CONCENTRACIÓN DE CADMIO EN AGUA, SEDIMENTOS, Eichhornia crassipes Y Pomacea canaliculata EN EL RÍO GUAYAS (ECUADOR) Y SUS AFLUENTES

Abstract

In Ecuador there is evidence of contamination by Cd in the Gulf of Guayaquil, however, little is known about the contamination by this metal in its tributaries. Evaluating the contamination by cadmium in water, sediments, flora as Eichhornia crassipes and fauna as Pomacea canaliculata in the Guayas river and the tributaries, Daule and Babahoyo rivers was the main purpose of this research. Nine stations were sampled, five samples of water, sediment and organisms were taken on each location. Cd concentrations and bioconcentration factors (BCF) were determined. In addition, pH, temperature and salinity parameters were measured. The concentrations of Cd in water were not detectable, while in sediments eight of a total of nine stations exceeded the maximum permissible limits according to the Ecuadorian standard and the Canadian Environmental Quality Guidelines. However, the bioavailable concentrations of the metal in the sediment were lower than the probable effect level (PEL) and the Canadian reference value, minimizing possible damage to the biota. The water hyacinth accumulated higher concentrations of Cd than the gastropod and presented BCF greater than one, indicating that it is a good biomonitor of Cd, unlike the snail. Correlation was also observed between the physical and chemical parameters and the availability of the metal in the sediment and its accumulation in the organisms. It is concluded that there is contamination by Cd in the three rivers and that the E. crassipes can be used as biomonitor of bioavailability of the metal in the ecosystem.