Applying Level â…£ Fugacity Model To Simulate Environmental Behavior Of Organic Pollutants

The multimedia environmental behavior of organic pollutants and their exposure risk to the ecosystems and human health has become more and more concerned by the researchers. Mathematical simulation is an important method used in studying environmental behavior of the pollutants. The fugacity model established by Mackay et al proved to be one of the most excellent environmental models because it can give accurate, comprehensive and reliable simulating results despite of its simple structure. As one of fugacity model, LevelⅣfugacity model can dynamically simulate the environmental behavior of organic pollutants, and was widely used by many researchers. It's an effective tool to study their concentration levels, and transfer processes between adjacent compartments quantitatively, and the results of simulation are significant to environmental pollution prediction, ecological risk assessment and optimization of environmental pollution control measures.LevelⅣfugacity model were applied to simulate the dynamic transfer and fate of HCHs. Dynamic model depending on temperature with fugacity approach not only described the fate of Persistent Organic Pollutants (POPs) in the environment, but also evaluated the influences of temperature on environmental fate of pollutants. A levelⅣfugacity model was also developed to simulate temperature effects on multimedia fate pollutants emitted from environmental accidents, using nitrobenzene released from the Songhua River pollution accident in late 2005 as a case. It is significant to learn about their environmental impacts, and provide environmental parameters and model framework for studying the fate of other organic pollutants.A levelⅣfugacity model was established to simulate the fate and transfer of HCH isomers in the lower reach of the Yellow River basin, China, during 1952～2010. The predicted concentrations of HCHs are in good agreement with the observed ones, as indicated by the residual errors being generally lower than 0.5 logarithmic units. The effects of extensive agricultural application and subsequent prohibition of HCHs are reflected by the temporal variation of HCHs predicted by the model. The proportions of HCH isomers in the environment also changed with time due to their different physicochemical properties. Althoughβ-HCH is not the main component of the technical HCHs, it has become the most abundant isomer in the environment because of its persistence. The dominant transfer processes between the adjacent compartments were deposition from air to soil, air diffusion through the air-water interface and runoff from soil to water. Sensitivity analysis showed that degradation rate in soil and parameters related to major sources had the strongest influence on the model result. Results of Monte Carlo simulation indicated the overall uncertainty of model predictions, and the coefficients of variation of the estimated concentrations of HCHs in all the compartments ranged from 0.5 to 5.8.A levelⅣfugacity model was developed to simulate temperature effects after the accident. The results of simulation show that with the decrease of temperature, the fugacity capacities and nitrobenzene transfer coefficients among different compartments increase. As temperature decreases, pollutants in air compartment tend to partition into the other condensed compartments. At 0℃, peak concentration of nitrobenzene in water and air can reach 4.9 and 4.7 times as high as their background concentrations, respectively. LevelⅣfugacity model was proved to be an efficient method to evaluate the influences of temperature on environmental fate of pollutants released from accidents.