Non-steady-state equilibrium model for the preliminary prediction of the fate of chemicals in the environment.

Prediction of the fate of chemicals in the environment is essential to the assessment of the potential hazard of chemicals. The fate of a chemical in the environment depends mainly upon (1) transfer processes between environmental compartments due to physicochemical properties, (2) transformation processes in each compartment, and (3) characteristics of the environment. Many equilibrium or kinetic models have been proposed to predict the fate of chemicals in the environment. Though kinetic models are useful in predicting the concentration-time profile of a chemical at the non-steady state, they are rather complicated. In this work is proposed a simple and useful equilibrium model for prediction of the mass and concentration distribution fraction, mean residence time, and concentration-time profile of a chemical released into the environment, an advantage of our model. For the validation of this model, the results were compared with data from Neely's pond experiment and field data monitored by the Japanese Environment Agency. The results show that the equilibrium model is valuable for preliminary prediction of the fate of chemicals that are priority chemicals for hazard assessment in the environment.