Seyler Patrick, Elbaz-Poulichet F. (1996). Biogeochemical control on the temporal variability of trace element concentrations in the Oubangui river (Central African Republic). Journal of Hydrology, 180 (1-4), p. 319-332. ISSN 0022-1694.
Titre du document
Biogeochemical control on the temporal variability of trace element concentrations in the Oubangui river (Central African Republic)
Année de publication
1996
Type de document
Article
Auteurs
Seyler Patrick, Elbaz-Poulichet F.
Source
Journal of Hydrology, 1996,
180 (1-4), p. 319-332 ISSN 0022-1694
Dissolved Ba, Cd, Co, Mn, Mo, Ni, Rb, Sb, Sr, U and V were measured in the Oubangui river (Central African Republic) during a complete flood period. The dissolved concentrations vary by factors ranging from 1.4 to 8.2 as a function of river discharge : Sr, Ba, Rb and Mo concentrations decrease with rising stage ; Ni, U, Sb, Cd, V and Mn concentrations increase with rising stage. These distributions are explained by a mixing of quick flow, mostly surface runoff with delayed flow, mostly groundwater. The dual origin of stream waters is demonstrated by the major element ratios, which are close to a silicate end-member during the high-flow period and trend towards a carbonate end-member during the low-flow period. Moreover, geological heterogeneities in the Oubangui basin may play a role in the variation of concentrations observed at the basin outlet. The previously indicated presence of a subsurface carbonate sequence in the lower part of the basin is confirmed. Cd, V, Mn and Co show peak concentrations during decreasing stage. We suggest that biological processes such as release from phytoplanktonic material and dissolution of oxides or carbonate phases may explain this maximum. (Résumé d'auteur)
Plan de classement
Transports solides et qualité physico-chimique des eaux [062MECEAU04]
Descripteurs
CHIMIE DE L'EAU ; GEOCHIMIE ; ELEMENT EN TRACE ; VARIATION TEMPORELLE
