Volatility testing of pesticides in a wind tunnel

In the Federal Republic of Germany data on the volatilisation potential of pesticides out of soil and from plant surfaces are required for registration (BBA, guideline part 4/6-1). To fulfill the requirements of the guideline, a wind tunnel was constructed. The system allows a broad range of test conditions. Experiments described here were performed using the following parameters: air velocity 1.0 - 1.2 m/s, relative air humidity 30 - 50 %, 20 - 25 degree C. Volatilisation was determined by diverting a proportion (ca. 2.5 %) of the air stream through polyurethane foam and measuring the quantity of adsorbed chemical. Results from experiments with model chemicals (lindane, simazine, di-(2-ethylhexyl)phthalatic acid ester, deltamethrin) are presented. While volatilisation within 24 h for simazine, di-(2-ethylhexyl)phthalatic acid ester, and deltamethrin was below 1 % (from soil and plants), approximately 50 % of the lindane deposit was volatilised from plant surfaces.