Predicting Pesticide Volatilization from Bare Soils

Abstract

Understanding the processes and mechanisms that affect pesticide volatilization from fields is important in developing methods to control emissions. Changes in ambient air temperature and atmospheric stability can strongly affect volatilization. A field study was conducted to measure the volatilization rate. A numerical model was developed to simulate pesticide fate, transport and volatilization. Three volatilization boundary conditions were used to assess the accuracy in predicting the volatilization rates. First, a stagnant boundary layer and isothermal conditions are assumed. Second, a temperature-dependent stagnant boundary layer is considered. A third boundary condition that couples soil and atmospheric processes was found to provide an accurate and realistic simulation of the instantaneous volatilization rates compared to the other boundary conditions. For certain information, such as cumulative emissions, all the boundary conditions yielded similar results and suggest that simpler methods may be useful for this information.