[Physico-chemical Characteristic Analysis of PM2.5 in the Highway Tunnel in the Plateau City of Kunming]

Cheng-Hui Wang; Kun Yan; Xin-Yu Han; Ze Shi; Li-Mei Bi; Feng Xiang; Ping Ning; Jian-Wu Shi

doi:10.13227/j.hjkx.201702052

[Physico-chemical Characteristic Analysis of PM_2.5 in the Highway Tunnel in the Plateau City of Kunming]

Huan Jing Ke Xue. 2017 Dec 8;38(12):4968-4975. doi: 10.13227/j.hjkx.201702052.

[Article in Chinese]

Authors

Cheng-Hui Wang¹, Kun Yan², Xin-Yu Han¹, Ze Shi², Li-Mei Bi^{1

2}, Feng Xiang^{1

2}, Ping Ning¹, Jian-Wu Shi¹

Affiliations

¹ Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
² Yunnan Environmental Monitoring Center, Kunming 650000, China.

PMID: 29964554
DOI: 10.13227/j.hjkx.201702052

Abstract

This research aimed to determine the characteristics of the motor vehicle exhaust emissions in the plateau area. The PM_2.5 was evaluated in the Caohai Tunnel of Kunming for this study by measuring the water-soluble inorganic ions, carbonaceous species, polycyclic aromatic hydrocarbons (PAHs), and inorganic elements in air samples. The results showed that the mass concentration of PM_2.5 in the tunnel was about 225.65-312.84 μg·m^-3, which is 11-14 times the PM_2.5 concentration in the ambient atmosphere. The carbonaceous species were the most abundant species, constituting 35.73% of the total PM_{2 5} mass, followed by inorganic elements constituting about 21.78% and the water-soluble inorganic ions in the range of 4.79%-5.52%. The smallest proportion of the PM_2.5 was PAH, constituting about 0.25%-0.32%. The Ca²⁺ and SO₄^2- concentrations were the highest among the water-soluble inorganic ions, which accounted for about 77.78%-80.17% of the total ions and from the crust source. NH₄⁺ and NO₃^- are relatively high, coming mainly from automobile exhausts. The 4 and 6 ring PAHs with higher molecular weight and lower volatility were the dominant components of PM_2.5 in the Caohai Tunnel. The automobile exhaust contributing to PAHs in PM_2.5 is very significant. The most poisonous single BaP concentration is 23-29 times higher than the state regulations exposure limit, and it has reached a hazardous level. It is obvious that there are health risks from the exposure to PM_2.5 in the plateau highway tunnel. A principal component analysis (PCA) showed that the sources of road dust and automobile exhaust emission were about 61.64%, followed by mechanical wear and emissions that accounted for about 17.49% and tire wear emission sources that accounted for 9.11% of the total PM_2.5. Under the conditions of hypobaric hypoxia in the Yun-Gui plateau, there is a greater chance of incomplete combustion of motor vehicle fuels, resulting in the increase in OC and PAHs in PM_2.5 emissions.

Keywords: PM2.5; automobile exhaust; chemical composition; plateau tunnel; principal component analysis (PCA).

Publication types

English Abstract