Introduction to ModelMaker Soils & Environmental Exposure Assessment Introduction to ModelMaker Sabine Beulke, CSL, York, UK FOCUS Work Group on Degradation Kinetics Estimating Persistence and Degradation Kinetics from Environmental Fate Studies in EU Registration Brussels, 26-27 January 2005 PSD, 6-7 March 2003

Curve fitting with ModelMaker

Model construction

Model components Compartment Flow Variable Part of the system with defined boundaries which can store the quantity of interest (e.g. a pesticide) Represents the movement of the quantity from one compartment to another Parent in soil Metabolite in soil Parent  Metabolite Change of quantity in compartment with time dCompartment / dt = + Flows in - Flows out Variable Quantity which is a function of other model components or a function of an independent variable (e.g. time) DT50 as a function of other model parameters

Initial conditions and parameters For each compartment, the starting point (quantity present at the beginning of the simulation) must be defined Parent: 100% applied radioactivity Metabolite: zero Parameters are constants which do not change during the simulation kparent degradation rate constant for the parent in soil M0 initial amount of the parent compound ffM formation fraction

ModelMaker toolbar run model optimise model create graph create table add and define parameters compartment flow variable