Column Leaching Experiments for Aged Residues of Pesticides: Interpretation and Criteria
Kolomstudies voor verouderd residu van bestrijdingsmiddelen: Interpretatie en criteria
Freijer JI , Broerse SQ , Hassanizadeh SM , Linden AMA van der , Veling EJM
RIVM Report 715801004
National authorities in European countries prescribe several experiments to assess the transformation and leaching potential of pesticides. One of these experiments, the aged residue leaching test (ARL test), is required to assess the risk of leaching of pesticides and their metabolites to groundwater. This report gives a mathematical description of the dynamic processes occurring during the experiment. An interpretation method is proposed to translate the results of these experiments to compound properties such as half-life, formation fraction, and sorption coefficient in the soil. These data can be used in simulation models to perform risk analysis using realistic environmental scenarios. The interpretation method employs the PESTRAS model, which is a simulation model describing transport, transformation, degradation and sorption of organic contaminants in soil. The model is used in the inverse way: the system parameters of interest are derived from output variables. It is concluded that the newly proposed interpretation method is more suitable to analyze results of ARL tests than the traditional approaches. Especially, if attention is given to the documentation of the experimental conditions and if sufficient measurements are performed, relatively accurate estimates of the parameters of interest can be made.