Diurnal and seasonal variations of carbonyls and their effect on ozone concentrations in the atmosphere of Monterrey, Mexico

Figures & data

Figure 1. Geographical location of the Monterrey Metropolitan Area and SIMA monitoring stations.

Figure 2. Specific sampling location.

Table 1. CO CODs

Monitoring station	NE	C	NW	SW
SE	0.22	0.16	0.28	0.28
NE		0.30	0.39	0.47
C			0.23	0.24
NW				0.18

Figure 3. Wind currents at arrival at the monitoring stations of the (a) southeast, (b) center, and (c) northwest. Wind speed in meters per second (m/sec).

Table 2. Carbonyl concentrations^a (ppbv)

	Spring 2011	Autumn 2011	Spring 2012	Autumn 2012
Formaldehyde	25.7 ± 24.1 (28)	41.7 ± 18.9 (28)	26.1 ± 9.6 (28)	15.9 ± 9.6 (28)
Acetaldehyde	5.2 ± 6.2 (28)	15.7 ± 9.0 (28)	11.6 ± 6.5 (28)	5.7 ± 4.4 (27)
Acetone	7.1 ± 5.31 (28)	15.4 ± 10.0 (28)	7.7 ± 3.4 (28)	7.1 ± 3.2 (28)
Propionaldehyde	0.7 ± 0.9 (28)	2.3 ± 1.1(28)	1.9 ± 2.6 (28)	1.2 ± 0.5 (14)
Crotonaldehyde	0.2 ± 0.1 (22)	1.5 ± 2.1 (24)	1.4 ± 0.6 (27)	0.4 ± 0.3 (26)
2-Butanone	1.0 ± 1.0 (28)	4.0 ± 1.3 (28)	5.7 ± 2.2 (28)	2.9 ± 1.1 (27)
Benzaldehyde	0.1 ± 0.1 (27)	0.8 ± 0.4 (28)	0.8 ± 0.3 (25)	NA^b
Valeraldehyde	0.1 ± 0.1 (25)	0.6 ± 0.4 (28)	0.6 ± 0.4 (20)	1.2 ± 0.3 (19)
Toluenaldehyde	0.2 ± 0.2 (20)	04. ± 0.1 (26)	0.5 ± 0.7 (28)	NA^b
Hexaldehyde	0.1 ± 0.1 (25)	0.7 ± 0.3 (26)	1.1 ± 0.4 (28)	NA^b

Notes: ^aConcentrations ± standard deviation (n>minimum detection limit).

^bNot available because n >minimum detection limit is less than 25% of the samples.

Table 3. Meteorological conditions in Monterrey during the sampling periods

Sampling	T^a	T^b	Ozone^c	Rainfall^d	Solar radiation^e	Wind^f
Spring 2011	29.7	21/39	0.033	0.20 (0.2)	0.43	9.57, E-NE
Autumn 2011	21.9	12/30	0.032	0.00 (0.0)	0.29	6.32, E-SE
Spring 2012	30.9	21/40	0.034	0.02 (0.1)	0.47	8.45, E-NE
Autumn 2012	26.2	19/36	0.025	0.67 (5.6)	0.27	5.15, E-SE

Notes: ^aAverage temperature, °C, in the Obispado monitoring station of SIMA.

^bMinimum/máximum temperature, °C, in the Obispado monitoring station of SIMA.

^cAverage concentration, ppm, in the Obispado Monitoring Station of SIMA.

^dTotal mm (sum of total mm of the five monitoring stations used in COD analysis).

^eAverage solar radiation, kW/m².

^fAverage speed (km/hr), average wind direction in the Obispado monitoring station of SIMA.

Figure 4. Average diurnal variation of (a) formaldehyde, (b) acetaldehyde, (c) acetone, and (d) propionaldehyde. Concentration (ppbv) is read from the left of the graph, time interval (hours) from the bottom. Figure presents mean (⌖), median (line), and outliers (*).

Table 4. Correlations^a for the 6:00 a.m. to 10:00 a.m. sampling interval

Variables	1^b	2	3	4	5	6	7	8	9	10
Formaldehyde (1)	1.0
Acetaldehyde (2)	0.9	1.0
Acetone (3)	0.5	0.7	1.0
Propionaldehyde (4)	0.8	0.9	0.6	1.0
Crotonaldehyde (5)				0.5	1.0
2-Butanone (6)	0.5	0.5		0.4	0.8	1.0
Benzaldehyde (7)	0.7	0.8	0.6	0.9	0.6	0.6	1.0
Valeraldehyde (8)	0.5	0.6	0.5	0.6		0.5	0.7	1.0
Toluenaldehyde (9)				0.5			0.6		1.0
Hexaldehyde (10)	0.5	0.6		0.6	0.6	0.8	0.7	0.5	0.5	1.0
CO				–0.4					–0.4	–0.5
PM10	0.4						0.5		0.5
Temperature							–0.5
Solar radiation	0.5	0.4			0.6	0.6				0.7
Wind speed				–0.4	–0.4	–0.4	–0.7	–0.6		–0.4

Notes: ^aStatistically significant (α = 0.05)

^bNumber of the carbonyls denoted on variable column.

