Bathymétrie d’une baie lagunaire et son incidence sur la répartition des métaux lourds : cas de la baie d’Abouabou en lagune Ebrié, Côte d’Ivoire

La lagune Ebrié et ses baies sont le siège d’une sédimentation active notamment par les métaux lourds (zinc, fer, cuivre, manganèse, mercure et cadmium). La baie d’Abouabou, qui appartient à cette lagune, n’échappe pas à ce phénomène. Plusieurs facteurs peuvent influencer la répartition de ces métaux dans les fonds lagunaires. A partir de la bathymétrie de la baie, il a été mis en évidence l’influence de celle-ci sur la répartition de ces métaux. La nouvelle carte bathymétrique réalisée a révélé un taux de comblement de la baie de l’ordre de 14 cm/an entre 1979 et 2000.Mots-clés: lagune Ebrié, baie d’Abouabou, métaux lourds, bathymétrie, Côte d’Ivoire Bathymetry of a bay and its impact on the variation of heavy metals: cas of Abouabou bay in Ebrié Lagoon, Côte d’Ivoire The Ebrié lagoon and its bays are the area of an active sedimentation especially by the heavy metals polluting (zinc, iron, copper, manganese, mercury and cadmium). It is the case of the bay of Abouabou of the Ebrié lagoon. Several factors can influence the variation of these metals in the lagoon. From the bathymetry, it was highlighted the influence of this one on the distribution of these metals. Moreover bathymetry revealed that this bay undergoes a filling which is estimated at 3 m between 1979 and 2000.Keywords: EbriéLagoon, Abouabou bay, heavy Metals, Bathymetry, Côte d’Ivoir

Contamination, risk, and source apportionment of potentially toxic microelements in river sediments and soil after extreme flooding in the Kolubara River catchment in Western Serbia

Climate change is contributing to an increase in extreme weather events. This results in a higher river flooding risk, causing a series of environmental disturbances, including potential contamination of agricultural soil. In Serbia, the catastrophic floods of 2014 affected six river basins, including the Kolubara River Basin, as one of the larger sub-catchments of the large regional Sava River Basin, which is characterized by large areas under agricultural cultures, various geological substrates, and different types of industrial pollution. The main aim of this study was to establish the sources of potentially toxic elements in soil and flood sediments and the effect of the flood on their concentrations. Field sampling was performed immediately after water had receded from the flooded area in May 2014. In total, 36 soil samples and 28 flood sediment samples were collected. After acid digestion (HNO3), concentrations of the most frequent potentially toxic elements (PTE) in agricultural production (As, Cd, Cr, Cu, Ni, Pb, Zn) and Co which are closely related to the geological characteristics of river catchments, were analyzed. The origin, source, and interrelations of microelements, as well as BACKGROUND: values of the PTE of the river catchment, the pollution index (Pi), enrichment factor (Ef), and geological index (Igeo), were determined, using statistical methods such as Pearson correlations, principal component analysis (PCA), and multiple linear regression (MLRA). The content of the hot acid-extractable forms of the elements, PCA, and MLRA revealed a heavy geological influence on microelement content, especially on Ni, Cr, and Co, while an anthropogenic influence was observed for Cu, Zn, and Cd content. This mixed impact was primarily related to mines and their impact on As and Pb content. The pseudo-total concentrations of all the analyzed elements did not prove to be a danger in the catchment area, except for Cu in some samples, indicating point-source pollution, and Ni, whose pseudo-total content could be a limiting factor in agricultural production. For the Ef, the Ni content in 59% soil and 68% flood sediment samples is classified into influence classes. The similar pseudo-total contents of the elements studied in soil samples and flood sediment and their origin indicate that the long-term soil formation process is subject to periodic flooding in the Kolubara River Basin without any significant changes taking place. This implies that floods are not an endangering factor in terms of the contamination of soil by potentially toxic elements in the explored area