SYKEmo219 Pesticide groundwater leaching modelling in risk assessment in Finland: interim report

Timo Seppälä ja Markku Yli-Halla, 2001

Finnish Environment Institute Mimeograph 219, 99 p.
URN:ISBN:9521108835. The publication is available only in printed form ISBN 952-11-0883-5

Abstract

Pesticide approval and risk assessment are moving from national level to EU level. In the European risk assessment the role of pesticide fate modelling is increasing. European Union (FOCUS Groundwater working group) has prepared 9 scenarios for four groundwater leaching models that will be used in the common EU level risk assessment. This publication deals with the European FOCUS scenario representing the Northern region (Jokioinen) and presents provisional. national pesticide risk assessmment scenarios, which cover the Finnish climatie and soil in more depth. These scenarios are prepared for MACRO-DB. In addition, the publication compares, the leaching of three herbicides (metribuzin, ethofumesate and tribenuron-methyl) in Jokioinen FOCUS scenario modelled with PESTLA with the results of the prepared national scenarios modelled with MACRO-DB.

In Finnish conditions the most important factor contributing to the pesticide leaching into groundwater are preferential flow in the macropores of some soils, low temperature, precipitation falling as rain or snow depending on air temperature, soil groundfrost and its effects on soil. hydrology (cracks and water freeze). According to the provisional results obtained in this modelling excercise, the leaching was higher in national scenarios with MACRO-DB than in the European FOCUS seenario Jokioinen and PESTLA. In addition, in the Jokioinen clftnate the pesticides modelled degraded slower than in Uppsala climate used för comparison.

Because of the Finnish environmental and agricultural properties being so, different from the rest of the EU the preparation of national scnearios should be continued in the future, in order to assure identifyffig pesticides and conditions that pose threat to groundwaters in the course of pesticide risk assessment and product approval, as well as the safe uses. This requires use of several soil types and approaches in modelling.

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