Laraque Alain, Moquet J. S., Alkattan R., Steiger J., Mora A., Adèle Georges, Castellanos B., Lagane C., Lopez J. L., Perez J., Rodriguez M., Rosales J. (2013). Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river : the Orinoco, Venezuela. Journal of South American Earth Sciences, 44 (SI), p. 4-17. ISSN 0895-9811.
Titre du document
Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river : the Orinoco, Venezuela
Année de publication
2013
Auteurs
Laraque Alain, Moquet J. S., Alkattan R., Steiger J., Mora A., Adèle Georges, Castellanos B., Lagane C., Lopez J. L., Perez J., Rodriguez M., Rosales J.
Source
Journal of South American Earth Sciences, 2013,
44 (SI), p. 4-17 ISSN 0895-9811
Seasonal variations of total dissolved fluxes of the lower Orinoco River were calculated taking into account four complete hydrological cycles during a five-year period (2005-2010). The modern concentrations of total dissolved solids (TDS) of the Orinoco surface waters were compared with data collected during the second half of the last century published in the literature. This comparison leads to the conclusion that chemical composition did not evolve significantly at least over the last thirty to forty years. Surface waters of the Orinoco at Ciudad Bolivar are between bicarbonated calcic and bicarbonated mixed. In comparison to mean values of concentrations of total dissolved solids (TDS) of world river surface waters (89.2 mg l(-1)), the Orinoco River at Ciudad Bolivar presents mainly low mineralized surface waters (2005-10: TDS 30 mg l(-1)). The TDS fluxes passing at this station in direction to the Atlantic Ocean between 2005 and 2010 were estimated at 30 x 10(6) t yr(-1), i.e. 36 t km(-2) yr(-1). It was observed that the seasonal variations (dry season vs wet season) of total dissolved fluxes (TDS and dissolved organic carbon (DoC)) are mainly controlled by discharge variations. Two groups of elements have been defined from dilution curves and molar ratio diagrams. Ca2+, Mg2+, HCO3-, Cl- and Na+ mainly come from the same geographic and lithologic area, the Andes. K+ and SiO2 essentially come from the Llanos and the Guayana Shield. These findings are important for understanding fundamental geochemical processes within the Orinoco River basin, but also as a baseline study in the perspective of the development of numerous mining activities related with aluminum and steel industries; and the plans of the Venezuelan government to construct new fluvial ports on the lower Orinoco for the transport of hydrocarbons.
Plan de classement
Hydrologie [062]
Description Géographique
VENEZUELA ; ZONE TROPICALE ; ORENOQUE
Localisation
Fonds IRD [F B010060396]
Identifiant IRD
fdi:010060396
