Aldicarb transport in subsurface environment: Comparison of models

In this paper, two different pesticide transport simulation models are pres ented and compared to carry out preliminary analysis on the applicability o f those models in determining ground-water vulnerability to aldicarb contam ination. The first model is a physically based analytical model that simula tes 1D pesticide movement in soils, based on the concept of complete mixing and 2D advective-dispersive transport in the aquifer. The second model is a numerical simulation model that links the existing numerical codes PRZM2, MODFLOW, and MT3D to simulate pesticide transport in the subsurface. The c oncentrations of aldicarb residues in soil and in the aquifer calculated by the two models are found to be in good agreement. However, the analytical model tends to produce an earlier arrival of the peak concentration in each year due to the assumption of complete mixing. It is also found that the i nfiltrating water following aldicarb application plays a significant role o n the leaching potential of aldicarb, which is also affected by various met eorological and hydrological factors as well as by agricultural practices.