Assess PCDD/Fs Transfer in the Environmental Medium by Fugacity Model

• Main Authors: LO MING TE, 羅明德
• Other Authors: Lin Chieh
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/35089849284783410246

碩士 === 國立屏東科技大學 === 環境工程與科學系 === 94 === Following the development of civilization, the releases of man-made chemicals to the environment are increased day by day. Many among these substances are toxics. The common monitoring and modeling methods were used to evaluate fates of these compounds and their concentrations in the various parts of environment. Although the actual concentrations could be monitored through field sampling, it was costly and labor-intensive. As to the modeling, different models need to be used in order to account for chemical releases to different media. In addition, the modelers require highly specific knowledge and large amount of meteorology and hydrology data. On the other hand, the multi-media Fugacity model showed its simplicity and good functionality for determining chemical fates in multimedia transport, air, water, soil and others. It could predict the equilibrium concentrations of chemicals in various media compartment, justify the needs for further sampling, analysis and assessment, and further reduce the labor and cost for risk assessment. In order to evaluate the ability of the Fugacity model for simplifying the risk assessment, this study selected a MSWI. Using the data from the permit applications, this study modeled the fates of various pollutants by the Fugacity model and further explored the feasibility of simplify the process of risk assessment. This study would focus on 17 congeners. After collecting the emission data from the permit applications, this study further analyzed by USEPA FIRE databank to generate the emission rate and amount of pollutants. After further modeling efforts by Fugacity simulation, these results were compared with the monitoring data and were used for risk assessment. The estimated total PCDD/Fs concentration were 7.59E-06 ng/Nm3 for air, 5.49E-06 ng/L for water, 6.84E-04 ng/g for soil and4.86E-04 ng/g for sediment. The model predictions were lower than monitoring data less one order. It conjectured that sources contribution and modeling bulk dimention. Mass fluxes between the compartments were calculated. The results show that main part of PCDD/Fs from the stack emission fall down to soil mainly, minor part moves to sediment compartment, then others medium. From the model estimates, major mass fluxes coming from emission source were shown to go to the soil and water through wet/dry deposition, then go to degradation mainly in the soil(99.5~89.2%) and sediment(10.2~0.4﹪). The results of this study indicated that the Fugacity model is obvious easier, simpler, more versatile, and faster mean. It can save labor and money. Therefore, the Fugacity model can be used as the screen tool in risk assessment or exposure potential in order to examine the fates of certain chemicals after their releases to the environment. It can also be used in the environmental impact assessment and quality management to justify the emission control of chemicals.