Distribution and health risk assessment of cadmium, lead, and mercury in freshwater fish from the right bank of Senegal River in Mauritania.

Clarias gariepinus (African catfish) and Oreochromis niloticus (Tilapia fish) from the right North bank of the Senegal River in Mauritania (Rosso, Boghé, and Kaédi) were sampled during 1-year monitoring and tested for lead (Pb), cadmium (Cd), and mercury (Hg) levels. Fishing from the Senegal River is an essential source of food for the local population and these two species are the most common. Muscle presents higher Hg concentrations than liver and gills for both species. Gill Hg concentrations from Kaédi are higher than Boghé and Rosso for both species. The Cd levels measured in gills were low in the different locations and revealed high variation throughout the 1-year study. No significant differences were observed between concentrations of Cd in Clarias gariepinus and Oreochromis niloticus parts. Statistical treatment did not show a considerable variation of Pb concentration between the different parts, revealing lower levels in gills from Boghé than the ones from Kaédi and Rosso. The associated human health risk was calculated from the concentration levels using the target hazard quotient (THQ) approach. Even though all the THQ values and the hazard index were lower than 1 for the determined trace metals when the exposure frequency was not greater than three times a week, eating frequency in the studied locations sometimes is greater than five, thus posing a health risk, especially at Kaédi and Boghé.

Assessment of Trace Metals in Camelus dromedarius Meat from Mauritania.

In Mauritania, the dromedary breeding is the most widespread pastoral activity, and it is considered as the first source of animal protein; however, the research on meat is relatively rare compared with fish, especially in relation with the presence of trace metals. In this work, livers, kidneys, and muscles of 25 Camelus dromedarius were collected from butcheries in Nouakchott (Mauritania) between February and April 2020 to study the concentration of trace metals (three essential metals: cooper (Cu), iron (Fe), and zinc (Zn), and four toxic metals: mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb)). Statistical treatment did not show significant differences associated with age (P = 0.7004), sex (P = 0.9353), or type of diet (0.9951) in the found concentration of the target substances, but the differences were significant between metals and between organs (P < 0.0001). The mean concentrations of the essential metals were 0.80 mg/100 g for Cu, 6.02 mg/100 g for Fe, and 3.28 mg/100 g for Zn, and the ratios between these concentrations were significant (P < 0.0001 in all cases), with [Fe] > [Zn] > [Cu]. Cu was most concentrated in the liver, Fe in the kidney, and Zn in muscle. The mean concentrations of toxic metals were 0.055 mg/kg for As, 0.064 mg/kg for Cd, 0.040 mg/kg for Pb, and 0.027 mg/kg for Hg. They also exhibited significant difference between organs. Hg and Pb showed their largest concentrations in the liver, whereas As and Cd reached their maximum values in the kidney. Therefore, the found concentrations in all cases were lower than the admissible level of trace metals.

Hydrocarbon pollution in Atlantic coast of Mauritania (Levrier Bay Zone): Call for sustainable management.

Levrier Bay is an important fishing area which is under growing anthropogenic pressures seriously threatening this treasure. Among these pressures Polycyclic Aromatic Hydrocarbon are of great environmental concern. Therefore, 16 EPA-PAHs were analyzed using GC-MS in Perna perna species and sediment. Comparison with Dakar (Senegal) and Moroccan coasts shows that PAHs levels are strikingly lower than that of heavily polluted Dakar coast (2474 µg/kg); nevertheless, comparable to Moroccan Casablanca and Tangier coasts (245 and 351 µg/kg, respectively). Ratio analysis indicates the predominance of pyrogenic sources and partial contribution of automotive traffic for the half of 4 sites. Furthermore, statistical analys shows that there are no significative differences, except for Benzo(b)Fluorentene in P. perna tissue and 4 PAHs (Fluorene; Fluorenthene; Pyrene; diBenzo(ah)Anthracene and dBahANT) in sediment for sites samples. Furthermore, bioconcentration indicates that P. perna is an excellent PAHs bioindicator. This points the necessity for immediate introduction of a sound Pollutants monitoring system.