Identification of haze-creating sources from fine particulate matter in Dhaka aerosol using carbon fractions

Figures & data

Figure 1. Map of Dhaka, Bangladesh, showing the location of the sampling site.

Table 1. Summary of fine particulate mass, fractions of OC and EC, and elemental concentrations (ng/m³) used for PMF modeling (2010–2011)

	Fine particulate matter concentration
Parameter	Mean	STD	Median	Min	Max
Mass	85,083	70,114	52,593	11,389	327,917
Na	431	653	144	13.9	4266
Mg	86.3	55.0	84.7	2.76	325
Al	342	243	293	44.8	1384
Si	1259	1025	936	181	5080
S	3721	3204	2374	257	14,546
Cl	1412	2003	533	40.7	10,093
K	1395	1021	964	225	4815
Ca	265	179	228	53.8	1173
Ti	27.8	28.5	16.8	1.09	161
Fe	373	287	305	75.1	2431
Ni	8.74	6.54	5.00	3.37	42.0
Cu	34.7	60.1	13.9	3.89	334
Zn	1621	2345	698	26.33	13,672
Pb	340	403	194	15.42	2271
OC1	695	1571	161	17.89	7656
OC2	5705	3862	4114	1449	20,805
OC3	6602	4004	5510	1304	25,760
OC4	2738	2216	1950	626	14,061
OP	7564	9710	2973	422	44,398
EC1	12,098	9622	7857	1494	41,432
EC2	716	464	644	35.8	2272
bext (km^−1)	0.90	0.41	0.78	0.64	4.33

Figure 2. Variation of PM fraction (FPM), black carbon (BC), organic carbon (OC), and b_ext during the study period.

Table 2. Average source contributions derived from the PMF modeling

	Modeling with OC and EC			Modeling with fraction of OC and EC
Source	Mass	OC	EC	Mass	OC	EC
Road dust	3.34	0.57	0.50	6.59	1.91	1.92
Sea salt and Zn	3.21	0.00	0.00	4.42	0.26	0.05
Soil dust	14.5	4.40	2.39	4.03	0.78	0.14
Motor vehicle	36.0	9.28	3.01
Brick kiln	24.5	7.95	6.29	31.2	7.91	5.99
Gasoline				5.39	1.40	0.75
Diesel				16.8	4.73	1.54
Fugitive Pb				7.9	3.77	1.98

Figure 3. Source profiles for fine particulate matter using total OC and EC.

Figure 4. Time-series plots of source contributions for fine particulate matter using total OC and EC.

Figure 5. CPF plots for the source contributions using total OC and EC.

Figure 6. Source composition profiles for fine particulate matter using fractions of OC and EC.

Figure 7. Time-series plots of source contributions for fine particulate matter using fractions of OC and EC.

Figure 8. CPF plots for the source contributions using fractions of OC and EC.

Table 3. Means and standard deviations of visibility, and extinction coefficient in different season during study period

	Visibility,	Bext,
Season	km	km^−1
Pre-monsoon	5.14 ± 0.45	0.76 ± 0.07
Monsoon	5.46 ± 0.38	0.72 ± 0.05
Post-monsoon	4.93 ± 0.68	0.81 ± 0.11
Winter	3.34 ± 1.01	1.34 ± 0.70

Table 4. Results of the stepwise multiple linear regression analyses

Source	Coefficient estimate (m^2/g)	Standard error (m^2/g)	t Statistic	P Value
Soil dust	62.1	10.1	6.18	0.00
Brick kilns	6.6	1.0	6.42	0.00
Gasoline	27.2	5.6	4.88	0.00
Diesel	6.8	1.1	6.11	0.00
Pb	7.8	3.2	2.39	0.02

Figure 9. Time-series plot of extinction coefficient per unit particle mass (m²/g).