International conference on heavy metals in the environment

Mercury contamination of waters and soils is an environmental problem of increasing concern throughout the Amazon River baxin. In order to better understand the sources of Hg in a major tributary to the Amazon, a monthly time series spanning an entire hydrological cycle has been measured for two rivers of the Upper Madeira drainage basin. At both gauging stations, we observe a hydrological control on the temporal variability of the dissolved and the total mercury (THg) concentrations: they increase in phase with increasing discharge and we observe the highest THg concentrations at the peak stage. Mercury associated with particles represents more than 90% of the TH g in high-water period, and tends to decrease only slowly with falling river stage. This suggests that weathering processes are still active during this last stage. One of the principal factors controlling the distribution of Hg in Andean waters is apparently the process of soil erosion. (Résumé d'auteur

Weathering over a large range of erosion solid products: Insights from Amazon river depth-samplings

International audienc

El mercurio en la amazonia boliviana : sintesis del conocimiento sobre la contaminacion por mercurio en aguas, sedimentos y peces del rio Beni y sus tributarios, impactos sobre las poblaciones riberenas; C 010057498

La contaminacion por mercurio de los rios constituye un problema cada vez mas preocupante en toda la cuenca amazonica. Este mercurio tiene origenes naturales como las emisiones volcanicas o termales, la disolucion de algunas rocas o la erosion de los suelos que, en esta zona del mundo, presentan concentraciones en metales pesados muy elevadas. El mercurio puede provenir tambien de las actividades de explotacion auriferas, cada vez mas numerosas en la Amazonia, region afectada por la "fiebre del oro" nuevamente en los anos 70. (Résumé d'auteur