Characterization and source identification of airborne particulate loadings at receptor site-classes of Lagos Mega-City, Nigeria

Figures & data

Figure 1. Map showing the entire study area and the actual sampling points.

Table 1. Elemental concentration values for standard reference material (SRM-1633a)

Element	Certified Value (μg/g)	This Work (μg/g)
As	145 ± 15	140 ± 9
Cr	196 ± 6	190 ± 30
Fe	94000 ± 1000	92000 ± 8000
Na	1700 ± 100	1550 ± 92
Sb	6.8 ± 0.4	6.7 ± 0.4
Zn	220 ± 10	250 ± 48

Table 2. Summary of PM_2.5 and PM_{2.5–1 0} mass concentration

Site-class	Parameter	PM2.5 (μg/m^3)	PM2.5–10 (μg/m^3)
Residential	Mean	28.01	64.50
	Standard deviation	15.15	21.84
	Median	31.98	56.10
	Maximum	49.86	109.13
	Minimum	6.43	40.86
Heavy traffic	Mean	30.88	48.27
	Standard deviation	6.84	12.41
	Median	29.89	48.65
	Maximum	44.43	66.44
	Minimum	20.25	30.88
Marine	Mean	25.27	26.11
	Standard deviation	12.18	15.62
	Median	23.93	28.15
	Maximum	44.00	53.29
	Minimum	2.86	4.43
Industrial	Mean	25.55	28.18
	Standard deviation	15.93	11.57
	Median	20.50	28.00
	Maximum	66.57	46.83
	Minimum	12.00	12.71

Figure 2. (a) Box-whisker plot for PM_2.5 for the site-classes. (b) Box-whisker plot for PM_2.5–10 for the site-classes. (c) Box-whisker plot for PM₁₀ for the site-classes.

Figure 3. Weekdays mean mass concentration (μg/m³) of particulate matter.

Figure 4. Weekends mean mass concentration (μg/m³) of particulate matter.

Figure 5. Scatter plot for PM_2.5 versus PM₁₀ at the four site-classes.

Table 3. Summary of concentration of elements in PM_2.5 and PM_{2.5–1 0}

	PM2.5 (ng/m^3)		PM2.5–10 (ng/m^3)
Element	Mean	SE	Mean	SE
As	7.05	1.41	20.98	4.2
Br	881.01	26.43	518.30	15.55
Ce	20.55	5.96	91.39	26.50
K	5406.97	811.05	12870.23	1930.53
La	2.26	0.34	28.03	4.20
Mo	27.96	4.20	35.84	5.38
Na	5312.01	159.36	35208.57	1056.26
Sb	35.5	3.20	20.70	1.86
Sm	0.37	0.07	3.13	0.56
Zn	603.49	84.49	1146.88	160.56

Table 4. PCFA on PM_2.5 and PM_{2.5–1 0} elemental concentration (μg/g) at the residential site-class

PM2.5 (Fine)					PM2.5–10 (Coarse)
Element	Factor 1	Factor 2	Factor 3	Communality	Element	Factor 1	Factor 2	Factor 3	Communality
As	0.371	0.164	0.859	0.923	As	0.167	0.855	0.459	0.841
Br	0.955	0.125	0.255	0.955	Br	0.420	0.075	0.841	0.661
Ce	0.990	0.120	−0.023	0.886	Ce	0.292	0.930	−0.083	0.952
K	0.590	0.805	0.058	0.762	K	0.692	0.565	0.403	0.961
La	0.889	0.453	−0.033	0.826	La	0.896	0.357	0.247	0.934
Mo	−0.212	−0.254	0.886	0.799	Na	0.483	0.863	0.130	0.998
Na	0.867	0.495	0.029	0.931	Sb	0.772	0.317	0.488	0.935
Sb	0.188	0.979	−0.073	0.801	Sm	0.915	0.304	0.164	0.852
Sm	0.998	0.141	−0.017	0.915	Zn	0.857	0.257	0.425	0.974
Zn	0.123	0.990	−0.064	0.834
Variance	4.991	3.178	1.604			3.971	3.052	1.611
% Variance	49.91	31.78	16.04			44.12	33.91	17.9
Possible origin	Traffic emission	Biomass burning/Traffic-related	Coal combustion/Industrial emission			Traffic-related	Sea salt/Industrial emission	Traffic emission
Note: Key signature tracers are in bold.