Table 5. Correlations^a for the 10:00 a.m. to 2:00 p.m. sampling interval

Variables	1^b	2	3	4	5	6	7	8	9	10
Formaldehyde (1)	1.0
Acetaldehyde (2)	0.9	1.0
Acetone (3)	0.7	0.8	1.0
Propionaldehyde (4)	0.8	0.9	0.8	1.0
Crotonaldehyde (5)	0.6	0.7	0.6	0.8	1.0
2-Butanone (6)	0.6	0.7	0.6	0.6	0.8	1.0
Benzaldehyde (7)	0.8	0.8	0.7	0.7	0.6	0.5	1.0
Valeraldehyde (8)		0.5	0.4	0.6		0.5	0.6	1.0
Toluenaldehyde (9)							0.5	0.7	1.0
Hexaldehyde (10)	0.5	0.6	0.5	0.6	0.6	0.7		0.6		1.0
CO										–0.6
O3	0.7	0.6	0.5	0.4	0.4
NO				0.5		0.4	0.5
NO2	0.4					0.4				0.5
PM10	0.6	0.4		0.5			0.6
PM2.5				0.5			0.4
Solar radiation								–0.4
Wind speed							–0.4	–0.6	–0.6

Notes: ^aStatistically significant (α = 0.05).

^bNumber of the carbonyls denoted on variable column.

Table 6. Correlations^a for the 2:00 p.m. to 6:00 p.m. sampling interval

Variables	1^b	2	3	4	5	6	7	8	9	10
Formaldehyde (1)	1.0
Acetaldehyde (2)	0.9	1.0
Acetone (3)	0.8	0.8	1.0
Propionaldehyde (4)	0.9	0.8	0.8	1.0
Crotonaldehyde (5)	0.5	0.6	0.5	0.7	1.0
2-Butanone (6)	0.6	0.6	0.5	0.7	0.8	1.0
Benzaldehyde (7)	0.8	0.7	0.6	0.9	0.6	0.6	1.0
Valeraldehyde (8)				0.6		0.5	0.6	1.0
Toluenaldehyde (9)	0.6	0.7	0.5	0.7		0.6			1.0
Hexaldehyde (10)	0.5	0.9		0.5	0.6	0.7		0.8	0.7	1.0
CO				–0.5			–0.5			–0.5
O3	0.4	0.4	0.5	0.5		0.6			0.5
NO					–0.4	–0.6
NO2				0.5		0.6		0.4	0.5	0.5
NOX	–0.6		–0.4
PM10				0.7			0.6		0.5
PM2.5				0.4
Solar radiation				–0.5			–0.4
Wind Speed				–0.6			–0.7	–0.5

Notes: ^aStatistically significant (α = 0.05).

^bNumber of the carbonyls denoted on variable column.

Table 7. Correlations^a for the 6:00 p.m. to 10:00 p.m. sampling interval

Variables	1^b	2	3	4	5	6	7	8	9	10
Formaldehyde (1)	1.0
Acetaldehyde (2)	0.7	1.0
Acetone (3)	0.8	0.6	1.0
Propionaldehyde (4)	0.7	0.8	0.8	1.0
Crotonaldehyde (5)		0.4			1.0
2-Butanone (6)		0.7		0.5	0.8	1.0
Benzaldehyde (7)	0.5		0.4	0.4			1.0
Valeraldehyde (8)		0.6		0.5		0.5	0.6	1.0
Toluenaldehyde (9)		0.6	0.7	0.7		0.5			1.0
Hexaldehyde (10)		0.9		0.7	0.6	0.8	0.5	0.7	0.7	1.0
CO			–0.5	–0.6	–0.4	–0.5			–0.5
NOX	–0.5
PM10	0.4		0.5	0.4
PM2.5							–0.5
Temperature			–0.5	–0.6			–0.5
Solar radiation	–0.4		–0.6	–0.6			–0.6
Wind speed	–0.4	–0.4	–0.4	–0.7			–0.7	–0.6

Notes: ^aStatistically significant (α = 0.05).

^bNumber of the carbonyls denoted on variable column.

Figure 5. Average diurnal variation of (a) solar radiation, (b) temperature, (c) ozone, (d) carbon monoxide, and (e) NOx.

Figure 6. Carbonyls–NOx–O₃ relationship: (a) 6–10 hr, (b) 10–14 hr, (c) 14–18 hr, and (d) 18–22 hr.