Quantitative Prediction of Atrazine Sorption in a Manitoba Soil Using Conventional Chemical Kinetics Instead of Empirical Parameters

How to predict the persistence and leaching of organic chemicals in soils is a long-standing environmental issue. The injection of soil slurries into an HPLC together with separate solution-phase analysis permits the resolution of total sorption into intraparticle-diffused and labile-sorbed fractions. Sorption site stoichiometry was revealed, and two-step sorption was confirmed. This permitted conventional chemical kinetics including Laidler's integral rate law for second-order kinetics to be adapted to the natural mixture of irregular sorption sites. Quantitative predictions were successfully tested, and the effects of site saturation on the kinetics were demonstrated. Other authors have independently published evidence related to sorption site stoichiometry, by using scanning tunnelling and fluorescence microscopy for sorption onto idealized crystals. This presents opportunities for research advances in two directions. HPLC and microscopy methods could be used together for sorption mechanisms in both environmental and pure crystal systems.