The Lake Togo-Lagoon of Aného is located in the coastal zone where phosphorite mining is carried out. This mining discharges all kinds of waste such as fuel oil into the surrounding environment without prior treatment. Moreover, the hydrosystem receives runoff and river inputs after having crossed and leached from mining and urban soils. This study aims to determine the polycyclic aromatic hydrocarbons (PAHs) contamination in commercially consumed fish species (Chrysichthys nigrodigitatus) from that hydrosystem and the associated health risks for consumers. For that, fish sample collection was performed during the dry season. Afterwards, their muscles, gills, and livers were cut and 12 PAHs were analyzed using gas chromatography coupled with a mass spectrometer (GC-MS). The total PAHs (tPAHs) concentrations in fish tissues ranged from 5.24 to 48.40 µg/kg with average concentration of 14.51 ± 8.95 µg/kg in muscles, from 5.90 to 28.20 µg/kg averaging 14.90 ± 5.19 µg/kg in gills, and from 43.20 to 149.00 µg/kg with an average of 80.74 ± 27.08 µg/kg in livers. The average concentrations of low molecular weight PAHs (LMW PAHs) were 10.82 ± 9.61 µg/kg in muscles, 8.25 ± 5.43 µg/kg in gills, and 47.97 ± 22.56 µg/kg in livers whereas those of high molecular weight of PAHs (HMW PAHs) were 4.10 ± 2.14 µg/kg in muscles, 7.98 ± 3.96 µg/kg in gills, and 32.77 ± 8.66 µg/kg in livers. An overall trend of decreasing concentrations with increasing fish size classes was observed for some PAHs (Naphtalene, Pyrene in muscles, for Pyrene, Benzo(a)Anthracene, Chrysene in gills and for Naphtalene, Phenanthrene in livers). The PAHs in these fish might have pyrogenic and petrogenic sources, with the dominance of pyrogenic, and all of the total hazard quotients (THQ) are less than 1. This situation must not be neglected for better planning sustainable management of the target ecosystem.

La bioaccumulation du cadmium, du plomb et de l’arsenic par les poissons et bivalves couramment pêchés dans le système lagunaire togolais a été évaluée afin d’en estimer les risques sanitaires liés à leur consommation. Il ressort des résultats que tous les poissons analysés sont pollués. Les moyennes des teneurs en cadmium (0,33 mg/kg pour Caranx hippos à 0,98 mg/kg pour Hemichromis fasciatus), en plomb (1,17 mg/kg pour Liza falcipinnis à 2,89 mg/kg pour Lutjanus goreensis) et en arsenic (9,41 mg/kg pour C. hippos à 22,54 mg/kg pour Pomadasys jubelini) sont supérieures aux normes fixées par l’OMS. Les Facteurs de Bioconcentration (FBC) varient de 6,94 à 20,36 pour le Cd, de 9,58 à 23,67 pour le Pb et de 2,30 à 5,52 pour l’As. Quant aux bivalves les teneurs moyennes indiquent une forte concentration en Arsenic (56,06 mg/kg pour Senilia senilis et 47,76 mg/kg pour Crassostrea gasar) suivie du plomb (2,83 mg/kg pour S. senilis et 2,95 mg/kg pour C. gasar) et enfin le cadmium (0,97 mg/kg pour S. senilis et 0,83 mg/kg pour C. gasar). Les FBC varient de 16,6 à 19,14 pour le Cd, de 39,86 à 41,55 pour le Pb et de 19,10 à 34,42 pour l’As. En outre, il a été montré que la bioaccumulation de ces trois éléments varie en fonction de l’espèce considérée ainsi que de son habitat. La consommation de ces poissons et bivalves pourrait avoir des impacts négatifs sur la santé humaine en général et celle des enfants en particulier.

The hydrosystem composed of Lake Togo, Lagoon of Togoville, and Lagoon of Aného is located in the coastal zone of Togo and receives important and different kinds of mining waste that cause its degradation. This study aims to evaluate the physicochemical and metallic quality of these waters and determine the possible sources of these contaminants using geostatistical, multivariate, and special analysis methods. These waters were very mineralized according to the average conductivity (15.51 mS/cm). Average contents (μg/L) in trace elements varied from 2.46 μg/L for As to 141.63 μg/L for Pb. Average levels of Cd, Pb, Cr, and Ni were significantly higher than the WHO standards. Trace elements and physicochemical parameters showed strong spatial variations with the highest values recorded downstream of the hydrosystem. The main possible source of trace element pollution was the intrusion of seawater loaded with phosphate effluent, followed by atmospheric deposition and soil leaching. This hydrosystem, therefore, deserves special attention for better planning its management.