Journal of Environmental Science and Health Part A (2009) 44, 1327–1334 Copyright C  Taylor & Francis Group, LLC ISSN: 1093-4529 (Print); 1532-4117 (Online) DOI: 10.1080/10934520903213020 Atmospheric deposition of polychlorinated dibenzo- p -dioxins and dibenzofurans on the soils in the vicinity of municipal solid waste incinerators YEE-LIN WU 1,2 , LONG-FULL LIN 3 , SHUN-I SHIH 3 , KUEI-MIN YU 1,2 , LIEN-TE HSIEH 4 , LIN-CHI WANG 5 and GUO-PING CHANG-CHIEN 5 1 Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan 2 Sustainable Environment Research Center, National Cheng Kung University, Tainan, Taiwan 3 Department of Environmental Engineering, Kun Shan University, Tainan, Taiwan 4 Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan 5 Department of Chemical and Materials Engineering, Cheng Shiu University, Kaohsiung County, Taiwan This study focuses on the atmospheric deposition of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) on the soils in the vicinity of two municipal solid waste incinerators (MSWIs), which were located in the Gangshan (GS) and the Renwu (RW) Townships of southern Taiwan. PCDD/Fs in the soils were sampled simultaneously with those in the ambient air and analyzed for 17 2,3,7,8-substituted PCDD/Fs. The results show that the mean contents of PCDD/Fs in the soils near MSWI-GS and MSWI-RW were 2.65 and 1.20 ng I-TEQ/kg dry weight, respectively. Annual wet deposition fluxes of total PCDD/Fs were 119 and 113 ng/m 2 -year in the ambient air near MSWI-GS and MSWI-RW, respectively. The results obtained in this study are much higher than those estimated for the Atlantic Ocean, where the average wet deposition was only 45 ng/m 2 -year. The annual dry deposition fluxes accounted for 58.2 and 66.7%, respectively, indicating that dry deposition was more dominant than wet deposition in the atmospheric deposition processes. The congener profiles of 17 2,3,7,8-substituted PCDD/Fs showed that OCDD dominates in the soils. The contributions of OCDD in the soils near MSWI-GS and MSWI-RW were 73.4 and 67.1%, respectively, while they were only 41.4 and 31.2% in the atmospheric deposition, respectively. These results imply that OCDD is more persistent in the environment than other congeners. The results of the present study strongly suggest that exposure to PCDD/Fs in these areas should be reduced. Keywords: PCDDs, PCDFs, atmospheric wet deposition, soils. Introduction Polychlorinated dibenzo- p-dioxins (PCDDs) and poly- chlorinated dibenzofurans (PCDFs) were first found in the fly ash and flue gas of municipal solid waste incinerators (MSWIs). [1] Due to the persistent and bioaccumulating na- ture of PCDD/Fs, their presence in the environment is of great concern. According to data reported by the US EPA, [2] most PCDD/Fs (92%) are released to the environ- ment through air, and these will be subject to atmospheric deposition and become the sources of PCDD/Fs in soil. [3] Address correspondence to Long-Full Lin, Department of En- vironmental Engineering, Kun Shan University, 949 Da-Wan Rd., Yung Kung, Tainan County 710, Taiwan. E-mail: long- full@mail.ksu.edu.tw Received March 6, 2009. In our previous work, the atmospheric dry deposition fluxes of total PCDD/Fs in the vicinity of 2 MSWIs was investigated. [4] The results are considerably higher than those measured in Guangzhou, China, [3] which was 6.2 pg WHO-TEQ/m 2 -day, and also much higher than those in the Atlantic Ocean, 9 ng/m 2 -yr. [5] For wet deposition, the estimated wet deposition flux for the Atlantic Ocean was 45 ng/m 2 -yr. [6] In Houston, TX USA, between December 2003 and April 2004, average total dry deposition fluxes of 351 and 125 pg/m 2 -day were found at Clinton Drive and Lang Road, respectively. Moreover, a wet deposition flux of 2.873 pg/m 2 -day was measured at the Clinton Drive site. [7] Consequently, suggestions for reducing exposure to PCDD/Fs at these areas have been made. In this study, the characteristics of PCDD/Fs in soils as well as the atmospheric deposition in the vicinity of two MSWIs located in southern Taiwan are investigated. A total of 55 soil samples were taken and analyzed for Downloaded By: [2007-2008-2009 National Cheng Kung University] At: 12:32 8 October 2009