Heavy metals pollution in bottom surface sediments, and metal fluxes through the sediment/ water interface, Milliardaires bay, Ebrie lagoon (Côte d’Ivoire)
 

Accepted 24^th June, 2014

INZA Bakary1*, Yao Koffi Marcellin1, Etchian Assoi Olivier3, Soro Métongo Bernard 1 ,Trokourey Albert 2, Bokra Yobou2

¹ Centre de Recherches Océanologiques (CRO). Laboratoire de Chimie. 29 Rue des pêcheurs /BP V 18 Abidjan
Côte d’Ivoire. Fax – (225) 21 35 11 55
² Université Félix Houphouët Boigny. UFR SSMT. Laboratoire de Chimie Physique.22 BP 582 Abidjan 22.
³ Laboratoire de biologie et cytologie animales, UFR- SN, Université Nangui Abrogoua – 02 BP 801 Abidjan 02,

Côte d’Ivoire.

*Corresponding author E-mail: inza.bakary@yahoo.fr
 

Milliardaires Bay, Ebrie Lagoon, bottom surface sediments and near bottom waters were sampled and analysed for cadmium, lead, zinc and copper using atomic absorption spectrophotometry. Contents of these four metal elements were determined, also, in interstitial water sediment, obtained by centrifugation at 4000 rpm for 20 min. Statistical analysis using the Pearson correlation matrix showed that there is a significant relationship between metals on the one hand, and on the other hand metals and certain physico-chemical parameters of the sediments. The toxic capacity of the heavy metals analyzed in the sediments was evaluated by using the index of geoaccumulation (Igeo). The results obtained revealed high indices of Igeo for all metals. The concentrations of Cd and Pb belong to classs (4-5) of Müler and vary from strongly to extremely polluted. Those of Zn and Cu indicate a pollution of the area studied with average values of Igeo which vary from class 2 to class 3. Net metals input, calculated on the basis of sedimentation rate and concentration in the uppermost sediments, gave mean values fluctuating between 17 and 646 ng/m2/h. Concentrations of metals (Cd, Pb, Zn and Cu) remobilized from sediments due to diffusion were calculated. The results showed that the diffusion of these elements, from sediments towards overlying water, represents a substantial proportion of the input (Cd: 29.5%; Pb: 5.8%; Zn: 8.7%; Cu: 4.1 %).

Key words: Heavy metals, correlation, potential toxicity, remobilisation, Ebrié Lagoon

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