A NEW LABORATORY MODEL FOR STUDYING THE VOLATILIZATION OF PESTICIDES UNDER CONTROLLED CONDITIONS

A new laboratory chamber is presented, constructed for studying the volatilization of C-14-labelled pesticides from plant and soil surfaces. After application in a separate chamber using a computer controlled system and a spraying nozzle also used in agricultural practice, the experimental platform (0.5 m2) is introduced into the volatilization chamber. An air-conditioning system provides for temperature and relative humidity conditions between 10 and 30-degrees-C and 35 to 90%, respectively. High wind speeds up to 2.5 m/s can be simulated above pure soil surfaces or above plants, and low wind speeds up to 0.3 m/s are possible in the plant stand, similar to practical outdoor conditions. The chamber is closed, thus the evaluation of a total mass balance sheet of the radioactivity applied is possible using a high volume sampling system. First measurements show that the application technique used is precise (S.D. 8% and 9%) and the wind speeds measured at different points in the volatilization chamber are uniform.