Pesticide Leaching Model
PELMO is a one dimensional simulation model simulating the vertical movement of pesticides in soil by chromatographic leaching. The first version of PELMO was released in 1991 (Klein, 1991). PELMO is an official FOCUS model for pesticide registration in the EU. The latest version used for FOCUS groundwater simulations is FOCUS PELMO 6.6.4.
The major objective of FOCUS is to establish a harmonised approach for European Tier 1. Therefore, in FOCUS PELMO nine EU scenarios are implemented which collectively represent agriculture across Europe. The scenarios do not mimic specific fields, and nor are they necessarily representative of the agriculture at the location after which they are named or in the Member States where they are located.
For its simulations PELMO uses a water flow (tipping bucket approach) using a variable time step for all hydrological processes. In the FOCUS version run-off or preferential flow are not considered. Pesticide movement is calculated based on the convection-dispersion equation. Degradation in soil is based on first order. However, rate constants are corrected for depth, soil moisture, and soil temperature. Sorption to soil is simulated based on the Freundlich equation. Additionally, kinetic sorption can be considered using the Streck-model. It is possible to simulate not only the fate of the parent compound but the fate of up of up to eight transformation products.