Simulação Numérica da Dispersão-Advecção de Pesticidas sob o Efeito da Temperatura do Solo: o Modelo DAPESTE

A dispersion-advection equation, which is denominated DAPESTE model, of one-dimensional evolution to simulate pesticide leaching in soil with sinusoidal function to describe the daily average soil temperature at different depths will be presented. In numerical simulation, the Finite Elements Method (FEM) will be used for the space semi-discretization and the Backward Euler Method for time discretization. It will be used appropriated FEM for dispersion-advection problems in which the predominat advective transport over the dispersive one. Let us suppose that the pesticide diffusivities in the gaseous and aqueous soil phases depend on the soil temperature. In this way, the effective hydrodynamic dispersion coefficient of the dispersion-advection equation will depend on the soil temperature. The pesticide air-water partition coefficient of the Henry law, varying with the temperature, will be determined by the Clausius-Clapeyron equation. The van't Hoff equation will be used to determine the temperature dependence of the pesticide soil sorption coefficient. The Arrhenius equation will be used to estimated the effect of the soil temperature on the pesticide degradation rate. These temperature dependence relationships can help comprehend the pesticide behavior in the soil under different scenarios of the soil temperatures, especially in pesticide concentration leaching and its half-life in soil.