Muller K. auteur aut IRD Duwig Céline auteur aut IRD Prado B. auteur aut IRD Siebe C. auteur aut IRD Hidalgo C. auteur aut IRD Etchevers J. auteur aut IRD text journalArticle eng text/pdf born digital access In the Mezquital Valley, Mexico, crops have been irrigated with untreated municipal wastewater for more than a century. Atrazine has been applied to maize and alfalfa grown in the area for weed control for 15 years. Our objectives were to analyse (i) how wastewater irrigation affects the filtering of atrazine, and (ii) if the length of irrigation has a significant impact. We compared atrazine sorption to Phaeozems that have been irrigated with raw wastewater for 35 (P35) and 85 (P85) years with sorption to a non-irrigated (P0) Phaeozem soil under rainfed agriculture. The use of bromide as an inert water tracer in column experiments and the subsequent analysis of the tracers' breakthrough curves allowed the calibration of the hydrodynamic parameters of a two-site non equilibrium convection-dispersion model. The quality of the irrigation water significantly altered the soils' hydrodynamic properties (hydraulic conductivity, dispersivity and the size of pores that are hydraulically active). The impacts on soil chemical properties (total organic carbon content and pH) were not significant, while the sodium adsorption ratio was significantly increased. Sorption and desorption isotherms, determined in batch and column experiments, showed enhanced atrazine sorption and reduced and slower desorption in wastewater-irrigated soils. These effects increased with the length of irrigation. The intensified sorption-desorption hysteresis in wastewater-irrigated soils indicated that the soil organic matter developed in these soils had fewer high-energy, easily accessible sorption sites available, leading to lower and slower atrazine desorption rates. This study leads to the conclusion that wastewater irrigation decreases atrazine mobility in the Mezquital valley Phaeozems by decreasing the hydraulic conductivity and increasing the soil's sorption capacity. specialized Pesticide pesticide mobility filtering soil organic matter normalized sorption coefficient non-equilibrium sorption dissolved organic matter 076 068 098 47 1 30-41 2012 0360-1234 https://www.documentation.ird.fr/hor/fdi:010055750 10.1080/03601234.2012.606416 0360-1234 [F B010055750] https://www.documentation.ird.fr/hor/fdi:010055750 https://www.documentation.ird.fr/intranet/publi/2012/04/010055750.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2012-05-04 2017-08-23 fdi:010055750 fre