Table 2.

Means ± standard deviations (SD) of concentrations of trace elements in quasi-UFP, accumulation, and coarse mode PM at both low-SES community and high-SES community sites (June 2013 to November 2013)

	Coarse mode			Accumulation mode			Quasi-UFP mode
	Low SES	High SES	p value	Low SES	High SES	p value	Low SES	High SES	p value
Mass μg/m3)	11.3 ± 2.90	9.62 ± 2.93	0.014*	5.84 ± 1.98	4.41 ± 1.97	0.014*	5.76 ± 1.33	5.22 ± 1.32	0.302
Na	235 ± 134	154 ± 129	0.625	95.8 ± 75.1	135 ± 108	0.152	25.1 ± 7.26	24.5 ± 13.5	0.889
Mg	54.1 ± 24.9	27.0 ± 17.0	0.018*	27.7 ± 20.4	28.9 ± 23.0	0.816	3.72 ± 2.55	3.22 ± 2.90	0.650
Al	84.2 ± 36.6	31.5 ± 13.0	0.004*	64.9 ± 57.2	55.7 ± 54.3	0.380	32.8 ± 37.0	30.4 ± 28.3	0.854
K	37.3 ± 17.4	18.4 ± 8.65	0.080	37.0 ± 56.3	30.4 ± 36.4	0.322	37.9 ± 36.2	36.1 ± 32.9	0.896
Ca	117 ± 43.5	26.1 ± 12.9	0.009	29.0 ± 15.9	10.2 ± 9.57	<0.001*	8.39 ± 3.50	7.16 ± 1.15	0.247
V	0.53 ± 0.18	0.22 ± 0.11	0.036*	0.75 ± 0.33	0.45 ± 0.19	<0.001*	1.72 ± 0.62	0.73 ± 0.33	<0.001*
Mn	4.33 ± 1.65	1.22 ± 0.38	0.034*	3.46 ± 1.48	1.91 ± 0.80	<0.001*	3.51 ± 1.75	1.45 ± 0.65	0.001*
Fe	160 ± 67.0	63.2 ± 21.8	0.043*	102 ± 51.4	69.6 ± 46.0	0.100	50.0 ± 24.7	32.1 ± 14.6	0.036*
Co	0.11 ± 0.06	0.13 ± 0.08	0.383	0.24 ± 0.11	0.29 ± 0.17	0.381	0.17 ± 0.02	0.18 ± 0.03	0.545
Ni	0.50 ± 0.18	0.32 ± 0.15	0.035*	0.76 ± 0.31	0.75 ± 0.34	0.918	1.57 ± 0.76	1.07 ± 0.61	0.074
Cu	2.09 ± 1.09	2.52 ± 1.04	0.431	8.29 ± 2.19	7.34 ± 1.80	0.241	3.19 ± 1.22	2.84 ± 0.45	0.352
Zn	6.79 ± 4.50	6.72 ± 3.43	0.973	9.10 ± 4.06	18.2 ± 11.4	0.016*	7.93 ± 7.16	19.0 ± 14.2	0.021*
As	0.19 ± 0.11	0.23 ± 0.18	0.629	0.68 ± 0.36	0.75 ± 0.42	0.660	0.49 ± 0.22	0.46 ± 0.28	0.728
Se	1.59 ± 1.56	2.16 ± 1.87	0.539	1.07 ± 0.58	1.17 ± 0.56	0.668	0.96 ± 0.09	0.95 ± 0.15	0.856
Ba	14.2 ± 7.52	6.19 ± 3.74	0.027*	11.1 ± 6.73	5.01 ± 3.39	0.009*	1.05 ± 1.01	0.82 ± 1.02	0.579
Pb	0.59 ± 0.30	0.45 ± 0.10	0.281	0.53 ± 0.25	0.59 ± 0.40	0.676	0.85 ± 0.40	1.04 ± 0.35	0.206

Unit: ng/m³

^*Comparisons with significant differences (p < 0.05)