Pesticide dispersion–advection equation with soil temperature effect: Fid-Bau Portal

Pesticide dispersion–advection equation with soil temperature effect

Paraiba, Lourival Costa / Pulino, Petronio

10.1002/env.593.abs

A dispersion–advection equation, denoted as a DAPESTE model, of one‐dimensional evolution to simulate pesticide leaching in soil with a sinusoidal function to describe the daily average soil temperature at different depths is presented. In numerical simulation, the finite element method (FEM) will be used for space semi‐discretization and the regressive Eüler method (REM) for time discretization. It will be used as an FEM for dispersion–advection problems in which the advective transport predominates 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 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 estimate 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. Copyright © 2003 John Wiley & Sons, Ltd.