Bouchez J. auteur aut IRD Moquet J. S. auteur aut IRD Espinoza J. C. auteur aut IRD Martinez Jean-Michel auteur aut IRD Guyot Jean-Loup auteur aut IRD Lagane Christelle auteur aut IRD Filizola N. auteur aut IRD Noriega L. auteur aut IRD Sanchez L. H. auteur aut IRD Pombosa R. auteur aut IRD text journalArticle eng text/pdf born digital access Large hydrological systems aggregate compositionally different waters derived from a variety of pathways. In the case of continental-scale rivers, such aggregation occurs noticeably at confluences between tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We build up a simple model for tributary mixing to predict the behavior of C-Q relationships during aggregation. We test a set of predictions made in the context of the largest world's river, the Amazon. In particular, we predict that the C-Q relationships of the rivers draining heterogeneous catchments should be the most "dilutional" and should display the widest hysteresis loops. To check these predictions, we compute 10 day-periodicity time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations located throughout the Amazon basin. In agreement with the model predictions, C-Q relationships of most solutes shift from a fairly "chemostatic" behavior (nearly constant C) at the Andean mountain front and in pure lowland areas, to more "dilutional" patterns (negative C-Q relationship) toward the system mouth. More prominent C-Q hysteresis loops are also observed at the most downstream stations. Altogether, this study suggests that mixing of water and solutes between different flowpaths exerts a strong control on C-Q relationships of large-scale hydrological systems. specialized concentration-discharge (C-Q) relationships Amazon River C-Q hysteresis loops tributary mixing spectral analysis 062 020 53 11 8660-8685 2017 0043-1397 https://www.documentation.ird.fr/hor/fdi:010071962 10.1002/2017wr020591 0043-1397 [F B010071962] https://www.documentation.ird.fr/hor/fdi:010071962 https://www.documentation.ird.fr/intranet/publi/2018/01/010071962.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2018-02-05 2023-07-11 fdi:010071962 fre