| Summary: | 碩士 === 國立成功大學 === 環境工程學系碩博士班 === 91 === This study investigates the characteristics of polychlorinated
dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in leaves of the Ficus species in rural areas, Taiwan. The main objective of this study is to evaluate the transfer of atmospheric compounds into leaves. Additionally, a model to estimate the leaf content is developed and its results compared with the actual leaf content in Ficus species. Furthemore, the total degradation coefficient and half-life of PCDD/Fs in Ficus is estimated. The following conclusions are drawn. 1. The PCDD/Fs concentration in the atmosphere are between 0.129∼1.115 pg/Nm3, the average is 0.493pg/ Nm3.The PCDD/Fs concentrations in the atmosphere in the TD area is from 0.009 to 0.103 I-TEQ-pg/Nm3 with a nean value of 0.033 I-TEQ-pg/ Nm3. 2. The percentage of particle-bound of PCDD/Fs range from 48.9％（2,3,7,8-TCDF） to 96.9％（OCDD）. 3.The maximum pore diameter that allowed suspension particle entering in the leaves of Ficus species is 3.2 μm and the particle-bound of PCDD/Fs with aerodynamic diameter（dae）＜3.2 μm is 92.4％. 4.The PCDD/Fs leaf content in Ficus Species of TD area is form 0.178∼1.861 I-TEQ-pg/g（mean=0.467 I-TEQ-pg/g）. The PCDD/Fs content , adsorbed on the leaves’ surfaces, is from 0.0021 to 0.0084I-TEQ-g/g (mean = 0.0062 pg-I-TEQ/g). 5.The average percentage of PCDD/Fs content absorded in and adsorbed on the surfaces of the leaves of Ficus are 99.07％ and 0.93％,respectively. 6. The result of this study revealed that the primary pathway for PCDD/Fs entering the leaves was by particle phase absorption (86.4%). This result is different from the report by previous study that the gas phase PCDD/Fs was the main pathway entering the leaves. 7. The degradation coefficient ktot（including the photolysis and the biodegradation coefficient）of total PCDDs was determined as 0.0390 day-1 by using pseudo first kinetics：Cr=Cee-ktott, while that of total PCDFs was 0.0603 day-1 and the degradation coefficient of total PCDD/Fs was 0.0499 day-1, respectively. 8.The degradtion half-life of PCDD/Fs, estimated the pseudo first-order rate constant kp for photolysis and kb for biodegradation, were as follows . The half-life time of PCDDs in Ficus leaves is from 327 hours （1,2,3,4,7,8-HxCDD） to 458 hours （OCDD）and the average is 426 hours. The half-life time of PCDFs in Ficus leaves is from 240 hours（1,2,3,7,8,9-HxCDF） to 297 hours（1,2,3,7,8-PeCDF）and the mean half-life of seventeen PCDD/F congeners was 276 hours.
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