Seasonal and Decadal Variations in Lead Sources to Eastern North Atlantic Mussels
Bibliographic record
Abstract
The concentration of Pb and its stable isotope composition were measured in 216 composite samples of 50 blue mussels (Mytilus edulis (M. edulis)) collected quarterly between 1985 and 2005 at three sites along the French Atlantic coast, one in the La Fresnaye Bay and the others in the Loire and Seine River estuaries. Depending on the sites and time periods, Pb concentrations were 5-66 times higher than the natural background value for the North Atlantic. Even for the samples with the lowest Pb concentrations, the isotopic signature of Pb is very different than that of the regional natural Pb, suggesting that most of the bioaccumulated Pb is anthropogenic in origin. Stable Pb isotope ratios measured in the mussels differ markedly from that of Pb emitted in Western Europe as a result of leaded gasoline combustion, which was still a dominant source of contaminant Pb to the atmosphere during most of our study period. The isotope composition of Pb in the mussels was instead more typical of that of the Pb released to the environment by wastewater treatment plants, municipal waste incinerators, and industries such as metal refineries and smelters. Continental runoff, rather than atmospheric deposition, is therefore identified as the leading transport pathway of Pb along the French Atlantic coast. From the strong seasonal variations in (206)Pb/(208)Pb ratios in the mussels from the Seine Estuary site we also conclude that the resuspension of contaminated sediments, triggered by high river runoff events, is a chief factor affecting the bioaccumulation of Pb in M. edulis . The value of this organism as a biomonitor of coastal contamination is thus further demonstrated.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.002 |
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".