Modelling the pesticide concentration in a rice field by a level IV fugacity model coupled with a dispersion-advection equation

The numerical simulation of a level IV fugacity model coupled to a dispersion-advection equation to simulate the environmental concentration of a pesticide in rice fields is presented. The model simulates the dynamic distribution of the pesticide in a compartmental system constituted by air, water, rice plants and bottom sediment together with saturated soil layers. The level IV fugacity model is given by a linear system of ordinary differential equations that considers the fugacities and, consequently, the concentrations of the pesticide in air, water, rice plants and bottom sediment. The dispersion-advection equation simulates the pesticide leaching in the saturated layers of the soil, considering the hydrodynamic dispersion, the pesticide degradation rate and the soil pesticide absorption in the saturated soil layer.