Spatial and Temporal Stability of Major and Trace Element Leaching in Urban Stormwater Sediments
Bibliographic record
Abstract
Urban sediment generated by stormwater management techniques are highly contaminated with various trace elements. The characterization of trace element speciation and mobility are critical information to improve environmental risk assessment. This study investigates the spatial and temporal variability of major and trace element release from a sedimentary layer in Django Reinhart stormwater infiltration basin (Chassieu, eastern suburbs of Lyon, France). Sampling was conducted for 3 zones and two dates. Chemical characterization was performed (X-Ray diffraction, ICP-AES). The samples were submitted to Acid Neutralization Capacity & Base Neutralization Capacity ANC-BNC tests, according to European standard 14429 (AFNOR, 2015). Solid matrices were mixed with acid or basic solutions and physicochemical parameters and major and trace element release (i.e. Al, Ca, Fe, P, S, Si, Cu, Zn and total carbon) were followed as a function of pH. The results show that the urban sediment has no significant spatial and temporal variability with regards to element release. This observation is all the more surprising that the samples were collected in three contrasting zones regarding stormwater supply and hydric conditions. Element release follows the same trends as a function of pH with a bell-shaped solubilization curve exhibiting with the highest solubility at extreme pH values. However, the samples showed slight differences concerning the release of major elements. Such differences are related to slight differences in total mineral contents (organic matter, carbonates…) and chemical composition of the sediments. The results show that despite the varying environmental conditions, the sediment chemical properties can be considered as very stable and uniform over space, depending mainly on the local geochemical context and watershed characteristics. This study highlights the strength and affluence of the information obtained by ANC-BNC tests on the release of major and traces metal elements by urban sediments and brings relevant information regarding the management of these sediments.
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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 | 0.001 | 0.001 |
| 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) | 0.000 | 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".