Both Phase Distributions and Dry Deposition of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans in the Ambient Air of Northern Taiwan

• Main Authors: Kai-LunCheng, 鄭凱倫
• Other Authors: Wen-Jhy Lee
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/58570791557252131218

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 101 === The objectives of this study were to know the concentration, gas-particle partitioning properties, and dry deposition process of PCDD/Fs in the ambient air in northern Taiwan. During each sampling period from 2006 to 2011, 21 sampling sites, with maximum ground concentration of PCDD/Fs from the emission of each MSWI found by ISCST model, near three municipal solid waste incinerators located in northern Taiwan were selected. Air samples were analyzed for specific 17 PCDD/F congeners, and the protocol for QA/QC is strictly followed. From congener profiles of PCDD/Fs-I-TEQ in particle phase, the 2,3,4,7,8-PeCDF was the most predominant congener and follow by 1,2,3,4,7,8-HxCDF and 1,2,3,6,7,8-HxCDF. For PCDD/Fs-I-TEQ in gas phase, the 2,3,4,7,8-PeCDF was most dominant one and followed by 2,3,7,8-TeCDD/F and 1,2,3,4,7,8-CDD. For the gas-particle partitioning properties of total PCDD/Fs-I-TEQ, the highest percentage of particle phase occurred in January (46.7%), followed by February (45.0%) and March (45.6%), and the highest percentage of gas phase occurred in July (87.6%), followed by August (87.4%). For the phase distributions of total PCDD/Fs-I-TEQ in six years, the percentage of particle phase ranged from 25.8% to 32.0%, with an average of 28.1%, and the percentage of gas phase ranged from 68.0% to 74.2%, with an average of 71.2%. There was no significant difference among each year. Mean fraction of PCDD/Fs-I-TEQ dry deposition flux contributed by the particle phase were between 87.0% and 98.3%, and averaged 94.2%. The above results displayed that the particulates is the predominant factor controlling the PCDD/F dry deposition flux in the atmosphere. Modeled mean monthly dry deposition of PCDD/Fs-I-TEQ ranged from 0.102 (in March) to 0.307 ng-I-TEQ/m2-month (in June), probably due to the higher TSP concentration in March and fewer sunny days in summer. Modeled yearly mean dry deposition of PCDD/Fs-I-TEQ ranged from 1.352 to 2.766 ng-I-TEQ/m2-year, with the significantly lower value in 2009 and 2011, may because of relatively lower PCDD/Fs concentrations. Mean yearly dry deposition velocities of PCDD/Fs-I-TEQ in six years were 0.403 - 0.506 cm/s. Both temperature and TSP concentration were similar during 2006-2011, therefore, the dry deposition velocity in each year was very close. This study provides useful information for looking more inside on the behavior of PCDD/Fs in the ambient air, which is a great benefit for establishing good strategy for the PCDD/Fs control.