Mercury Concentration Profile in Sediment Cores of a Tropical Lagoon under High Anthropogenic Activities around an Urban City—Abidjan, Côte d’Ivoire

The present study focuses on the quantification of mercury in sediment cores from Cocody, Banco, Koumassi and Milliardaires bays in Abidjan, Côte d’Ivoire. It aims at assessing the state of mercury contamination of the lagoon bottom using DMA-80 (Direct Mercury Analyser). The automatic analyzer DMA-80 mercury is an innovative instrument for the analysis of mercury at very low content in solid and liquid samples in five minutes, without requiring any prior steps of pretreatment wet. The results showed, according to the lithological description of different bays, that the cored sediments consist of mud, sand, sandy mud or muddy sand with occasional shells. In addition, our results showed the presence of mercury in the sediments of the lagoon bottom at a degree of contamination that varies from moderate to very high according to the calculated contamination factor (CF) values. The highest contamination was observed in Cocody Bay at the surface with a contamination factor of 7.5, while the lowest contamination was observed in Milliardaires Bay at the water-sediment interface with a contamination factor of 1.67. In addition, mercury concentrations compared to sediment guide values (SQGs) reveal that these sediments mostly show occasional biological effects but no toxicity except Koumassi core (sediments at 20 cm depth). Also, dredging, hydrodynamics have probably impacted the mercury content. The depositional environment of mercury metal is therefore a limiting factor for its fate in the aquatic environment.

Antioxidant Activity Evaluation in a Series of Heterocyclic Compounds Derived from 1,8-Diaminonaphthalene

From (2,3-dihydro-1H-perimidin-2-yl)-phenyl, the substitution of OH group in ortho or para position on the phenyl ring, allows us to synthesize the studied compounds. These three compounds have been characterized by conventional spectroscopic methods (NMR and MS). The interest of this work is to review the antioxidant activity of our compounds. The antioxidant activity screening carried out according to FRAP and DPPH methods revealed significant anti-free radical properties for compounds 1 and 2 even at low concentrations. In contrast to the compound 2, compound 3 for which the OH group is substituted in para position has the lowest activity in both cases. Therefore the para position seems to be the least sensitive position to increase the antioxidant activity of this pharmacophore.