended coastal marine sediments
Bibliographic record
Abstract
Abstract Total dissolved Cu (TDCu) was photoproduced from suspensions of estuarine and coastal marine sediments from varied biogeochemical settings after exposure to the equivalent of 1 day of sunlight. Net photorelease (defined as the difference between mean light and dark concentrations) of TDCu occurred in 10 of 13 experiments and ranged from 1.1 nM to 11.8 nM (0.88–46.1 nmol Cu g −1 dry sediment). Photorelease was observed over environmentally relevant total suspended sediment concentrations ranging from 38 mg L −1 to 460 mg L −1 . The magnitude of photorelease was directly correlated to the 1 M HCl‐extractable Cu and Fe contents of sediments. Photoreleased Cu was likely associated with organic matter and/or Fe oxyhydroxides, both of which are photoreactive. Photoreleased TDCu persisted for at least 24 h after irradiation indicating that the Cu was not immediately scavenged back onto particles, most likely because it was stabilized by complexation with dissolved organic matter. Results of this study are important because a conservative estimate of the areal flux of TDCu from irradiation of a modest suspended sediment loading of 100 mg L −1 in the top 100 cm of a sunlit water column would be 460 nmol m −2 d −1 , which is comparable to or significantly larger than benthic and riverine fluxes of the metal in estuarine and coastal environments. These results suggest that photolytic fluxes are a significant yet previously unrecognized source of bioactive Cu to natural waters.
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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) | 0.001 | 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".