Vertical and Diurnal Characterization of Volatile Organic Compounds in Ambient Air in Urban Areas

Figures & data

Table 1. Diurnal variation of individual VOC concentrations (ppb) detected at five heights during four time periods on August 3, 2008

	2 m				13 m				32 m				58 m				111 m
VOC	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	MDL
Ethene + acetylene + ethane	154	–	31.9	20.3	88.1	22.5	33.4	–	83.4	19.1	23.8	16.8	67.1	–	18.6	–	72.3	–	16.0	–	0.68
Propene (propylene)	5.31	2.00	2.56	2.00	4.37	2.18	2.56	–	6.12	1.44	1.87	1.44	7.36	1.56	1.75	–	6.30	1.31	1.50	–	0.84
Isobutane	1.87	1.19	–	1.50	1.50	–	–	1.19	1.62	1.06	–	–	1.50	–	–	–	–	–	–	–	0.08
1-Butene	4.43	2.81	–	1.50	–	2.12	2.50	–	1.81	–	1.75	–	–	–	–	–	–	–	–	–	0.09
Butane	3.99	3.50	2.18	2.56	3.12	1.75	2.56	1.93	–	2.50	–	–	1.75	–	–	–	–	–	–	–	0.09
Isopentane	28.9	26.3	14.4	8.18	17.2	12.2	12.1	5.49	14.3	8.18	8.24	4.68	11.2	6.05	6.87	2.81	7.80	4.06	5.24	3.43	0.06
Pentane	8.93	8.74	4.24	2.87	6.55	–	–	–	5.99	2.87	2.68	–	–	–	2.75	–	–	–	–	–	0.18
2-Methyl pentane	5.74	3.74	2.81	1.31	3.81	2.50	2.56	2.18	3.18	1.56	1.81	1.25	2.12	1.06	1.31	–	1.62	0.75	1.00	–	0.09
3-Methyl pentane	4.18	3.99	2.68	1.31	3.56	2.18	2.93	2.12	3.18	1.50	1.87	–	2.25	–	1.44	–	1.37	–	–	–	0.01
Hexane	3.68	2.75	2.06	–	2.00	1.31	1.37	1.19	1.56	–	1.50	–	1.56	–	–	–	–	–	–	–	0.04
Benzene	7.43	2.93	2.31	–	5.18	2.93	2.43	3.31	4.43	–	–	–	3.31	–	–	–	–	–	–	–	0.05
Cyclohexane	3.81	–	–	–	3.56	–	–	–	3.00	–	–	–	3.56	–	–	–	4.24	–	–	–	0.07
Toluene	12.7	4.43	11.1	–	10.3	4.18	6.93	24.9	9.92	4.18	4.87	–	9.30	–	3.37	9.24	9.86	–	–	–	0.08
Ethyl benzene	2.37	0.94	1.25	–	1.69	0.94	1.12	7.55	10.1	–	–	1.25	1.31	–	–	–	1.56	–	–	–	0.10
m,p-Xylene	5.62	2.68	3.50	–	3.81	2.43	3.25	2.75	4.87	1.87	2.12	3.18	2.87	–	–	–	3.25	2.25	–	–	0.04
Styrene	–	–	–	–	–	–	–	2.37	16.8	–	–	–	–	–	–	–	–	–	–	–	0.06
o-Xylene	2.62	1.12	1.56	–	1.75	–	1.31	–	2.06	–	–	1.19	1.31	–	–	–	1.37	–	–	–	0.04
m-Ethyl toluene	2.68	1.25	1.69	–	1.56	–	1.25	–	1.37	–	–	–	–	–	–	–	–	–	–	–	0.07
1,2,4-Trimethylbenzene	3.68	2.12	2.37	–	2.06	1.69	1.69	–	2.06	–	–	–	1.69	–	–	–	1.81	–	–	–	0.03
n-Undecane	1.44	1.19	–	–	1.62	1.56	–	–	1.56	1.00	–	–	1.37	1.12	–	–	–	–	–	–	0.09
Dodecane	–	1.19	–	–	2.00	2.12	–	–	1.87	1.25	–	–	1.93	2.18	–	–	–	–	–	–	0.09
Others ^a	8.36	7.86	1.56	–	1.44	–	–	–	3.43	–	–	–	3.93	–	–	–	–	–	–	–	NA
TVOC ^b	272	81	88	42	165	63	78	55	183	46	50	30	125	12	36	12	112	8	24	3	NA
Total number of species	19	18	15	9	19	15	15	11	20	12	10	7	17	5	7	2	11	4	4	1	NA
Notes:The emptycells(–)indicate the data are zero or below the detection limit of the analytical method used. MDL = method detection limit, NA = not applicable. ^a Sum of species other than those listed; ^bSum of 101 VOCS.

Figure 1. Vertical profiles of TVOC concentrations at heights of 2, 13, 32, 58, and 111 m at four periods of time during a day (7:00–9:00 a.m., 12:00–2:00 p.m., 5:00–7:00 p.m., and 11:00 p.m.–1:00 a.m.).

Figure 2. Vertical profiles of temperature at heights of 2, 13, 32, 58, and 111 m at four periods of time during a day (7:00–9:00 a.m., 12:00–2:00 p.m., 5:00–7:00 p.m., and 11:00 p.m.–1:00 a.m.).

Figure 3. Diurnal profiles of TVOCs at heights of 2, 13, 32, 58, and 111 m at four periods of time during a day (7:00–9:00 a.m., 12:00–2:00 p.m., 5:00–7:00 p.m., and 11:00 p.m.–1:00 a.m.).

Figure 4. Vertical profiles of BTEX concentrations: time periods from (a) 7:00–9:00 a.m., (b) 12:00–2:00 p.m., (c). 5:00–7:00 p.m., and (d) 11:00 p.m.–1:00 a.m.

Table 2. T/B, m,p-X/B, o-X/B, and X/E concentration ratios in this study

	2 m			13 m				32 m	58 m
Ratio	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	7:00 to 9:00 a.m.	12:00 to 2:00 p.m.	5:00 to 7:00 p.m.	11:00 p.m. to 1:00 a.m.	7:00 to 9:00 a.m.	7:00 to 9:00 a.m.	Automotive Exhaust
T/B	1.71	1.51	4.81	1.99	1.43	2.85	7.53	2.24	2.81	2.7 ^a
m,p-X/B	0.76	0.91	1.51	0.73	0.83	1.33	0.83	1.10	0.87	1.8 ^b
o-X/B	0.35	0.38	0.68	0.34	–	0.54	–	0.46	0.40	0.9 ^c
X/E	3.42	4.22	3.92	3.29	2.67	4.18	0.37	0.68	3.23	2.2–3.8 ^d , 1.5–2.2 ^e
Notes: ^aBrocco et al.23; ^bStevenson et al.24; ^cGuicherit25; ^dHsieh et al.19; ^eHo et al.26

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