Distribution of heavy metals in sediment along the Southern coast of Vietnam
Bibliographic record
Abstract
Abstract The heavy metals (HM), particularly As, Cd, Pb and Hg, are considered most toxic to biota and environment. In this study, spatial and seasonal distribution of HMs (Cd, Pb, Hg and As) were measured in two sediment fractions (< 63 μm and 63 – 500 μm) collected in the farming area of blood cockle. A total of 104 sediment sampled along the Southern coast of Vietnam between December 2012 and July 2015 were examined. The average concentrations (μg/g) of As, Cd, Pb and Hg in sediment fraction of 63 – 500 μm ranged from 4.16 to 16.8, < 0.004 to 0.219, 9.52 to 17.3 and 0.031 to 0.076, respectively. While, the mean levels (μg/g) of As, Cd, Pb and Hg in sediment fraction of < 63 μm ranged from 4.59 to 12.8, < 0.004 to 0.187, 9.94 to 14.6 and 0.042 to 0.080, respectively. Generally, no statistically significant differences were found for concentrations of HMs in both fractions between two seasons and among provinces. The concentrations of HMs analyzed in sediment were compared to quality guidelines for the protection of aquatic life recommended by the Canadian Council of Ministers of the Environment (CCME) and the Vietnamese organizations (QCVN 43 : 2012/BTNMT). HM levels in all samples were lower than the Vietnamese regulation and the probable effect level in the CCME guideline. However, As levels in 67/103 and 84/104 of two fractions of < 63 μm and 63 – 500 μm, respectively, exceeded the threshold effect level of 7.24 μg/g in the CCME standard. It suggested that As accumulated in sediment in these provinces could be harmful to the aquatic organism.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".