Development of global scale multimedia contaminant fate model: incorporating paddy field compartment.

An approach to incorporate the paddy field compartment into the newly developing multimedia fate model "the National Institute for Agro-Environmental Sciences' multimedia environmental fate model (NIAES-MMM-Global)" used to estimate the long-term fate in global environment of current-use pesticides (CUPs) and persistent organic pollutants (POPs) emitted from Japan and all of Asia is presented here. Effects of the rice plant upon the overall environmental fate of targeted chemicals such as CUPs and POPs are assessed by comparing the maximum reservoir capacity (MRC) values calculated with and without the inclusion of rice plants. Rice plants exert a marked effect on the environmental fate of these chemicals and should be considered when paddy field is incorporated into multimedia models to execute predictions that are more reliable. Moreover, the results suggest that the seasonal changes of the rice plant should also be reflected in the models. Accordingly, the scenario description for inclusion of the paddy field compartment in the multimedia models is discussed.