Atmospheric transport and deposition of pesticides: An assessment of current knowledge

The current knowledge on atmospheric transport and deposition of pesticides is reviewed and discussed by a working group of experts during the Worksho p on Fate of pesticides in the atmosphere; implications for risk assessment , held in Driebergen, the Netherlands, 22-24 April, 1998. In general there is a shortage of measurement data to evaluate the deposition and re-emissio n processes. It was concluded that the mechanisms of transport and dispersi on of pesticides can be described similarly to those for other air pollutio n components and these mechanisms are rather well-known. Large uncertaintie s are present in the exchange processes at the interface between air and so il/water/vegetation. In all process descriptions the uncertainty in the phy sicochemical properties play an important role. Particularly those in the v apour pressure, Henry's law constant and its temperature dependency. More a ccurate data on physicochemical properties and particularly the temperature dependencies is needed.