Contribution to the study of the seasonal dynamics of trace metals in the open waters at the water-sediment interface from a tropical lagoon estuary

Abstract

The study of the seasonal dynamics of As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, and Zn in the open waters at the water-sediment interface from the lagoon area II of Ébrié system were monitored for a year (from June 2020 to May 2021). In implementation of this study, the water samples were monthly collected near the water-sediment interface from this lagoon area (less than 50 cm) in five sampling sites and, analyzed in accordance to MA 203-Met ICP-MSMS standard. The results were highlighted the relative important of the seasonal trace metals contents of these open waters. All their seasonal trace metals contents were decreased gradually from hot season to flood season. Cr, followed respectively by Cd and Cu were the least abundant; while Ni, followed by As, were the most abundant in these open waters in all seasons over this period.

Trace Metals Behaviors in the Superficial Sediments from a Tropical Lagoon

“…One of transitional waters with a relatively high state of pollution in Côte d'Ivoire is the area II of Ébrié system. This fact has been highlighted by the recent works of Mahi et al [12][13][14]. These studies showed that the open waters of this lagoon area present a relatively significant state of degradation with likely high ecological risks.…”

“…This could essentially explain the low organic content of these superficial sediments during all this period. Biogeochemical processes and the reducer character of its open waters, particularly that of its open water at the water-sediment interface [12][13][14], contribute to the reduction of organic into these substrates. The dominance of these superficial sediments by coarse sand would lead to the obtaining of their medium moisture content.…”

“…Localization of the lagoon area II of Ébrié system [12,14]. This aquatic ecosystem is dominated by depths below -3 m [18;19].…”

“…This study was conducted in the same time as those Mahi et al [12][13][14]. So, the samples of the superficial sediments from this aquatic ecosystem were monthly collected in the five sampling sites (Figure 2), that the characteristics were given by Mahi et al [12].…”

“…The seasonal pH, redox potential, salinity, conductivity, particle size distribution, as well organic matter, dissolved oxygen and moisture contents of the open water at the water-sediment interface used in this study were obtained by Mahi et al [14] in this lagoon area in same the study period. The mean (m), standard deviation (s), Variation Coefficient (VC (%)), Minimum and Maximum values (Min-Max) of the different results obtained were implemented using Statistica software version 13.2…”