State of trace element contamination of sediments from the Nangbéto hydroelectric dam lake (Togo)
Bibliographic record
Abstract
The Nangbéto hydroelectric dam lake, which is a spillway for agricultural input residues, urban and industrial effluents present in the Mono basin, is exposed to all forms of pollution. The aim of this work is to estimate the content of seven trace elements present in the sediments of the aforementioned lake in order to assess the ecological risk incurred by the aquatic biocenosis and therefore by man. Forty-two sediment samples (21 per season) are realized in different areas of the Lake. Cd, Pb, Ni, Cu, Cr, As and Hg are measured out in the sediments by the flame atomic absorption spectrophotometer in these pre-mineralized samples. The results show average contents varying from the lowest level 0.04 mg / kg for Hg to the highest 12.15 mg / kg for Cu in the rainy season and from 0.03 mg / kg for Hg and for As to 9.14 mg/kg for Cu in the dry season. All of these values are below Canadian sediment quality standards. The strongest average geoaccumulation indices (Igeo) are obtained for Pb with values less than 2. The mean values of the contamination factor (FC) are less than 1. The mean indices of contamination (Im) are less than 2, threshold d 'an onset of polymetallic contamination. The ecological risk (Ri) in relation to the contamination of the sediments of the Lake with trace elements is low in any season (Ri <40) and this implies a low risk of contamination of the biocenosis. However, the present study only deals with metallic trace elements. It does not take into account other pollutants, nor the potential "cocktail" effects between them. Additional work should therefore be continued in this direction to consolidate the low risk recorded for the biocenosis. Le Lac du barrage hydroélectrique de Nangbéto qui constitue un déversoir des résidus des intrants agricoles, des effluents urbains et industriels présent dans le bassin du Mono est exposé à toutes formes de pollution. Le but de ce travail est de quantifier les teneurs de sept (7) éléments traces dans les sédiments dudit Lac afin d’évaluer le risque écologique encouru par la biocénose aquatique et partant par l’homme.Quarante-deux (42) échantillons de sédiments (21 par saison) sont échantillonnés dans différentes zones du Lac. Le Cd, Pb, Ni, Cu, Cr, As et Hg sont dosés dans les sédiments par le spectrophotomètre d’absorption atomique à flamme dans ces échantillons minéralisés. Les résultats montrent des teneurs moyennes variant de la plus faible teneur 0,04mg/kg pour le Hg à la plus forte (12,15mg/kg) pour le Cu en saison pluvieuse et de 0,03 mg/kg pour le Hg et pour l’As à la plus forte (9,14 mg/kg) pour le Cu en saison sèche. Toutes ces valeurs sont inférieures aux normes canadiennes de qualité des sédiments. Les plus forts indices de géoaccumulation (Igeo) moyens sont obtenus chez le Pb avec des valeurs inférieures à 2. Les valeurs moyennes de facteur de contamination (FC) sont inférieures à 1. Les indices moyens de contamination (Im) sont inférieurs à 2, seuil d’un début de contamination polymétallique. Le risque écologique (Ri) par rapport à la contamination des sédiments du Lac en éléments traces est faible en toute saison (Ri < 40) et cela implique un faible risque de contamination de la biocénose. La présente étude ne porte toutefois que sur les éléments traces métalliques. Elle ne tient compte ni des autres polluants, ni des effets "cocktail" potentiels entre eux. Un travail complémentaire devra donc être poursuivi dans ce sens pour consolider le faible risque enregistré pour la biocénose.
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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 | 0.000 | 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 teacher head, 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".