Characterization of the fate and distribution of methoxyfenozide in a water-plant-fish-sediment microcosm using a multimedia fugacity model.

Methoxyfenozide is widely employed in paddy land and can flow out into the aquatic environment. The present study combines two approaches, namely, an aquatic microcosm simulation experiment and a multimedia fugacity model, to study the fate and distribution of methoxyfenozide in an aquatic microcosm containing water, sediment, aquatic plants, and zebrafish. The model results indicated that the simulated concentrations agreed with the observed values within one order of magnitude. The degradation rate was less than 7.0% in the three types of aquatic microcosms at 740 h in the model. Methoxyfenozide exhibited very high persistence in the aquatic microcosm. Water played a key role in the fate of methoxyfenozide, acting as a sink in the simulated aquatic environment, followed by sediment. Only approximately 2% of methoxyfenozide entered the organisms (zebrafish and Egeria densa Planch). Methoxyfenozide underwent a significant transport process between the water and sediment. The applications of multimedia fugacity models are useful for understanding the behaviors, fate, and transport of pesticides after their release into the environment and to facilitate risk assessment and management activities.