Table 5. PCFA on PM_2.5 and PM_{2.5–1 0} elemental concentration (μg/g) at the traffic site-class

PM2.5 (Fine)					PM2.5–10 (Coarse)
Element	Factor 1	Factor 2	Factor 3	Communality	Element	Factor 1	Factor 2	Communality
As	0.018	0.881	0.473	0.996	As	0.942	0.319	0.841
Br	0.926	0.648	0.116	0.892	Br	0.295	0.937	0.965
Ce	0.686	0.376	0.007	0.998	Ce	0.995	0.103	0.968
K	0.694	0.676	0.235	0.996	K	0.679	0.733	0.998
La	0.627	0.722	0.278	0.995	La	0.796	0.604	0.999
Mo	−0.096	0.327	0.939	0.996	Na	0.219	0.973	0.996
Na	0.960	0.274	−0.060	0.999	Sb	0.381	0.922	0.996
Sb	0.961	−0.075	−0.264	1.000	Sm	0.875	0.483	0.999
Sm	0.682	0.685	0.243	0.996	Zn	0.826	0.562	0.999
Zn	0.845	0.521	0.111	0.997
Variance	5.236	3.244	1.396			4.701	4.240
% Variance	52.36	32.44	13.96			52.23	47.11
Possible origin	Traffic emission/ Sea salt	Coal combustion	Industrial emission			Traffic-related/ Industrial emission	Sea salt/ Traffic emission
Note: Key signature tracers are in bold.

Table 6. PCFA on PM_2.5 and PM_{2.5–1 0} elemental concentration (μg/g) at the marine site-class

PM2.5 (Fine)					PM2.5–10 (Coarse)
Element	Factor 1	Factor 2	Factor 3	Communality	Element	Factor 1	Factor 2	Factor 3	Communality
As	0.793	0.474	0.282	0.895	As	0.866	0.489	−0.044	0.996
Br	0.679	0.707	0.117	0.982	Br	0.215	0.750	0.595	0.964
Ce	0.642	0.755	−0.113	0.945	Ce	0.981	−0.015	0.148	1.000
K	0.727	0.683	−0.055	0.989	K	0.749	0.621	0.190	0.998
La	0.921	0.371	−0.107	0.962	La	0.445	0.893	0.048	0.997
Mo	−0.163	0.063	0.968	0.917	Mo	0.902	0.048	−0.035	1.000
Na	0.254	0.963	0.086	0.792	Na	0.880	0.147	0.401	0.999
Sb	0.937	0.284	−0.199	0.961	Sb	0.115	0.182	0.974	0.996
Sm	0.927	0.307	−0.213	0.972	Sm	0.728	0.672	0.069	0.998
Zn	0.836	0.402	−0.287	0.997	Zn	−0.436	0.805	0.333	0.995
Variance	5.407	3.165	1.232			4.840	3.141	1.643
% Variance	54.07	31.65	12.32			48.4	31.41	16.43
Possible origin	Traffic- related	Sea salt	Industrial emission			Sea salt/ Industrial emission	Traffic emission	Traffic- related
Note: Key signature tracers are in bold.

Table 7. PCFA on PM_2.5 and PM_{2.5–1 0} elemental concentration (μg/g) at the industrial site-class

PM2.5 (Fine)					PM2.5–10 (Coarse)
Element	Factor 1	Factor 2	Factor 3	Communality	Element	Factor 1	Factor 2	Communality
As	−	−	−	−	As	−0.316	−0.942	0.698
Br	0.314	0.073	0.946	0.376	Br	0.880	0.374	0.889
Ce	0.839	0.508	0.197	0.995	Ce	0.896	0.443	0.987
K	0.975	−0.001	0.220	0.986	K	0.789	0.597	0.989
La	0.841	0.504	0.197	0.995	La	0.834	0.549	0.998
Mo	0.957	−0.199	0.213	0.984	Mo	0.818	0.570	0.995
Na	0.319	0.944	0.085	1.000	Na	0.963	0.224	0.869
Sb	−0.035	0.999	0.006	0.995	Sb	0.902	0.429	0.983
Sm	0.806	0.561	0.190	0.996	Sm	0.823	0.563	0.996
Zn	0.900	0.383	0.209	0.996	Zn	0.847	0.529	0.999
Variance	4.938	2.908	1.154		6.813	3.037
%Variance	54.87	32.31	12.82		68.13	30.37
Possible origin	Industrial/Biomass burning	Traffic- related/Sea salt	Traffic emission		Traffic- related/Sea salt	Industrial/Biomassburning
Note: Key signature tracers are in bold.