Production and application of many synthetic organic chemicals have led to widespread contamination of the air, water and soil environments. The mass transport of volatile organic compounds from liquid phase into air phase is an important pathway in determining the fate of such chemicals released into the environment. A comprehensive investigation on the mass transfer rate of four selected high volatile chemicals, benzene, toluene, trichloroethylene (TCE) and tetrachloroethylene (PCE) under various environmental condition has been conducted in this research.

For volatilization of chemicals from water into air under different turbulent intensities in bulk water, four conditions were identified as ideal stagnant condition, near stagnant condition, completely mixed condition without breaking surface film and completely mixed condition with broken film. A mathematical model was developed by solving a partial differential equation with appropriate boundary condition (Fick's diffusion law) to predict volatilization from stagnant water. This model was further simplified to approximate solution with a relative error of less than 9.5%. The laboratory experiments were conducted and the results were used to calibrate the developed model. It was found that the volatilization rate constant was inversely proportional to 1.81th power of water depth.

For water bulk turbulent condition, a mathematical model incorporating an idealized surface film renewal concept was used to predict volatilization rate. The experiments were conducted under nine different turbulent intensities, expressed in terms of velocity gradient (G), equal to 0, 25, 50, 75, 100, 125, 150, 175 and 200 s$\sp{-1}$ and four different water depths of 0.6, 1.2, 1.5 and 1.8 m. The developed model was verified and calibrated with the observed experimental data.

The effect of surface shear caused by wind on the volatilization rate was studied by simulating 5 different wind velocities, 0, 0.5, 1.0, 2.0, 3.5 and 5.0 m/s. It was found that increasing the wind velocities from 0 to 5 m/s had increased the volatilization rate constant by 5 to 6 times.

Evaporation of pure chemicals from point sources under stagnant air condition and strong wind condition were theoretically modelled and experimentally simulated. It was found that the vapour pressure, molecular mass and temperature were important parameters in determining the evaporation rates for both conditions. The diameter of point source was found to be important for stagnant air condition, but irrelevant for strong wind condition.

The models developed in this study and further verified and calibrated by the experimental results, should provide a useful tool to predict the fate of high volatile organic chemicals when released into the environment.