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 PARENT SESSION
6B The use of ecological models and concepts in aquatic higher tier risk assessment
9:00 AM to 7:00 PM, Tuesday, 08 May 2001
Session Chair:
(T/FF226) Interpretation of lysimeter studies for risk assessment of pesticide leaching.
Verschoor, Anja1, Boesten, Jos2, Brouwer, Willem3, Leistra, Minze2, van der Linden, Ton1, Linders, Jan1, Pol, Werner4, 1 2 3 4
ABSTRACT- In the Netherlands, lysimeter studies should be provided if it is concluded in tier 1 assessments that a pesticide may exceed the maximum average annual concentration in groundwater of 0.001  g/l. The purpose of lysimeter experiments is to study pesticide leaching under more realistic natural conditions. The study should show whether the maximum average annual concentration remains below 0.1 g/l under Dutch use conditions. The purpose of standardising the lysimeter experiments is to extrapolate the result of a particular lysimeter experiment to Dutch use conditions. The impact of specific climatic conditions, soil profile and cropping on the measured leaching is considered in the standardisation procedure. Information about the DT50 and Kom in the lysimeter soil will improve the reliability of the standardisation substantially. A lysimeter study with parallel laboratory is recommended, and enhances the quality of the lysimeter study. In cases in which the DT50 and Kom in the lysimeter soil are not available, it depends on the conditions and results of the experiment whether standardisation is required. In the standardisation procedure leaching of pesticides measured in the lysimeter is compared with calculated leaching in the lysimeter. The ratio between the two is used as a correction factor for the calculated leaching under Dutch use conditions. Examples on the use of lysimeter results in the registration procedure will be given.
Key words: Lysimeter interpretation, Pesticide leaching, Risk assessment
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