MODELING TRANSPORT OF ATRAZINE THROUGH CALCAREOUS SOILS FROM SOUTH FLORIDA

摘要

A study was carried out on water and pesticide transport in three calcareous soils (Perrine, Krome, and Chekika) of South Florida. Tritium and bromide were used as tracers for water flow and atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) was used as a probe chemical representing neutral organic compounds. Atrazine sorption isotherms were linear for all soils, and atrazine transport through water-saturated soil columns during steady water flow exhibited chemical non-equilibrium for Perrine and Krome soils columns. Apart from non-equilibrium chemical sorption, Chekika soil columns also had an added effect of mobile and immobile water zones that induced physical non- equilibrium during water movement. Simulation of leaching data revealed that the Convective-Dispersive Equilibrium (CDE) model could describe tracer breakthrough curves (BTCs) for Perrine and Krome soils, and the Two Site Non-Equilibrium (TSNE) model described atrazine BTCs. However, tracer BTCs from Chekika soil were described by the Two Region Non-Equilibrium (TRNE) model. None of the non-equilibrium models could describe atrazine BTCs obtained from Chekika soil due to the presence of both physical and chemical non-equilibrium in the system