CALIBRATION AND TESTING OF A DYNAMIC FLOW-THROUGH CHAMBER FOR FIELD DETERMINATION OF METHYL-BROMIDE VOLATILIZATION FLUX

Accurate emission measurement of highly volatile chemicals such as met hyl bromide (MeBr) is a crucial step in assessing their potential for environmental contamination. Use of flux chambers is a simple method f or measuring emission rate under field conditions. To validate the app licability of a dynamic flow-through chamber for measuring MeBr emissi on, we provide a complete presentation of calibration and testing of t he chamber. The calibration was made under a controlled system subject to ambient temperature changes. Two field experiments were conducted to test the chamber for measuring MeBr flux under conditions similar t o commercial soil fumigation practices. In both the calibration and th e two field experiments, the chamber provided accurate emission estima tes. The maximum mass balance error was < 10% which is comparable to t he micrometerological method. Because of its simplicity, we believe th is dynamic flux chamber can be used reliably in quantifying the emissi on dynamics of highly volatile chemicals such as MeBr. (C) 1997 Publis hed by Elsevier Science Ltd.