Role of soil heterogeneities onto pesticide fate: a pore-scale study with lattice Boltzmann
Résumé
The objective of this work is to link soil structure with physico-chemical and biological functioning of soil. To do so, we present a numerical study using a pore scale model that take into account the
soil heterogeneities in an explicit manner as input data of the model. The model uses a voxel-based approach, so that pore space geometry was fully described from Xray-CT images of undisturbed soil samples. Pesticides like the herbicide isoproturon that are polar molecules are known to sorb preferentially onto hydrophobic surfaces (Benoit et al., 1999). Thus, we used 3D images of the same scanned soil in which particulate organic matter (POM) were spatially located in the pore space (Elyeznasni et al., submitted). Finally, different spatial locations of the soil microorganisms
were simulated in the pore space geometry. The pore space model chosen was the lattice Boltzmann (LB) scheme that easily allows to handle complex geometry such as porous medium. We extended the two-relaxation-time LB model of Ginzburg (2005) used to solve the advection-dispersion equation to reactive sorption and degradation.