The dissolved load of the Amazon River is generally considered to be lowlyimpacted by anthropogenic activities. In this work, based on the chemical and hydrologicaldatabase of the Environmental Research Observatory—HYBAM (http://www.ore-hybam.org), we explore the importance of the Peruvian Foreland petroleum activity on the dis-solved Na and Cl fluxes of the Amazon River. The main result of this study allows ussuggesting that oil extraction activity, concentrated in the El Tigre River basin, a small foreland watershed in the Peruvian Amazon, influenced drastically the Na and Cl expor-tation of the Amazon River during the 2006–2007 period. During these years, the dis-solved exportations of this basin represented almost 20 % of the annual dissolved ClAmazon flux and almost 12 % of the annual dissolved Na Amazon flux for a mean annualdischarge\1 % of the Amazon River discharge. Since th...

In Ecuador and Peru, geochemical information from Pacific coastal rivers is limited and scarce. Here, we present an unedited database of major element concentrations from five HYBAM observatory stations monitored monthly between 4 and 10 years, and the discrete sampling of 23 Andean rivers distributed along the climate gradient of the Ecuadorian and Peruvian Pacific coasts. Concentration (C) vs. discharge (Q) relationships of the five monitored basins exhibit a clear dilution behavior for evaporites and/or pyrite solutes, while the solute concentrations delivered by other endmembers are less variable. Spatially, the annual specific fluxes for total dissolved solids (TDS), Ca2+, HCO3 −, K+, Mg2+, and SiO2 are controlled on the first order by runoff variability, while Cl−, Na+ and SO4 2− are controlled by the occurrence of evaporites and/or pyrite. The entire Pacific basin in Ecuador...

The aim of the present study is to estimate the export fluxes of major dissolved species at the scale of the Amazon basin, to identify the main parameters controlling their spatial distribution and to identify the role of discharge variability in the variability of the total dissolved solid (TDS) flux through the hydrological cycle. Data are compiled from the monthly hydrochemistry and daily discharge database of the “Programa Climatologico y Hidrologico de la Cuenca Amazonica de Bolivia” (PHICAB) and the HYBAM observatories from 34 stations distributed over the Amazon basin (for the 1983–1992 and 2000–2012 periods, respectively). This paper consists of a first global observation of the fluxes and temporal dynamics of each geomorphological domain of the Amazon basin. Based on mean interannual monthly flux calculations, we estimated that the Amazon basin delivered approximately 27...

This study is a geochemical investigation of the Andean and Foreland basins of the Amazon River at high spatial and time resolution, carried out within the framework of the HYBAM research program (Hydro-geodynamics of the Amazon Basin). Monthly sampling was carried out at 27 gauging stations located in the upper tributaries of the Amazon Basin (from north to south: the Napo, Marañon, Ucayali, Madre de Dios-Beni and Mamore Rivers). The aim of this paper is to estimate the present-day chemical weathering rate (CWR), as well as the flux of CO2 consumption from total and silicate weathering in the Andes and Foreland Amazon basins, and to discuss their distribution as a function of geomorphic and structural parameters. Based on the forward method, the Napo and other Ecuadorian basins present high silicate weathering rates in comparison with the other basins. We confirm that the Marañon and ...