ADSORPTION-DESORPTION OF ATRAZINE IN THE SATURATED ZONE - APPLICATIONS TO AQUIFER FORMATIONS OF THE PARIS AREA - THE SENONIAN CHALKSTONE AND THE CHAMPIGNY LIMESTONE

The transport of atrazine in the surface or underground water bodies h as been the object of important work devoted to the unsaturated zone a nd to the kinetic aspects of these phenomena (Brusseau, 1989; Weber, 1 991). However, results do not allow a full explanation of atrazine con centrations found in natural water bodies. In order to account for atr azine concentrations as measured in natural aqueous systems, two pheno mena are often referred to: biodegradation and adsorption. Recent stud ies pointed out that biodegradation had a negligible effect. The prese nt report summarizes results found for two major aquifer formations of the Parisian region (Senonian chalkstone and Champigny limestone) whi ch show that for atrazine and for the kind of formation studied adsorp tion-desorption phenomena in the saturated zone have a negligible effe ct as well. The authors consider that future work on this topic should be devoted to the assessment of adsorption-desorption kinetic rates i n biofilms, poorly crystallized phases and oxide and oxy-hydroxide sur faces.