Abstract:

In the spring of 2014, air samples were collected from a typical traffic area and a background area of Nanjing using Tedlar bags. In line with the methods of USEPA TO-15, a total of 30 kinds of volatile organic chemicals were detected. VOCs pollution of the air in the typical area and its diurnal variation were alsocharacterized. Results show that the concentration of VOCs in the air of the traffic area ranged from 122.58 to 236.97 μg·m^-3, with the average value being (149.31±36.70)μg·m^-3; while that in the background area was between 27.24 and 54.68 μg·m^-3, with the average value reaching (43.29±10.53)μg·m^-3.With respect to types of pollutants, olefins, aromatics, halogenated hydrocarbons and esters are the most prevalent contaminants in the atmosphere. In the traffic area, BTEX was the dominant volatile contaminant, ranging from 18.72 to 41.28 μg·m^-3 in concentration and averaging (25.39±7.63) μg·m^-3. As for diurnal variation of BTEX, its peaks appear at 9:00, 12:00 and 18:00, which is closely related to traffic volume. By contrast, the concentration of BTEX was relatively low without apparent variation in the air of the background area. The principal component analysis of BTEX in the traffic area reveals that benzene, ethylbenzene, p-m-xylene, o-xylene, 4-ethyl, 1, 3, 5-trimethylbenzene, 1, 2, 4 – trimethylbenzene were the major contributors to the pollution. Automobile exhaust was the principal source of BTEX contaminants in the traffic area.

Key words: traffic area, volatile organic compounds, BTEX, diurnal variation, principal component analysis