Volume 11, No. 6, November 2011, Pages 763-775 PDF(475 KB)
Measurements and Correlations of MTBE and BETX in Traffic Tunnels
Lien-Te Hsieh1,2, Ya-Fen Wang3, Hsi-Hsien Yang4, Hsiao-Hsuan Mi5
1 Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, 1 Shuefu Fu Road, Pingtung 912, Taiwan
2 Emerging Compounds Research Center (ECOREC), National Pingtung University of Science and Technology, 1 Shuefu Fu Road, Pingtung 912, Taiwan
3 Department of Bioenvironmental Engineering and R&D Center of Membrane Technology, Chung Yuan Christian University, Chung-Li, 320, Taiwan
4 Department of Environmental Engineering and Management, Chaoyang University of Technology, Wufong, Taichung 413, Taiwan
5 Department of Environmental Engineering & Science, Chia Nan University of Pharmacy and Science, Tainan County 71743, Taiwan
In this study, the concentrations of five volatile organic compounds (VOCs), including BTEX and methyl tertiary-butyl ether (MTBE), were investigated in five different traffic tunnels (including Liangshan, Yueguangshan, Zoying, Guogang and Zhongliao tunnels) in southern Taiwan. Results showed that Guogang Tunnel was the most polluted with the highest average levels of both MTBE and BTEX while ethylbenzene had the lowest levels. The range of measured concentration of toluene in Liangshan, Yueguangshan, Zoying, Guogang and Zhongliao tunnels were from 5.6 to 6.2 (mean = 1.6), from 0.0 to 62.3 (mean = 17.6), from 2.7 to 26.7 (mean = 13.1), from 15.2 to 125.5 (mean = 57.5), and from 43.7 to 197.1 (mean = 115.8) μg/m3, respectively. In Guogang Tunnel, the average MTBE–BTEX ratios at two peak rush periods were (5.0:1, 5:3, 4:1, 0:1, 5:1.1) and (5.7:1, 3:3, 2:1, 0:1, 4:1.1). From morning till night, the ratios at different sampling periods in the five different tunnels suggest the existence of both different traffic flow and variations in traffic fleet type in different tunnels. T/B ratio ranged from 0 to 2.3, from 0 to 1.9, from 0.6 to 2.5, from 0.9 to 2.6 and from 0 to 10.5 in Liangshan, Yueguangshan, Zoying, Guogang and Zhongliao tunnels, respectively. We also observed a wide range of (m+p+o)-xylenes/ethylbenzene (ΣX/E) or m,p-X/E ratio in all five tunnels. The m,p-xylene/ethylbenzene ratio ranged from 2.2 to 5.7, from 1.4 to 3.3, from 2.0 to 7.7, from 1.4 to 1.5 and from 5.5 to 8.1 in Liangshan, Yueguangshan, Zoying, Guogang and Zhongliao Tunnels, respectively. Notably, those high ΣX/E ratios in all tunnels reflect a fresh air parcel in the tunnels due to the enclosed/half-enclosed environment. Nevertheless, it is important that the characteristics of X/E in different traffic tunnels are explored.
Characteristic ratio; Tunnel; Traffic; BTEX; MTBE.