Vietnam has a double burden of dioxin from both industrial sources and historical sources. To evaluate the concentration of PCDD/Fs in ambient air in different areas of Vietnam and their possible sources, atmospheric samples were collected from three areas namely Son La (rural area) and Da Nang (harbor – Agent Orange hotspot area), and Ho Chi Minh City (metropolitan – industrial city). Vapour and solid phases of PCDD/Fs were collected and analysed following the TO-9A sampling method. Principal Component Analysis and Positive Matrix Factorization model were applied to characterise the possible source. The average concentrations of PCDD/Fs were found to be 21.3 ± 13 fg I-TEQ/m(3) in Son La (n = 32), 65.2 ± 34 fg I-TEQ/m(3) in Da Nang (n = 16) and 139 ± 84 fg I-TEQ/m(3) in Ho Chi Minh City (n = 8). The findings of this study targeted open burning (42%) and biomass burning (51%) as the major emission sources of PCDD/Fs in ambient air of Son La, Vietnam. Major possible sources of PCDD/Fs in Da Nang could be transportation activities (64%), however, the other factor (36%) was suspected to be contaminated with 2,3,7,8-TeCDD from Agent Orange. Most of PCDD/Fs emitted in Ho Chi Minh City related to industrial activities (93%).
Authors: Ngo TH, Hien TT, Thuan NT, Minh NH, Chi KH. ;Full Source: Chemosphere. 2017 May 11; 182:647-655. doi: 10.1016/j.chemosphere.2017.05.050. [Epub ahead of print] ;