PARENT SESSION

3F - Coastal Zone Mgnt
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Zaucke, P.¹, ¹

(WEP/186) Mercury, arsenic and selenium distribution in a tropical estuarine lagoon (Côte d'Ivoire and Ghana, Western Africa).

Claon, Stéphane^{1, 3}, Bouho , Jerome², Kouadio , Luc Philippe ¹, Sess , Daniel ², Casellas, Claude³, Potin-Gautier, Martine⁴, Rambaud, André³, ¹ University of Cocody, Abidjan, Côte d'Ivoire³ University of Montpellier, Montpellier, France² CIAPOL, Abidjan, Côte d'Ivoire⁴ University of Pau, Pau, France

ABSTRACT- The coastal Aby Lagoon (Côte d'Ivoire and Ghana, Western Africa) is the receiving body of the Tano River which has gold mining activities in its catchments area in Ghana. This study aimed to evaluate contaminants distribution in a tropical climate and determine pertinent indicators or bioindicators of three telluric or anthropic pollutants: mercury, arsenic and selenium. Total concentrations of these elements were evaluated in environmental samples (water, sediments, plants and fish species) from the end of the dry season (May) to the end of the rainy season (August). Water and sediments were sampled in the river, near the banks of the lagoon and in the central channel (<0.5m and >5m). In water, the highest values were observed in May and under the halocline (>5m). In sediments concentrations of 0.54-16.54 mg Hg.kg^-1 dw, 2.8-100 mg.As.kg^-1dw and 0.5-4.6 mg.Se kg^-1dw were observed. The highest values were found in the deep channel influenced by the halocline. The highest concentrations in fish species were observed in Chrysichthys maurus which is the most locally consumed fish. Nevertheless these values still under the limit value recommended by WHO. Plants species content in mercury varied from 0.05-0.82 mg.kg^-1dw while arsenic and selenium concentrations were 0.06-7.42 and 0.27-2.02 mg.kg^-1dw respectively; the most accumulating plant being Pistia stratiotes.

Key words: Arsenic , Mercury, Selenium, Tropical Estuarine Ecosystem